mod input;
mod picker;
mod runtime;
mod session;
mod workspace_input;

#[cfg(test)]
mod tests;

use std::io::Write;
use std::path::PathBuf;
use std::sync::mpsc::{Receiver, Sender};
use std::time::{Duration, Instant};

use anyhow::Result;
use crossterm::{
    event::{self, Event},
    execute,
    terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen},
};
use ratatui::{backend::CrosstermBackend, Terminal};

use crate::cli::DEFAULT_TASK_CONFIG_PATH;
use crate::model::{
    ControllerState, Plan, Screen, SessionEntry, SessionSelection, StatusSnapshot, TaskConfig,
    UsageSnapshot,
};
use crate::ui::{self, scroll::VerticalScrollState, SessionRenderRow, SessionView, SidebarView};

pub(crate) const USAGE_REFRESH_INTERVAL: Duration = Duration::from_secs(120);
pub(crate) const CREATE_MODELS: [&str; 4] = [
    "gpt-5.4",
    "gpt-5.4-mini",
    "gpt-5.3-codex",
    "gpt-5.3-codex-spark",
];
pub(crate) const CREATE_MENU_ROWS: usize = 3;
pub(crate) const PICKER_MENU_ROWS: usize = 3;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum PickerFocus {
    List,
    Settings,
}

#[derive(Debug, Clone)]
#[allow(clippy::large_enum_variant)]
pub enum AppEvent {
    Session(SessionEntry),
    Snapshot {
        goal_md: String,
        standards_md: String,
        plan: Plan,
        state: ControllerState,
    },
    CodexUsage {
        input_tokens: u64,
        output_tokens: u64,
    },
}

#[derive(Debug)]
pub enum ControlCommand {
    Submit(String),
    Pause,
    Resume,
    Stop,
    Quit,
}

pub(crate) struct WorkspaceRuntime {
    pub(crate) task_config: TaskConfig,
    pub(crate) goal_md: String,
    pub(crate) standards_md: String,
    pub(crate) plan: Plan,
    pub(crate) state: ControllerState,
    pub(crate) input: String,
    pub(crate) session_entries: Vec<SessionEntry>,
    pub(crate) event_rx: Receiver<AppEvent>,
    pub(crate) control_tx: Sender<ControlCommand>,
    pub(crate) session_input_tokens: Option<u64>,
    pub(crate) session_output_tokens: Option<u64>,
    pub(crate) usage_snapshot: UsageSnapshot,
    pub(crate) last_usage_refresh: Instant,
    pub(crate) session_follow_output: bool,
    pub(crate) session_scrollbar: VerticalScrollState,
    pub(crate) session_rows: Vec<SessionRenderRow>,
    pub(crate) session_view: Option<SessionView>,
    pub(crate) session_view_area: ratatui::layout::Rect,
    pub(crate) sidebar_follow_output: bool,
    pub(crate) sidebar_scrollbar: VerticalScrollState,
    pub(crate) sidebar_view: Option<SidebarView>,
    pub(crate) sidebar_view_area: ratatui::layout::Rect,
    pub(crate) session_selection: Option<SessionSelection>,
    pub(crate) session_drag_active: bool,
}

pub struct App {
    pub screen: Screen,
    pub picker_items: Vec<crate::model::ControllerSummary>,
    pub picker_selected: usize,
    pub picker_focus: PickerFocus,
    pub picker_menu_selected: usize,
    pub picker_model_index: usize,
    pub picker_fast_mode: bool,
    pub picker_allow_branching: bool,
    pub create_input: String,
    pub create_model_index: usize,
    pub create_menu_selected: usize,
    pub create_fast_mode: bool,
    pub create_allow_branching: bool,
    pub create_error: Option<String>,
    pub default_task_path: PathBuf,
    pub(crate) frame_tick: u64,
    pub(crate) workspace: Option<WorkspaceRuntime>,
}

impl App {
    pub fn bootstrap(task_path: Option<PathBuf>) -> Result<Self> {
        let default_task_path = PathBuf::from(DEFAULT_TASK_CONFIG_PATH);
        let mut app = Self {
            screen: Screen::ControllerPicker,
            picker_items: Vec::new(),
            picker_selected: 0,
            picker_focus: PickerFocus::List,
            picker_menu_selected: 0,
            picker_model_index: 0,
            picker_fast_mode: false,
            picker_allow_branching: false,
            create_input: String::new(),
            create_model_index: 0,
            create_menu_selected: 0,
            create_fast_mode: false,
            create_allow_branching: false,
            create_error: None,
            default_task_path: default_task_path.clone(),
            frame_tick: 0,
            workspace: None,
        };

        if let Some(task_path) = task_path {
            app.open_workspace_from_task_file(task_path)?;
        } else {
            app.refresh_picker()?;
        }

