// main_screen.rs — F1 main view rendering
//
// The default four-pane layout: autonomous, conversation, tools, status bar.
// Contains draw_main (the App method), draw_conversation_pane, and draw_pane.

use ratatui::{
    layout::{Constraint, Direction, Layout, Rect},
    style::{Color, Modifier, Style},
    text::{Line, Span},
    widgets::{Block, Borders, Paragraph, Wrap},
    Frame,
    crossterm::event::{KeyCode, KeyEvent, KeyModifiers, MouseEvent, MouseEventKind, MouseButton},
};

use super::{
    ActivePane, App, HotkeyAction, Marker, PaneState, ScreenAction, ScreenView,
    new_textarea, screen_legend,
};
use crate::user::ui_channel::{UiMessage, StreamTarget};

pub(crate) struct InteractScreen {
    pub(crate) autonomous: PaneState,
    pub(crate) conversation: PaneState,
    pub(crate) tools: PaneState,
    pub(crate) textarea: tui_textarea::TextArea<'static>,
    pub(crate) input_history: Vec<String>,
    pub(crate) history_index: Option<usize>,
    pub(crate) active_pane: ActivePane,
    pub(crate) pane_areas: [Rect; 3],
    pub(crate) needs_assistant_marker: bool,
    pub(crate) turn_started: Option<std::time::Instant>,
    pub(crate) call_started: Option<std::time::Instant>,
    pub(crate) call_timeout_secs: u64,
}

impl InteractScreen {
    pub fn new() -> Self {
        Self {
            autonomous: PaneState::new(true),
            conversation: PaneState::new(true),
            tools: PaneState::new(false),
            textarea: new_textarea(vec![String::new()]),
            input_history: Vec::new(),
            history_index: None,
            active_pane: ActivePane::Conversation,
            pane_areas: [Rect::default(); 3],
            needs_assistant_marker: false,
            turn_started: None,
            call_started: None,
            call_timeout_secs: 60,
        }
    }

    /// Process a UiMessage — update pane state.
    pub fn handle_ui_message(&mut self, msg: &UiMessage, app: &mut App) {
        match msg {
            UiMessage::TextDelta(text, target) => match target {
                StreamTarget::Conversation => {
                    if self.needs_assistant_marker {
                        self.conversation.pending_marker = Marker::Assistant;
                        self.needs_assistant_marker = false;
                    }
                    self.conversation.current_color = Color::Reset;
                    self.conversation.append_text(text);
                }
                StreamTarget::Autonomous => {
                    self.autonomous.current_color = Color::Reset;
                    self.autonomous.append_text(text);
                }
            },
            UiMessage::UserInput(text) => {
                self.conversation.push_line_with_marker(text.clone(), Color::Cyan, Marker::User);
                self.turn_started = Some(std::time::Instant::now());
                self.needs_assistant_marker = true;
                app.status.turn_tools = 0;
            }
            UiMessage::ToolCall { name, args_summary } => {
                app.status.turn_tools += 1;
                let line = if args_summary.is_empty() { format!("[{}]", name) }
                    else { format!("[{}] {}", name, args_summary) };
                self.tools.push_line(line, Color::Yellow);
            }
            UiMessage::ToolResult { result, .. } => {
                for line in result.lines() {
                    self.tools.push_line(format!("  {}", line), Color::DarkGray);
                }
                self.tools.push_line(String::new(), Color::Reset);
            }
            UiMessage::DmnAnnotation(text) => {
                self.autonomous.push_line(text.clone(), Color::Yellow);
                self.turn_started = Some(std::time::Instant::now());
                self.needs_assistant_marker = true;
                app.status.turn_tools = 0;
            }
            UiMessage::StatusUpdate(info) => {
                if !info.dmn_state.is_empty() {
                    app.status.dmn_state = info.dmn_state.clone();
                    app.status.dmn_turns = info.dmn_turns;
                    app.status.dmn_max_turns = info.dmn_max_turns;
                }
                if info.prompt_tokens > 0 { app.status.prompt_tokens = info.prompt_tokens; }
                if !info.model.is_empty() { app.status.model = info.model.clone(); }
                if !info.context_budget.is_empty() { app.status.context_budget = info.context_budget.clone(); }
            }
            UiMessage::Activity(text) => {
                if text.is_empty() {
                    self.call_started = None;
                } else if app.activity.is_empty() || self.call_started.is_none() {
                    self.call_started = Some(std::time::Instant::now());
                    self.call_timeout_secs = crate::config::get().api_stream_timeout_secs;
                }
                app.activity = text.clone();
            }
            UiMessage::Reasoning(text) => {
                self.autonomous.current_color = Color::DarkGray;
                self.autonomous.append_text(text);
            }
            UiMessage::Debug(text) => {
                self.tools.push_line(format!("[debug] {}", text), Color::DarkGray);
            }
            UiMessage::Info(text) => {
                self.conversation.push_line(text.clone(), Color::Cyan);
            }
            UiMessage::ContextInfoUpdate(info) => { app.context_info = Some(info.clone()); }
            UiMessage::AgentUpdate(agents) => { app.agent_state = agents.clone(); }
            _ => {}
        }
    }

