//! World editor mode: state, rendering, and the editor pause menu.
//!
//! The editor is a separate top-level [`Mode`](crate::mode::Mode): it holds its
//! own freshly reloaded [`World`] and never ticks the game. The board is shown
//! with a blinking cursor (moved with the arrow keys or a right-click) and a
//! resizable right-hand sidebar that hosts the [menu tree](MenuLevel): a breadcrumb
//! title and letter-keyed choices that open [dialogs](kiln_ui::dialog) or descend into
//! sub-menus. `Esc` walks back up the tree, opening the overlay
//! [editor menu](editor_menu::editor_menu_items) at the root.

use crate::editor_menu;
use crate::editor_menu::{MenuEntry, MenuLevel};
use crate::log::{LogWidget, log_preview_line};
use crate::render::{BoardWidget, board_to_screen, screen_to_board};
use crate::ui::Ui;
use crate::utils::rgba8_to_color;
use kiln_core::cp437::tile_to_char;
use kiln_core::glyph::Glyph;
use kiln_core::log::LogLine;
use kiln_core::world::World;
use kiln_core::{Archetype, Board};
use kiln_ui::code_editor::{CodeEditor, CodeEditorOutcome};
use kiln_ui::dialog::{Dialog, DialogResult, ListDialogResponse};
use kiln_ui::glyph_dialog::GlyphDialog;
use ratatui::Frame;
use ratatui::crossterm::event::Event;
use ratatui::layout::{Constraint, Layout, Rect, Spacing};
use ratatui::style::{Color, Style};
use ratatui::symbols::merge::MergeStrategy;
use ratatui::text::{Line, Span};
use ratatui::widgets::{Block, Paragraph};
use std::cell::{Ref, RefMut};

/// How long each half of the cursor blink lasts, in seconds.
const BLINK_SECS: f32 = 0.5;
/// Default sidebar width in terminal columns (borders included).
const DEFAULT_SIDEBAR_WIDTH: u16 = 24;
/// Smallest width either the sidebar or the board may shrink to when resizing.
const MIN_PANEL_WIDTH: u16 = 8;
/// The cursor glyph: a solid full block (CP437 219) drawn in light gray.
const CURSOR_CHAR: char = '█';
/// Height (in rows) of the drawing-controls footer pinned to the sidebar bottom.
const DRAW_FOOTER_HEIGHT: u16 = 5;

/// All state for an active editing session.
///
/// Built by reloading the world file, so the running game has no bearing on what
/// the editor shows. Holds no [`GameState`](kiln_core::game::GameState) — editing
/// never ticks the game.
pub(crate) struct EditorState {
    /// The freshly reloaded world being edited.
    pub(crate) world: World,
    /// Key (in [`World::boards`]) of the board currently being edited.
    board_name: String,
    /// The sidebar menu navigation stack; the last element is the current level.
    /// Starts as `[MenuLevel::Main]` and is never emptied below that root.
    pub(crate) menu: Vec<MenuLevel>,
    /// The currently open dialog overlay, if any. While `Some`, the editor is in
    /// [`InputMode::Dialog`](crate::input::InputMode::Dialog).
    pub(crate) dialog: Option<Dialog<EditorState>>,
    /// The open script code editor, if any. While `Some` it replaces the board view and
    /// the editor is in [`InputMode::CodeEditor`](crate::input::InputMode::CodeEditor).
    pub(crate) code_editor: Option<CodeEditor>,
    /// The open glyph picker overlay, if any. While `Some` the editor is in
    /// [`InputMode::GlyphDialog`](crate::input::InputMode::GlyphDialog).
    pub(crate) glyph_dialog: Option<GlyphDialog<EditorState>>,
    /// Cursor position in board cells, clamped to the board bounds.
    cursor: (i32, i32),
    /// The archetype the drawing tools stamp on [`place_current`](EditorState::place_current).
    /// Defaults to [`Archetype::Wall`]; the UI to change it comes later.
    current_archetype: Archetype,
    /// The glyph the drawing tools stamp. Starts as the current archetype's default
    /// glyph and is edited via the glyph picker (`g`).
    current_glyph: Glyph,
    /// Whether draw mode is on: when set, moving the cursor stamps the current thing
    /// into each newly-entered cell (as if `space` were pressed after the move).
    draw_mode: bool,
    /// Width of the right-hand sidebar in terminal columns (mouse-resizable).
    sidebar_width: u16,
    /// Whether the blinking cursor is currently in its visible phase.
    blink_on: bool,
    /// Time accumulated toward the next blink toggle.
    blink_timer: f32,
    /// Inner board rect from the last [`draw_editor`] call, used to convert a
    /// right-click's screen position back to a board cell (written during render,
    /// read during input — the same pattern as `ScrollOverlayState::max_scroll`).
    last_board_area: Rect,
    /// Editor-side log lines (the editor has no game log to draw from).
    log: Vec<LogLine>,
}