        Ok(app)
    }

    pub fn run(&mut self) -> Result<()> {
        enable_raw_mode()?;
        let mut stdout = std::io::stdout();
        execute!(
            stdout,
            EnterAlternateScreen,
            crossterm::event::EnableMouseCapture
        )?;
        let backend = CrosstermBackend::new(stdout);
        let mut terminal = Terminal::new(backend)?;

        let result = self.run_loop(&mut terminal);

        self.shutdown_runtime();
        disable_raw_mode()?;
        execute!(
            terminal.backend_mut(),
            crossterm::event::DisableMouseCapture,
            LeaveAlternateScreen
        )?;
        terminal.show_cursor()?;

        result
    }

    pub fn workspace_status_snapshot(&self) -> Option<StatusSnapshot> {
        let workspace = self.workspace.as_ref()?;
        Some(StatusSnapshot {
            controller_id: workspace.task_config.controller_id(),
            branch: if workspace.state.allow_branching {
                workspace.task_config.branch.clone()
            } else {
                "current".to_string()
            },
            started_at: workspace.state.started_at.clone(),
            phase: workspace.state.phase.clone(),
            iteration: workspace.state.iteration,
            session_input_tokens: workspace.session_input_tokens,
            session_output_tokens: workspace.session_output_tokens,
            usage: workspace.usage_snapshot.clone(),
        })
    }

    pub(crate) fn create_model(&self) -> &'static str {
        CREATE_MODELS
            .get(self.create_model_index)
            .copied()
            .unwrap_or(CREATE_MODELS[0])
    }

    pub(crate) fn picker_model(&self) -> &'static str {
        CREATE_MODELS
            .get(self.picker_model_index)
            .copied()
            .unwrap_or(CREATE_MODELS[0])
    }

    pub(crate) fn selected_picker_controller_id(&self) -> Option<&str> {
        self.picker_items
            .get(self.picker_selected)
            .map(|controller| controller.id.as_str())
    }

    pub(crate) fn shift_create_model(&mut self, delta: isize) {
        let len = CREATE_MODELS.len() as isize;
        let next = (self.create_model_index as isize + delta).rem_euclid(len);
        self.create_model_index = next as usize;
    }

    pub(crate) fn toggle_create_fast_mode(&mut self) {
        self.create_fast_mode = !self.create_fast_mode;
    }

    pub(crate) fn toggle_create_allow_branching(&mut self) {
        self.create_allow_branching = !self.create_allow_branching;
    }

    pub(crate) fn move_create_menu_selection(&mut self, delta: isize) {
        let next = (self.create_menu_selected as isize + delta)
            .clamp(0, (CREATE_MENU_ROWS.saturating_sub(1)) as isize);
        self.create_menu_selected = next as usize;
    }

    pub(crate) fn shift_picker_model(&mut self, delta: isize) {
        let len = CREATE_MODELS.len() as isize;
        let next = (self.picker_model_index as isize + delta).rem_euclid(len);
        self.picker_model_index = next as usize;
    }

    pub(crate) fn toggle_picker_fast_mode(&mut self) {
        self.picker_fast_mode = !self.picker_fast_mode;
    }

    pub(crate) fn toggle_picker_allow_branching(&mut self) {
        self.picker_allow_branching = !self.picker_allow_branching;
    }

    pub(crate) fn move_picker_menu_selection(&mut self, delta: isize) {
        let next = (self.picker_menu_selected as isize + delta)
            .clamp(0, (PICKER_MENU_ROWS.saturating_sub(1)) as isize);
        self.picker_menu_selected = next as usize;
    }

    pub(crate) fn reset_picker_menu(&mut self) {
        self.picker_focus = PickerFocus::List;
        self.picker_menu_selected = 0;
    }