    fn scroll_active_up(&mut self, n: u16) {
        match self.active_pane {
            ActivePane::Autonomous => self.autonomous.scroll_up(n),
            ActivePane::Conversation => self.conversation.scroll_up(n),
            ActivePane::Tools => self.tools.scroll_up(n),
        }
    }

    fn scroll_active_down(&mut self, n: u16) {
        match self.active_pane {
            ActivePane::Autonomous => self.autonomous.scroll_down(n),
            ActivePane::Conversation => self.conversation.scroll_down(n),
            ActivePane::Tools => self.tools.scroll_down(n),
        }
    }

    pub fn handle_mouse(&mut self, mouse: MouseEvent) {
        match mouse.kind {
            MouseEventKind::ScrollUp => self.scroll_active_up(3),
            MouseEventKind::ScrollDown => self.scroll_active_down(3),
            MouseEventKind::Down(MouseButton::Left) => {
                let (x, y) = (mouse.column, mouse.row);
                for (i, area) in self.pane_areas.iter().enumerate() {
                    if x >= area.x && x < area.x + area.width && y >= area.y && y < area.y + area.height {
                        self.active_pane = match i { 0 => ActivePane::Autonomous, 1 => ActivePane::Conversation, _ => ActivePane::Tools };
                        break;
                    }
                }
            }
            _ => {}
        }
    }
}

impl ScreenView for InteractScreen {
    fn label(&self) -> &'static str { "interact" }

    fn tick(&mut self, frame: &mut Frame, area: Rect,
            key: Option<KeyEvent>, app: &mut App) -> Option<ScreenAction> {
        // Handle keys
        if let Some(key) = key {
            match key.code {
                KeyCode::Esc => return Some(ScreenAction::Hotkey(HotkeyAction::Interrupt)),
                KeyCode::Enter if !key.modifiers.contains(KeyModifiers::ALT) && !key.modifiers.contains(KeyModifiers::SHIFT) => {
                    let input: String = self.textarea.lines().join("\n");
                    if !input.is_empty() {
                        if self.input_history.last().map_or(true, |h| h != &input) {
                            self.input_history.push(input.clone());
                        }
                        self.history_index = None;
                        // TODO: push to submitted via app or return action
                    }
                }
                KeyCode::Up if key.modifiers.contains(KeyModifiers::CONTROL) => self.scroll_active_up(3),
                KeyCode::Down if key.modifiers.contains(KeyModifiers::CONTROL) => self.scroll_active_down(3),
                KeyCode::Up => {
                    if !self.input_history.is_empty() {
                        let idx = match self.history_index { None => self.input_history.len() - 1, Some(i) => i.saturating_sub(1) };
                        self.history_index = Some(idx);
                        let mut ta = new_textarea(self.input_history[idx].lines().map(String::from).collect());
                        ta.move_cursor(tui_textarea::CursorMove::End);
                        self.textarea = ta;
                    }
                }
                KeyCode::Down => {
                    if let Some(idx) = self.history_index {
                        if idx + 1 < self.input_history.len() {
                            self.history_index = Some(idx + 1);
                            let mut ta = new_textarea(self.input_history[idx + 1].lines().map(String::from).collect());
                            ta.move_cursor(tui_textarea::CursorMove::End);
                            self.textarea = ta;
                        } else {
                            self.history_index = None;
                            self.textarea = new_textarea(vec![String::new()]);
                        }
                    }
                }
                KeyCode::PageUp => self.scroll_active_up(10),
                KeyCode::PageDown => self.scroll_active_down(10),
                KeyCode::Tab => {
                    self.active_pane = match self.active_pane {
                        ActivePane::Autonomous => ActivePane::Tools,
                        ActivePane::Tools => ActivePane::Conversation,
                        ActivePane::Conversation => ActivePane::Autonomous,
                    };
                }
                _ => { self.textarea.input(key); }
            }
        }

