-- Lumacs Configuration File
-- This file is executed on startup and allows you to customize keybindings,
-- create commands, and extend the editor with Lua.

-- Lumacs Configuration File
-- This file is executed on startup and allows you to customize keybindings,
-- create commands, and extend the editor with Lua.

-- editor:message("Loading init.lua...")

-- ============================================================================
-- MODE SYSTEM (Emacs-style Major and Minor Modes)
-- ============================================================================

-- Mode registries
local major_modes = {}
local minor_modes = {}

-- Active modes per buffer (keyed by buffer name)
local buffer_major_modes = {}
local buffer_minor_modes = {}

-- Define a major mode
function define_major_mode(name, config)
    major_modes[name] = {
        name = name,
        file_patterns = config.file_patterns or {},
        setup = config.setup or function() end,
        cleanup = config.cleanup or function() end,
        highlight = config.highlight or nil,
        keybindings = config.keybindings or {},
        comment_syntax = config.comment_syntax or "--",
    }
    editor:message(string.format("[Mode] Registered major mode: %s", name))
end

-- Define a minor mode
function define_minor_mode(name, config)
    minor_modes[name] = {
        name = name,
        setup = config.setup or function() end,
        cleanup = config.cleanup or function() end,
        keybindings = config.keybindings or {},
        global = config.global or false, -- If true, applies to all buffers
    }
    editor:message(string.format("[Mode] Registered minor mode: %s", name))
end

-- Activate a major mode for the current buffer
function activate_major_mode(mode_name)
    local buf = editor.buffer
    local buf_name = buf:name()
    local mode = major_modes[mode_name]

    if not mode then
        editor:message("Unknown major mode: " .. mode_name)
        return false
    end

    -- Deactivate current major mode if any
    if buffer_major_modes[buf_name] then
        deactivate_major_mode()
    end

    editor:message(string.format("[Mode] Activating major mode '%s' for buffer '%s'", mode_name, buf_name))

    -- Store active mode
    buffer_major_modes[buf_name] = mode_name

    -- Set up event handler for auto-highlighting
    if mode.highlight then
        buf:on_buffer_event(function(event_data)
            local current_buf = editor.buffer
            if event_data.event == lumacs.BufferEvent.Loaded or
               event_data.event == lumacs.BufferEvent.LanguageChanged then
                mode.highlight()
                editor:message(string.format("[Mode] Auto-highlighted buffer with %s", mode_name))
            end
        end)

        -- Highlight immediately
        mode.highlight()
    end

    -- Apply mode-specific keybindings (these are temporary for this buffer)
    for key, func in pairs(mode.keybindings) do
        editor:bind_key(key, func)
    end

    -- Run setup function
    mode.setup()

    editor:message(string.format("Major mode: %s", mode_name))
    return true
end

-- Deactivate current major mode
function deactivate_major_mode()
    local buf = editor.buffer
    local buf_name = buf:name()
    local mode_name = buffer_major_modes[buf_name]

    if not mode_name then
        return
    end

    local mode = major_modes[mode_name]
    if mode and mode.cleanup then
        mode.cleanup()
    end

    buffer_major_modes[buf_name] = nil
    editor:message(string.format("[Mode] Deactivated major mode '%s'", mode_name))
end

-- Toggle a minor mode
function toggle_minor_mode(mode_name)
    local buf = editor.buffer
    local buf_name = buf:name()
    local mode = minor_modes[mode_name]

    if not mode then
        editor:message("Unknown minor mode: " .. mode_name)
        return
    end

    -- Initialize minor modes table for this buffer
    if not buffer_minor_modes[buf_name] then
        buffer_minor_modes[buf_name] = {}
    end
    local is_active = buffer_minor_modes[buf_name][mode_name]



    if is_active then
        -- Deactivate
        if mode.cleanup then
            mode.cleanup()
        end
        buffer_minor_modes[buf_name][mode_name] = nil
        editor:message(string.format("Minor mode disabled: %s", mode_name))
    else
        -- Activate
        buffer_minor_modes[buf_name][mode_name] = true
        if mode.setup then
            mode.setup()
        end
        editor:message(string.format("Minor mode enabled: %s", mode_name))
    end
end

-- Auto-detect and activate major mode based on file extension
function auto_activate_major_mode()
    local buf = editor.buffer
    local buf_name = buf:name()

    -- Try to match file pattern
    for mode_name, mode in pairs(major_modes) do
        for _, pattern in ipairs(mode.file_patterns) do
            if string.match(buf_name, pattern) then
                activate_major_mode(mode_name)
                return
            end
        end
    end

    -- No match, use fundamental mode (default)
    editor:message(string.format("[Mode] No major mode matched for '%s', using fundamental-mode", buf_name))
end

-- Get current major mode name
function current_major_mode()
    local buf = editor.buffer
    local buf_name = buf:name()
    return buffer_major_modes[buf_name] or "fundamental-mode"
end

-- ============================================================================
-- MAJOR MODES
-- ============================================================================

-- Lua Mode
define_major_mode("lua-mode", {
    file_patterns = {"%.lua$"},
    comment_syntax = "--",

    highlight = function()
        local buf = editor.buffer
        buf:clear_styles()

        -- Keywords to highlight
        local keywords = {
            "function", "local", "end", "if", "then", "else", "elseif",
            "for", "while", "do", "return", "break", "and", "or", "not",
            "true", "false", "nil", "in", "repeat", "until"
        }

        -- Highlight each line
        for line_num = 0, buf:line_count() - 1 do
            local line_text = buf:line(line_num)

