# Filter Enhancements v0.4.0

## Overview
This document describes the four major filter enhancements implemented in CAT Editor v0.4.0:

1. ✅ Filter panel added to Document View
2. ✅ Filter highlighting in Document View
3. ✅ Keyboard shortcuts for filter operations
4. ✅ Filter preferences saved to project files

---

## 1. Filter Panel in Document View

### What Was Added
- Complete filter panel UI at the top of Document View (matching Grid View and List View)
- Includes all filter controls:
  - Mode toggle buttons (🔍 Filter / 💡 Highlight)
  - Source filter entry field
  - Target filter entry field
  - Status dropdown (All/untranslated/draft/translated/approved)
  - Apply button (🔍 Apply)
  - Clear button (✕ Clear)
  - Results label showing filter statistics

### Implementation Details
- **Location**: Lines 1596-1710 in `cat_editor_prototype.py`
- **Pattern**: Reuses shared filter variables (`filter_source_var`, `filter_target_var`, `filter_status_var`)
- **Button References**: Stores `doc_filter_mode_btn` and `doc_highlight_mode_btn` for this view

### User Benefits
- Consistent filtering experience across all three views
- No need to switch views to access filters
- Filter while viewing document in natural flow

---

## 2. Filter Highlighting in Document View

### What Was Added
Document View now visually highlights segments that match active filters:

**In Paragraphs:**
- Matching segments get bright yellow background (`#FFEB3B`)
- 2px solid border to stand out from status colors
- Highlight tag raised above status tag for visibility

**In Table Cells:**
- Same bright yellow highlighting
- Applied to entire cell content
- Works in both Filter and Highlight modes

### Implementation Details
- **Paragraph Highlighting**: Lines 1964-1972
- **Table Cell Highlighting**: Lines 2074-2079
- **Logic**: Uses `should_highlight_segment(seg)` to determine matches
- **Tag System**: Creates `highlight_{seg.id}` tags with raised priority

### Code Example
```python
# Apply filter highlighting if active and segment matches
if self.filter_active and self.should_highlight_segment(seg):
    highlight_tag = f"highlight_{seg.id}"
    para_text.tag_add(highlight_tag, start_pos, end_pos)
    para_text.tag_config(highlight_tag, borderwidth=2, relief='solid', 
                       background='#FFEB3B')  # Bright yellow for filter matches
    para_text.tag_raise(highlight_tag)
```

### User Benefits
- Easy to spot matching segments in document flow
- Visual feedback confirms filter is working
- Distinct from status colors (no confusion)
- Works in both Filter Mode (fewer segments) and Highlight Mode (all segments with highlights)

---

## 3. Keyboard Shortcuts for Filter Operations

### New Shortcuts Added

| Shortcut | Action | Description |
|----------|--------|-------------|
| **Ctrl+M** | Toggle Filter Mode | Switch between Filter Mode (🔍) and Highlight Mode (💡) |
| **Ctrl+Shift+A** | Apply Filters | Apply current filter criteria |
| **Ctrl+Shift+F** | Focus Filter | Set keyboard focus to source filter field |

### Existing Shortcuts (for reference)
- `Ctrl+1` - Switch to Grid View
- `Ctrl+2` - Switch to List View
- `Ctrl+3` - Switch to Document View
- `Ctrl+F` - Find/Replace dialog
- `Enter` in filter fields - Apply filters

### Implementation Details
- **Bindings**: Lines 176-180 in `cat_editor_prototype.py`
- **Menu Integration**: Lines 169-176 (View menu shows shortcuts)
- **Helper Functions**: Lines 3855-3883

### Helper Functions
```python
def toggle_filter_mode(self):
    """Toggle between filter and highlight modes (Ctrl+M)"""
    new_mode = 'highlight' if self.filter_mode == 'filter' else 'filter'
    self.set_filter_mode(new_mode)

def focus_filter_source(self):
    """Focus the source filter entry field (Ctrl+Shift+F)"""
    # Recursively searches widget tree for source filter entry
    # Sets focus when found

def _focus_filter_recursive(self, widget):
    """Helper: Recursively search for source filter entry"""
    # Checks if widget is Entry with filter_source_var
    # Returns True when found and focused
```

### User Benefits
- Faster workflow without mouse
- Quick mode switching with Ctrl+M
- Jump to filter field instantly with Ctrl+Shift+F
- Power users can work entirely with keyboard

---

## 4. Filter Preferences Saved to Project Files

### What Is Saved
When saving a project, the following filter state is preserved:

```json
{
  "filter_preferences": {
    "mode": "filter",                    // or "highlight"
    "source_filter": "contract",         // Current source filter text
    "target_filter": "",                 // Current target filter text
    "status_filter": "untranslated",     // Current status selection
    "active": true                       // Whether filters are active
  }
}
```

### What Happens on Load
When loading a project:
1. Filter fields are restored to saved values
2. Filter mode buttons update to match saved mode
3. If filters were active, they are automatically applied
4. Visual state matches exactly how you left it

### Implementation Details

**Save Logic** (Lines 4320-4335):
```python
'filter_preferences': {
    'mode': self.filter_mode,
    'source_filter': self.filter_source_var.get() if hasattr(self, 'filter_source_var') else '',
    'target_filter': self.filter_target_var.get() if hasattr(self, 'filter_target_var') else '',
    'status_filter': self.filter_status_var.get() if hasattr(self, 'filter_status_var') else 'All',
    'active': self.filter_active
}
```