impl EditorState {
    /// Builds an editor session for `world`, starting on its designated start board.
    pub(crate) fn new(world: World) -> Self {
        let board_name = world.start.clone();
        Self {
            world,
            board_name,
            menu: vec![MenuLevel::Main],
            dialog: None,
            code_editor: None,
            glyph_dialog: None,
            cursor: (0, 0),
            current_archetype: Archetype::Wall,
            current_glyph: Archetype::Wall.default_glyph(),
            draw_mode: false,
            sidebar_width: DEFAULT_SIDEBAR_WIDTH,
            blink_on: true,
            blink_timer: 0.0,
            last_board_area: Rect::default(),
            log: vec![LogLine::raw("editing — press [esc] for the menu")],
        }
    }

    /// The breadcrumb for the current menu path, e.g. `"World"` or `"World > Scripts"`.
    fn breadcrumb(&self) -> String {
        self.menu
            .iter()
            .map(|l| l.title())
            .collect::<Vec<_>>()
            .join(" > ")
    }

    /// The menu level currently shown in the sidebar (top of the stack).
    fn current_menu(&self) -> MenuLevel {
        *self.menu.last().expect("menu stack is never empty")
    }

    /// Handles `Esc` in the menu: pops to the parent level, or — at the root world
    /// menu — opens the existing overlay editor menu (Play / Quit / Resume).
    pub(crate) fn menu_escape(&mut self, ui: &mut Ui) {
        if self.menu.len() > 1 {
            self.menu.pop();
        } else {
            ui.open_menu(editor_menu::editor_menu_items());
        }
    }

    /// Dispatches a letter key against the current menu level: asks MenuLevel what it should
    /// do with the key, and passes an &mut EditorState to do it.
    pub(crate) fn menu_key(&mut self, c: char) {
        self.current_menu().perform_key(c, self);
    }

    /// Opens a text dialog to rename the world; OK writes [`World::name`].
    pub(crate) fn open_name_dialog(&mut self) {
        let current = self.world.name.clone();
        self.dialog = Some(Dialog::text(
            "World Name",
            current,
            |opt, ed: &mut EditorState| {
                if let Some(s) = opt {
                    ed.world.name = s;
                }
            },
        ));
    }

    /// Opens a list dialog to choose the entry board; selecting one writes [`World::start`].
    pub(crate) fn open_entry_dialog(&mut self) {
        let mut names: Vec<String> = self.world.boards.keys().cloned().collect();
        names.sort();
        self.dialog = Some(Dialog::list(
            "Entry Board",
            names,
            false,
            |resp, ed: &mut EditorState| {
                if let ListDialogResponse::Select(s) = resp {
                    ed.world.start = s;
                }
            },
        ));
    }

    /// Opens a list dialog of the world's scripts; selecting one opens it in the code editor.
    pub(crate) fn open_scripts_dialog(&mut self) {
        let mut names: Vec<String> = self.world.scripts.keys().cloned().collect();
        names.sort();
        self.dialog = Some(Dialog::list(
            "Scripts",
            names,
            true,
            |resp, ed: &mut EditorState| match resp {
                ListDialogResponse::Select(name) | ListDialogResponse::Create(name) => {
                    let source = ed.world.scripts.get(&name).cloned().unwrap_or_default();
                    ed.code_editor = Some(CodeEditor::new(&name, &source));
                }
                ListDialogResponse::Cancel => {}
            },
        ));
    }

    /// Closes the code editor, saving its text back into the in-memory script pool
    /// (mirrors how the Name/Entry-board dialogs mutate the loaded `World`).
    pub(crate) fn close_script_editor(&mut self) {
        if let Some(editor) = self.code_editor.take() {
            self.world
                .scripts
                .insert(editor.name().to_string(), editor.text());
        }
    }

