use ratatui::{
    prelude::*,
    widgets::{Block, Borders, List, ListItem, Paragraph, Tabs},
};

use crate::config::Config;
use crate::session::store::StateStore;
use crate::session::{Session, SessionState};

pub struct Dashboard {
    db: StateStore,
    cfg: Config,
    sessions: Vec<Session>,
    selected_pane: Pane,
    selected_session: usize,
    show_help: bool,
    scroll_offset: usize,
}

#[derive(Debug, Clone, Copy, PartialEq)]
enum Pane {
    Sessions,
    Output,
    Metrics,
}

impl Dashboard {
    pub fn new(db: StateStore, cfg: Config) -> Self {
        let sessions = db.list_sessions().unwrap_or_default();
        Self {
            db,
            cfg,
            sessions,
            selected_pane: Pane::Sessions,
            selected_session: 0,
            show_help: false,
            scroll_offset: 0,
        }
    }

    pub fn render(&self, frame: &mut Frame) {
        let chunks = Layout::default()
            .direction(Direction::Vertical)
            .constraints([
                Constraint::Length(3), // Header
                Constraint::Min(10),   // Main content
                Constraint::Length(3), // Status bar
            ])
            .split(frame.area());

        self.render_header(frame, chunks[0]);

        if self.show_help {
            self.render_help(frame, chunks[1]);
        } else {
            let main_chunks = Layout::default()
                .direction(Direction::Horizontal)
                .constraints([
                    Constraint::Percentage(35), // Session list
                    Constraint::Percentage(65), // Output/details
                ])
                .split(chunks[1]);

            self.render_sessions(frame, main_chunks[0]);

            let right_chunks = Layout::default()
                .direction(Direction::Vertical)
                .constraints([
                    Constraint::Percentage(70), // Output
                    Constraint::Percentage(30), // Metrics
                ])
                .split(main_chunks[1]);

            self.render_output(frame, right_chunks[0]);
            self.render_metrics(frame, right_chunks[1]);
        }

        self.render_status_bar(frame, chunks[2]);
    }

    fn render_header(&self, frame: &mut Frame, area: Rect) {
        let running = self
            .sessions
            .iter()
            .filter(|s| s.state == SessionState::Running)
            .count();
        let total = self.sessions.len();

        let title = format!(" ECC 2.0 | {running} running / {total} total ");
        let tabs = Tabs::new(vec!["Sessions", "Output", "Metrics"])
            .block(Block::default().borders(Borders::ALL).title(title))
            .select(match self.selected_pane {
                Pane::Sessions => 0,
                Pane::Output => 1,
                Pane::Metrics => 2,
            })
            .highlight_style(
                Style::default()
                    .fg(Color::Cyan)
                    .add_modifier(Modifier::BOLD),
            );

        frame.render_widget(tabs, area);
    }

    fn render_sessions(&self, frame: &mut Frame, area: Rect) {
        let items: Vec<ListItem> = self
            .sessions
            .iter()
            .enumerate()
            .map(|(i, s)| {
                let state_icon = match s.state {
                    SessionState::Running => "●",
                    SessionState::Idle => "○",
                    SessionState::Completed => "✓",
                    SessionState::Failed => "✗",
                    SessionState::Stopped => "■",
                    SessionState::Pending => "◌",
                };
                let style = if i == self.selected_session {
                    Style::default()
                        .fg(Color::Cyan)
                        .add_modifier(Modifier::BOLD)
                } else {
                    Style::default()
                };
                let text = format!(
                    "{state_icon} {} [{}] {}",
                    &s.id[..8.min(s.id.len())],
                    s.agent_type,
                    s.task
                );
                ListItem::new(text).style(style)
            })
            .collect();

        let border_style = if self.selected_pane == Pane::Sessions {
            Style::default().fg(Color::Cyan)
        } else {
            Style::default()
        };

        let list = List::new(items).block(
            Block::default()
                .borders(Borders::ALL)
                .title(" Sessions ")
                .border_style(border_style),
        );
        frame.render_widget(list, area);
    }

    fn render_output(&self, frame: &mut Frame, area: Rect) {
        let content = if let Some(session) = self.sessions.get(self.selected_session) {
            format!(
                "Agent output for session {}...\n\n(Live streaming coming soon)",
                session.id
            )
        } else {
            "No sessions. Press 'n' to start one.".to_string()
        };