            -- Highlight keywords
            for _, keyword in ipairs(keywords) do
                local start_pos = 1
                while true do
                    local pattern = "%f[%w]" .. keyword .. "%f[%W]"
                    local pos = string.find(line_text, pattern, start_pos)
                    if not pos then break end

                    local range = lumacs.Range(
                        lumacs.Position(line_num, pos - 1),
                        lumacs.Position(line_num, pos + #keyword - 1)
                    )

                    buf:set_style(range, lumacs.TextAttribute(lumacs.ColorType.Keyword, 0))
                    start_pos = pos + #keyword
                end
            end

            -- Highlight strings
            local start_pos = 1
            while true do
                local quote_start = string.find(line_text, '"', start_pos, true)
                if not quote_start then break end

                local quote_end = string.find(line_text, '"', quote_start + 1, true)
                if not quote_end then break end

                local range = lumacs.Range(
                    lumacs.Position(line_num, quote_start - 1),
                    lumacs.Position(line_num, quote_end)
                )

                buf:set_style(range, lumacs.TextAttribute(lumacs.ColorType.String, 0))
                start_pos = quote_end + 1
            end

            -- Highlight comments
            local comment_pos = string.find(line_text, "--", 1, true)
            if comment_pos then
                local range = lumacs.Range(
                    lumacs.Position(line_num, comment_pos - 1),
                    lumacs.Position(line_num, #line_text)
                )

                buf:set_style(range, lumacs.TextAttribute(lumacs.ColorType.Comment, 0))
            end
        end
    end,

    setup = function()
        editor:message("[lua-mode] Lua mode activated")
    end,

    cleanup = function()
        editor:message("[lua-mode] Lua mode deactivated")
    end,

    keybindings = {
        -- Lua-specific keybindings can go here
    }
})

-- Fundamental Mode (default/fallback)
define_major_mode("fundamental-mode", {
    file_patterns = {},

    setup = function()
        editor:message("[fundamental-mode] Fundamental mode activated")
    end
})

-- ============================================================================
-- MINOR MODES
-- ============================================================================

-- Auto-save minor mode
define_minor_mode("auto-save-mode", {
    global = false,

    setup = function()
        -- TODO: Set up auto-save timer
        editor:message("[auto-save-mode] Auto-save enabled")
    end,

    cleanup = function()
        editor:message("[auto-save-mode] Auto-save disabled")
    end
})

-- Line numbers minor mode (conceptual - already always shown)
define_minor_mode("line-numbers-mode", {
    global = true,

    setup = function()
        editor:message("[line-numbers-mode] Line numbers enabled")
    end,

    cleanup = function()
        editor:message("[line-numbers-mode] Line numbers disabled")
    end
})

-- ============================================================================
-- GLOBAL KEYBINDINGS
-- ============================================================================

-- Example: Custom keybindings
-- Syntax: editor:bind_key("key", function() ... end)

-- Basic Editing Commands (moved from C++ fallback)
function lumacs_insert_newline()
    local cursor = editor.cursor
    editor.buffer:insert_newline(cursor)
    editor:set_cursor(lumacs.Position(cursor.line + 1, 0))
end
editor:bind_key("Return", lumacs_insert_newline)
editor:register_command("insert-newline", "Insert a new line at cursor position.", lumacs_insert_newline, true)

function lumacs_backward_delete_char()
    local cursor_original = editor.cursor

    -- If at (0,0), nothing to delete before it.
    if cursor_original.column == 0 and cursor_original.line == 0 then
        return
    end

    -- Call erase_char with the current cursor position.
    -- erase_char will internally delete the char at (pos.column - 1).
    editor.buffer:erase_char(cursor_original) 
    
    -- The cursor position should be adjusted *after* the erase.
    -- This is the same logic as before, calculating the new cursor position.
    local new_cursor_pos = cursor_original
    if new_cursor_pos.column > 0 then
        new_cursor_pos = lumacs.Position(new_cursor_pos.line, new_cursor_pos.column - 1)
    elseif new_cursor_pos.line > 0 then
        -- If line was joined, new cursor is at end of previous line.
        local prev_line_len = #editor.buffer:line(new_cursor_pos.line - 1)
        new_cursor_pos = lumacs.Position(new_cursor_pos.line - 1, prev_line_len)
    end
    editor.cursor = new_cursor_pos
end
editor:bind_key("Backspace", lumacs_backward_delete_char)
editor:register_command("backward-delete-char", "Delete the character before cursor.", lumacs_backward_delete_char, true)

editor:bind_key("C-m", lumacs_backward_delete_char)
editor:register_command("backward-delete-char", "Delete the character before cursor.", lumacs_backward_delete_char, true)

function lumacs_delete_char()
    local cursor = editor.cursor
    editor.buffer:erase_char(lumacs.Position(cursor.line, cursor.column + 1))
end
editor:bind_key("Delete", lumacs_delete_char)
editor:register_command("delete-char", "Delete the character at cursor position.", lumacs_delete_char, true)

-- Navigation Commands (explicitly bound arrow keys)
editor:bind_key("ArrowUp", function() editor:move_up() end)
editor:bind_key("ArrowDown", function() editor:move_down() end)
editor:bind_key("ArrowLeft", function() editor:move_left() end)
editor:bind_key("ArrowRight", function() editor:move_right() end)

editor:bind_key("Home", function() editor:move_to_line_start() end)
editor:bind_key("End", function() editor:move_to_line_end() end)

-- Generic self-insert command for printable characters
-- This command is special; it's called by the C++ core if no other binding matches a printable char.
function self_insert_command(args)
    local char_to_insert = args[1]
    if not char_to_insert then return end

    local cursor = editor.cursor
    editor.buffer:insert(cursor, char_to_insert)
    editor:move_right()
end
editor:register_command("self-insert-command", "Insert the character pressed.", self_insert_command, true)

-- Emacs-style navigation (Ctrl+N/P for next/previous line)
editor:bind_key("C-n", function()
    editor:move_down()
    editor:message("Moved down")
end)

editor:bind_key("C-p", function()
    editor:move_up()
    editor:message("Moved up")
end)

editor:bind_key("C-f", function()
    editor:move_right()
end)

editor:bind_key("C-b", function()
    editor:move_left()
end)

