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

print("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 "--",
    }
    print(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
    }
    print(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
        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

    print(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()
                print(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
        bind_key(key, func)
    end

    -- Run setup function
    mode.setup()

    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
    print(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
        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
        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
        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)
    print(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()
        print("[lua-mode] Lua mode activated")
    end,

    cleanup = function()
        print("[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()
        print("[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
        print("[auto-save-mode] Auto-save enabled")
    end,

    cleanup = function()
        print("[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()
        print("[line-numbers-mode] Line numbers enabled")
    end,

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

-- Custom command: Save buffer
bind_key("C-s", function()
    local buf = editor.buffer
    if buf:save() then
        message("Buffer saved: " .. buf:name())
    else
        message("Failed to save buffer")
    end
end)

-- Custom command: Insert timestamp
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)
    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)
    message("Jumped to line " .. line_num)
end

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

    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
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
        message("Found '" .. query .. "' at " .. res.start.line .. ":" .. res.start.column)
        -- Optional: Highlight the found range?
    else
        message("'" .. query .. "' not found")
    end
end

-- Example binding: Find "TODO"
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
        message("Already at first line")
        return
    end

    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)
    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
        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)
    message("Swapped line down")
end

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

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

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

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

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

-- Command Mode (Minibuffer)
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
bind_key("C-@", function()
    local buf = editor.buffer
    local cursor = editor.cursor
    buf:set_mark(cursor)
    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
bind_key("C-x C-x", function()
    local buf = editor.buffer
    local mark = buf:mark()

    if not mark then
        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
    message("Mark and point exchanged")
end)

-- C-x h (mark-whole-buffer) - Select entire buffer
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)
    message("Buffer marked")
end)

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

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

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

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

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

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

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

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

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

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

-- Manual re-highlight key (re-applies current major mode's highlighting)
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

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

-- Mode information and control
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"
    message(string.format("Major: %s | Minor: %s", mode_name, minor_str))
end)

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

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

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

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

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

-- Test control keys (ncurses versions)
bind_key("C-k", function()
    message("C-k pressed! (Control key working with ncurses)")
end)

bind_key("C-s", function()
    local buf = editor.buffer
    if buf:save() then
        message("Buffer saved with C-s (ncurses)!")
    else
        message("Failed to save buffer")
    end
end)

-- Welcome message
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()