    /// Opens a list dialog of the world's boards. Select-only for now (no side effect).
    pub(crate) fn open_boards_dialog(&mut self) {
        let mut names: Vec<String> = self.world.boards.keys().cloned().collect();
        names.sort();
        self.dialog = Some(Dialog::list(
            "Boards",
            names,
            false,
            |_resp, _ed: &mut EditorState| {},
        ));
    }

    /// Opens the glyph picker seeded from the current drawing glyph. On OK the chosen
    /// glyph becomes the new drawing glyph (used by subsequent placements).
    pub(crate) fn open_glyph_picker(&mut self) {
        self.glyph_dialog = Some(GlyphDialog::new(
            "Glyph",
            self.current_glyph,
            |chosen, ed: &mut EditorState| {
                if let Some(g) = chosen {
                    ed.current_glyph = g;
                }
            },
        ));
    }

    /// Stamps the current drawing thing (archetype + glyph) into the cell under the
    /// cursor, applying the placement rules (see [`Board::place_archetype`]).
    pub(crate) fn place_current(&mut self) {
        let (x, y) = (self.cursor.0 as usize, self.cursor.1 as usize);
        let (arch, glyph) = (self.current_archetype, self.current_glyph);
        self.board_mut().place_archetype(x, y, arch, glyph);
    }

    /// Toggles draw mode (whether cursor movement auto-stamps the current thing).
    pub(crate) fn toggle_draw_mode(&mut self) {
        self.draw_mode = !self.draw_mode;
        if self.draw_mode {
            self.place_current()
        }
    }

    /// Borrows the board currently being edited.
    pub(crate) fn board(&self) -> Ref<'_, Board> {
        self.world.boards[&self.board_name].borrow()
    }

    /// Mutably borrows the board currently being edited.
    pub(crate) fn board_mut(&self) -> RefMut<'_, Board> {
        self.world.boards[&self.board_name].borrow_mut()
    }

    /// Advances the cursor blink by `dt` seconds (the editor's only animation).
    pub(crate) fn tick(&mut self, dt: f32) {
        self.blink_timer += dt;
        if self.blink_timer >= BLINK_SECS {
            self.blink_timer -= BLINK_SECS;
            self.blink_on = !self.blink_on;
        }
    }

    /// Moves the cursor by `(dx, dy)`, clamped to the board bounds. When draw mode is
    /// on and the cursor lands on a new cell, stamps the current thing there.
    pub(crate) fn move_cursor(&mut self, dx: i32, dy: i32) {
        let (w, h) = {
            let b = self.board();
            (b.width as i32, b.height as i32)
        };
        let before = self.cursor;
        self.cursor.0 = (self.cursor.0 + dx).clamp(0, w - 1);
        self.cursor.1 = (self.cursor.1 + dy).clamp(0, h - 1);
        if self.draw_mode && self.cursor != before {
            self.place_current();
        }
    }

    /// Moves the cursor to the cell under a screen position, if it lands on the
    /// board (right-click handling). No-op when the click is off the board. When draw
    /// mode is on and the cursor lands on a new cell, stamps the current thing there.
    pub(crate) fn set_cursor_at_screen(&mut self, sx: u16, sy: u16) {
        let cell = screen_to_board(self.last_board_area, &self.board(), sx, sy);
        if let Some((bx, by)) = cell {
            let target = (bx as i32, by as i32);
            let moved = target != self.cursor;
            self.cursor = target;
            if self.draw_mode && moved {
                self.place_current();
            }
        }
    }

    /// Resizes the sidebar to `target` columns, clamped so neither the sidebar nor
    /// the board can shrink below [`MIN_PANEL_WIDTH`] (mirrors [`LogState::resize`]).
    pub(crate) fn resize_sidebar(&mut self, target: u16, total_w: u16) {
        let max = total_w.saturating_sub(MIN_PANEL_WIDTH).max(MIN_PANEL_WIDTH);
        self.sidebar_width = target.clamp(MIN_PANEL_WIDTH, max);
    }
}

/// Handles an input event while a dialog is open ([`InputMode::Dialog`](crate::input::InputMode::Dialog)).
///
/// Forwards the event to the dialog; on `Submit`/`Cancel` it takes the dialog out of
/// [`EditorState::dialog`] (so the callback receives an un-borrowed `&mut EditorState`)
/// and fires the callback via [`Dialog::finish`].
pub(crate) fn handle_dialog_input(event: Event, ed: &mut EditorState) {
    let Some(dialog) = ed.dialog.as_mut() else {
        return;
    };
    match dialog.handle_event(&event) {
        DialogResult::Continue => {}
        result => {
            let dialog = ed.dialog.take().expect("dialog present");
            dialog.finish(result, ed);
        }
    }
}

