From 2d9a90a5817e22f0558c6e5d8099cbfbf8c8bec3 Mon Sep 17 00:00:00 2001
From: Georgios Voulgaris <georgevoulg28@gmail.com>
Date: Tue, 16 Dec 2025 17:23:36 +0100
Subject: [PATCH 1/4] Implemented API: 4.8 Make response of GET /collections
 and GET /collections/{id} STAC-Conform

STAC API Validator - Conformance Validation Complete
Successfully ran the STAC API Validator locally against the API and confirmed full conformance with both Core and Collections specifications.

1. stac_extensions field - Changed from null to empty array [] (STAC spec requires array type)
Updated: routes/collections.js

2.Collection type field - Added type: 'Collection' to all in-memory test collections
Updated: data/collections.js

3. String IDs - Converted numeric database IDs to strings (STAC requires string IDs)
Updated: routes/collections.js

4. Provider roles as arrays - Changed from comma-separated string to proper array
Updated: buildCollectionSearchQuery.js using string_to_array()

5. Remove null optional fields - Assets and summaries now omitted if null (not included as null)
Updated: routes/collections.js

6. Test updated - Fixed test expectation for provider roles SQL pattern
Updated: buildCollectionSearchQuery.aggregates.test.js
---
 .github/workflows/api-ci.yml                  | 106 +++++++-
 api/.env.example                              |  31 ---
 api/__tests__/api.test.js                     |  45 +++-
 ...ldCollectionSearchQuery.aggregates.test.js |   2 +-
 api/__tests__/collectionSearch.test.js        |   6 +-
 api/data/collections.js                       |  47 +++-
 api/db/buildCollectionSearchQuery.js          |   7 +-
 api/db/db_APIconnection.js                    |  20 +-
 api/routes/collections.js                     | 249 ++++++++++++++----
 db/init/06_seed_data.sql                      | 190 +++++++++++++
 10 files changed, 602 insertions(+), 101 deletions(-)
 delete mode 100644 api/.env.example
 create mode 100644 db/init/06_seed_data.sql

diff --git a/.github/workflows/api-ci.yml b/.github/workflows/api-ci.yml
index 5394698..03407ce 100644
--- a/.github/workflows/api-ci.yml
+++ b/.github/workflows/api-ci.yml
@@ -199,12 +199,114 @@ jobs:
           cd api
           npm audit --audit-level=moderate
         continue-on-error: true
+
+  # Job 4: STAC API Validator (Core + Collections)
+  stac-api-validator:
+    name: STAC API Validator
+    runs-on: ubuntu-latest
+    needs: [test, build]
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22.x
+          cache: 'npm'
+          cache-dependency-path: api/package-lock.json
+
+      - name: Create .env file
+        working-directory: api
+        run: |
+          cat > .env << EOF
+          # Server Configuration
+          PORT=3000
+          NODE_ENV=test
+          
+          # Database Configuration
+          DB_HOST=${{ secrets.DB_HOST }}
+          DB_PORT=${{ secrets.DB_PORT }}
+          DB_NAME=${{ secrets.DB_NAME }}
+          DB_USER=${{ secrets.DB_USER }}
+          DB_PASSWORD=${{ secrets.DB_PASSWORD }}
+          DB_SSL=false
+          
+          # Connection Pool Configuration
+          DB_POOL_MAX=20
+          DB_POOL_MIN=2
+          DB_IDLE_TIMEOUT=30000
+          DB_CONNECTION_TIMEOUT=10000
+          
+          # CORS Configuration
+          CORS_ORIGIN=*
+          
+          # API Configuration
+          API_TITLE=STAC Atlas
+          API_DESCRIPTION=A centralized platform for managing, indexing, and providing STAC Collection metadata
+          API_VERSION=1.1.0
+          EOF
+
+      - name: Install dependencies
+        run: |
+          cd api
+          npm ci
+
+      - name: Start API server
+        working-directory: api
+        run: |
+          npm start > $GITHUB_WORKSPACE/api/api-server.log 2>&1 &
+          echo $! > $GITHUB_WORKSPACE/api/api-server.pid
+
+      - name: Wait for API to be ready
+        run: |
+          for i in {1..12}; do
+            if curl -fsS http://localhost:3000/collections > /dev/null; then
+              exit 0
+            fi
+            sleep 5
+          done
+          echo "API did not become ready in time" >&2
+          exit 1
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install STAC API Validator
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install stac-api-validator
+
+      - name: Run STAC API Validator (core + collections)
+        run: |
+          python -m stac_api_validator \
+            --root-url http://localhost:3000 \
+            --conformance core \
+            --conformance collections \
+            --collection sentinel-2-l2a
+
+      - name: Kill API server
+        if: always()
+        run: |
+          if [ -f "$GITHUB_WORKSPACE/api/api-server.pid" ]; then
+            kill "$(cat $GITHUB_WORKSPACE/api/api-server.pid)" || true
+          fi
+
+      - name: Upload API server log
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: stac-api-server-log
+          path: api/api-server.log
+          retention-days: 7
   
-  # Job 4: Status-Check for Branch Protection
+  # Job 5: Status-Check for Branch Protection
   ci-success:
     name: CI Success
     runs-on: ubuntu-latest
-    needs: [test, build]
+    needs: [test, build, stac-api-validator]
     if: always()
     
     steps:
diff --git a/api/.env.example b/api/.env.example
deleted file mode 100644
index 5906869..0000000
--- a/api/.env.example
+++ /dev/null
@@ -1,31 +0,0 @@
-# Server Configuration
-PORT=3000
-NODE_ENV=development
-
-
-# Database Configuration (Debian Server)
-# Option 1: Use DATABASE_URL (PostgreSQL connection string)
-# add DB_USER and DB_PASSWORD values
-DATABASE_URL= postgresql://[**DB_USER**]:[**DB_PASSWORD**]@atlas.stacindex.org:5432/stac_db
-
-# Option 2: Use individual variables (currently active)
-DB_HOST=atlas.stacindex.org
-DB_PORT=5433 # 5432 for production
-DB_NAME=stac_db
-DB_USER= 
-DB_PASSWORD= 
-DB_SSL=false
-
-# Connection Pool Configuration
-DB_POOL_MAX=20
-DB_POOL_MIN=2
-DB_IDLE_TIMEOUT=30000
-DB_CONNECTION_TIMEOUT=10000
-
-# CORS Configuration
-CORS_ORIGIN=*
-
-# API Configuration
-API_TITLE=STAC Atlas
-API_DESCRIPTION=A centralized platform for managing, indexing, and providing STAC Collection metadata
-API_VERSION=1.1.0
diff --git a/api/__tests__/api.test.js b/api/__tests__/api.test.js
index 6c77a1f..7874c2a 100644
--- a/api/__tests__/api.test.js
+++ b/api/__tests__/api.test.js
@@ -71,10 +71,10 @@ describe('STAC API Core Endpoints', () => {
   });
 
   describe('GET /collections', () => {
-    it('should return a FeatureCollection structure', async () => {
+    it('should return a Collections structure', async () => {
       const response = await request(app).get('/collections').expect(200);
-
-      expect(response.body).toHaveProperty('type', 'FeatureCollection');
+      
+  //  expect(response.body).toHaveProperty('type', 'FeatureCollection'); (not sure if needed because some test fail)
       expect(response.body).toHaveProperty('collections');
       expect(response.body).toHaveProperty('links');
       expect(response.body).toHaveProperty('context');
@@ -88,6 +88,22 @@ describe('STAC API Core Endpoints', () => {
       expect(response.body.context).toHaveProperty('limit');
       expect(response.body.context).toHaveProperty('matched');
     });
+
+    it('should return STAC Collection objects with required fields', async () => {
+      const response = await request(app).get('/collections').expect(200);
+
+      if (response.body.collections.length > 0) {
+        const collection = response.body.collections[0];
+        expect(collection).toHaveProperty('id');
+        expect(collection).toHaveProperty('stac_version');
+        expect(collection).toHaveProperty('title');
+        expect(collection).toHaveProperty('description');
+        expect(collection).toHaveProperty('license');
+        expect(collection).toHaveProperty('extent');
+        expect(collection).toHaveProperty('links');
+        expect(Array.isArray(collection.links)).toBe(true);
+      }
+    });
   });
 
   describe('GET /queryables', () => {
@@ -128,5 +144,28 @@ describe('STAC API Core Endpoints', () => {
       expect(response.body).toHaveProperty('description');
       expect(response.body).toHaveProperty('id', 'non-existent-id');
     });
+
+    it('should return STAC Collection object with required fields', async () => {
+      const response = await request(app).get('/collections/sentinel-2-l2a').expect(200);
+
+      expect(response.body).toHaveProperty('id', 'sentinel-2-l2a');
+      expect(response.body).toHaveProperty('stac_version');
+      expect(response.body).toHaveProperty('title');
+      expect(response.body).toHaveProperty('description');
+      expect(response.body).toHaveProperty('license');
+      expect(response.body).toHaveProperty('extent');
+      expect(response.body).toHaveProperty('links');
+      expect(Array.isArray(response.body.links)).toBe(true);
+    });
+
+    it('should include self and root links', async () => {
+      const response = await request(app).get('/collections/sentinel-2-l2a').expect(200);
+
+      const links = response.body.links;
+      const linkRels = links.map(link => link.rel);
+
+      expect(linkRels).toContain('self');
+      expect(linkRels).toContain('root');
+    });
   });
 });
diff --git a/api/__tests__/buildCollectionSearchQuery.aggregates.test.js b/api/__tests__/buildCollectionSearchQuery.aggregates.test.js
index 069ea46..cb7ea9e 100644
--- a/api/__tests__/buildCollectionSearchQuery.aggregates.test.js
+++ b/api/__tests__/buildCollectionSearchQuery.aggregates.test.js
@@ -64,7 +64,7 @@ describe('buildCollectionSearchQuery - aggregated fields', () => {
 
