// 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,
};

use super::{ActivePane, App, Marker, PaneState, screen_legend};

impl App {
    /// Draw the main (F1) screen — four-pane layout with status bar.
    pub(crate) fn draw_main(&mut self, frame: &mut Frame, size: Rect) {
        // Main layout: content area + active tools overlay + status bar
        let active_tools = self.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 !self.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 self.status.turn_tools > 0 {
            format!(" ({}t)", self.status.turn_tools)
        } else {
            String::new()
        };
        let activity_part = if self.activity.is_empty() {
            String::new()
        } else {
            format!(" | {}{}{}", self.activity, tools_info, timer)
        };

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

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

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