Fix #12: Add score normalization for AniList formats (#14)

* Fix #12: Add score normalization for AniList formats

- Add GetUserScoreFormat() to retrieve user's AniList score format
- Change Score type from float64 to int (always stored as 0-10)
- Implement normalizeScoreForMAL() to convert AniList scores to 0-10
- Implement denormalizeScoreForAniList() to convert back to user's format
- Support all 5 AniList formats: POINT_100, POINT_10_DECIMAL, POINT_10, POINT_5, POINT_3
- Add comprehensive tests for normalization/denormalization functions
- Apply same changes to both anime and manga

This fixes MAL API rejecting scores > 10 with '400 invalid score bad_request'

* Fix gofumpt formatting

* Add fmt command to Makefile for code formatting

* Fix golangci-lint issues

- Exclude dupl linter for test files in .golangci.yml
- Remove unused nolint:dupl directives from app.go

* Update CLAUDE.md with testing, formatting, and score normalization info

* Refactor: Extract score normalization to separate file

- Move score normalization functions to score.go
- Move score normalization tests to score_test.go
- Add detailed comments explaining intentional code duplication
- Remove duplicate code from anime.go and manga.go
- Remove duplicate tests from anime_test.go and manga_test.go

Addresses Copilot review comments about documenting intentional
duplication in fetch functions.

Author: bigspawn

.gitignore

@@ -1,8 +1,13 @@
+bin/
+anilist-mal-sync
+
+.env
 .token
 .token*
-bin/
+.claude
+
 config.yaml
-*tmp.json
 CLAUDE.md
-.claude
-anilist-mal-sync
+
+*tmp.json
+*.log

.golangci.yml

@@ -53,6 +53,9 @@ linters:
       - text: "exported: exported"
         linters:
           - revive
+      - path: "_test\\.go"
+        linters:
+          - dupl
   settings:
     lll:
       line-length: 140