       expect(sql).toMatch(/jsonb_agg\(jsonb_build_object\(/);
       expect(sql).toMatch(/'name', p\.provider/);
-      expect(sql).toMatch(/'roles', cpr\.collection_provider_roles/);
+      expect(sql).toMatch(/'roles', string_to_array\(cpr\.collection_provider_roles, ','\)/);
       expect(sql).toMatch(/FROM collection_providers cpr/);
       expect(sql).toMatch(/JOIN providers p ON p\.id = cpr\.provider_id/);
       expect(sql).toMatch(/WHERE cpr\.collection_id = c\.id/);
diff --git a/api/__tests__/collectionSearch.test.js b/api/__tests__/collectionSearch.test.js
index 25c16c5..d4514f8 100644
--- a/api/__tests__/collectionSearch.test.js
+++ b/api/__tests__/collectionSearch.test.js
@@ -13,8 +13,8 @@ describe('Collection Search API - Query Parameters', () => {
       const response = await request(app)
         .get('/collections')
         .expect(200);
-      
-      expect(response.body).toHaveProperty('type', 'FeatureCollection');
+
+   // expect(response.body).toHaveProperty('type', 'FeatureCollection') (not sure if needed because some test fail)
       expect(response.body).toHaveProperty('collections');
       expect(response.body).toHaveProperty('context');
       expect(response.body.context.limit).toBe(10); // default limit
@@ -366,7 +366,7 @@ describe('Collection Search API - Query Parameters', () => {
         .expect(200);
       
       expect(response.body).toMatchObject({
-        type: 'FeatureCollection',
+      //type: 'FeatureCollection', (not sure if needed because some test fail)
         collections: expect.any(Array),
         links: expect.any(Array),
         context: {
diff --git a/api/data/collections.js b/api/data/collections.js
index e58bcbf..49e037c 100644
--- a/api/data/collections.js
+++ b/api/data/collections.js
@@ -14,6 +14,8 @@ module.exports = [
     description: 'Sentinel-2 Level-2A processed imagery from Copernicus',
     keywords: ['sentinel-2', 'optical', 'multispectral'],
     license: 'CC-BY-4.0',
+    created: '2018-01-01T00:00:00Z',
+    updated: '2025-01-01T00:00:00Z',
     providers: [
       {
         name: 'ESA',
@@ -25,16 +27,26 @@ module.exports = [
       spatial: { bbox: [[-180, -90, 180, 90]] },
       temporal: { interval: [['2015-06-23T00:00:00Z', null]] }
     },
+    summaries: {
+      'eo:bands': [
+        { name: 'B2', common_name: 'blue' },
+        { name: 'B3', common_name: 'green' },
+        { name: 'B4', common_name: 'red' },
+        { name: 'B5', common_name: 'nir' }
+      ]
+    },
     links: [
       {
         rel: 'self',
         href: 'https://example.com/collections/sentinel-2-l2a',
-        type: 'application/json'
+        type: 'application/json',
+        title: 'Sentinel-2 L2A Collection'
       },
       {
         rel: 'parent',
         href: 'https://example.com/',
-        type: 'application/json'
+        type: 'application/json',
+        title: 'Parent'
       }
     ]
   },
@@ -46,6 +58,8 @@ module.exports = [
     description: 'Landsat 8 Collection 1 Level 1 data',
     keywords: ['landsat', 'optical', 'multispectral'],
     license: 'CC0-1.0',
+    created: '2013-02-11T00:00:00Z',
+    updated: '2024-06-01T00:00:00Z',
     providers: [
       {
         name: 'USGS',
@@ -57,16 +71,26 @@ module.exports = [
       spatial: { bbox: [[-180, -90, 180, 90]] },
       temporal: { interval: [['2013-02-11T00:00:00Z', null]] }
     },
+    summaries: {
+      'eo:bands': [
+        { name: 'B1', common_name: 'coastal' },
+        { name: 'B2', common_name: 'blue' },
+        { name: 'B3', common_name: 'green' },
+        { name: 'B4', common_name: 'red' }
+      ]
+    },
     links: [
       {
         rel: 'self',
         href: 'https://example.com/collections/landsat-8-l1',
-        type: 'application/json'
+        type: 'application/json',
+        title: 'Landsat 8 Level-1'
       },
       {
         rel: 'parent',
         href: 'https://example.com/',
-        type: 'application/json'
+        type: 'application/json',
+        title: 'Parent'
       }
     ]
   },
@@ -78,6 +102,8 @@ module.exports = [
     description: 'MODIS daily composites from NASA Earth Observatories',
     keywords: ['modis', 'daily', 'thermal', 'visible'],
     license: 'CC0-1.0',
+    created: '2000-02-24T00:00:00Z',
+    updated: '2023-12-31T00:00:00Z',
     providers: [
       {
         name: 'NASA',
@@ -89,16 +115,25 @@ module.exports = [
       spatial: { bbox: [[-180, -90, 180, 90]] },
       temporal: { interval: [['2000-02-24T00:00:00Z', null]] }
     },
+    summaries: {
+      'eo:bands': [
+        { name: '1', common_name: 'red' },
+        { name: '2', common_name: 'nir' },
+        { name: '31', common_name: 'thermal' }
+      ]
+    },
     links: [
       {
         rel: 'self',
         href: 'https://example.com/collections/modis',
-        type: 'application/json'
+        type: 'application/json',
+        title: 'MODIS Daily'
       },
       {
         rel: 'parent',
         href: 'https://example.com/',
-        type: 'application/json'
+        type: 'application/json',
+        title: 'Parent'
       }
     ]
   }
diff --git a/api/db/buildCollectionSearchQuery.js b/api/db/buildCollectionSearchQuery.js
index 8d43cee..b8eb94c 100644
--- a/api/db/buildCollectionSearchQuery.js
+++ b/api/db/buildCollectionSearchQuery.js
@@ -217,7 +217,7 @@ function buildCollectionSearchQuery(params) {
     LEFT JOIN LATERAL (
       SELECT jsonb_agg(jsonb_build_object(
         'name', p.provider,
-        'roles', cpr.collection_provider_roles
+        'roles', string_to_array(cpr.collection_provider_roles, ',')
       ) ORDER BY p.provider) AS providers
       FROM collection_providers cpr
       JOIN providers p ON p.id = cpr.provider_id
@@ -272,7 +272,10 @@ function buildCollectionSearchQuery(params) {
   // Note: sortby.field is validated against a whitelist in the calling code; only collection
   // table columns are allowed for sorting (not aggregated fields like keywords/providers).
   if (sortby) {
-    sql += ` ORDER BY c.${sortby.field} ${sortby.direction}`;
+    const sortField = sortby.field;
+    const dir = sortby.direction;
+    const collate = sortField === 'license' ? ' COLLATE "C"' : '';
+    sql += ` ORDER BY c.${sortField}${collate} ${dir}, c.id ASC`;
   } else if (q) {
     sql += ` ORDER BY rank DESC, c.id ASC`;
   } else {
diff --git a/api/db/db_APIconnection.js b/api/db/db_APIconnection.js
index b3a93fc..1cfd0bb 100644
--- a/api/db/db_APIconnection.js
+++ b/api/db/db_APIconnection.js
@@ -1,5 +1,7 @@
 const { Pool } = require('pg');
-require('dotenv').config();
+require('dotenv').config({ override: true });
+
+const IS_TEST = process.env.NODE_ENV === 'test' || process.env.JEST_WORKER_ID !== undefined;
 
 // PostgreSQL/PostGIS database connection
 // Support both DATABASE_URL and individual environment variables
@@ -46,7 +48,7 @@ pool.on('error', (err) => {
 });
 
 // Handle pool connection events for monitoring (only in non-test environments)
-if (process.env.NODE_ENV !== 'test') {
+if (!IS_TEST) {
   pool.on('connect', (client) => {
     console.log('New client connected to pool');
   });
@@ -107,16 +109,18 @@ async function testConnection(retries = 3, delay = 2000) {
         waitingCount: pool.waitingCount
       };
       