-- Emacs-style line navigation
editor:bind_key("C-a", function()
    editor:move_to_line_start()
end)

editor:bind_key("C-e", function()
    editor:move_to_line_end()
end)

-- M-f (forward-word) - Move forward one word
editor:bind_key("M-f", function()
    editor:move_forward_word()
end)

-- M-b (backward-word) - Move backward one word
editor:bind_key("M-b", function()
    editor:move_backward_word()
end)

-- C-v (scroll-up) - Page down
editor:bind_key("C-v", function()
    editor:page_down()
end)

-- M-v (scroll-down) - Page up
editor:bind_key("M-v", function()
    editor:page_up()
end)

-- M-< (beginning-of-buffer) - Go to start
editor:bind_key("M-<", function()
    editor:goto_beginning()
    editor:message("Beginning of buffer")
end)

-- M-> (end-of-buffer) - Go to end
editor:bind_key("M->", function()
    editor:goto_end()
    editor:message("End of buffer")
end)

-- M-g M-g (goto-line) - Jump to line number
editor:bind_key("M-g g", function()
    editor:command_mode()
    -- TODO: Implement line number input in command mode
end)

-- Note: C-s binding moved to avoid conflicts with isearch

-- Custom command: Insert timestamp
editor:bind_key("C-t", function()
    local cursor_pos = editor.cursor
    local timestamp = os.date("%Y-%m-%d %H:%M:%S")
    editor.buffer:insert(cursor_pos, timestamp)
    editor:message("Inserted timestamp")
end)

-- Example: Helper functions you can define
function goto_line(line_num)
    local pos = lumacs.Position(line_num - 1, 0)
    editor:set_cursor(pos)
    editor:message("Jumped to line " .. line_num)
end

-- Example: Buffer inspection
function buffer_info()
    local buf = editor.buffer
    local cursor = editor.cursor

    editor:message(string.format(
        "Buffer: %s | Lines: %d | Cursor: %d,%d | Modified: %s",
        buf:name(),
        buf:line_count(),
        cursor.line + 1,
        cursor.column + 1,
        buf:is_modified() and "yes" or "no"
    ))
end

-- Bind to show buffer info
-- Note: C-i and Tab are indistinguishable in most terminals (both send ASCII 9)
-- Using C-u instead for buffer info
editor:bind_key("C-u", buffer_info)

-- Search helper function
function find_next(query)
    local buf = editor.buffer
    local cursor = editor.cursor
    -- Start searching AFTER the current cursor position to find the next occurrence
    -- Otherwise we might find the same one if we are sitting on it.
    -- A simple way is to advance column by 1 for the search start.
    local search_start = lumacs.Position(cursor.line, cursor.column + 1)

    -- If at end of line, search from start of next line is handled by find() implementation?
    -- Buffer::find currently implements simple linear search from a position.
    -- If column is beyond end, it should handle it. Let's trust the C++ impl or adjust.

    local res = buf:find(query, search_start)
    if res then
        editor.cursor = res.start
        editor:message("Found '" .. query .. "' at " .. res.start.line .. ":" .. res.start.column)
        -- Optional: Highlight the found range?
    else
        editor:message("'" .. query .. "' not found")
    end
end

-- Example binding: Find "TODO"
editor:bind_key("C-o", function() find_next("TODO") end)

-- Line swapping functions (like Emacs M-up/down or VS Code Alt+arrows)
function swap_line_up()
    local buf = editor.buffer
    local cursor = editor.cursor

    -- Can't move first line up
    if cursor.line == 0 then
        editor:message("Already at first line")
        return
    end

    editor:message("DEBUG: Starting swap_line_up, cursor at line " .. cursor.line)

    -- Get the current line and above line text
    local current_line = buf:line(cursor.line)
    local above_line = buf:line(cursor.line - 1)

    -- Strategy: Replace both lines with them swapped
    -- Delete from start of line above to end of current line (not including next line)
    local delete_start = lumacs.Position(cursor.line - 1, 0)
    local delete_end = lumacs.Position(cursor.line, string.len(current_line))

    local range = lumacs.Range(delete_start, delete_end)
    buf:erase(range)

    -- Insert them back in swapped order
    -- Add extra newline if above_line is empty to preserve it
    local insert_pos = lumacs.Position(cursor.line - 1, 0)
    local text = current_line .. "\n" .. above_line
    if above_line == "" then
        text = text .. "\n"
    end
    buf:insert(insert_pos, text)

    -- Move cursor up to follow the line
    editor.cursor = lumacs.Position(cursor.line - 1, cursor.column)
    editor:message("Swapped line up")
end

function swap_line_down()
    local buf = editor.buffer
    local cursor = editor.cursor

    -- Can't move last line down
    if cursor.line >= buf:line_count() - 1 then
        editor:message("Already at last line")
        return
    end

    -- Get the current line and the line below
    local current_line = buf:line(cursor.line)
    local below_line = buf:line(cursor.line + 1)

    -- Strategy: Replace both lines with them swapped
    -- Delete from start of current line to end of line below (not including line after)
    local delete_start = lumacs.Position(cursor.line, 0)
    local delete_end = lumacs.Position(cursor.line + 1, string.len(below_line))
    local range = lumacs.Range(delete_start, delete_end)
    buf:erase(range)

    -- Insert them back in swapped order
    -- Add extra newline if current_line is empty to preserve it
    local insert_pos = lumacs.Position(cursor.line, 0)
    local text = below_line .. "\n" .. current_line
    if current_line == "" then
        text = text .. "\n"
    end
    buf:insert(insert_pos, text)

    -- Move cursor down to follow the line
    editor.cursor = lumacs.Position(cursor.line + 1, cursor.column)
    editor:message("Swapped line down")
end

