# Phase 2: Buffer Management - COMPLETE! ✅

## Overview

Phase 2 implementation is complete! Lumacs now supports full buffer management, allowing you to work with multiple files effectively. The editor has jumped from **~55% to ~70% Emacs compatibility**.

## What Was Implemented

### 1. Buffer Switching (C-x b) ⭐⭐⭐

**Efficiently switch between open buffers.**

- **Command:** `C-x b` (switch-to-buffer)
- **Features:**
  - Minibuffer prompt
  - **Tab Completion:** Cycle through available buffer names
  - Auto-activates major mode for the switched buffer
  - Displays progress (e.g., `[1/3]`) when cycling

### 2. Buffer List (C-x C-b) ⭐⭐⭐

**View and manage all open buffers.**

- **Command:** `C-x C-b` (list-buffers)
- **Features:**
  - Opens a read-only `*Buffer List*` buffer
  - Shows: Modification status (`*`), Buffer Name, Size (lines), and File Path
  - Formatted in columns for readability
  - Refreshes content on every invocation

### 3. Safe Buffer Killing (C-x k) ⭐⭐⭐

**Close buffers safely.**

- **Command:** `C-x k` (kill-buffer)
- **Features:**
  - Minibuffer prompt with tab completion
  - **Safety Check:** Warns if the buffer is modified (`Buffer modified! Kill anyway? (y/n)`)
  - Prevents closing the last buffer (keeps at least one open)
  - Automatically switches windows displaying the killed buffer to another buffer

## Architecture Changes

### C++ Core (`src/`, `include/lumacs/`)
- **Buffer Class:** Added `clear()` method to efficiently empty a buffer (exposed to Lua).
- **EditorCore:** 
  - Added `get_buffer_names()`, `get_buffer_by_name()`, `switch_buffer_in_window()`, `close_buffer()`, `get_all_buffer_info()`.
  - Implemented logic to handle buffer closing safety.
- **NcursesEditor (`src/main_ncurses.cpp`):**
  - Added input modes: `BufferSwitch`, `KillBuffer`, `ConfirmKill`.
  - Implemented generic tab completion logic for minibuffer.
  - Added visual feedback for modes in status line.

### Lua Configuration (`init.lua`)
- Bound `C-x b`, `C-x k`, `C-x C-b` to new functionality.
- Implemented `C-x C-b` formatting logic in Lua using `get_all_buffer_info` and `Buffer:clear()`.

## Testing

### Manual Verification:
1. **Switch Buffer:** Open multiple files (`./build/lumacs file1 file2`). Use `C-x b` to switch. Press Tab to cycle.
2. **List Buffers:** Press `C-x C-b`. Check the `*Buffer List*` content. Modify a buffer and check for `*` marker.
3. **Kill Buffer:**
   - Kill an unmodified buffer (`C-x k` -> Name -> Enter). It should close immediately.
   - Modify a buffer. Try to kill it. Check for warning prompt `(y/n)`.
   - Press `n`: Cancelled.
   - Press `y`: Buffer closed.

### Unit Tests:
- Added `Buffer_Clear` test to `tests/test_buffer.cpp` to verify `Buffer::clear()` functionality.

## Keybinding Summary

| Key | Command | Description |
|-----|---------|-------------|
| `C-x b` | switch-to-buffer | Switch to another buffer (Tab completion) |
| `C-x C-b` | list-buffers | List all open buffers |
| `C-x k` | kill-buffer | Close current or specified buffer |

## Emacs Compatibility Progress

**Before Phase 2:** ~55/100
**After Phase 2:** ~70/100 ✅

We now have:
✅ Working Minibuffer with completion
✅ Multiple buffer management
✅ Safety mechanisms (modified check)
✅ Buffer list visualization

## What's Next: Phase 3

Phase 3 focuses on **Enhanced Editing**:
1. **Word operations** (M-d, M-DEL, M-t)
2. **Case conversion** (M-u, M-l, M-c)
3. **Comment/Uncomment** (M-;)
4. **Incremental Search** (C-s, C-r)