-      console.log('✓ Database connection successful');
-      console.log(`  Database: ${result.rows[0].database}`);
-      console.log(`  PostgreSQL version: ${result.rows[0].version.split(',')[0]}`);
-      console.log(`  Pool status: ${poolInfo.totalCount} total, ${poolInfo.idleCount} idle, ${poolInfo.waitingCount} waiting`);
+      if (!IS_TEST) {
+        console.log('✓ Database connection successful');
+        console.log(`  Database: ${result.rows[0].database}`);
+        console.log(`  PostgreSQL version: ${result.rows[0].version.split(',')[0]}`);
+        console.log(`  Pool status: ${poolInfo.totalCount} total, ${poolInfo.idleCount} idle, ${poolInfo.waitingCount} waiting`);
+      }
       return true;
     } catch (error) {
       console.error(`✗ Connection attempt ${i + 1}/${retries} failed:`, error.message);
       
       if (i < retries - 1) {
-        console.log(`  Retrying in ${delay / 1000} seconds...`);
+        if (!IS_TEST) console.log(`  Retrying in ${delay / 1000} seconds...`);
         await new Promise(resolve => setTimeout(resolve, delay));
       }
     }
@@ -247,7 +251,7 @@ async function queryByDistance(table, point, distance, geomColumn = 'spatial_ext
 async function closePool() {
   try {
     await pool.end();
-    console.log('✓ Database connection pool closed');
+    if (!IS_TEST) console.log('✓ Database connection pool closed');
   } catch (error) {
     console.error('Error closing database pool:', error.message);
     throw error;
diff --git a/api/routes/collections.js b/api/routes/collections.js
index 6f83a2f..565b342 100644
--- a/api/routes/collections.js
+++ b/api/routes/collections.js
@@ -38,39 +38,123 @@ router.get('/', validateCollectionSearchParams, async (req, res, next) => {
     // validated parameters from middleware
     const { q, bbox, datetime, limit, sortby, token } = req.validatedParams;
 
-    // build SQL querry and parameters
-    const { sql, values } = buildCollectionSearchQuery({
-      q,
-      bbox,
-      datetime,
-      limit,
-      sortby,
-      token
-    });
+    // try to use database
+    let collections;
+    try {
+      // build SQL querry and parameters
+      const { sql, values } = buildCollectionSearchQuery({
+        q,
+        bbox,
+        datetime,
+        limit,
+        sortby,
+        token
+      });
+
+      // execute Query against database
+      collections = await runQuery(sql, values);
+
+      // Shape DB rows to STAC structure if needed (add extent)
+      collections = collections.map(row => {
+        if (row && (row.extent || (!row.spatial_extend && !row.temporal_extend_start && !row.temporal_extend_end))) {
+          return row;
+        }
+
+        const extent = {};
+        if (row.spatial_extend) {
+          // We set a world bbox here; adjust if precise bbox is required later
+          extent.spatial = { bbox: [[-180, -90, 180, 90]] };
+        }
+        if (row.temporal_extend_start || row.temporal_extend_end) {
+          const start = row.temporal_extend_start ? new Date(row.temporal_extend_start).toISOString() : null;
+          const end = row.temporal_extend_end ? new Date(row.temporal_extend_end).toISOString() : null;
+          extent.temporal = { interval: [[start, end]] };
+        }
+        return Object.assign({}, row, { extent });
+      });
+    } catch (dbError) {
+      // Fallback to in-memory data store if database is not available
+      console.warn('Database query failed, using in-memory data store:', dbError.message);
+      collections = collectionsStore;
+      
+      // Apply basic filtering to in-memory data
+      if (q) {
+        const qLower = q.toLowerCase();
+        collections = collections.filter(c => 
+          (c.title && c.title.toLowerCase().includes(qLower)) ||
+          (c.description && c.description.toLowerCase().includes(qLower)) ||
+          (c.keywords && c.keywords.some(k => k.toLowerCase().includes(qLower)))
+        );
+      }
+      
+      if (sortby) {
+        // sortby is normalized by validator to { field: <db_field>, direction: 'ASC'|'DESC' }
+        const dbField = sortby.field;
+        const direction = sortby.direction;
+
+        // Map DB field names to in-memory keys
+        const inMemoryFieldMap = {
+          id: 'id',
+          title: 'title',
+          license: 'license',
+          created_at: 'created',
+          updated_at: 'updated'
+        };
+
+        const fieldKey = inMemoryFieldMap[dbField] || dbField;
+
+        collections = [...collections].sort((a, b) => {
+          const aVal = a[fieldKey] ?? '';
+          const bVal = b[fieldKey] ?? '';
 
-    // execute Query against database
-    const collections = await runQuery(sql, values);
+          // Date-aware compare for created/updated
+          const isDateField = fieldKey === 'created' || fieldKey === 'updated';
+          let comparison;
+          if (isDateField) {
+            const aTime = aVal ? new Date(aVal).getTime() : 0;
+            const bTime = bVal ? new Date(bVal).getTime() : 0;
+            comparison = aTime === bTime ? 0 : (aTime < bTime ? -1 : 1);
+          } else {
+            comparison = String(aVal).localeCompare(String(bVal));
+          }
+
+          return direction === 'DESC' ? -comparison : comparison;
+        });
+      }
+      
+      // Apply pagination
+      const start = token || 0;
+      collections = collections.slice(start, start + limit);
+    }
+    
     const returned = collections.length;
 
     // Get total count for matched field
-    // Build count query using same WHERE conditions
-    const { sql: countSql, values: countValues } = buildCollectionSearchQuery({
-      q,
-      bbox,
-      datetime,
-      limit: null, // No limit for count
-      sortby: null, // No sorting for count
-      token: null   // No offset for count
-    });
-    
-    // Replace SELECT with COUNT(*)
-    const countQuery = countSql
-      .replace(/SELECT[\s\S]*?FROM/, 'SELECT COUNT(*) as total FROM')
-      .replace(/ORDER BY.*$/, '')
-      .replace(/LIMIT.*$/, '');
-    
-    const countResult = await runQuery(countQuery, countValues);
-    const matched = parseInt(countResult[0]?.total || 0);
+    let matched;
+    try {
+      // Build count query using same WHERE conditions
+      const { sql: countSql, values: countValues } = buildCollectionSearchQuery({
+        q,
+        bbox,
+        datetime,
+        limit: null, // No limit for count
+        sortby: null, // No sorting for count
+        token: null   // No offset for count
+      });
+      
+      // Replace SELECT with COUNT(*)
+      const countQuery = countSql
+        .replace(/SELECT[\s\S]*?FROM/, 'SELECT COUNT(*) as total FROM')
+        .replace(/ORDER BY.*$/, '')
+        .replace(/LIMIT.*$/, '');
+      
+      const countResult = await runQuery(countQuery, countValues);
+      matched = parseInt(countResult[0]?.total || 0);
+    } catch (countError) {
+      // Fallback to in-memory count
+      console.warn('Count query failed, using in-memory count:', countError.message);
+      matched = collectionsStore.length;
+    }
 
     // Base URL for links
     const baseHost = `${req.protocol}://${req.get('host')}`;
@@ -82,8 +166,15 @@ router.get('/', validateCollectionSearchParams, async (req, res, next) => {
       type: 'application/json'
     });
 
+    // self link should mirror the requested URL (no synthesized query params)
+    const selfLink = {
+      rel: 'self',
+      href: `${baseHost}${req.originalUrl || req.baseUrl}`,
+      type: 'application/json'
+    };
+
     const links = [
-      buildLink('self', token),
+      selfLink,
       {
         rel: 'root',
         href: baseHost,
@@ -102,9 +193,55 @@ router.get('/', validateCollectionSearchParams, async (req, res, next) => {
       links.push(buildLink('prev', prevToken));
     }
 
+    // Add required links to each collection if not present
+    const enrichedCollections = collections.map(collection => {
+      const colSelfHref = `${baseHost}/collections/${collection.id}`;
+      const rootHref = baseHost;
+
+      const existingLinks = Array.isArray(collection.links) ? collection.links.slice() : [];
+      const filteredLinks = existingLinks.filter(l => !l || !['self', 'root', 'parent'].includes(l.rel));
+
+      filteredLinks.push({
+        rel: 'self',
+        href: colSelfHref,
+        type: 'application/json',
+        title: collection.title || collection.id
+      });
+
+      filteredLinks.push({
+        rel: 'root',
+        href: rootHref,
+        type: 'application/json',
+        title: 'STAC Atlas'
+      });
+
+      filteredLinks.push({
+        rel: 'parent',
+        href: rootHref,
+        type: 'application/json',
+        title: 'Parent'
+      });
+
+      // Ensure stac_extensions is an array (STAC spec requires array, not null)
+      const stac_extensions = Array.isArray(collection.stac_extensions) 
+        ? collection.stac_extensions 
+        : [];
+
+      // Ensure id is a string (STAC spec requires string IDs)
+      const id = typeof collection.id === 'string' ? collection.id : String(collection.id);
+
+      // Remove null optional fields or convert to correct type for STAC compliance
+      const cleaned = Object.assign({}, collection, { id, links: filteredLinks, stac_extensions });
+      
+      // Remove null assets, summaries (optional in STAC, should be omitted if not present)
+      if (cleaned.assets === null) delete cleaned.assets;
+      if (cleaned.summaries === null) delete cleaned.summaries;
+
+      return cleaned;
+    });
+    
     res.json({
-      type: 'FeatureCollection',
-      collections,
+      collections: enrichedCollections,
       links,
       context: {
         returned,
@@ -151,24 +288,46 @@ router.get('/:id', (req, res) => {
   const rootHref = baseHost;
 
   const existingLinks = Array.isArray(collection.links) ? collection.links.slice() : [];
+  const filteredLinks = existingLinks.filter(l => !l || !['self', 'root', 'parent'].includes(l.rel));
 
-  const hasRel = (rel) => existingLinks.some(l => l && l.rel === rel);
+  filteredLinks.push({
+    rel: 'self',
+    href: selfHref,
+    type: 'application/json',
+    title: collection.title || collection.id
+  });
 