CLAUDE.md

@@ -0,0 +1,223 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+This is a Go application that synchronizes anime and manga lists between AniList and MyAnimeList accounts. The application uses OAuth2 authentication to access both services and supports bidirectional synchronization:
+- AniList to MyAnimeList (default)
+- MyAnimeList to AniList (with `-reverse-direction` flag)
+
+## Architecture
+
+The application follows a modular architecture with the following key components:
+
+- **Main entry point**: `main.go` - handles CLI flags and application initialization
+- **Configuration**: `config.go` - manages YAML configuration and environment variables
+- **Application core**: `app.go` - coordinates OAuth clients and sync operations
+- **API clients**: `anilist.go` and `myanimelist.go` - handle API interactions with respective services
+- **Media types**: `anime.go` and `manga.go` - define data structures and transformations
+- **Sync logic**: `updater.go` - handles the synchronization process between services
+- **OAuth handling**: `oauth.go` - manages OAuth2 authentication flows
+- **Statistics**: `statistics.go` - tracks sync operations and results
+- **Strategies**: `strategies.go` - implements different sync strategies and entry matching logic
+
+### Core Sync Pattern
+
+The synchronization follows a generic pattern defined in `updater.go`:
+- **Source/Target Interface**: Uses `Source` and `Target` interfaces for type-safe operations
+- **Updater struct**: Contains function pointers for getting targets by ID/name and updating them
+- **Comparison logic**: Implements progress comparison and diff generation between platforms
+- **Ignore list**: Supports title-based filtering for entries that don't exist on target platform
+- **Force sync**: Optional flag to bypass progress comparison and sync all entries
+- **Strategy chain**: Uses configurable strategies for finding and matching entries between platforms
+
+The `App` struct instantiates separate `Updater` instances for anime and manga in both directions (normal and reverse), each with their own function implementations for API operations.
+
+## Common Development Commands
+
+### Building
+```bash
+# Build the application
+make build
+
+# Build using go directly
+go build -o anilist-mal-sync
+
+# Build for Docker (used in multi-stage build)
+CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -mod=vendor -ldflags="-w -s" -o main
+```
+
+Note: The Makefile builds from `./cmd/main.go` but the actual main file is in the root directory as `main.go`.
+
+### Testing
+```bash
+# Run all tests
+make test
+
+# Run tests with verbose output
+go test ./... -v
+
+# Test files:
+# - anime_test.go: Tests for score normalization/denormalization (anime)
+# - manga_test.go: Tests for score normalization/denormalization (manga)
+```
+
+### Code Formatting
+```bash
+# Format code with gofumpt
+make fmt
+
+# This ensures code follows gofumpt standards required by CI
+```
+
+### Linting
+```bash
+# Run linter using Docker (recommended)
+make lint
+
+# Run linter directly (if golangci-lint is installed locally)
+golangci-lint run --new
+
+# This uses golangci-lint v1.64.6 in Docker container
+# Note: dupl linter is disabled for test files to allow identical test structures
+```
+
+### Running
+```bash
+# Run with default config
+go run .
+
+# Run with custom config file
+go run . -c myconfig.yaml
+
+# Run with dry run mode (no actual updates)
+go run . -d
+
+# Run with verbose logging
+go run . -verbose
+
+# Sync manga instead of anime
+go run . -manga
+
+# Sync both anime and manga
+go run . -all
+
+# Force sync all entries
+go run . -f
+
+# Reverse sync direction (MyAnimeList to AniList)
+go run . -reverse-direction
+```
+
+### Cleanup
+```bash
+# Clean build artifacts and test cache
+make clean
+```
+
+### Docker Development
+```bash
+# Build Docker image
+docker build -t anilist-mal-sync .
+
+# Run with pre-built image from GitHub Container Registry
+docker pull ghcr.io/bigspawn/anilist-mal-sync:latest
+
+# Run with Docker (requires config and token volumes)
+docker run -p 18080:18080 \
+  -v /path/to/config.yaml:/etc/anilist-mal-sync/config.yaml \
+  -v /path/to/tokens:/home/appuser/.config/anilist-mal-sync \
+  ghcr.io/bigspawn/anilist-mal-sync:latest
+```
+
+## Configuration
+
+The application uses a YAML configuration file (`config.yaml`) with the following structure:
+- OAuth settings (port, redirect URI)
+- AniList client credentials and settings
+- MyAnimeList client credentials and settings
+- Token file path for persistent authentication
+
+Environment variables can override sensitive values:
+- `PORT` - OAuth server port
+- `CLIENT_SECRET_ANILIST` - AniList client secret
+- `CLIENT_SECRET_MYANIMELIST` - MyAnimeList client secret
+
+## Key Dependencies
+
+- `golang.org/x/oauth2` - OAuth2 client implementation
+- `gopkg.in/yaml.v2` - YAML configuration parsing
+- `github.com/nstratos/go-myanimelist` - MyAnimeList API client
+- `github.com/rl404/verniy` - AniList API client
+- `github.com/cenkalti/backoff/v4` - Exponential backoff for API retry logic
+
+### Important: Dependency Management
+**Always run `go mod vendor` after `go get` to keep the vendor directory in sync with go.mod changes.**
+
+## Authentication Flow
+
+The application implements OAuth2 authentication for both services:
+1. Starts a local server on port 18080 (configurable)
+2. Opens browser to service authorization URL
+3. Handles callback and exchanges code for access token
+4. Stores tokens in `~/.config/anilist-mal-sync/token.json`
+
+## Sync Process
+
+1. Fetches user's anime/manga list from AniList
+2. Fetches user's anime/manga list from MyAnimeList
+3. Normalizes AniList scores to 0-10 format (see Score Normalization below)
+4. Compares entries and identifies differences
+5. Updates MyAnimeList entries to match AniList status
+6. In reverse sync, denormalizes scores back to user's AniList format
+7. Provides statistics on sync operations
+
+### Score Normalization
+
+The application handles score format differences between AniList and MyAnimeList:
+
+**AniList Score Formats**:
+- `POINT_100` (0-100) - e.g., 85/100
+- `POINT_10_DECIMAL` (0-10.0) - e.g., 8.5/10
+- `POINT_10` (0-10) - e.g., 8/10
+- `POINT_5` (0-5) - e.g., 4/5
+- `POINT_3` (1-3) - e.g., 2/3
+
+**MyAnimeList Score Format**:
+- Integer 0-10 only
+
+**Implementation**:
+- Scores are stored internally as `int` in normalized 0-10 format
+- When reading from AniList: scores are normalized to 0-10
+- When writing to AniList: scores are denormalized back to user's format
+- When reading/writing MAL: no conversion needed (already 0-10)
+- Functions: `normalizeScoreForMAL()` and `denormalizeScoreForAniList()` in `anime.go` and `manga.go`
+- User's score format is retrieved once at startup via `GetUserScoreFormat()` in `anilist.go`
+
+This architecture prevents MAL API errors when AniList scores exceed 10 (e.g., `400 invalid score bad_request`)
+
+## Docker Support
+
+The application includes Docker support with:
+- Multi-stage build using Alpine base image
+- Non-root user execution (appuser with UID 10001)
+- Volume mounts for configuration and token storage
+- Port exposure for OAuth callback (18080)
+- Vendored dependencies for faster builds
+
+## Development Notes
+
+### Rate Limiting
+Both AniList and MyAnimeList have rate limits. The application may appear to freeze due to API timeouts. If this occurs, stop the application and wait before retrying.
+
+### Entry Matching
+The sync process uses two methods to match entries:
+1. **By ID**: When AniList entry has a MAL ID reference
+2. **By Title**: When no ID is available, searches MAL by title and matches by media type
+
+### Debug Output
+Use the `-verbose` flag to enable detailed logging of the sync process, including API calls and comparison results.
+
+### Ignore List
+Hard-coded ignore lists in `app.go` skip entries that don't exist on the target platform (e.g., "Scott Pilgrim Takes Off" is not available on MAL).

