Add ICS calendar feed import with automatic blocking timeframes

[datengraben]

Summary

This PR introduces a new ICS (iCalendar) feed synchronization system that allows administrators to configure external calendar feeds and automatically create blocking timeframes for items/locations during calendar events. This makes items unavailable in the booking system when they're marked as busy in external calendars.

Key Changes

• New ICSImport Service (src/Service/ICSImport.php):

  • Fetches and parses ICS calendar feeds from external URLs
  • Extracts VEVENT blocks and handles various datetime formats (UTC, timezone-aware, floating, all-day events)
  • Creates HOLIDAYS_ID blocking timeframes for each event × item × location combination
  • Implements cleanup logic to remove timeframes when events are deleted from the feed
  • Supports RFC 5545 line folding and ICS text escape sequences
  • Handles timezone conversions to the WordPress site timezone

• New ICSFeed Custom Post Type (src/Wordpress/CustomPostType/ICSFeed.php):

  • Manages ICS feed configuration posts with CMB2 metabox
  • Allows administrators to configure: feed URL, target items, target locations, and lookahead window
  • Provides "Sync now" action in both list view and edit screen for manual synchronization
  • Displays sync status (last sync time, error messages) in the admin interface
  • Stores metadata for tracking synced events and their source feeds

• Scheduler Integration (src/Service/Scheduler.php):

  • Registers hourly cron job to automatically sync all published ICS feeds
  • Ensures feeds are kept in sync without manual intervention

• Plugin Registration (src/Plugin.php):

  • Registers the new ICSFeed custom post type in the plugin initialization

• Comprehensive Test Suite (tests/php/Service/ICSImportTest.php):

  • Unit tests for ICS parsing (VEVENT extraction, datetime parsing with various formats)
  • Integration tests for feed synchronization, cleanup, and deduplication
  • HTTP mocking for testing without external dependencies

Notable Implementation Details

• Datetime Handling: Properly handles UTC (Z suffix), timezone-aware (TZID parameter), floating, and all-day events, converting all to WordPress site timezone
• Event Deduplication: Uses composite UIDs (event-uid:item-id:location-id) to track synced events and prevent duplicates on re-sync
• Cleanup Strategy: Removes timeframes for events no longer present in the feed while preserving manually-created timeframes
• Full-Day Timeframes: Creates blocking timeframes as full-day events (midnight to 23:59) matching the existing timeframe convention
• Error Handling: Stores sync errors in post metadata for admin visibility without blocking the sync process

https://claude.ai/code/session_01WxALKfRznRXqZRu6LQ2a23