**Load Logic** (Lines 4388-4414):
```python
# Load filter preferences if they exist
if 'filter_preferences' in data:
    prefs = data['filter_preferences']
    if hasattr(self, 'filter_source_var'):
        self.filter_source_var.set(prefs.get('source_filter', ''))
    if hasattr(self, 'filter_target_var'):
        self.filter_target_var.set(prefs.get('target_filter', ''))
    if hasattr(self, 'filter_status_var'):
        self.filter_status_var.set(prefs.get('status_filter', 'All'))
    self.filter_mode = prefs.get('mode', 'filter')
    self.filter_active = prefs.get('active', False)
    
    # Update button states to match loaded mode
    # ... button config code ...
    
    # Apply the filters if they were active
    if self.filter_active:
        self.apply_filters()
```

### User Benefits
- Resume work exactly where you left off
- No need to re-enter filter criteria
- Filter mode preference remembered per project
- Seamless workflow across sessions

---

## View Menu Addition

A new **View** menu was added to provide easy access to filter operations:

```
View
├─ Grid View                 (Ctrl+1)
├─ List View                 (Ctrl+2)
├─ Document View             (Ctrl+3)
├─ ─────────────────
├─ Toggle Filter Mode        (Ctrl+M)
├─ Apply Filters             (Ctrl+Shift+A)
├─ Clear Filters
└─ Focus Filter              (Ctrl+Shift+F)
```

**Location**: Lines 169-176 in `cat_editor_prototype.py`

---

## Testing Checklist

### ✅ Filter Panel in Document View
- [x] Panel appears at top of Document View
- [x] Mode buttons work (Filter/Highlight)
- [x] Source filter field accepts text
- [x] Target filter field accepts text
- [x] Status dropdown shows all options
- [x] Apply button triggers filtering
- [x] Clear button resets all filters
- [x] Results label shows correct counts

### ✅ Filter Highlighting in Document View
- [x] Matching paragraphs highlighted in yellow
- [x] Matching table cells highlighted in yellow
- [x] Highlight visible over status colors
- [x] Border makes highlights stand out
- [x] Works in Filter Mode (fewer segments)
- [x] Works in Highlight Mode (all segments)

### ✅ Keyboard Shortcuts
- [x] Ctrl+M toggles between modes
- [x] Ctrl+Shift+A applies filters
- [x] Ctrl+Shift+F focuses source filter
- [x] Enter in filter fields applies filters
- [x] Shortcuts work in all three views

### ✅ Filter Preferences Saving
- [x] Filters saved to project JSON
- [x] Filters restored on project load
- [x] Mode buttons update on load
- [x] Active filters auto-apply on load
- [x] Works with older project files (no errors if missing)

---

## Backward Compatibility

### Old Project Files
- Projects without `filter_preferences` load normally
- No errors or warnings
- Filters simply start in default state (Filter Mode, All filters clear)

### Version Compatibility
- Project version remains `0.3.2`
- New field is optional (doesn't break older versions)
- If older editor opens new project file, it ignores `filter_preferences`

---

## User Workflow Examples

### Example 1: Working with Untranslated Legal Terms
1. User opens project
2. Types "contract" in source filter
3. Selects "untranslated" status
4. Presses Ctrl+Shift+A (or clicks Apply)
5. Switches to Document View (Ctrl+3)
6. Sees only untranslated segments with "contract" highlighted in yellow
7. Saves project - filters are preserved
8. Next day: Opens project, filters already active, continues work

### Example 2: Reviewing Translated Medical Terms
1. User switches to Highlight Mode (Ctrl+M)
2. Types "patient" in source filter
3. Presses Apply
4. All segments visible, "patient" segments highlighted
5. Reviews context around highlighted segments
6. Saves project - Highlight Mode preference saved

### Example 3: Quick Filter Toggle
1. User working in filtered view (showing only 50 of 500 segments)
2. Needs to see full context
3. Presses Ctrl+M to switch to Highlight Mode
4. All 500 segments now visible, 50 highlighted
5. Presses Ctrl+M again to return to filtered view

---

## Performance Notes

### Highlighting Performance
- Highlighting is applied during render (not real-time)
- Minimal performance impact (tag-based, not re-rendering)
- No noticeable lag even with 1000+ segments

### Filter Application
- Filters now manual (button-triggered, not real-time)
- No performance issues while typing
- User controls when filtering happens

### Project Load Time
- Filter restoration is instant
- No delay loading projects with saved filters
- Auto-apply on load is fast (uses existing apply_filters logic)

---

## Future Enhancement Ideas

### Not Implemented (Optional for Future)
1. **Filter History** - Remember last 5 filter combinations
2. **Regex Support** - Allow regex patterns in filter fields
3. **Saved Filter Presets** - Name and save common filter combinations
4. **Multi-Field Highlighting** - Different colors for source vs target matches
5. **Filter Statistics** - Show match counts per status in tooltip
6. **Export Filtered View** - Export only filtered segments to TSV/DOCX

---

## Summary of Changes

### Files Modified
- `cat_editor_prototype.py` - Main application file

### Lines Changed
- **Document View Filter Panel**: ~110 lines added (1596-1710)
- **Document View Highlighting**: ~15 lines modified (1964-1972, 2074-2079)
- **Keyboard Shortcuts**: ~10 lines added (176-180, 169-176)
- **Helper Functions**: ~35 lines added (3855-3883)
- **Project Save**: ~12 lines added (4320-4335)
- **Project Load**: ~32 lines added (4388-4414)

### Total Impact
- **~214 lines** of new/modified code
- **Zero breaking changes** to existing functionality
- **100% backward compatible** with old project files

---

## Version History
- **v0.4.0** - October 3, 2025
  - Added filter panel to Document View
  - Implemented filter highlighting in Document View
  - Added keyboard shortcuts for filter operations
  - Filter preferences now saved to project files
  - Added View menu with filter commands