-  if (!hasRel('self')) {
-    existingLinks.push({ rel: 'self', href: selfHref, type: 'application/json' });
-  }
+  filteredLinks.push({
+    rel: 'root',
+    href: rootHref,
+    type: 'application/json',
+    title: 'STAC Atlas'
+  });
 
-  if (!hasRel('root')) {
-    existingLinks.push({ rel: 'root', href: rootHref, type: 'application/json' });
-  }
+  filteredLinks.push({
+    rel: 'parent',
+    href: rootHref,
+    type: 'application/json',
+    title: 'Parent'
+  });
 
-  // Prefer an existing parent link if present, otherwise fall back to root
-  if (!hasRel('parent')) {
-    existingLinks.push({ rel: 'parent', href: rootHref, type: 'application/json' });
-  }
+  // Ensure stac_extensions is an array (STAC spec requires array, not null)
+  const stac_extensions = Array.isArray(collection.stac_extensions) 
+    ? collection.stac_extensions 
+    : [];
+
+  // Ensure id is a string (STAC spec requires string IDs)
+  const collectionId = typeof collection.id === 'string' ? collection.id : String(collection.id);
+
+  // Build response and remove null optional fields for STAC compliance
+  const result = Object.assign({}, collection, { id: collectionId, links: filteredLinks, stac_extensions });
+  
+  // Remove null assets, summaries (optional in STAC, should be omitted if not present)
+  if (result.assets === null) delete result.assets;
+  if (result.summaries === null) delete result.summaries;
 
-  // Return the collection with a normalized `links` array
-  res.json(Object.assign({}, collection, { links: existingLinks }));
+  // Return the collection with a normalized `links` array and stac_extensions
+  res.json(result);
 });
 
 module.exports = router;
diff --git a/db/init/06_seed_data.sql b/db/init/06_seed_data.sql
new file mode 100644
index 0000000..209deaa
--- /dev/null
+++ b/db/init/06_seed_data.sql
@@ -0,0 +1,190 @@
+-- I did not wrote this code myself. It was generated by ChatGPT based on my instructions. It needs to be reviewed and tested.
+
+
+-- Seed data for collections, keywords, and providers (idempotent)
+-- This script can be executed repeatedly without creating duplicates.
+
+-- Root catalog (optional)
+INSERT INTO catalog (stac_version, type, title, description)
+SELECT '1.0.0', 'Catalog', 'STAC Atlas Root', 'Root STAC catalog for tests'
+WHERE NOT EXISTS (
+  SELECT 1 FROM catalog WHERE title = 'STAC Atlas Root'
+);
+
+-- Keywords
+INSERT INTO keywords (keyword) VALUES
+  ('sentinel-2'),
+  ('optical'),
+  ('multispectral'),
+  ('landsat'),
+  ('modis'),
+  ('daily'),
+  ('thermal'),
+  ('visible')
+ON CONFLICT (keyword) DO NOTHING;
+
+-- Providers
+INSERT INTO providers (provider) VALUES
+  ('ESA'),
+  ('USGS'),
+  ('NASA')
+ON CONFLICT (provider) DO NOTHING;
+
+-- Sentinel-2 L2A
+DO $$
+DECLARE
+  v_collection_id INTEGER;
+  v_provider_id INTEGER;
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM collection WHERE title = 'Sentinel-2 L2A Collection'
+  ) THEN
+    INSERT INTO collection (
+      stac_version, type, title, description, license,
+      spatial_extend, temporal_extend_start, temporal_extend_end,
+      is_api, is_active, full_json, created_at, updated_at
+    ) VALUES (
+      '1.0.0', 'Collection', 'Sentinel-2 L2A Collection',
+      'Sentinel-2 Level-2A processed imagery from Copernicus', 'CC-BY-4.0',
+      ST_MakeEnvelope(-180, -90, 180, 90, 4326),
+      '2015-06-23T00:00:00Z'::timestamp, '2025-01-01T00:00:00Z'::timestamp,
+      TRUE, TRUE,
+      jsonb_build_object(
+        'id','sentinel-2-l2a',
+        'stac_version','1.0.0',
+        'title','Sentinel-2 L2A Collection'
+      ),
+      '2018-01-01T00:00:00Z'::timestamp,
+      '2025-01-01T00:00:00Z'::timestamp
+    );
+  END IF;
+
+  SELECT id INTO v_collection_id FROM collection WHERE title = 'Sentinel-2 L2A Collection' ORDER BY id DESC LIMIT 1;
+
+  -- Ensure temporal end is set if previously null
+  UPDATE collection
+  SET temporal_extend_end = updated_at
+  WHERE id = v_collection_id AND temporal_extend_end IS NULL;
+
+  INSERT INTO collection_keywords (collection_id, keyword_id)
+  SELECT v_collection_id, k.id FROM keywords k
+  WHERE k.keyword IN ('sentinel-2','optical','multispectral')
+    AND NOT EXISTS (
+      SELECT 1 FROM collection_keywords ck WHERE ck.collection_id = v_collection_id AND ck.keyword_id = k.id
+    );
+
+  SELECT id INTO v_provider_id FROM providers WHERE provider = 'ESA';
+  IF v_provider_id IS NOT NULL THEN
+    INSERT INTO collection_providers (collection_id, provider_id, collection_provider_roles)
+    SELECT v_collection_id, v_provider_id, 'producer,licensor'
+    WHERE NOT EXISTS (
+      SELECT 1 FROM collection_providers cp WHERE cp.collection_id = v_collection_id AND cp.provider_id = v_provider_id
+    );
+  END IF;
+END $$;
+
+-- Landsat 8 Level-1
+DO $$
+DECLARE
+  v_collection_id INTEGER;
+  v_provider_id INTEGER;
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM collection WHERE title = 'Landsat 8 Level-1'
+  ) THEN
+    INSERT INTO collection (
+      stac_version, type, title, description, license,
+      spatial_extend, temporal_extend_start, temporal_extend_end,
+      is_api, is_active, full_json, created_at, updated_at
+    ) VALUES (
+      '1.0.0', 'Collection', 'Landsat 8 Level-1',
+      'Landsat 8 Collection 1 Level 1 data', 'CC0-1.0',
+      ST_MakeEnvelope(-180, -90, 180, 90, 4326),
+      '2013-02-11T00:00:00Z'::timestamp, '2024-06-01T00:00:00Z'::timestamp,
+      TRUE, TRUE,
+      jsonb_build_object(
+        'id','landsat-8-l1',
+        'stac_version','1.0.0',
+        'title','Landsat 8 Level-1'
+      ),
+      '2013-02-11T00:00:00Z'::timestamp,
+      '2024-06-01T00:00:00Z'::timestamp
+    );
+  END IF;
+
+  SELECT id INTO v_collection_id FROM collection WHERE title = 'Landsat 8 Level-1' ORDER BY id DESC LIMIT 1;
+
+  -- Ensure temporal end is set if previously null
+  UPDATE collection
+  SET temporal_extend_end = updated_at
+  WHERE id = v_collection_id AND temporal_extend_end IS NULL;
+
+  INSERT INTO collection_keywords (collection_id, keyword_id)
+  SELECT v_collection_id, k.id FROM keywords k
+  WHERE k.keyword IN ('landsat','optical','multispectral')
+    AND NOT EXISTS (
+      SELECT 1 FROM collection_keywords ck WHERE ck.collection_id = v_collection_id AND ck.keyword_id = k.id
+    );
+
+  SELECT id INTO v_provider_id FROM providers WHERE provider = 'USGS';
+  IF v_provider_id IS NOT NULL THEN
+    INSERT INTO collection_providers (collection_id, provider_id, collection_provider_roles)
+    SELECT v_collection_id, v_provider_id, 'producer'
+    WHERE NOT EXISTS (
+      SELECT 1 FROM collection_providers cp WHERE cp.collection_id = v_collection_id AND cp.provider_id = v_provider_id
+    );
+  END IF;
+END $$;
+
+-- MODIS Daily
+DO $$
+DECLARE
+  v_collection_id INTEGER;
+  v_provider_id INTEGER;
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM collection WHERE title = 'MODIS Daily'
+  ) THEN
+    INSERT INTO collection (
+      stac_version, type, title, description, license,
+      spatial_extend, temporal_extend_start, temporal_extend_end,
+      is_api, is_active, full_json, created_at, updated_at
+    ) VALUES (
+      '1.0.0', 'Collection', 'MODIS Daily',
+      'MODIS daily composites from NASA Earth Observatories', 'CC0-1.0',
+      ST_MakeEnvelope(-180, -90, 180, 90, 4326),
+      '2000-02-24T00:00:00Z'::timestamp, '2023-12-31T00:00:00Z'::timestamp,
+      TRUE, TRUE,
+      jsonb_build_object(
+        'id','modis',
+        'stac_version','1.0.0',
+        'title','MODIS Daily'
+      ),
+      '2000-02-24T00:00:00Z'::timestamp,
+      '2023-12-31T00:00:00Z'::timestamp
+    );
+  END IF;
+
+  SELECT id INTO v_collection_id FROM collection WHERE title = 'MODIS Daily' ORDER BY id DESC LIMIT 1;
+
+  -- Ensure temporal end is set if previously null
+  UPDATE collection
+  SET temporal_extend_end = updated_at
+  WHERE id = v_collection_id AND temporal_extend_end IS NULL;
+
+  INSERT INTO collection_keywords (collection_id, keyword_id)
+  SELECT v_collection_id, k.id FROM keywords k
+  WHERE k.keyword IN ('modis','daily','thermal','visible')
+    AND NOT EXISTS (
+      SELECT 1 FROM collection_keywords ck WHERE ck.collection_id = v_collection_id AND ck.keyword_id = k.id
+    );
+
+  SELECT id INTO v_provider_id FROM providers WHERE provider = 'NASA';
+  IF v_provider_id IS NOT NULL THEN
+    INSERT INTO collection_providers (collection_id, provider_id, collection_provider_roles)
+    SELECT v_collection_id, v_provider_id, 'producer,licensor'
+    WHERE NOT EXISTS (
+      SELECT 1 FROM collection_providers cp WHERE cp.collection_id = v_collection_id AND cp.provider_id = v_provider_id
+    );
+  END IF;
+END $$;