/// Handles an input event while the glyph picker is open ([`InputMode::GlyphDialog`](crate::input::InputMode::GlyphDialog)).
///
/// Mirrors [`handle_dialog_input`]: forwards to the picker and, on `Submit`/`Cancel`,
/// takes it out of [`EditorState::glyph_dialog`] and fires its callback via
/// [`GlyphDialog::finish`].
pub(crate) fn handle_glyph_dialog_input(event: Event, ed: &mut EditorState) {
    let Some(dialog) = ed.glyph_dialog.as_mut() else {
        return;
    };
    match dialog.handle_event(&event) {
        DialogResult::Continue => {}
        result => {
            let dialog = ed.glyph_dialog.take().expect("glyph dialog present");
            dialog.finish(result, ed);
        }
    }
}

/// Handles an input event while the code editor is open ([`InputMode::CodeEditor`](crate::input::InputMode::CodeEditor)).
///
/// Forwards key/mouse events to the editor; on `Exit` (Esc) it closes and saves the script.
pub(crate) fn handle_code_editor_input(event: Event, ed: &mut EditorState) {
    let Some(editor) = ed.code_editor.as_mut() else {
        return;
    };
    if let CodeEditorOutcome::Exit = editor.handle_event(&event) {
        ed.close_script_editor();
    }
}

/// Renders the editor: the board (with a blinking cursor and coordinate readout),
/// the right-hand sidebar, and — when open — the bottom log panel spanning the
/// full width (board and sidebar sit side-by-side above it).
pub(crate) fn draw_editor(frame: &mut Frame, ed: &mut EditorState, ui: &mut Ui) {
    let (board_area, sidebar_area, log_area) = editor_layout(frame.area(), ui, ed.sidebar_width);

    // ── Board area: the open script editor, else the board with its cursor ────
    if let Some(editor) = ed.code_editor.as_mut() {
        // A script is being edited: the code editor takes the board's place.
        editor.draw(frame, board_area);
    } else {
        let inner = {
            let board = ed.board();
            // Title carries the board name (top-left) and live cursor coords (top-right).
            let mut block = Block::bordered()
                .title(format!(" {} ", board.name))
                .title_top(
                    Line::from(format!(" ({}, {}) ", ed.cursor.0, ed.cursor.1)).right_aligned(),
                )
                .merge_borders(MergeStrategy::Exact);
            // When the log is closed, preview the latest line in the bottom border.
            if log_area.is_none() {
                block = block.title_bottom(log_preview_line(&ed.log).left_aligned());
            }
            let inner = block.inner(board_area);
            frame.render_widget(block, board_area);
            frame.render_widget(BoardWidget::new(&board), inner);

            // Overlay the cursor during its visible phase (a light-gray solid block).
            if ed.blink_on {
                let (cx, cy) = (ed.cursor.0 as usize, ed.cursor.1 as usize);
                if let Some((sx, sy)) = board_to_screen(inner, &board, cx, cy)
                    && let Some(cell) = frame.buffer_mut().cell_mut((sx, sy))
                {
                    cell.set_char(CURSOR_CHAR)
                        .set_fg(Color::Rgb(180, 180, 180))
                        .set_bg(Color::Black);
                }
            }
            inner
        };
        // Record the board rect for right-click hit-testing (board borrow now dropped).
        ed.last_board_area = inner;
    }