        let border_style = if self.selected_pane == Pane::Output {
            Style::default().fg(Color::Cyan)
        } else {
            Style::default()
        };

        let paragraph = Paragraph::new(content).block(
            Block::default()
                .borders(Borders::ALL)
                .title(" Output ")
                .border_style(border_style),
        );
        frame.render_widget(paragraph, area);
    }

    fn render_metrics(&self, frame: &mut Frame, area: Rect) {
        let content = if let Some(session) = self.sessions.get(self.selected_session) {
            let m = &session.metrics;
            format!(
                "Tokens: {} | Tools: {} | Files: {} | Cost: ${:.4} | Duration: {}s",
                m.tokens_used, m.tool_calls, m.files_changed, m.cost_usd, m.duration_secs
            )
        } else {
            "No metrics available".to_string()
        };

        let border_style = if self.selected_pane == Pane::Metrics {
            Style::default().fg(Color::Cyan)
        } else {
            Style::default()
        };

        let paragraph = Paragraph::new(content).block(
            Block::default()
                .borders(Borders::ALL)
                .title(" Metrics ")
                .border_style(border_style),
        );
        frame.render_widget(paragraph, area);
    }

    fn render_status_bar(&self, frame: &mut Frame, area: Rect) {
        let text = " [n]ew session  [s]top  [Tab] switch pane  [j/k] scroll  [?] help  [q]uit ";
        let paragraph = Paragraph::new(text)
            .style(Style::default().fg(Color::DarkGray))
            .block(Block::default().borders(Borders::ALL));
        frame.render_widget(paragraph, area);
    }

    fn render_help(&self, frame: &mut Frame, area: Rect) {
        let help = vec![
            "Keyboard Shortcuts:",
            "",
            "  n       New session",
            "  s       Stop selected session",
            "  Tab     Next pane",
            "  S-Tab   Previous pane",
            "  j/↓     Scroll down",
            "  k/↑     Scroll up",
            "  r       Refresh",
            "  ?       Toggle help",
            "  q/C-c   Quit",
        ];

        let paragraph = Paragraph::new(help.join("\n")).block(
            Block::default()
                .borders(Borders::ALL)
                .title(" Help ")
                .border_style(Style::default().fg(Color::Yellow)),
        );
        frame.render_widget(paragraph, area);
    }

    pub fn next_pane(&mut self) {
        self.selected_pane = match self.selected_pane {
            Pane::Sessions => Pane::Output,
            Pane::Output => Pane::Metrics,
            Pane::Metrics => Pane::Sessions,
        };
    }

    pub fn prev_pane(&mut self) {
        self.selected_pane = match self.selected_pane {
            Pane::Sessions => Pane::Metrics,
            Pane::Output => Pane::Sessions,
            Pane::Metrics => Pane::Output,
        };
    }

    pub fn scroll_down(&mut self) {
        if self.selected_pane == Pane::Sessions && !self.sessions.is_empty() {
            self.selected_session = (self.selected_session + 1).min(self.sessions.len() - 1);
        } else {
            self.scroll_offset = self.scroll_offset.saturating_add(1);
        }
    }

    pub fn scroll_up(&mut self) {
        if self.selected_pane == Pane::Sessions {
            self.selected_session = self.selected_session.saturating_sub(1);
        } else {
            self.scroll_offset = self.scroll_offset.saturating_sub(1);
        }
    }

    pub fn new_session(&mut self) {
        // TODO: Open a dialog to create a new session
        tracing::info!("New session dialog requested");
    }

    pub fn stop_selected(&mut self) {
        if let Some(session) = self.sessions.get(self.selected_session) {
            let _ = self.db.update_state(&session.id, &SessionState::Stopped);
            self.refresh();
        }
    }

    pub fn refresh(&mut self) {
        self.sessions = self.db.list_sessions().unwrap_or_default();
    }

    pub fn toggle_help(&mut self) {
        self.show_help = !self.show_help;
    }

    pub async fn tick(&mut self) {
        // Periodic refresh every few ticks
        self.sessions = self.db.list_sessions().unwrap_or_default();
    }
}