-- Bind to M-ArrowUp and M-ArrowDown (Meta/Alt + arrows)
editor:bind_key("M-ArrowUp", swap_line_up)
editor:bind_key("M-ArrowDown", swap_line_down)

-- ============================================================================
-- WINDOW MANAGEMENT
-- ============================================================================

-- Split horizontal (like Emacs C-x 2, simplified to M-2)
editor:bind_key("M-2", function()
    editor:split_horizontally()
    editor:message("Split horizontally")
end)

-- Split vertical (like Emacs C-x 3, simplified to M-3)
editor:bind_key("M-3", function()
    editor:split_vertically()
    editor:message("Split vertically")
end)

-- Close window (like Emacs C-x 0, simplified to M-0)
editor:bind_key("M-0", function()
    editor:close_window()
    editor:message("Closed window")
end)

-- Command Mode (Minibuffer)
editor:bind_key("M-x", function()
    editor:command_mode()
end)

-- ============================================================================
-- MARK AND REGION (Emacs-style selection)
-- ============================================================================

-- C-@ or C-SPC (set-mark-command) - Set the mark at cursor
editor:bind_key("C-@", function()
    local buf = editor.buffer
    local cursor = editor.cursor
    buf:set_mark(cursor)
    editor:message("Mark set")
end)

-- For terminals that don't support C-@, also bind to C-SPC (but C-SPC is hard to detect)
-- Most terminals send C-@ for C-SPC, so the above should work

-- C-x C-x (exchange-point-and-mark) - Swap cursor and mark
editor:bind_key("C-x C-x", function()
    local buf = editor.buffer
    local mark = buf.mark

    if not mark then
        editor:message("No mark set")
        return
    end

    local cursor = editor.cursor
    buf:set_mark(cursor)  -- Set mark at old cursor position
    editor.cursor = mark  -- Move cursor to old mark position
    editor:message("Mark and point exchanged")
end)

-- C-x h (mark-whole-buffer) - Select entire buffer
editor:bind_key("C-x h", function()
    local buf = editor.buffer
    -- Set mark at beginning
    buf:set_mark(lumacs.Position(0, 0))
    -- Move cursor to end
    local last_line = buf:line_count() - 1
    local last_col = #buf:line(last_line)
    editor.cursor = lumacs.Position(last_line, last_col)
    editor:message("Buffer marked")
end)

-- ============================================================================
-- KILL RING (Emacs cut/copy/paste)
-- ============================================================================

-- C-w (kill-region) - Cut selection
editor:bind_key("C-w", function()
    editor:kill_region()
end)

-- M-w (kill-ring-save) - Copy selection
editor:bind_key("M-w", function()
    editor:copy_region_as_kill()
end)

-- C-k (kill-line) - Cut from cursor to end of line
editor:bind_key("C-k", function()
    editor:kill_line()
    editor:message("Killed line")
end)

-- C-y (yank) - Paste
editor:bind_key("C-y", function()
    editor:yank()
end)

-- M-y (yank-pop) - Cycle through kill ring after yanking
editor:bind_key("M-y", function()
    editor:yank_pop()
end)

-- M-d (kill-word) - Kill word forward
editor:bind_key("M-d", function()
    editor:kill_word()
end)

-- M-Backspace (backward-kill-word) - Kill word backward
editor:bind_key("M-Backspace", function()
    editor:backward_kill_word()
end)

-- ============================================================================
-- UNDO/REDO
-- ============================================================================

-- C-/ or C-_ for undo (traditional Emacs binding)
editor:bind_key("C-/", function()
    if editor:undo() then
        editor:message("Undid change")
    else
        editor:message("Nothing to undo")
    end
end)

-- Also keep C-z for undo (common in other editors)
editor:bind_key("C-z", function()
    if editor:undo() then
        editor:message("Undid change")
    else
        editor:message("Nothing to undo")
    end
end)

-- C-x u for redo (less common but sometimes used)
editor:bind_key("C-x u", function()
    if editor:redo() then
        editor:message("Redid change")
    else
        editor:message("Nothing to redo")
    end
end)

-- Manual re-highlight key (re-applies current major mode's highlighting)
editor:bind_key("C-l", function()
    local mode_name = current_major_mode()
    local mode = major_modes[mode_name]

    if mode and mode.highlight then
        mode.highlight()

        -- Debug: Count applied styles
        local buf = editor.buffer
        local styles_count = 0
        for line = 0, buf:line_count() - 1 do
            local styles = buf:get_line_styles(line)
            styles_count = styles_count + #styles
        end

        editor:message(string.format("Re-highlighted with %s (%d styles)", mode_name, styles_count))
    else
        editor:message("Current mode has no highlighting: " .. mode_name)
    end
end)

-- Mode information and control
editor:bind_key("C-h m", function()
    local mode_name = current_major_mode()
    local buf = editor.buffer
    local buf_name = buf:name()

    -- Get active minor modes
    local minor_list = {}
    if buffer_minor_modes[buf_name] then
        for mode, _ in pairs(buffer_minor_modes[buf_name]) do
            table.insert(minor_list, mode)
        end
    end

    local minor_str = #minor_list > 0 and table.concat(minor_list, ", ") or "none"
    editor:message(string.format("Major: %s | Minor: %s", mode_name, minor_str))
end)

-- Test Escape key binding
editor:bind_key("Escape", function()
    editor:message("Escape pressed! (Direct binding works)")
end)

-- C-x sequence bindings (Emacs style)
editor:bind_key("C-x o", function()
    editor:next_window()
    editor:message("Switched window with C-x o")
end)

editor:bind_key("C-x 2", function()
    editor:split_horizontally()
    editor:message("Split horizontally with C-x 2")
end)

editor:bind_key("C-x 3", function()
    editor:split_vertically()
    editor:message("Split vertically with C-x 3")
end)

editor:bind_key("C-x 0", function()
    editor:close_window()
    editor:message("Closed window with C-x 0")
end)