        // Draw
        self.draw_main(frame, area, app);
        None
    }
}

impl InteractScreen {
    /// Draw the main (F1) screen — four-pane layout with status bar.
    pub(crate) fn draw_main(&mut self, frame: &mut Frame, size: Rect, app: &App) {
        // Main layout: content area + active tools overlay + status bar
        let active_tools = app.active_tools.lock().unwrap();
        let tool_lines = active_tools.len() as u16;
        let main_chunks = Layout::default()
            .direction(Direction::Vertical)
            .constraints([
                Constraint::Min(3),              // content area
                Constraint::Length(tool_lines),   // active tools (0 when empty)
                Constraint::Length(1),            // status bar
            ])
            .split(size);

        let content_area = main_chunks[0];
        let tools_overlay_area = main_chunks[1];
        let status_area = main_chunks[2];

        // Content: left column (55%) + right column (45%)
        let columns = Layout::default()
            .direction(Direction::Horizontal)
            .constraints([
                Constraint::Percentage(55),
                Constraint::Percentage(45),
            ])
            .split(content_area);

        let left_col = columns[0];
        let right_col = columns[1];

        // Left column: autonomous (35%) + conversation (65%)
        let left_panes = Layout::default()
            .direction(Direction::Vertical)
            .constraints([
                Constraint::Percentage(35),
                Constraint::Percentage(65),
            ])
            .split(left_col);

        let auto_area = left_panes[0];
        let conv_area = left_panes[1];

        // Store pane areas for mouse click detection
        self.pane_areas = [auto_area, conv_area, right_col];

        // Draw autonomous pane
        let auto_active = self.active_pane == ActivePane::Autonomous;
        draw_pane(frame, auto_area, "autonomous", &mut self.autonomous, auto_active,
            Some(&screen_legend()));

        // Draw tools pane
        let tools_active = self.active_pane == ActivePane::Tools;
        draw_pane(frame, right_col, "tools", &mut self.tools, tools_active, None);

        // Draw conversation pane (with input line)
        let conv_active = self.active_pane == ActivePane::Conversation;

        // Input area: compute visual height, split, render gutter + textarea
        let input_text = self.textarea.lines().join("\n");
        let input_para_measure = Paragraph::new(input_text).wrap(Wrap { trim: false });
        let input_line_count = (input_para_measure.line_count(conv_area.width.saturating_sub(5)) as u16)
            .max(1)
            .min(5);

        let conv_chunks = Layout::default()
            .direction(Direction::Vertical)
            .constraints([
                Constraint::Min(1),                 // conversation text
                Constraint::Length(input_line_count), // input area
            ])
            .split(conv_area);

        let text_area_rect = conv_chunks[0];
        let input_area = conv_chunks[1];

        draw_conversation_pane(frame, text_area_rect, &mut self.conversation, conv_active);