    pub(crate) fn reset_create_form(&mut self) {
        self.create_input.clear();
        self.create_model_index = 0;
        self.create_menu_selected = 0;
        self.create_fast_mode = false;
        self.create_allow_branching = false;
        self.create_error = None;
    }

    pub(crate) fn reset_picker_form(&mut self) {
        self.picker_focus = PickerFocus::List;
        self.picker_menu_selected = 0;
        self.picker_model_index = 0;
        self.picker_fast_mode = false;
        self.picker_allow_branching = false;
    }

    pub(crate) fn sync_picker_settings_from_selected_controller(&mut self) {
        let Some(controller) = self.picker_items.get(self.picker_selected) else {
            self.reset_picker_form();
            return;
        };

        self.picker_model_index = CREATE_MODELS
            .iter()
            .position(|model| *model == controller.run_model)
            .unwrap_or(0);
        self.picker_fast_mode = controller.fast_mode;
        self.picker_allow_branching = controller.allow_branching;
        self.picker_menu_selected = 0;
        self.picker_focus = PickerFocus::List;
    }

    pub(crate) fn workspace(&self) -> Option<&WorkspaceRuntime> {
        self.workspace.as_ref()
    }

    pub(crate) fn workspace_input(&self) -> Option<&str> {
        self.workspace
            .as_ref()
            .map(|workspace| workspace.input.as_str())
    }

    pub(crate) fn workspace_session_selection(&self) -> Option<&SessionSelection> {
        self.workspace
            .as_ref()
            .and_then(|workspace| workspace.session_selection.as_ref())
    }

    pub(crate) fn workspace_session_rows(&self) -> Option<&[SessionRenderRow]> {
        self.workspace
            .as_ref()
            .map(|workspace| workspace.session_rows.as_slice())
    }

    pub(crate) fn workspace_session_view(&self) -> Option<&SessionView> {
        self.workspace
            .as_ref()
            .and_then(|workspace| workspace.session_view.as_ref())
    }

    pub(crate) fn workspace_sidebar_view(&self) -> Option<&SidebarView> {
        self.workspace
            .as_ref()
            .and_then(|workspace| workspace.sidebar_view.as_ref())
    }

    pub(crate) fn heartbeat_frame(&self) -> u64 {
        self.frame_tick
    }

    pub(crate) fn workspace_session_scroll(&self) -> usize {
        let Some(workspace) = self.workspace.as_ref() else {
            return 0;
        };

        let max_scroll = self
            .workspace_session_line_count()
            .saturating_sub(workspace.session_scrollbar.viewport_lines);
        if workspace.session_follow_output {
            max_scroll
        } else {
            workspace.session_scrollbar.position_lines.min(max_scroll)
        }
    }

    pub(crate) fn workspace_session_line_count(&self) -> usize {
        self.workspace
            .as_ref()
            .map(|workspace| workspace.session_scrollbar.content_lines)
            .unwrap_or_default()
    }

    fn run_loop(
        &mut self,
        terminal: &mut Terminal<CrosstermBackend<std::io::Stdout>>,
    ) -> Result<()> {
        loop {
            self.drain_workspace_events()?;
            self.maybe_refresh_usage()?;
            self.update_workspace_viewport(terminal.size()?.into());
            self.tick_session_scroll_repeat();
            self.frame_tick = self.frame_tick.wrapping_add(1);

            terminal.backend_mut().write_all(b"\x1b[?2026h")?;
            terminal.draw(|frame| ui::render(frame, self))?;
            terminal.backend_mut().write_all(b"\x1b[?2026l")?;
            terminal.backend_mut().flush()?;

            if event::poll(Duration::from_millis(50))? && self.handle_pending_events(terminal)? {
                break;
            }
        }

        Ok(())
    }

    fn handle_pending_events(
        &mut self,
        terminal: &mut Terminal<CrosstermBackend<std::io::Stdout>>,
    ) -> Result<bool> {
        loop {
            match event::read()? {
                Event::Key(key) => {
                    if self.handle_key(key)? {
                        return Ok(true);
                    }
                }
                Event::Mouse(mouse) => self.handle_mouse(mouse, terminal.size()?.into())?,
                Event::Resize(_, _) => self.update_workspace_viewport(terminal.size()?.into()),
                _ => {}
            }

            if !event::poll(Duration::ZERO)? {
                return Ok(false);
            }
        }
    }
}