-- ============================================================================
-- BUFFER MANAGEMENT (C-x b, C-x C-b, C-x k)
-- ============================================================================

-- C-x b: Switch to buffer (with tab completion)
editor:bind_key("C-x b", function()
    editor:buffer_switch_mode()
end)

-- C-x k: Kill buffer (with tab completion)
editor:bind_key("C-x k", function()
    editor:kill_buffer_mode()
end)

-- C-x C-b: List all buffers
editor:bind_key("C-x C-b", function()
    local buffer_info = editor:get_all_buffer_info()

    if #buffer_info == 0 then
        editor:message("No buffers open")
        return
    end

    -- Format buffer list
    local lines = {}
    table.insert(lines, "Buffer List:")
    table.insert(lines, "------------")
    table.insert(lines, "")
    table.insert(lines, string.format("% -3s % -20s % -10s %s", "Mod", "Name", "Size", "File"))
    table.insert(lines, string.format("% -3s % -20s % -10s %s", "---", "----"))

    for i, info in ipairs(buffer_info) do
        local modified = info.modified and " * " or "   "
        local filepath = ""
        if info.filepath then
            filepath = tostring(info.filepath)
        end

        local line = string.format("%s % -20s % -10d %s",
            modified,
            info.name,
            info.size,
            filepath
        )
        table.insert(lines, line)
    end

    local list_text = table.concat(lines, "\n")
    local list_buf_name = "*Buffer List*"

    -- Switch to or create buffer
    local list_buf = editor:get_buffer_by_name(list_buf_name)
    if list_buf then
        editor:switch_buffer_in_window(list_buf_name)
    else
        editor:new_buffer(list_buf_name)
    end

    local buf = editor.buffer
    buf:clear()
    buf:insert(lumacs.Position(0,0), list_text)
    editor:goto_beginning()

    editor:message(string.format("Buffer list (%d buffers)", #buffer_info))
end)

-- ============================================================================
-- CASE CONVERSION (M-u, M-l, M-c)
-- ============================================================================

-- M-u (upcase-word)
editor:bind_key("M-u", function()
    local start_pos = editor.cursor
    editor:move_forward_word()
    local end_pos = editor.cursor

    local range = lumacs.Range(start_pos, end_pos)
    local text = editor.buffer:get_text_in_range(range)

    if #text > 0 then
        editor.buffer:replace(range, string.upper(text))
    end
end)

-- M-l (downcase-word)
editor:bind_key("M-l", function()
    local start_pos = editor.cursor
    editor:move_forward_word()
    local end_pos = editor.cursor

    local range = lumacs.Range(start_pos, end_pos)
    local text = editor.buffer:get_text_in_range(range)

    if #text > 0 then
        editor.buffer:replace(range, string.lower(text))
    end
end)

-- M-c (capitalize-word)
editor:bind_key("M-c", function()
    local start_pos = editor.cursor
    editor:move_forward_word()
    local end_pos = editor.cursor

    local range = lumacs.Range(start_pos, end_pos)
    local text = editor.buffer:get_text_in_range(range)

    if #text > 0 then
        local cap_text = text:sub(1,1):upper() .. text:sub(2):lower()
        editor.buffer:replace(range, cap_text)
    end
end)

-- C-x C-u (upcase-region)
editor:bind_key("C-x C-u", function()
    local range = editor.buffer:get_region(editor.cursor)
    if not range then
        editor:message("No active region")
        return
    end

    local text = editor.buffer:get_text_in_range(range)
    if #text > 0 then
        editor.buffer:replace(range, string.upper(text))
        editor.buffer:deactivate_mark()
    end
end)

-- C-x C-l (downcase-region)
editor:bind_key("C-x C-l", function()
    local range = editor.buffer:get_region(editor.cursor)
    if not range then
        editor:message("No active region")
        return
    end

    local text = editor.buffer:get_text_in_range(range)
    if #text > 0 then
        editor.buffer:replace(range, string.lower(text))
        editor.buffer:deactivate_mark()
    end
end)

-- ============================================================================
-- COMMENTING (M- ;)
-- ============================================================================

function escape_pattern(text)
    return text:gsub("([^%w])", "%%%1")
end

function comment_dwim()
    local mode_name = current_major_mode()
    local mode = major_modes[mode_name]
    local prefix = mode and mode.comment_syntax or "--"
    local escaped_prefix = escape_pattern(prefix)

    local range = editor.buffer:get_region(editor.cursor)

    if range then
        -- Region handling
        local start_line = range.start.line
        local end_line = range["end"].line

        -- Check if all lines are commented
        local all_commented = true
        for i = start_line, end_line do
            local line = editor.buffer:line(i)
            -- Ignore empty lines for decision
            if #line > 0 and not string.match(line, "^%s*" .. escaped_prefix) then
                all_commented = false
                break
            end
        end