From ac1ffe2125c442d41800489ca60b60123da65ea3 Mon Sep 17 00:00:00 2001
From: Georgios Voulgaris <georgevoulg28@gmail.com>
Date: Tue, 16 Dec 2025 18:05:14 +0100
Subject: [PATCH 2/4] Added some comments

---
 .../buildCollectionSearchQuery.aggregates.test.js        | 1 +
 api/data/collections.js                                  | 9 ++++++---
 api/db/buildCollectionSearchQuery.js                     | 5 ++++-
 api/db/db_APIconnection.js                               | 2 ++
 api/routes/collections.js                                | 7 +++++++
 5 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/api/__tests__/buildCollectionSearchQuery.aggregates.test.js b/api/__tests__/buildCollectionSearchQuery.aggregates.test.js
index cb7ea9e..3238572 100644
--- a/api/__tests__/buildCollectionSearchQuery.aggregates.test.js
+++ b/api/__tests__/buildCollectionSearchQuery.aggregates.test.js
@@ -59,6 +59,7 @@ describe('buildCollectionSearchQuery - aggregated fields', () => {
       expect(sql).toMatch(/WHERE cse\.collection_id = c\.id/);
     });
 
+    // Provider roles are converted to arrays in SQL via string_to_array
     test('includes LATERAL JOIN for providers with roles', () => {
       const { sql } = buildCollectionSearchQuery({ limit: 10, token: 0 });
 
diff --git a/api/data/collections.js b/api/data/collections.js
index 49e037c..738084c 100644
--- a/api/data/collections.js
+++ b/api/data/collections.js
@@ -5,6 +5,9 @@
 // containing common STAC fields (id, title, description, keywords, extent, etc).
 // In a production deployment this should be replaced by a database query
 // that returns fully validated STAC Collection objects.
+// Minimal in-memory STAC Collection samples used for fallback/tests.
+// Production uses DB-backed collections; these ensure endpoints remain functional
+// and STAC-compliant when the DB is unavailable.
 module.exports = [
   {
     id: 'sentinel-2-l2a',
@@ -12,7 +15,7 @@ module.exports = [
     type: 'Collection',
     title: 'Sentinel-2 L2A Collection',
     description: 'Sentinel-2 Level-2A processed imagery from Copernicus',
-    keywords: ['sentinel-2', 'optical', 'multispectral'],
+    keywords: ['sentinel-2', 'optical', 'multispectral'], // basic tags for fallback search
     license: 'CC-BY-4.0',
     created: '2018-01-01T00:00:00Z',
     updated: '2025-01-01T00:00:00Z',
@@ -24,8 +27,8 @@ module.exports = [
       }
     ],
     extent: {
-      spatial: { bbox: [[-180, -90, 180, 90]] },
-      temporal: { interval: [['2015-06-23T00:00:00Z', null]] }
+      spatial: { bbox: [[-180, -90, 180, 90]] }, // world bbox placeholder
+      temporal: { interval: [['2015-06-23T00:00:00Z', null]] } // open-ended until latest
     },
     summaries: {
       'eo:bands': [
diff --git a/api/db/buildCollectionSearchQuery.js b/api/db/buildCollectionSearchQuery.js
index b8eb94c..75849d5 100644
--- a/api/db/buildCollectionSearchQuery.js
+++ b/api/db/buildCollectionSearchQuery.js
@@ -114,7 +114,7 @@ function buildCollectionSearchQuery(params) {
   const values = [];
   let i = 1;
 
-  // Full-text search using weighted tsvector across title (weight A) and description (weight B).
+  // Full-text search using tsvector across title and description.
   //
   // Notes:
   // - Currently only title and description are included in the weighted tsvector.
@@ -199,6 +199,8 @@ function buildCollectionSearchQuery(params) {
   //
   // LATERAL JOINs aggregate related data (keywords, extensions, providers, assets, summaries,
   // and crawl timestamps) from normalized tables without duplicating collection rows.
+  // NOTE: Provider roles are stored as a comma-separated string and converted to array
+  // via string_to_array for STAC compliance.
   // Each LEFT JOIN LATERAL subquery returns a single aggregated row per collection.
   let sql = selectPart + `
     FROM collection c
@@ -274,6 +276,7 @@ function buildCollectionSearchQuery(params) {
   if (sortby) {
     const sortField = sortby.field;
     const dir = sortby.direction;
+    // Apply ASCII collation only for license to match deterministic tests
     const collate = sortField === 'license' ? ' COLLATE "C"' : '';
     sql += ` ORDER BY c.${sortField}${collate} ${dir}, c.id ASC`;
   } else if (q) {
diff --git a/api/db/db_APIconnection.js b/api/db/db_APIconnection.js
index 1cfd0bb..309fe71 100644
--- a/api/db/db_APIconnection.js
+++ b/api/db/db_APIconnection.js
@@ -1,6 +1,7 @@
 const { Pool } = require('pg');
 require('dotenv').config({ override: true });
 
+// Detect Jest/test environment to suppress noisy pool logs during tests
 const IS_TEST = process.env.NODE_ENV === 'test' || process.env.JEST_WORKER_ID !== undefined;
 
 // PostgreSQL/PostGIS database connection
@@ -48,6 +49,7 @@ pool.on('error', (err) => {
 });
 
 // Handle pool connection events for monitoring (only in non-test environments)
+// These logs can cause Jest "Cannot log after tests" warnings, so we guard them.
 if (!IS_TEST) {
   pool.on('connect', (client) => {
     console.log('New client connected to pool');
diff --git a/api/routes/collections.js b/api/routes/collections.js
index 565b342..ebce8af 100644
--- a/api/routes/collections.js
+++ b/api/routes/collections.js
@@ -32,6 +32,9 @@ async function runQuery(sql, params = []) {
  * Validated/normalized values are available in req.validatedParams.
  */
 router.get('/', validateCollectionSearchParams, async (req, res, next) => {
+  // STAC Collections endpoint (DB-first with safe in-memory fallback).
+  // Normalizes STAC-required fields (extent, links), coerces IDs to strings,
+  // and removes null optional fields for spec compliance.
   // TODO: Think about the parameters `provider` and `license` - They are mentioned in the bid, but not in the STAC spec
   // TODO: Implement CQL2 filtering (GET endpoint) and add validator for `filter`, filter-lang` parameters
   try {
@@ -55,6 +58,7 @@ router.get('/', validateCollectionSearchParams, async (req, res, next) => {
       collections = await runQuery(sql, values);
 
       // Shape DB rows to STAC structure if needed (add extent)
+      // DB stores spatial/temporal separately; STAC expects `extent` combining them.
       collections = collections.map(row => {
         if (row && (row.extent || (!row.spatial_extend && !row.temporal_extend_start && !row.temporal_extend_end))) {
           return row;
@@ -74,6 +78,7 @@ router.get('/', validateCollectionSearchParams, async (req, res, next) => {
       });
     } catch (dbError) {
       // Fallback to in-memory data store if database is not available
+      // Keep behavior consistent: basic q filter, sort, and pagination.
       console.warn('Database query failed, using in-memory data store:', dbError.message);
       collections = collectionsStore;
       
@@ -264,6 +269,8 @@ router.get('/', validateCollectionSearchParams, async (req, res, next) => {
  * - 404 NotFound with proper error format if collection does not exist
  */
 router.get('/:id', (req, res) => {
+  // STAC single-collection endpoint backed by in-memory store.
+  // Normalizes links, ensures `stac_extensions`, and converts id to string.
   // TODO: Create a proper validator middleware for :id parameter to avoid SQL injection, etc.
   const { id } = req.params;
   

From 255fe0b5d6d4b5783c9b3fc88eafa87b3664a507 Mon Sep 17 00:00:00 2001
From: Georgios Voulgaris <georgevoulg28@gmail.com>
Date: Wed, 17 Dec 2025 12:21:46 +0100
Subject: [PATCH 3/4] Changed some files as said in the comments on Github -
 Deleted data folder - api.test.js tests first collection from the db -
 db_APIconnection changed some IS TEST

---
 .github/workflows/api-ci.yml           |   3 +-
 api/.env.example                       |  31 ++++++
 api/__tests__/api.test.js              |  25 ++++-
 api/__tests__/collectionSearch.test.js |   2 -
 api/data/collections.js                | 143 -------------------------
 api/db/db_APIconnection.js             |  14 ++-
 api/routes/collections.js              |   1 -
 7 files changed, 59 insertions(+), 160 deletions(-)
 create mode 100644 api/.env.example
 delete mode 100644 api/data/collections.js

diff --git a/.github/workflows/api-ci.yml b/.github/workflows/api-ci.yml
index 03407ce..f8d9a24 100644
--- a/.github/workflows/api-ci.yml
+++ b/.github/workflows/api-ci.yml
@@ -284,8 +284,7 @@ jobs:
           python -m stac_api_validator \
             --root-url http://localhost:3000 \
             --conformance core \
-            --conformance collections \
-            --collection sentinel-2-l2a
+            --conformance collections
 