        // " > " gutter + textarea, aligned with conversation messages
        let input_chunks = Layout::default()
            .direction(Direction::Horizontal)
            .constraints([
                Constraint::Length(3),  // " > " gutter
                Constraint::Min(1),    // textarea
            ])
            .split(input_area);

        let gutter = Paragraph::new(Line::styled(
            " > ",
            Style::default().fg(Color::Cyan).add_modifier(Modifier::BOLD),
        ));
        frame.render_widget(gutter, input_chunks[0]);
        frame.render_widget(&self.textarea, input_chunks[1]);

        // Draw active tools overlay
        if !active_tools.is_empty() {
            let tool_style = Style::default().fg(Color::Yellow).add_modifier(Modifier::DIM);
            let tool_text: Vec<Line> = active_tools.iter().map(|t| {
                let elapsed = t.started.elapsed().as_secs();
                let line = if t.detail.is_empty() {
                    format!("  [{}] ({}s)", t.name, elapsed)
                } else {
                    format!("  [{}] {} ({}s)", t.name, t.detail, elapsed)
                };
                Line::styled(line, tool_style)
            }).collect();
            let tool_para = Paragraph::new(tool_text);
            frame.render_widget(tool_para, tools_overlay_area);
        }

        // Draw status bar with live activity indicator
        let timer = if !app.activity.is_empty() {
            let total = self.turn_started.map(|t| t.elapsed().as_secs()).unwrap_or(0);
            let call = self.call_started.map(|t| t.elapsed().as_secs()).unwrap_or(0);
            format!(" {}s, {}/{}s", total, call, self.call_timeout_secs)
        } else {
            String::new()
        };
        let tools_info = if app.status.turn_tools > 0 {
            format!(" ({}t)", app.status.turn_tools)
        } else {
            String::new()
        };
        let activity_part = if app.activity.is_empty() {
            String::new()
        } else {
            format!(" | {}{}{}", app.activity, tools_info, timer)
        };

        let budget_part = if app.status.context_budget.is_empty() {
            String::new()
        } else {
            format!(" [{}]", app.status.context_budget)
        };

        let left_status = format!(
            " {} | {}/{} dmn | {}K tok in{}{}",
            app.status.dmn_state,
            app.status.dmn_turns,
            app.status.dmn_max_turns,
            app.status.prompt_tokens / 1000,
            budget_part,
            activity_part,
        );

        let proc_indicator = if app.running_processes > 0 {
            format!(" {}proc", app.running_processes)
        } else {
            String::new()
        };
        let reason_indicator = if app.reasoning_effort != "none" {
            format!(" reason:{}", app.reasoning_effort)
        } else {
            String::new()
        };
        let right_legend = format!(
            "{}{} ^P:pause ^R:reason ^K:kill | {} ",
            reason_indicator,
            proc_indicator,
            app.status.model,
        );

        // Pad the middle to fill the status bar
        let total_width = status_area.width as usize;
        let used = left_status.len() + right_legend.len();
        let padding = if total_width > used {
            " ".repeat(total_width - used)
        } else {
            " ".to_string()
        };

        let status = Paragraph::new(Line::from(vec![
            Span::styled(&left_status, Style::default().fg(Color::White).bg(Color::DarkGray)),
            Span::styled(padding, Style::default().bg(Color::DarkGray)),
            Span::styled(
                right_legend,
                Style::default().fg(Color::DarkGray).bg(Color::Gray),
            ),
        ]));

        frame.render_widget(status, status_area);
    }
}

/// Draw the conversation pane with a two-column layout: marker gutter + text.
/// The gutter shows a marker at turn boundaries, aligned with the input gutter.
fn draw_conversation_pane(
    frame: &mut Frame,
    area: Rect,
    pane: &mut PaneState,
    is_active: bool,
) {
    let border_style = if is_active {
        Style::default().fg(Color::Cyan)
    } else {
        Style::default().fg(Color::DarkGray)
    };

    let block = Block::default()
        .title(" conversation ")
        .borders(Borders::ALL)
        .border_style(border_style);

    let inner = block.inner(area);
    frame.render_widget(block, area);

    if inner.width < 5 || inner.height == 0 {
        return;
    }

    // Split inner area into gutter (2 chars) + text
    let cols = Layout::default()
        .direction(Direction::Horizontal)
        .constraints([
            Constraint::Length(2),
            Constraint::Min(1),
        ])
        .split(inner);

    let gutter_area = cols[0];
    let text_area = cols[1];