        -- Apply change
        for i = start_line, end_line do
            local line = editor.buffer:line(i)
            local line_range = lumacs.Range(lumacs.Position(i, 0), lumacs.Position(i, #line))

            if #line > 0 then
                if all_commented then
                    -- Uncomment
                    local s, e = string.find(line, escaped_prefix)
                    if s then
                        local suffix = line:sub(e+1)
                        if suffix:sub(1,1) == " " then suffix = suffix:sub(2) end
                        local new_line = line:sub(1, s-1) .. suffix
                        editor.buffer:replace(line_range, new_line)
                    end
                else
                    -- Comment (if not already commented)
                    if not string.match(line, "^%s*" .. escaped_prefix) then
                        local indent = string.match(line, "^%s*")
                        local content = line:sub(#indent + 1)
                        local new_line = indent .. prefix .. " " .. content
                        editor.buffer:replace(line_range, new_line)
                    end
                end
            end
        end

    else
        -- Single line
        local line_num = editor.cursor.line
        local line = editor.buffer:line(line_num)
        local line_range = lumacs.Range(lumacs.Position(line_num, 0), lumacs.Position(line_num, #line))

        if string.match(line, "^%s*" .. escaped_prefix) then
            -- Uncomment
            local s, e = string.find(line, escaped_prefix)
            if s then
                local suffix = line:sub(e+1)
                if suffix:sub(1,1) == " " then suffix = suffix:sub(2) end
                        local new_line = line:sub(1, s-1) .. suffix
                editor.buffer:replace(line_range, new_line)
            end
        else
            -- Comment
            local indent = string.match(line, "^%s*")
            local content = line:sub(#indent + 1)
            local new_line = indent .. prefix .. " " .. content
            editor.buffer:replace(line_range, new_line)
        end
    end
end

editor:bind_key("M-;", comment_dwim)

-- ============================================================================
-- REGISTERS (C-x r s, C-x r i)
-- ============================================================================

-- Helper function to prompt for register character
function get_register_char(prompt_msg)
    editor:message(prompt_msg)
    -- For now we'll use a simple approach - this would need UI integration
    -- In a full implementation, this would wait for a single character input
    -- For demo purposes, we'll use 'a' as default
    return 'a'
end

-- C-x r s (copy-to-register) - Save region to register
editor:bind_key("C-x r s", function()
    local register_char = get_register_char("Save to register:")
    editor:copy_region_to_register(register_char)
end)

-- C-x r i (insert-register) - Insert from register
editor:bind_key("C-x r i", function()
    local register_char = get_register_char("Insert register:")
    editor:yank_from_register(register_char)
end)

-- ============================================================================
-- RECTANGLES (C-x r k/y/t)
-- ============================================================================

-- C-x r k (kill-rectangle) - Cut rectangular region
editor:bind_key("C-x r k", function()
    editor:kill_rectangle()
end)

-- C-x r y (yank-rectangle) - Paste rectangular region
editor:bind_key("C-x r y", function()
    editor:yank_rectangle()
end)

-- C-x r t (string-rectangle) - Fill rectangle with text
editor:bind_key("C-x r t", function()
    -- For demo purposes, we'll fill with asterisks
    -- In a full implementation, this would prompt for text input
    editor:string_rectangle("*")
    editor:message("Rectangle filled with '*' - C-x r t demo")
end)

-- ============================================================================
-- KEYBOARD MACROS (F3, F4)
-- ============================================================================

-- F3 - start-kbd-macro
editor:bind_key("F3", function()
    editor:start_kbd_macro()
end)

-- F4 - end-kbd-macro or call-last-kbd-macro
editor:bind_key("F4", function()
    editor:end_kbd_macro_or_call()
end)

-- ============================================================================
-- INCREMENTAL SEARCH (C-s, C-r)
-- ============================================================================

-- C-s (save-buffer) - changed from isearch to save for now
editor:bind_key("C-s", function()
    local buf = editor.buffer
    if buf:save() then
        editor:message("Buffer saved: " .. buf:name())
    else
        editor:message("Failed to save buffer")
    end
end)

-- C-r (isearch-backward)
editor:bind_key("C-r", function()
    editor:isearch_backward_mode()
end)

-- Note: C-k and C-s already defined above, removed duplicates

-- ============================================================================
-- CONFIGURATION FUNCTIONS
-- ============================================================================

-- Toggle line numbers on/off
function toggle_line_numbers()
    local config = editor.config
    local current = config:get_bool("show_line_numbers", true)
    config:set("show_line_numbers", not current)

    if not current then
        editor:message("Line numbers enabled")
    else
        editor:message("Line numbers disabled")
    end
end

-- Set line number width
function set_line_number_width(width)
    editor.config:set("line_number_width", width)
    editor:message("Line number width set to " .. width)
end

-- Show current configuration
function show_config()
    local config = editor.config
    local show_nums = config:get_bool("show_line_numbers", true)
    local width = config:get_int("line_number_width", 6)
    editor:message(string.format("Line numbers: %s, Width: %d", show_nums and "on" or "off", width))
end

-- Toggle modeline (status bar for each window) function
function toggle_modeline()
    local current = editor.config:get_bool("show_modeline", true)
    editor.config:set_bool("show_modeline", not current)
    if current then
        editor:message("Modeline disabled")
    else
        editor:message("Modeline enabled")
    end
end

-- Bind configuration functions
editor:bind_key("C-x l", toggle_line_numbers)  -- C-x l to toggle line numbers
editor:bind_key("C-x m", toggle_modeline)      -- C-x m to toggle modeline
editor:bind_key("C-x C-c", function() editor:quit() end)  -- C-x C-c to quit
editor:bind_key("C-x C-s", show_config)        -- C-x C-s to show config

-- Load theme configuration
dofile("themes.lua")

-- Welcome message
editor:message("Lumacs ready! C-k=kill, C-y=yank, C-@=mark, C-w=cut, M-w=copy, M-f/b=word, C-v/M-v=page")

-- Auto-activate mode for initial buffer
auto_activate_major_mode()



-- File and Buffer Commands
editor:register_command("save-buffer", "Save current buffer", function(args)
    if editor.buffer:save() then
        editor:message("Saved " .. editor.buffer:name())
    else
        editor:message("Save failed")
    end
end, true, "b") -- "b" means prompt for existing buffer name

editor:register_command("find-file", "Find file", function(args)
    editor:find_file_mode()
end, true, "f") -- "f" means prompt for file name

editor:register_command("kill-buffer", "Kill buffer", function(args)
    editor:kill_buffer_mode()
end, true, "b")

editor:register_command("switch-buffer", "Switch buffer", function(args)
    editor:buffer_switch_mode()
end, true, "b")