       - name: Kill API server
         if: always()
diff --git a/api/.env.example b/api/.env.example
new file mode 100644
index 0000000..5906869
--- /dev/null
+++ b/api/.env.example
@@ -0,0 +1,31 @@
+# Server Configuration
+PORT=3000
+NODE_ENV=development
+
+
+# Database Configuration (Debian Server)
+# Option 1: Use DATABASE_URL (PostgreSQL connection string)
+# add DB_USER and DB_PASSWORD values
+DATABASE_URL= postgresql://[**DB_USER**]:[**DB_PASSWORD**]@atlas.stacindex.org:5432/stac_db
+
+# Option 2: Use individual variables (currently active)
+DB_HOST=atlas.stacindex.org
+DB_PORT=5433 # 5432 for production
+DB_NAME=stac_db
+DB_USER= 
+DB_PASSWORD= 
+DB_SSL=false
+
+# Connection Pool Configuration
+DB_POOL_MAX=20
+DB_POOL_MIN=2
+DB_IDLE_TIMEOUT=30000
+DB_CONNECTION_TIMEOUT=10000
+
+# CORS Configuration
+CORS_ORIGIN=*
+
+# API Configuration
+API_TITLE=STAC Atlas
+API_DESCRIPTION=A centralized platform for managing, indexing, and providing STAC Collection metadata
+API_VERSION=1.1.0
diff --git a/api/__tests__/api.test.js b/api/__tests__/api.test.js
index 7874c2a..f8e663a 100644
--- a/api/__tests__/api.test.js
+++ b/api/__tests__/api.test.js
@@ -74,7 +74,6 @@ describe('STAC API Core Endpoints', () => {
     it('should return a Collections structure', async () => {
       const response = await request(app).get('/collections').expect(200);
       
-  //  expect(response.body).toHaveProperty('type', 'FeatureCollection'); (not sure if needed because some test fail)
       expect(response.body).toHaveProperty('collections');
       expect(response.body).toHaveProperty('links');
       expect(response.body).toHaveProperty('context');
@@ -146,9 +145,18 @@ describe('STAC API Core Endpoints', () => {
     });
 
     it('should return STAC Collection object with required fields', async () => {
-      const response = await request(app).get('/collections/sentinel-2-l2a').expect(200);
+      // Dynamically get first available collection from DB
+      const collectionsResponse = await request(app).get('/collections').expect(200);
+      
+      if (collectionsResponse.body.collections.length === 0) {
+        console.warn('No collections available in DB, skipping test');
+        return;
+      }
+
+      const firstCollectionId = collectionsResponse.body.collections[0].id;
+      const response = await request(app).get(`/collections/${firstCollectionId}`).expect(200);
 
-      expect(response.body).toHaveProperty('id', 'sentinel-2-l2a');
+      expect(response.body).toHaveProperty('id', firstCollectionId);
       expect(response.body).toHaveProperty('stac_version');
       expect(response.body).toHaveProperty('title');
       expect(response.body).toHaveProperty('description');
@@ -159,7 +167,16 @@ describe('STAC API Core Endpoints', () => {
     });
 
     it('should include self and root links', async () => {
-      const response = await request(app).get('/collections/sentinel-2-l2a').expect(200);
+      // Dynamically get first available collection from DB
+      const collectionsResponse = await request(app).get('/collections').expect(200);
+      
+      if (collectionsResponse.body.collections.length === 0) {
+        console.warn('No collections available in DB, skipping test');
+        return;
+      }
+
+      const firstCollectionId = collectionsResponse.body.collections[0].id;
+      const response = await request(app).get(`/collections/${firstCollectionId}`).expect(200);
 
       const links = response.body.links;
       const linkRels = links.map(link => link.rel);
diff --git a/api/__tests__/collectionSearch.test.js b/api/__tests__/collectionSearch.test.js
index d4514f8..b0f66db 100644
--- a/api/__tests__/collectionSearch.test.js
+++ b/api/__tests__/collectionSearch.test.js
@@ -14,7 +14,6 @@ describe('Collection Search API - Query Parameters', () => {
         .get('/collections')
         .expect(200);
 
-   // expect(response.body).toHaveProperty('type', 'FeatureCollection') (not sure if needed because some test fail)
       expect(response.body).toHaveProperty('collections');
       expect(response.body).toHaveProperty('context');
       expect(response.body.context.limit).toBe(10); // default limit
@@ -366,7 +365,6 @@ describe('Collection Search API - Query Parameters', () => {
         .expect(200);
       
       expect(response.body).toMatchObject({
-      //type: 'FeatureCollection', (not sure if needed because some test fail)
         collections: expect.any(Array),
         links: expect.any(Array),
         context: {
diff --git a/api/data/collections.js b/api/data/collections.js
deleted file mode 100644
index 738084c..0000000
--- a/api/data/collections.js
+++ /dev/null
@@ -1,143 +0,0 @@
-// Small in-memory sample of collections for basic GET /collections implementation
-//
-// This file is intentionally simple and used only for local testing and
-// unit-tests. Each entry represents a minimal STAC Collection-like object
-// containing common STAC fields (id, title, description, keywords, extent, etc).
-// In a production deployment this should be replaced by a database query
-// that returns fully validated STAC Collection objects.
-// Minimal in-memory STAC Collection samples used for fallback/tests.
-// Production uses DB-backed collections; these ensure endpoints remain functional
-// and STAC-compliant when the DB is unavailable.
-module.exports = [
-  {
-    id: 'sentinel-2-l2a',
-    stac_version: '1.0.0',
-    type: 'Collection',
-    title: 'Sentinel-2 L2A Collection',
-    description: 'Sentinel-2 Level-2A processed imagery from Copernicus',
-    keywords: ['sentinel-2', 'optical', 'multispectral'], // basic tags for fallback search
-    license: 'CC-BY-4.0',
-    created: '2018-01-01T00:00:00Z',
-    updated: '2025-01-01T00:00:00Z',
-    providers: [
-      {
-        name: 'ESA',
-        roles: ['producer', 'licensor'],
-        url: 'https://www.esa.int/'
-      }
-    ],
-    extent: {
-      spatial: { bbox: [[-180, -90, 180, 90]] }, // world bbox placeholder
-      temporal: { interval: [['2015-06-23T00:00:00Z', null]] } // open-ended until latest
-    },
-    summaries: {
-      'eo:bands': [
-        { name: 'B2', common_name: 'blue' },
-        { name: 'B3', common_name: 'green' },
-        { name: 'B4', common_name: 'red' },
-        { name: 'B5', common_name: 'nir' }
-      ]
-    },
-    links: [
-      {
-        rel: 'self',
-        href: 'https://example.com/collections/sentinel-2-l2a',
-        type: 'application/json',
-        title: 'Sentinel-2 L2A Collection'
-      },
-      {
-        rel: 'parent',
-        href: 'https://example.com/',
-        type: 'application/json',
-        title: 'Parent'
-      }
-    ]
-  },
-  {
-    id: 'landsat-8-l1',
-    stac_version: '1.0.0',
-    type: 'Collection',
-    title: 'Landsat 8 Level-1',
-    description: 'Landsat 8 Collection 1 Level 1 data',
-    keywords: ['landsat', 'optical', 'multispectral'],
-    license: 'CC0-1.0',
-    created: '2013-02-11T00:00:00Z',
-    updated: '2024-06-01T00:00:00Z',
-    providers: [
-      {
-        name: 'USGS',
-        roles: ['producer'],
-        url: 'https://www.usgs.gov/'
-      }
-    ],
-    extent: {
-      spatial: { bbox: [[-180, -90, 180, 90]] },
-      temporal: { interval: [['2013-02-11T00:00:00Z', null]] }
-    },
-    summaries: {
-      'eo:bands': [
-        { name: 'B1', common_name: 'coastal' },
-        { name: 'B2', common_name: 'blue' },
-        { name: 'B3', common_name: 'green' },
-        { name: 'B4', common_name: 'red' }
-      ]
-    },
-    links: [
-      {
-        rel: 'self',
-        href: 'https://example.com/collections/landsat-8-l1',
-        type: 'application/json',
-        title: 'Landsat 8 Level-1'
-      },
-      {
-        rel: 'parent',
-        href: 'https://example.com/',
-        type: 'application/json',
-        title: 'Parent'
-      }
-    ]
-  },
-  {
-    id: 'modis',
-    stac_version: '1.0.0',
-    type: 'Collection',
-    title: 'MODIS Daily',
-    description: 'MODIS daily composites from NASA Earth Observatories',
-    keywords: ['modis', 'daily', 'thermal', 'visible'],
-    license: 'CC0-1.0',
-    created: '2000-02-24T00:00:00Z',
-    updated: '2023-12-31T00:00:00Z',
-    providers: [
-      {
-        name: 'NASA',
-        roles: ['producer', 'licensor'],
-        url: 'https://www.nasa.gov/'
-      }
-    ],
-    extent: {
-      spatial: { bbox: [[-180, -90, 180, 90]] },
-      temporal: { interval: [['2000-02-24T00:00:00Z', null]] }
-    },
-    summaries: {
-      'eo:bands': [
-        { name: '1', common_name: 'red' },
-        { name: '2', common_name: 'nir' },
-        { name: '31', common_name: 'thermal' }
-      ]
-    },
-    links: [
-      {
-        rel: 'self',
-        href: 'https://example.com/collections/modis',
-        type: 'application/json',
-        title: 'MODIS Daily'
-      },
-      {
-        rel: 'parent',
-        href: 'https://example.com/',
-        type: 'application/json',
-        title: 'Parent'
-      }
-    ]
-  }
-];
diff --git a/api/db/db_APIconnection.js b/api/db/db_APIconnection.js
index 309fe71..6313413 100644
--- a/api/db/db_APIconnection.js
+++ b/api/db/db_APIconnection.js
@@ -111,18 +111,16 @@ async function testConnection(retries = 3, delay = 2000) {
         waitingCount: pool.waitingCount
       };
       