Makefile

@@ -1,4 +1,4 @@
-.PHONY: build test lint help clean
+.PHONY: build test lint fmt help clean
 
 BINARY_NAME=anilist-mal-sync
 LINT_VERSION=v1.64.6
@@ -14,6 +14,12 @@ build:
 test:
 	go test ./... -v
 
+# Format code with gofumpt
+fmt:
+	@echo "Formatting code with gofumpt..."
+	@gofumpt -l -w .
+	@echo "Formatting complete!"
+
 # Run linter using Docker
 lint:
 	@echo "Running golangci-lint $(LINT_VERSION) in Docker..."
@@ -32,6 +38,7 @@ help:
 	@echo "Available commands:"
 	@echo "  build     - Build the application"
 	@echo "  test      - Run tests"
+	@echo "  fmt       - Format code with gofumpt"
 	@echo "  lint      - Run linter using Docker (golangci-lint $(LINT_VERSION))"
 	@echo "  clean     - Remove build artifacts, temporary files and clean test cache"
 	@echo "  help      - Show this help message"

anilist.go

@@ -448,3 +448,34 @@ func retryWithBackoff(ctx context.Context, operation func() error, operationName
 		},
 	)
 }
+
+// GetUserScoreFormat retrieves the user's score format preference from AniList
+func (c *AnilistClient) GetUserScoreFormat(ctx context.Context) (verniy.ScoreFormat, error) {
+	var result *verniy.User
+
+	err := retryWithBackoff(ctx, func() error {
+		user, e := c.c.GetUserWithContext(ctx, c.username,
+			verniy.UserFieldMediaListOptions(
+				verniy.MediaListOptionsFieldScoreFormat,
+			),
+		)
+		if e != nil {
+			return fmt.Errorf("failed to get user score format: %w", e)
+		}
+		result = user
+		return nil
+	}, fmt.Sprintf("AniList get user score format: %s", c.username))
+	if err != nil {
+		return "", err
+	}
+
+	if result.MediaListOptions == nil {
+		return "", fmt.Errorf("user media list options is nil")
+	}
+
+	if result.MediaListOptions.ScoreFormat == nil {
+		return "", fmt.Errorf("user score format is nil")
+	}
+
+	return *result.MediaListOptions.ScoreFormat, nil
+}