    // ── Sidebar: the current menu (breadcrumb title + letter-keyed choices) ───
    let sb_block = Block::bordered()
        .title(format!(" {} ", ed.breadcrumb()))
        .merge_borders(MergeStrategy::Exact);
    let sb_inner = sb_block.inner(sidebar_area);
    frame.render_widget(sb_block, sidebar_area);
    // One line per item (`[k] Label`); an item with a current value (e.g. the
    // world name) gets a second, indented line beneath it in a distinct color.
    // Blank/Separator entries render as spacers to group items.
    let key_style = Style::default().fg(Color::Rgb(150, 200, 255));
    let label_style = Style::default().fg(Color::White);
    let value_style = Style::default().fg(Color::Rgb(200, 180, 120));
    let sep_style = Style::default().fg(Color::DarkGray);
    let mut lines: Vec<Line> = Vec::new();
    for entry in ed.current_menu().entries() {
        match entry {
            MenuEntry::Item { key, label, .. } => {
                lines.push(Line::from(vec![
                    Span::styled(format!("[{}] ", key), key_style),
                    Span::styled(label, label_style),
                ]));
            }
            MenuEntry::Blank => lines.push(Line::from("")),
            // A horizontal rule spanning the sidebar's inner width.
            MenuEntry::Separator => lines.push(Line::from(Span::styled(
                "─".repeat(sb_inner.width as usize),
                sep_style,
            ))),
            MenuEntry::CurrentValue(val_f) => {
                let val = val_f(ed);
                lines.push(Line::from(Span::styled(format!("    {val}"), value_style)));
            }
        }
    }
    lines.push(Line::from(""));
    lines.push(Line::from(Span::styled(
        "[esc] menu",
        Style::default().fg(Color::DarkGray),
    )));
    // Split the sidebar: the menu fills the top, the drawing-controls footer (the
    // current thing being drawn) is pinned to the bottom regardless of menu level.
    let [menu_area, footer_area] =
        Layout::vertical([Constraint::Min(0), Constraint::Length(DRAW_FOOTER_HEIGHT)])
            .areas(sb_inner);
    frame.render_widget(Paragraph::new(lines), menu_area);
    frame.render_widget(
        Paragraph::new(draw_footer_lines(ed, key_style, label_style, sep_style)),
        footer_area,
    );

    // ── Log panel (full width, below board + sidebar) ─────────────────────────
    if let Some(log_area) = log_area {
        frame.render_stateful_widget(LogWidget::new(&ed.log), log_area, &mut ui.log);
    }
}

/// Builds the drawing-controls footer: the current archetype name, the glyph control
/// (label + a live preview of the current drawing glyph), and the place / draw-mode
/// key hints. Shown at the bottom of the sidebar regardless of the open menu level.
fn draw_footer_lines<'a>(
    ed: &EditorState,
    key_style: Style,
    label_style: Style,
    sep_style: Style,
) -> Vec<Line<'a>> {
    // A one-cell preview of the current glyph in its own fg/bg colors.
    let preview = Span::styled(
        tile_to_char(ed.current_glyph.tile).to_string(),
        Style::default()
            .fg(rgba8_to_color(ed.current_glyph.fg))
            .bg(rgba8_to_color(ed.current_glyph.bg)),
    );
    vec![
        // Separator marking off the footer from the menu above.
        Line::from(Span::styled("─".repeat(64), sep_style)),
        // The archetype currently being drawn (no UI to change it yet).
        Line::from(Span::styled(ed.current_archetype.name(), label_style)),
        Line::from(vec![
            Span::styled("[g] ", key_style),
            Span::styled("Glyph ", label_style),
            preview,
        ]),
        Line::from(vec![
            Span::styled("[spc] ", key_style),
            Span::styled("Place", label_style),
        ]),
        Line::from(vec![
            Span::styled("[tab] ", key_style),
            Span::styled(
                format!("Draw mode ({})", if ed.draw_mode { "on" } else { "off" }),
                label_style,
            ),
        ]),
    ]
}

/// Computes the board / sidebar / optional-log rects for the editor.
///
/// When the log is open the screen splits vertically first (so the log spans the
/// full width), then the top region splits horizontally into board + sidebar.
/// When closed, only the horizontal board/sidebar split applies. `Overlap(1)`
/// makes adjacent panels share their dividing border.
fn editor_layout(area: Rect, ui: &Ui, sidebar_width: u16) -> (Rect, Rect, Option<Rect>) {
    let split_h = |top: Rect| {
        Layout::horizontal([Constraint::Min(3), Constraint::Length(sidebar_width)])
            .spacing(Spacing::Overlap(1))
            .areas::<2>(top)
    };
    if ui.log.open {
        let [top, log_area] =
            Layout::vertical([Constraint::Min(3), Constraint::Length(ui.log.height)])
                .spacing(Spacing::Overlap(1))
                .areas(area);
        let [board_area, sidebar_area] = split_h(top);
        (board_area, sidebar_area, Some(log_area))
    } else {
        let [board_area, sidebar_area] = split_h(area);
        (board_area, sidebar_area, None)
    }
}