-      if (!IS_TEST) {
-        console.log('✓ Database connection successful');
-        console.log(`  Database: ${result.rows[0].database}`);
-        console.log(`  PostgreSQL version: ${result.rows[0].version.split(',')[0]}`);
-        console.log(`  Pool status: ${poolInfo.totalCount} total, ${poolInfo.idleCount} idle, ${poolInfo.waitingCount} waiting`);
-      }
+      console.log('✓ Database connection successful');
+      console.log(`  Database: ${result.rows[0].database}`);
+      console.log(`  PostgreSQL version: ${result.rows[0].version.split(',')[0]}`);
+      console.log(`  Pool status: ${poolInfo.totalCount} total, ${poolInfo.idleCount} idle, ${poolInfo.waitingCount} waiting`);
       return true;
     } catch (error) {
       console.error(`✗ Connection attempt ${i + 1}/${retries} failed:`, error.message);
       
       if (i < retries - 1) {
-        if (!IS_TEST) console.log(`  Retrying in ${delay / 1000} seconds...`);
+        console.log(`  Retrying in ${delay / 1000} seconds...`);
         await new Promise(resolve => setTimeout(resolve, delay));
       }
     }
@@ -253,7 +251,7 @@ async function queryByDistance(table, point, distance, geomColumn = 'spatial_ext
 async function closePool() {
   try {
     await pool.end();
-    if (!IS_TEST) console.log('✓ Database connection pool closed');
+    console.log('✓ Database connection pool closed');
   } catch (error) {
     console.error('Error closing database pool:', error.message);
     throw error;
diff --git a/api/routes/collections.js b/api/routes/collections.js
index ebce8af..c205b61 100644
--- a/api/routes/collections.js
+++ b/api/routes/collections.js
@@ -32,7 +32,6 @@ async function runQuery(sql, params = []) {
  * Validated/normalized values are available in req.validatedParams.
  */
 router.get('/', validateCollectionSearchParams, async (req, res, next) => {
-  // STAC Collections endpoint (DB-first with safe in-memory fallback).
   // Normalizes STAC-required fields (extent, links), coerces IDs to strings,
   // and removes null optional fields for spec compliance.
   // TODO: Think about the parameters `provider` and `license` - They are mentioned in the bid, but not in the STAC spec

From b5e39631732a7b466edb15d58bd509dda74cbd3e Mon Sep 17 00:00:00 2001
From: Georgios Voulgaris <georgevoulg28@gmail.com>
Date: Wed, 17 Dec 2025 14:31:22 +0100
Subject: [PATCH 4/4] deleted A DB file which we dont needed and deleted
 everything with the in memory data

---
 api/routes/collections.js | 120 ++++++++----------------
 db/init/06_seed_data.sql  | 190 --------------------------------------
 2 files changed, 41 insertions(+), 269 deletions(-)
 delete mode 100644 db/init/06_seed_data.sql

diff --git a/api/routes/collections.js b/api/routes/collections.js
index c205b61..173eea6 100644
--- a/api/routes/collections.js
+++ b/api/routes/collections.js
@@ -1,6 +1,5 @@
 const express = require('express');
 const router = express.Router();
-const collectionsStore = require('../data/collections'); // change with the real collections when we have them
 const { validateCollectionSearchParams } = require('../middleware/validateCollectionSearch');
 const { query } = require('../db/db_APIconnection');
 const { buildCollectionSearchQuery } = require('../db/buildCollectionSearchQuery');
@@ -76,59 +75,14 @@ router.get('/', validateCollectionSearchParams, async (req, res, next) => {
         return Object.assign({}, row, { extent });
       });
     } catch (dbError) {
-      // Fallback to in-memory data store if database is not available
-      // Keep behavior consistent: basic q filter, sort, and pagination.
-      console.warn('Database query failed, using in-memory data store:', dbError.message);
-      collections = collectionsStore;
-      
-      // Apply basic filtering to in-memory data
-      if (q) {
-        const qLower = q.toLowerCase();
-        collections = collections.filter(c => 
-          (c.title && c.title.toLowerCase().includes(qLower)) ||
-          (c.description && c.description.toLowerCase().includes(qLower)) ||
-          (c.keywords && c.keywords.some(k => k.toLowerCase().includes(qLower)))
-        );
-      }
-      
-      if (sortby) {
-        // sortby is normalized by validator to { field: <db_field>, direction: 'ASC'|'DESC' }
-        const dbField = sortby.field;
-        const direction = sortby.direction;
-
-        // Map DB field names to in-memory keys
-        const inMemoryFieldMap = {
-          id: 'id',
-          title: 'title',
-          license: 'license',
-          created_at: 'created',
-          updated_at: 'updated'
-        };
-
-        const fieldKey = inMemoryFieldMap[dbField] || dbField;
-
-        collections = [...collections].sort((a, b) => {
-          const aVal = a[fieldKey] ?? '';
-          const bVal = b[fieldKey] ?? '';
-
-          // Date-aware compare for created/updated
-          const isDateField = fieldKey === 'created' || fieldKey === 'updated';
-          let comparison;
-          if (isDateField) {
-            const aTime = aVal ? new Date(aVal).getTime() : 0;
-            const bTime = bVal ? new Date(bVal).getTime() : 0;
-            comparison = aTime === bTime ? 0 : (aTime < bTime ? -1 : 1);
-          } else {
-            comparison = String(aVal).localeCompare(String(bVal));
-          }
-
-          return direction === 'DESC' ? -comparison : comparison;
-        });
-      }
-      
-      // Apply pagination
-      const start = token || 0;
-      collections = collections.slice(start, start + limit);
+      // Database connection failed
+      console.error('Database query failed:', dbError.message);
+      res.status(503).json({
+        code: 'ServiceUnavailable',
+        description: 'Database service is not available',
+        error: dbError.message
+      });
+      return;
     }
     
     const returned = collections.length;
@@ -155,9 +109,14 @@ router.get('/', validateCollectionSearchParams, async (req, res, next) => {
       const countResult = await runQuery(countQuery, countValues);
       matched = parseInt(countResult[0]?.total || 0);
     } catch (countError) {
-      // Fallback to in-memory count
-      console.warn('Count query failed, using in-memory count:', countError.message);
-      matched = collectionsStore.length;
+      // Count query failed - database error
+      console.error('Count query failed:', countError.message);
+      res.status(503).json({
+        code: 'ServiceUnavailable',
+        description: 'Database service is not available',
+        error: countError.message
+      });
+      return;
     }
 
     // Base URL for links
@@ -267,24 +226,24 @@ router.get('/', validateCollectionSearchParams, async (req, res, next) => {
  * - 200 OK with full Collection object if found
  * - 404 NotFound with proper error format if collection does not exist
  */
-router.get('/:id', (req, res) => {
-  // STAC single-collection endpoint backed by in-memory store.
-  // Normalizes links, ensures `stac_extensions`, and converts id to string.
-  // TODO: Create a proper validator middleware for :id parameter to avoid SQL injection, etc.
-  const { id } = req.params;
-  
-  // Look up the collection in the data store by ID
-  // When connected to a DB, replace this with a SQL query (SELECT * FROM collections WHERE id = ?)
-  const collection = collectionsStore.find(c => c.id === id);
-  
-  if (!collection) {
-    // Return 404 with standardized error format
-    return res.status(404).json({
-      code: 'NotFound',
-      description: `Collection with id '${id}' not found`,
-      id: id
-    });
-  }
+router.get('/:id', async (req, res, next) => {
+  try {
+    const { id } = req.params;
+    
+    // Query the database for the collection by ID
+    const sql = 'SELECT * FROM collections WHERE id = $1';
+    const result = await query(sql, [id]);
+    
+    if (result.rows.length === 0) {
+      // Return 404 with standardized error format
+      return res.status(404).json({
+        code: 'NotFound',
+        description: `Collection with id '${id}' not found`,
+        id: id
+      });
+    }
+    
+    const collection = result.rows[0];
   
   // Return the full STAC Collection object
   // Ensure the response includes at least self, root and parent links.
@@ -326,14 +285,17 @@ router.get('/:id', (req, res) => {
   const collectionId = typeof collection.id === 'string' ? collection.id : String(collection.id);
 
   // Build response and remove null optional fields for STAC compliance
-  const result = Object.assign({}, collection, { id: collectionId, links: filteredLinks, stac_extensions });
+  const collectionResponse = Object.assign({}, collection, { id: collectionId, links: filteredLinks, stac_extensions });
   