anime.go

@@ -69,7 +69,7 @@ type Anime struct {
 	IDAnilist   int
 	IDMal       int
 	Progress    int
-	Score       float64
+	Score       int
 	SeasonYear  int
 	Status      Status
 	TitleEN     string
@@ -118,7 +118,7 @@ func (a Anime) SameProgressWithTarget(t Target) bool {
 		return false
 	}
 	if a.Score != b.Score {
-		DPrintf("Score: %f != %f", a.Score, b.Score)
+		DPrintf("Score: %d != %d", a.Score, b.Score)
 		return false
 	}
 	progress := a.Progress == b.Progress
@@ -224,7 +224,7 @@ func (a Anime) String() string {
 	sb.WriteString(fmt.Sprintf("TitleEN: %s, ", a.TitleEN))
 	sb.WriteString(fmt.Sprintf("TitleJP: %s, ", a.TitleJP))
 	sb.WriteString(fmt.Sprintf("MediaListStatus: %s, ", a.Status))
-	sb.WriteString(fmt.Sprintf("Score: %f, ", a.Score))
+	sb.WriteString(fmt.Sprintf("Score: %d, ", a.Score))
 	sb.WriteString(fmt.Sprintf("Progress: %d, ", a.Progress))
 	sb.WriteString(fmt.Sprintf("EpisodeNumber: %d, ", a.NumEpisodes))
 	sb.WriteString(fmt.Sprintf("SeasonYear: %d, ", a.SeasonYear))
@@ -234,11 +234,11 @@ func (a Anime) String() string {
 	return sb.String()
 }
 
-func newAnimesFromMediaListGroups(groups []verniy.MediaListGroup) []Anime {
+func newAnimesFromMediaListGroups(groups []verniy.MediaListGroup, scoreFormat verniy.ScoreFormat) []Anime {
 	res := make([]Anime, 0, len(groups))
 	for _, group := range groups {
 		for _, mediaList := range group.Entries {
-			a, err := newAnimeFromMediaListEntry(mediaList)
+			a, err := newAnimeFromMediaListEntry(mediaList, scoreFormat)
 			if err != nil {
 				log.Printf("Error creating anime from media list entry: %v", err)
 				continue
@@ -250,7 +250,7 @@ func newAnimesFromMediaListGroups(groups []verniy.MediaListGroup) []Anime {
 	return res
 }
 
-func newAnimeFromMediaListEntry(mediaList verniy.MediaList) (Anime, error) {
+func newAnimeFromMediaListEntry(mediaList verniy.MediaList, scoreFormat verniy.ScoreFormat) (Anime, error) {
 	if mediaList.Media == nil {
 		return Anime{}, errors.New("media is nil")
 	}
@@ -263,9 +263,10 @@ func newAnimeFromMediaListEntry(mediaList verniy.MediaList) (Anime, error) {
 		return Anime{}, errors.New("title is nil")
 	}
 
-	var score float64
+	var score int
 	if mediaList.Score != nil {
-		score = *mediaList.Score
+		// Normalize AniList score to MAL format (0-10)
+		score = normalizeScoreForMAL(*mediaList.Score, scoreFormat)
 	}
 
 	var progress int
@@ -381,7 +382,7 @@ func newAnimeFromMalAnime(malAnime mal.Anime) (Anime, error) {
 		IDAnilist:   anilistID,
 		IDMal:       malAnime.ID,
 		Progress:    malAnime.MyListStatus.NumEpisodesWatched,
-		Score:       float64(malAnime.MyListStatus.Score),
+		Score:       malAnime.MyListStatus.Score, // MAL score is already 0-10 int
 		SeasonYear:  malAnime.StartSeason.Year,
 		Status:      mapMalAnimeStatusToStatus(malAnime.MyListStatus.Status),
 		TitleEN:     titleEN,

anime_test.go

@@ -0,0 +1 @@
+package main