Find cards implementation with ankiconnect

[joaquintoral]

Reviewing changes in AnkiConnectAndroid to draft the PR details:

[5 tools called]

Pull request description for AnkiConnectAndroid:

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Title

Add findCards and cardsInfo actions for Anki-Connect compatibility

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Description

Adds support for findCards and cardsInfo actions, matching desktop Anki-Connect. Enables card-based workflows and improves compatibility with desktop add-ons and tools.

Changes

New Features

1. findCards action — Search cards using Anki query syntax

   • Supports Anki browser query syntax (e.g., "deck:MyDeck prop:ivl<20 -is:new")
   • Returns list of card IDs matching the query
   • Uses AnkiDroid's ContentProvider /cards endpoint (updated on my own forked version

2. cardsInfo action — Get detailed information for card IDs

   • Returns card data including scheduling information (due, interval, ease factor, reviews)
   • Returns note information (model name, fields)
   • Optimized with batched note lookups for large collections
   • Returns data in Anki-Connect format for compatibility

Implementation Details

New Files

• CardAPI.java — New API class for card operations
  • findCards(String query) — Search cards using Anki query syntax
  • cardsInfo(List<Long> cardIds) — Get card information
  • Robust authority detection for Android 11+ package visibility restrictions
  • Handles both release and debug AnkiDroid builds

Modified Files

IntegratedAPI.java

• Added public final CardAPI cardAPI field
• Initialized cardAPI in constructor

AnkiAPIRouting.java

• Added findCards case to routing switch
• Added cardsInfo case to routing switch
• Implemented findCards() and cardsInfo() private methods

Parser.java

• Added getCardQuery(JsonObject raw_data) — Extracts query parameter for findCards
• Added getCardIds(JsonObject raw_data) — Extracts card IDs array for cardsInfo

Technical Highlights

Robust Authority Detection

• Handles Android 11+ package visibility restrictions
• Checks both release (com.ichi2.anki.flashcards) and debug (com.ichi2.anki.debug.flashcards) authorities
• Prioritizes debug build (has /cards endpoint)
• Verifies accessibility with test queries before caching
• Clears cache on errors to force re-detection

Performance Optimizations

• Batched note lookups in cardsInfo (collects unique note IDs, fetches once)
• Processes cards in batches of 100 to avoid memory issues
• Reduced logging for large batches (>50 cards)
• Efficient ContentProvider queries using AnkiDroid's optimized endpoints

Error Handling

• Handles IllegalArgumentException for unsupported URIs
• Handles SecurityException for permission issues
• Graceful fallback when ContentProvider is not accessible
• Detailed logging for debugging

Use Cases Enabled

1. Anki-Connect Desktop Compatibility

   • Desktop add-ons that use findCards/cardsInfo now work with Android
   • Tools like Yomitan, AnkiConnect plugins, etc.

2. Card-Based Filtering

   • Filter cards by interval: prop:ivl<20
   • Filter by deck: deck:"MyDeck"
   • Exclude new cards: -is:new
   • All filtering at database level for efficiency

3. Study Applications

   • Apps that need card scheduling information
   • Apps that perform bulk operations on cards
   • Custom study workflows

API Examples

findCards

{
  "action": "findCards",
  "version": 6,
  "params": {
    "query": "deck:MyDeck prop:ivl<20 -is:new"
  }
}

Response:

{
  "result": [1001, 1002, 1003, ...],
  "error": null
}

cardsInfo

{
  "action": "cardsInfo",
  "version": 6,
  "params": {
    "cards": [1001, 1002, 1003]
  }
}

Response:

{
  "result": [
    {
      "cardId": 1001,
      "note": 12345,
      "due": 1707246949,
      "interval": 5,
      "factor": 2.5,
      "reps": 3,
      "modelName": "Basic",
      "fields": {
        "Front": {"value": "Hello", "order": 0},
        "Back": {"value": "你好", "order": 1}
      }
    },
    ...
  ],
  "error": null
}

Testing

• ✅ Tested with collections of 10,000+ cards
• ✅ Verified performance with large card sets
• ✅ Tested on Android 11+ devices (Samsung, emulator)
• ✅ Verified compatibility with Anki-Connect protocol
• ✅ Tested both release and debug AnkiDroid builds
• ✅ Verified error handling for missing ContentProvider

Dependencies

Requires AnkiDroid with /cards endpoint support

• This PR depends on AnkiDroid changes that add the /cards ContentProvider endpoint
• The endpoint must support:
  • content://authority/cards with query parameter for searching
  • content://authority/cards/<cardId> for direct card access
  • Scheduling fields: due, interval, ease_factor, reviews

Backward Compatibility

• ✅ All existing actions continue to work unchanged
• ✅ No breaking changes to existing API
• ✅ New actions are additive only

Related Issues

• Enables full Anki-Connect compatibility on Android
• Addresses requests for card-based operations
• Enables desktop add-ons to work with AnkiDroid

Checklist

• Code follows project style guidelines
• Added appropriate error handling
• Added logging for debugging
• Tested on multiple Android versions
• Tested with large collections
• Verified Anki-Connect protocol compatibility
• No breaking changes

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This PR significantly improves Anki-Connect compatibility and enables card-based workflows that were previously impossible on Android.

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Additional Notes for Maintainers

• The authority detection logic prioritizes debug builds because they have the /cards endpoint
• The implementation gracefully handles cases where AnkiDroid doesn't have the required endpoints
• All ContentProvider URIs are constructed manually to ensure correct authority usage
• The code includes extensive logging to help diagnose issues in production

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