use ratatui::crossterm::event::{Event, KeyCode, MouseEventKind};
use kiln_core::Direction;
use kiln_core::game::{GameState, ScrollLine};
use crate::resolve_choice;
use crate::scroll_overlay::ScrollAnimState;
use crate::ui::Ui;

/// Which input mode the front-end is currently in.
pub enum InputMode {
    /// Normal gameplay: arrow keys move the player, `l` toggles the log.
    /// The `bool` is whether the log panel is open (affects PageUp/Down and mouse).
    Board(bool),
    /// A scroll overlay is active; all input is captured for scroll navigation.
    Scroll,
}

/// Determines the current input mode from game and UI state.
pub(crate) fn current_input_mode(game: &GameState, ui: &Ui) -> InputMode {
    let scroll_active = game.active_scroll.is_some()
        && !matches!(ui.overlay.anim, Some(ScrollAnimState::Closing(_) | ScrollAnimState::Done));
    if scroll_active { InputMode::Scroll } else { InputMode::Board(ui.log.open) }
}

/// Handles an input event in [`InputMode::Board`]. Returns `true` if the player quit.
pub(crate) fn handle_board_input(event: Event, log_open: bool, terminal_h: u16, game: &mut GameState, ui: &mut Ui) -> bool {
    match event {
        Event::Key(key) => match key.code {
            KeyCode::Char('q') | KeyCode::Esc => return true,
            KeyCode::Up    => game.try_move(Direction::North),
            KeyCode::Down  => game.try_move(Direction::South),
            KeyCode::Left  => game.try_move(Direction::West),
            KeyCode::Right => game.try_move(Direction::East),
            KeyCode::Char('l') => ui.log.toggle(),
            KeyCode::PageUp   if log_open => ui.log.scroll_by(-5, game.log.len()),
            KeyCode::PageDown if log_open => ui.log.scroll_by(5, game.log.len()),
            _ => {}
        },
        Event::Mouse(m) if log_open => match m.kind {
            MouseEventKind::ScrollUp   => ui.log.scroll_by(-1, game.log.len()),
            MouseEventKind::ScrollDown => ui.log.scroll_by(1, game.log.len()),
            MouseEventKind::Drag(_) => {
                // The divider sits at row `total - height`; dragging up grows the panel.
                let target = terminal_h.saturating_sub(m.row);
                ui.log.resize(target, terminal_h);
            }
            _ => {}
        },
        _ => {}
    }
    false
}

/// Handles an input event in [`InputMode::Scroll`].
pub(crate) fn handle_scroll_input(event: Event, game: &mut GameState, ui: &mut Ui) {
    match event {
        Event::Key(key) => {
            let scroll = game.active_scroll.as_ref().unwrap();
            let has_choices = scroll.lines.iter().any(|l| matches!(l, ScrollLine::Choice { .. }));
            match key.code {
                // Esc dismisses only when there are no choices; with choices the player must select.
                KeyCode::Esc if !has_choices => ui.begin_close(None),
                KeyCode::Up   => ui.scroll_lines(-1),
                KeyCode::Down => ui.scroll_lines(1),
                KeyCode::Char(c) => {
                    if let Some(ch) = resolve_choice(&scroll.lines, c) {
                        ui.begin_close(Some(ch));
                    }
                }
                _ => {}
            }
        }
        Event::Mouse(m) => match m.kind {
            MouseEventKind::ScrollUp   => ui.scroll_lines(-1),
            MouseEventKind::ScrollDown => ui.scroll_lines(1),
            _ => {}
        },
        _ => {}
    }
}