-- Alias for switch-buffer to match Emacs expectations
editor:register_command("switch-to-buffer", "Switch buffer (Alias)", function(args)
    editor:buffer_switch_mode()
end, true, "b")

editor:register_command("list-buffers", "List all buffers", function(args)
    local buffer_info = editor:get_all_buffer_info()
    if #buffer_info == 0 then
        editor:message("No buffers open")
        return {success = true, message = "No buffers open"}
    end

    local lines = {}
    table.insert(lines, "Buffer List:")
    table.insert(lines, "------------")
    table.insert(lines, "")
    table.insert(lines, string.format("% -3s % -20s % -10s %s", "Mod", "Name", "Size", "File"))
    table.insert(lines, string.format("% -3s % -20s % -10s %s", "---", "----"))

    for i, info in ipairs(buffer_info) do
        local modified = info.modified and " * " or "   "
        local filepath = ""
        if info.filepath then filepath = tostring(info.filepath) end
        table.insert(lines, string.format("%s % -20s % -10d %s", modified, info.name, info.size, filepath))
    end

    local list_text = table.concat(lines, "\n")
    local list_buf_name = "*Buffer List*"
    local list_buf = editor:get_buffer_by_name(list_buf_name)
    if list_buf then
        editor:switch_buffer_in_window(list_buf_name)
    else
        editor:new_buffer(list_buf_name)
    end
    editor.buffer:clear()
    editor.buffer:insert(lumacs.Position(0,0), list_text)
    editor:goto_beginning()

    return {success = true, message = string.format("Buffer list (%d buffers)", #buffer_info)}
end, false) -- Not typically interactive through prompt


-- Navigation
editor:register_command("next-line", "Move cursor down", function() editor:move_down() end, true)
editor:register_command("previous-line", "Move cursor up", function() editor:move_up() end, true)
editor:register_command("forward-char", "Move cursor right", function() editor:move_right() end, true)
editor:register_command("backward-char", "Move cursor left", function() editor:move_left() end, true)
editor:register_command("forward-word", "Move forward one word", function() editor:move_forward_word() end, true)
editor:register_command("backward-word", "Move backward one word", function() editor:move_backward_word() end, true)
editor:register_command("beginning-of-buffer", "Go to beginning of buffer", function() editor:goto_beginning() end, true)
editor:register_command("end-of-buffer", "Go to end of buffer", function() editor:goto_end() end, true)
editor:register_command("scroll-up-command", "Page down", function() editor:page_down() end, true)
editor:register_command("scroll-down-command", "Page up", function() editor:page_up() end, true)

-- Window Management
editor:register_command("split-window-below", "Split window horizontally", function() editor:split_horizontally() end, true)
editor:register_command("split-window-right", "Split window vertically", function() editor:split_vertically() end, true)
editor:register_command("delete-window", "Close current window", function() editor:close_window() end, true)
editor:register_command("other-window", "Select other window", function() editor:next_window() end, true)
editor:register_command("delete-other-windows", "Delete all other windows", function()
    -- Simplified: keep closing others until only 1?
    -- Or just implement properly in C++ later.
    -- For now, assume users use C-x 1 if implemented?
    -- C-x 1 isn't implemented in init.lua yet.
    editor:message("delete-other-windows not implemented yet")
    return {success = false, message = "delete-other-windows not implemented yet"}
end, false)

-- Editing
editor:register_command("kill-line", "Kill rest of line", function() editor:kill_line() end, true)
editor:register_command("kill-region", "Kill selected region", function() editor:kill_region() end, true)
editor:register_command("copy-region-as-kill", "Copy region", function() editor:copy_region_as_kill() end, true)
editor:register_command("yank", "Paste from kill ring", function() editor:yank() end, true)
editor:register_command("undo", "Undo last change", function() if editor:undo() then editor:message("Undid") else editor:message("No undo") end end, true)
editor:register_command("redo", "Redo last undo", function() if editor:redo() then editor:message("Redid") else editor:message("No redo") end end, true)

-- Modes
editor:register_command("lua-mode", "Switch to Lua mode", function() activate_major_mode("lua-mode") end, true)
editor:register_command("fundamental-mode", "Switch to Fundamental mode", function() activate_major_mode("fundamental-mode") end, true)
editor:register_command("auto-save-mode", "Toggle auto-save", function() toggle_minor_mode("auto-save-mode") end, true)

editor:message("Commands loaded. Try M-x list-buffers")

-- ============================================================================
-- NEW COMMAND SYSTEM INTEGRATION
-- ============================================================================

-- Register additional commands with the new command system
editor:register_command("describe-mode", "Show current major and minor modes", function(args)
    local mode_name = current_major_mode()
    local buf = editor.buffer
    local buf_name = buf:name()

    local minor_list = {}
    if buffer_minor_modes[buf_name] then
        for mode, _ in pairs(buffer_minor_modes[buf_name]) do
            table.insert(minor_list, mode)
        end
    end

    local minor_str = #minor_list > 0 and table.concat(minor_list, ", ") or "none"
    return {success = true, message = string.format("Major: %s | Minor: %s", mode_name, minor_str)}
end, false)

editor:register_command("count-lines", "Count lines in buffer or region", function(args)
    local buf = editor.buffer
    local region = buf:get_region(editor.cursor)

    if region then
        local lines = region["end"].line - region.start.line + 1
        return {success = true, message = string.format("Region has %d lines", lines)}
    else
        local lines = buf:line_count()
        return {success = true, message = string.format("Buffer has %d lines", lines)}
    end
end, false)

editor:register_command("word-count", "Count words in buffer or region", function(args)
    local buf = editor.buffer
    local region = buf:get_region(editor.cursor)
    local text

    if region then
        text = buf:get_text_in_range(region)
    else
        text = buf:get_all_text()
    end

    local words = 0
    for word in text:gmatch("%S+") do
        words = words + 1
    end

    local target = region and "region" or "buffer"
    return {success = true, message = string.format("%s has %d words", target, words)}
end, false)

editor:register_command("goto-char", "Go to character position", function(args)
    if #args == 0 then
        return {success = false, message = "Character position required"}
    end

    local pos = tonumber(args[1])
    if not pos then
        return {success = false, message = "Invalid character position: " .. args[1]}
    end

    local buf = editor.buffer
    local text = buf:get_all_text()

    if pos < 1 or pos > #text then
        return {success = false, message = "Position out of range"}
    end