   // Remove null assets, summaries (optional in STAC, should be omitted if not present)
-  if (result.assets === null) delete result.assets;
-  if (result.summaries === null) delete result.summaries;
+  if (collectionResponse.assets === null) delete collectionResponse.assets;
+  if (collectionResponse.summaries === null) delete collectionResponse.summaries;
 
   // Return the collection with a normalized `links` array and stac_extensions
-  res.json(result);
+  res.json(collectionResponse);
+  } catch (error) {
+    next(error);
+  }
 });
 
 module.exports = router;
diff --git a/db/init/06_seed_data.sql b/db/init/06_seed_data.sql
deleted file mode 100644
index 209deaa..0000000
--- a/db/init/06_seed_data.sql
+++ /dev/null
@@ -1,190 +0,0 @@
--- I did not wrote this code myself. It was generated by ChatGPT based on my instructions. It needs to be reviewed and tested.
-
-
--- Seed data for collections, keywords, and providers (idempotent)
--- This script can be executed repeatedly without creating duplicates.
-
--- Root catalog (optional)
-INSERT INTO catalog (stac_version, type, title, description)
-SELECT '1.0.0', 'Catalog', 'STAC Atlas Root', 'Root STAC catalog for tests'
-WHERE NOT EXISTS (
-  SELECT 1 FROM catalog WHERE title = 'STAC Atlas Root'
-);
-
--- Keywords
-INSERT INTO keywords (keyword) VALUES
-  ('sentinel-2'),
-  ('optical'),
-  ('multispectral'),
-  ('landsat'),
-  ('modis'),
-  ('daily'),
-  ('thermal'),
-  ('visible')
-ON CONFLICT (keyword) DO NOTHING;
-
--- Providers
-INSERT INTO providers (provider) VALUES
-  ('ESA'),
-  ('USGS'),
-  ('NASA')
-ON CONFLICT (provider) DO NOTHING;
-
--- Sentinel-2 L2A
-DO $$
-DECLARE
-  v_collection_id INTEGER;
-  v_provider_id INTEGER;
-BEGIN
-  IF NOT EXISTS (
-    SELECT 1 FROM collection WHERE title = 'Sentinel-2 L2A Collection'
-  ) THEN
-    INSERT INTO collection (
-      stac_version, type, title, description, license,
-      spatial_extend, temporal_extend_start, temporal_extend_end,
-      is_api, is_active, full_json, created_at, updated_at
-    ) VALUES (
-      '1.0.0', 'Collection', 'Sentinel-2 L2A Collection',
-      'Sentinel-2 Level-2A processed imagery from Copernicus', 'CC-BY-4.0',
-      ST_MakeEnvelope(-180, -90, 180, 90, 4326),
-      '2015-06-23T00:00:00Z'::timestamp, '2025-01-01T00:00:00Z'::timestamp,
-      TRUE, TRUE,
-      jsonb_build_object(
-        'id','sentinel-2-l2a',
-        'stac_version','1.0.0',
-        'title','Sentinel-2 L2A Collection'
-      ),
-      '2018-01-01T00:00:00Z'::timestamp,
-      '2025-01-01T00:00:00Z'::timestamp
-    );
-  END IF;
-
-  SELECT id INTO v_collection_id FROM collection WHERE title = 'Sentinel-2 L2A Collection' ORDER BY id DESC LIMIT 1;
-
-  -- Ensure temporal end is set if previously null
-  UPDATE collection
-  SET temporal_extend_end = updated_at
-  WHERE id = v_collection_id AND temporal_extend_end IS NULL;
-
-  INSERT INTO collection_keywords (collection_id, keyword_id)
-  SELECT v_collection_id, k.id FROM keywords k
-  WHERE k.keyword IN ('sentinel-2','optical','multispectral')
-    AND NOT EXISTS (
-      SELECT 1 FROM collection_keywords ck WHERE ck.collection_id = v_collection_id AND ck.keyword_id = k.id
-    );
-
-  SELECT id INTO v_provider_id FROM providers WHERE provider = 'ESA';
-  IF v_provider_id IS NOT NULL THEN
-    INSERT INTO collection_providers (collection_id, provider_id, collection_provider_roles)
-    SELECT v_collection_id, v_provider_id, 'producer,licensor'
-    WHERE NOT EXISTS (
-      SELECT 1 FROM collection_providers cp WHERE cp.collection_id = v_collection_id AND cp.provider_id = v_provider_id
-    );
-  END IF;
-END $$;
-
--- Landsat 8 Level-1
-DO $$
-DECLARE
-  v_collection_id INTEGER;
-  v_provider_id INTEGER;
-BEGIN
-  IF NOT EXISTS (
-    SELECT 1 FROM collection WHERE title = 'Landsat 8 Level-1'
-  ) THEN
-    INSERT INTO collection (
-      stac_version, type, title, description, license,
-      spatial_extend, temporal_extend_start, temporal_extend_end,
-      is_api, is_active, full_json, created_at, updated_at
-    ) VALUES (
-      '1.0.0', 'Collection', 'Landsat 8 Level-1',
-      'Landsat 8 Collection 1 Level 1 data', 'CC0-1.0',
-      ST_MakeEnvelope(-180, -90, 180, 90, 4326),
-      '2013-02-11T00:00:00Z'::timestamp, '2024-06-01T00:00:00Z'::timestamp,
-      TRUE, TRUE,
-      jsonb_build_object(
-        'id','landsat-8-l1',
-        'stac_version','1.0.0',
-        'title','Landsat 8 Level-1'
-      ),
-      '2013-02-11T00:00:00Z'::timestamp,
-      '2024-06-01T00:00:00Z'::timestamp
-    );
-  END IF;
-
-  SELECT id INTO v_collection_id FROM collection WHERE title = 'Landsat 8 Level-1' ORDER BY id DESC LIMIT 1;
-
-  -- Ensure temporal end is set if previously null
-  UPDATE collection
-  SET temporal_extend_end = updated_at
-  WHERE id = v_collection_id AND temporal_extend_end IS NULL;
-
-  INSERT INTO collection_keywords (collection_id, keyword_id)
-  SELECT v_collection_id, k.id FROM keywords k
-  WHERE k.keyword IN ('landsat','optical','multispectral')
-    AND NOT EXISTS (
-      SELECT 1 FROM collection_keywords ck WHERE ck.collection_id = v_collection_id AND ck.keyword_id = k.id
-    );
-
-  SELECT id INTO v_provider_id FROM providers WHERE provider = 'USGS';
-  IF v_provider_id IS NOT NULL THEN
-    INSERT INTO collection_providers (collection_id, provider_id, collection_provider_roles)
-    SELECT v_collection_id, v_provider_id, 'producer'
-    WHERE NOT EXISTS (
-      SELECT 1 FROM collection_providers cp WHERE cp.collection_id = v_collection_id AND cp.provider_id = v_provider_id
-    );
-  END IF;
-END $$;
-
--- MODIS Daily
-DO $$
-DECLARE
-  v_collection_id INTEGER;
-  v_provider_id INTEGER;
-BEGIN
-  IF NOT EXISTS (
-    SELECT 1 FROM collection WHERE title = 'MODIS Daily'
-  ) THEN
-    INSERT INTO collection (
-      stac_version, type, title, description, license,
-      spatial_extend, temporal_extend_start, temporal_extend_end,
-      is_api, is_active, full_json, created_at, updated_at
-    ) VALUES (
-      '1.0.0', 'Collection', 'MODIS Daily',
-      'MODIS daily composites from NASA Earth Observatories', 'CC0-1.0',
-      ST_MakeEnvelope(-180, -90, 180, 90, 4326),
-      '2000-02-24T00:00:00Z'::timestamp, '2023-12-31T00:00:00Z'::timestamp,
-      TRUE, TRUE,
-      jsonb_build_object(
-        'id','modis',
-        'stac_version','1.0.0',
-        'title','MODIS Daily'
-      ),
-      '2000-02-24T00:00:00Z'::timestamp,
-      '2023-12-31T00:00:00Z'::timestamp
-    );
-  END IF;
-
-  SELECT id INTO v_collection_id FROM collection WHERE title = 'MODIS Daily' ORDER BY id DESC LIMIT 1;
-
-  -- Ensure temporal end is set if previously null
-  UPDATE collection
-  SET temporal_extend_end = updated_at
-  WHERE id = v_collection_id AND temporal_extend_end IS NULL;
-
-  INSERT INTO collection_keywords (collection_id, keyword_id)
-  SELECT v_collection_id, k.id FROM keywords k
-  WHERE k.keyword IN ('modis','daily','thermal','visible')
-    AND NOT EXISTS (
-      SELECT 1 FROM collection_keywords ck WHERE ck.collection_id = v_collection_id AND ck.keyword_id = k.id
-    );
-
-  SELECT id INTO v_provider_id FROM providers WHERE provider = 'NASA';
-  IF v_provider_id IS NOT NULL THEN
-    INSERT INTO collection_providers (collection_id, provider_id, collection_provider_roles)
-    SELECT v_collection_id, v_provider_id, 'producer,licensor'
-    WHERE NOT EXISTS (
-      SELECT 1 FROM collection_providers cp WHERE cp.collection_id = v_collection_id AND cp.provider_id = v_provider_id
-    );
-  END IF;
-END $$;