    // Get lines and markers
    let (lines, markers) = pane.all_lines_with_markers();
    let text_width = text_area.width;

    // Compute visual row for each logical line (accounting for word wrap)
    let mut visual_rows: Vec<u16> = Vec::with_capacity(lines.len());
    let mut cumulative: u16 = 0;
    for line in &lines {
        visual_rows.push(cumulative);
        let para = Paragraph::new(line.clone()).wrap(Wrap { trim: false });
        let height = para.line_count(text_width) as u16;
        cumulative += height.max(1);
    }
    let total_visual = cumulative;

    pane.last_total_lines = total_visual;
    pane.last_height = inner.height;

    if !pane.pinned {
        pane.scroll = total_visual.saturating_sub(inner.height);
    }

    // Render text column
    let text_para = Paragraph::new(lines.clone())
        .wrap(Wrap { trim: false })
        .scroll((pane.scroll, 0));
    frame.render_widget(text_para, text_area);

    // Render gutter markers at the correct visual rows
    let mut gutter_lines: Vec<Line<'static>> = Vec::new();
    let mut next_visual = 0u16;
    for (i, &marker) in markers.iter().enumerate() {
        let row = visual_rows[i];
        // Fill blank lines up to this marker's row
        while next_visual < row {
            gutter_lines.push(Line::raw(""));
            next_visual += 1;
        }
        let marker_text = match marker {
            Marker::User => Line::styled("● ", Style::default().fg(Color::Cyan)),
            Marker::Assistant => Line::styled("● ", Style::default().fg(Color::Magenta)),
            Marker::None => Line::raw(""),
        };
        gutter_lines.push(marker_text);
        next_visual = row + 1;

        // Fill remaining visual lines for this logical line (wrap continuation)
        let para = Paragraph::new(lines[i].clone()).wrap(Wrap { trim: false });
        let height = para.line_count(text_width) as u16;
        for _ in 1..height.max(1) {
            gutter_lines.push(Line::raw(""));
            next_visual += 1;
        }
    }

    let gutter_para = Paragraph::new(gutter_lines)
        .scroll((pane.scroll, 0));
    frame.render_widget(gutter_para, gutter_area);
}

/// Draw a scrollable text pane (free function to avoid borrow issues).
fn draw_pane(
    frame: &mut Frame,
    area: Rect,
    title: &str,
    pane: &mut PaneState,
    is_active: bool,
    left_title: Option<&str>,
) {
    let inner_height = area.height.saturating_sub(2);

    let border_style = if is_active {
        Style::default().fg(Color::Cyan)
    } else {
        Style::default().fg(Color::DarkGray)
    };

    let mut block = Block::default()
        .borders(Borders::ALL)
        .border_style(border_style);
    if let Some(left) = left_title {
        block = block
            .title_top(Line::from(left).left_aligned())
            .title_top(Line::from(format!(" {} ", title)).right_aligned());
    } else {
        block = block.title(format!(" {} ", title));
    }

    let lines = pane.all_lines();
    let paragraph = Paragraph::new(lines)
        .block(block.clone())
        .wrap(Wrap { trim: false });

    // Let ratatui tell us the total visual lines — no homegrown wrapping math.
    let total = paragraph.line_count(area.width.saturating_sub(2)) as u16;
    pane.last_total_lines = total;
    pane.last_height = inner_height;

    if !pane.pinned {
        pane.scroll = total.saturating_sub(inner_height);
    }

    let paragraph = paragraph.scroll((pane.scroll, 0));
    frame.render_widget(paragraph, area);
}