    -- Convert character position to line/column
    local line = 0
    local col = 0
    for i = 1, pos - 1 do
        if text:sub(i, i) == '\n' then
            line = line + 1
            col = 0
        else
            col = col + 1
        end
    end

    editor.cursor = lumacs.Position(line, col)
    return {success = true, message = string.format("Moved to character %d (line %d, column %d)", pos, line + 1, col + 1)}
end, true, "n")

editor:register_command("insert-date", "Insert current date", function(args)
    local cursor_pos = editor.cursor
    local timestamp = os.date("%Y-%m-%d")
    editor.buffer:insert(cursor_pos, timestamp)
    return {success = true, message = "Inserted current date"}
end, false)

editor:register_command("insert-datetime", "Insert current date and time", function(args)
    local cursor_pos = editor.cursor
    local timestamp = os.date("%Y-%m-%d %H:%M:%S")
    editor.buffer:insert(cursor_pos, timestamp)
    return {success = true, message = "Inserted current date and time"}
end, false)

editor:register_command("revert-buffer", "Reload buffer from file", function(args)
    local buf = editor.buffer
    local filepath = buf:filepath()

    if not filepath then
        return {success = false, message = "Buffer is not visiting a file"}
    end

    if buf:is_modified() then
        return {success = false, message = "Buffer has unsaved changes"}
    end

    if editor:load_file(filepath) then
        return {success = true, message = "Reverted " .. buf:name()}
    else
        return {success = false, message = "Failed to revert buffer"}
    end
end, false)

editor:register_command("rename-buffer", "Rename current buffer", function(args)
    if #args == 0 then
        return {success = false, message = "New buffer name required"}
    end

    local new_name = args[1]
    local buf = editor.buffer
    local old_name = buf:name()

    -- Check if name is already taken
    if editor:get_buffer_by_name(new_name) then
        return {success = false, message = "Buffer name already exists: " .. new_name}
    end

    buf:set_name(new_name)
    return {success = true, message = string.format("Renamed buffer '%s' to '%s'", old_name, new_name)}
end, true, "s") -- "s" means prompt for string

-- Development commands
editor:register_command("eval-expression", "Evaluate Lua expression", function(args)
    if #args == 0 then
        return {success = false, message = "Lua expression required"}
    end

    local expr = table.concat(args, " ")
    local func, err = load("return " .. expr)

    if not func then
        return {success = false, message = "Parse error: " .. err}
    end

    local success, result = pcall(func)
    if success then
        return {success = true, message = tostring(result)}
    else
        return {success = false, message = "Error: " .. tostring(result)}
    end
end, true, "s")

-- Example of how to define a custom command that changes theme based on time of day
editor:register_command("auto-theme", "Automatically set theme based on time of day", function(args)
    local hour = tonumber(os.date("%H"))
    local theme_name

    if hour >= 6 and hour < 18 then
        -- Daytime: use light theme
        theme_name = "gruvbox-light"
    elseif hour >= 18 and hour < 22 then
        -- Evening: use warm theme
        theme_name = "everforest-dark"
    else
        -- Night: use dark theme
        theme_name = "nord"
    end

    local success, message = editor:execute_command("set-theme", {theme_name})
    if success then
        return {success = true, message = string.format("Auto-selected %s theme for %d:00", theme_name, hour)}
    else
        return {success = false, message = "Failed to auto-select theme: " .. message}
    end
end, false)

editor:register_command("theme-demo", "Demonstrate theme switching", function(args)
    local themes = {"solarized-dark", "nord", "gruvbox-light", "dracula"}
    local demo_msg = "Theme demo - switching through: " .. table.concat(themes, ", ")

    -- This would ideally be enhanced with a timer to show themes in sequence
    -- For now, just switch to a demo theme
    local success, message = editor:execute_command("set-theme", {themes[1]})
    if success then
        return {success = true, message = demo_msg .. " (switched to " .. themes[1] .. ")"}
    else
        return {success = false, message = "Demo failed: " .. message}
    end
end, false)

-- ============================================================================
-- COMPLETION SYSTEM (Minibuffer Auto-Complete)
-- ============================================================================

-- Returns a list of completion candidates based on the current mode and input
function get_completion_candidates(mode_name, input)
    local candidates = {}

    if mode_name == "Command" then
        -- Command completion (M-x)
        for name, _ in pairs(lumacs.command_registry) do
            if name:find(input, 1, true) == 1 then -- Prefix match
                table.insert(candidates, name)
            end
        end
        table.sort(candidates)

    elseif mode_name == "BufferSwitch" or mode_name == "KillBuffer" then
        -- Buffer name completion
        local buffers = editor:get_buffer_names()
        for _, name in ipairs(buffers) do
            if name:find(input, 1, true) == 1 then -- Prefix match
                table.insert(candidates, name)
            end
        end
        table.sort(candidates)

    elseif mode_name == "FindFile" then
        -- File path completion (simple version)
        -- Note: Full file system completion is complex to do in pure Lua without bindings
        -- This is a placeholder or relies on a bound helper if available.
        -- For now, we'll return empty list or maybe just current directory files if exposed.
        -- Since we don't have 'ls' exposed, we can't do much here yet without C++ help.
    end

    return candidates
end