# Interactive Audio Stream Selection - Implementation Summary

## Changes Made

### 1. New Function: `prompt_user_audio_selection()` in audio_handler.py
- **Purpose**: Display audio streams and prompt user for selection
- **Input**: List of streams with (index, channels, bitrate, language, metadata)
- **Output**: Filtered list containing only user-selected streams
- **Features**:
  - Displays stream info: `Stream #X: YYch | Lang: YYY | Bitrate: XYZkbps`
  - Accepts comma-separated input: `1,2,3` or `1` or empty (keep all)
  - Validates input and logs selections
  - Falls back to keeping all streams on invalid input

### 2. Updated: `run_ffmpeg()` in encode_engine.py
- Now checks `audio_filter_config.get("interactive", False)`
- Routes to interactive prompt if `interactive=True`
- Routes to automatic filtering if `interactive=False`
- Both modes filter streams before codec selection

### 3. Updated: `process_folder()` in process_manager.py
- New parameter: `interactive_audio: bool = False`
- Builds audio_filter_config with both `enabled` and `interactive` fields
- If `--interactive` used without `--filter-audio`, enables both automatically

### 4. Updated: main.py
- New CLI argument: `--interactive`
- Action: `store_true` (binary flag)
- Passed through to `process_folder()`
- Help text: "Interactive mode: show audio streams and let user select which to keep (requires --filter-audio)"

## Usage Examples

### Example 1: Automatic Filtering (Existing)
```bash
python main.py "C:\Videos" --filter-audio
```
- Automatically keeps best English + Commentary
- No user interaction

### Example 2: Interactive Selection (New)
```bash
python main.py "C:\Videos" --filter-audio --interactive
```
- Shows each file's audio streams
- User picks which streams to keep
- Different selections per file allowed

### Example 3: Interactive Without --filter-audio
```bash
python main.py "C:\Videos" --interactive
```
- Same as Example 2 (enables filtering automatically)
- More intuitive UX

## Stream Display Format

When interactive mode runs, user sees:
```
================================================================================
🎵 AUDIO STREAM SELECTION
================================================================================

Stream #0: 2ch | Lang: eng | Bitrate: 128kbps

Stream #1: 6ch | Lang: eng | Bitrate: 448kbps

Stream #2: 2ch | Lang: spa | Bitrate: 128kbps

────────────────────────────────────────────────────────────────────────────
Enter stream numbers to keep (comma-separated, e.g.: 1,2 or just 2)
Leave blank to keep all streams
────────────────────────────────────────────────────────────────────────────
➜ Keep streams: 
```

## Logging Output

When user selects streams:
```
✅ Keeping 2 stream(s), removing 1 stream(s)

User selected 2 audio stream(s): [1, 2]
Removed 1 audio stream(s): [0]
```

## Audio Filter Config Structure

**Old (Automatic only)**:
```python
{
    "enabled": True/False
}
```

**New (With Interactive)**:
```python
{
    "enabled": True/False,
    "interactive": True/False
}
```

## Flow Diagram

```
main.py
  └─ parse args (--filter-audio, --interactive)
     └─ process_folder()
        └─ for each file:
           └─ run_ffmpeg()
              └─ get_audio_streams()
              └─ if audio_filter_config.enabled:
                 ├─ if audio_filter_config.interactive:
                 │  └─ prompt_user_audio_selection() ← NEW
                 │     └─ [User sees streams and selects]
                 └─ else:
                    └─ filter_audio_streams() (automatic)
              └─ encode with selected streams
```

## Input Validation

- **Valid**: `1`, `0,1,3`, `2, 3, 5` (spaces OK)
- **Invalid**: `abc`, `1.5`, `1-3` (ranges not supported)
- **On Invalid**: Keep all streams, log warning

## Edge Cases Handled

1. **No streams**: Return original (nothing to filter)
2. **Single stream**: Return as-is (no selection needed)
3. **Invalid stream indices**: Keep all streams
4. **Empty input**: Keep all streams
5. **No valid selections**: Keep all streams (with warning)

## Backward Compatibility

- Existing `--filter-audio` behavior unchanged (automatic mode)
- `--interactive` is optional, defaults to False
- No breaking changes to config.xml structure
- Language tagging (--language) still works alongside audio filtering