use crate::client::tui::app::{App, MessageRole};
use crate::session::{ToolStatus, TurnBlock, TurnPhase, TurnStatus};
use ratatui::{
    Frame,
    layout::Rect,
    style::{Color, Modifier, Style},
    text::{Line, Span},
    widgets::{Block, Borders, Paragraph},
};

pub fn render(frame: &mut Frame, area: Rect, app: &App) {
    let content_width = area.width.saturating_sub(4).max(1) as usize;
    let mut lines = Vec::new();
    if app.messages.is_empty() {
        lines.push(Line::from("开始一段对话，或从左侧选择已有会话。"));
    }
    for message in &app.messages {
        let (label, color) = match message.role {
            MessageRole::User => ("你", Color::Blue),
            MessageRole::Assistant => ("PicoBot", Color::Green),
            MessageRole::System => ("系统", Color::Yellow),
        };
        lines.push(Line::from(Span::styled(
            label,
            Style::default().fg(color).add_modifier(Modifier::BOLD),
        )));
        if let Some(reasoning) = &message.reasoning_content {
            lines.push(Line::from(Span::styled(
                "思考过程",
                Style::default()
                    .fg(Color::DarkGray)
                    .add_modifier(Modifier::ITALIC),
            )));
            push_wrapped(&mut lines, reasoning, content_width, Color::DarkGray);
        }
        for source_line in message.content.lines() {
            let wrapped = textwrap::wrap(source_line, content_width);
            if wrapped.is_empty() {
                lines.push(Line::from(""));
            } else {
                lines.extend(
                    wrapped
                        .into_iter()
                        .map(|line| Line::from(line.into_owned())),
                );
            }
        }
        if message.completion_status != crate::bus::CompletionStatus::Completed {
            lines.push(Line::from(Span::styled(
                format!("[{}]", message.completion_status.as_str()),
                Style::default().fg(Color::Yellow),
            )));
        }
        for attachment in &message.attachments {
            lines.push(Line::from(Span::styled(
                format!("  [附件 {}] {}", attachment.index + 1, attachment.name),
                Style::default().fg(Color::Cyan),
            )));
        }
        lines.push(Line::from(""));
    }
    if let Some(turn) = &app.active_turn {
        lines.push(Line::from(Span::styled(
            "PicoBot",
            Style::default()
                .fg(Color::Green)
                .add_modifier(Modifier::BOLD),
        )));
        for block in &turn.blocks {
            match block {
                TurnBlock::Reasoning { text, .. } => {
                    lines.push(Line::from(Span::styled(
                        "思考过程",
                        Style::default()
                            .fg(Color::DarkGray)
                            .add_modifier(Modifier::ITALIC),
                    )));
                    push_wrapped(&mut lines, text, content_width, Color::DarkGray);
                }
                TurnBlock::Assistant { text, .. } => {
                    push_wrapped(&mut lines, text, content_width, Color::Reset);
                }
                TurnBlock::Tool {
                    name,
                    status,
                    preview,
                    ..
                } => {
                    let status = match status {
                        ToolStatus::Running => "执行中",
                        ToolStatus::Completed => "已完成",
                        ToolStatus::Cancelled => "已停止",
                        ToolStatus::Failed => "失败",
                    };
                    lines.push(Line::from(Span::styled(
                        format!("工具 · {name} · {status}"),
                        Style::default().fg(Color::Magenta),
                    )));
                    if let Some(preview) = preview {
                        push_wrapped(&mut lines, preview, content_width, Color::DarkGray);
                    }
                }
            }
        }
        let phase = match turn.phase {
            TurnPhase::Queued => "排队中",
            TurnPhase::Reasoning => "思考中",
            TurnPhase::Responding => "生成中",
            TurnPhase::Acting => "调用工具中",
            TurnPhase::Finalizing => "收尾中",
        };
        let status = match turn.status {
            TurnStatus::Running => phase,
            TurnStatus::Completed => "已完成",
            TurnStatus::Cancelled => "已停止",
            TurnStatus::Failed => "失败",
        };
        lines.push(Line::from(Span::styled(
            format!("● {status}"),
            Style::default().fg(if turn.status == TurnStatus::Failed {
                Color::Red
            } else {
                Color::Cyan
            }),
        )));
        if let Some(error) = &turn.error {
            push_wrapped(&mut lines, error, content_width, Color::Red);
        }
        lines.push(Line::from(""));
    } else if app.pending_responses > 0 {
        lines.push(Line::from(Span::styled(
            "● 正在思考…",
            Style::default().fg(Color::Cyan),
        )));
    }

    let visible_height = area.height.saturating_sub(2);
    let line_count = u16::try_from(lines.len()).unwrap_or(u16::MAX);
    let max_scroll = line_count.saturating_sub(visible_height);
    let scroll = max_scroll.saturating_sub(app.chat_scroll_from_bottom.min(max_scroll));
    let title = if app.chat_scroll_from_bottom > 0 {
        " 对话 · 已暂停自动滚动 "
    } else {
        " 对话 "
    };
    frame.render_widget(
        Paragraph::new(lines)
            .scroll((scroll, 0))
            .block(Block::default().title(title).borders(Borders::ALL)),
        area,
    );
}

fn push_wrapped(lines: &mut Vec<Line<'static>>, text: &str, width: usize, color: Color) {
    for source_line in text.lines() {
        let wrapped = textwrap::wrap(source_line, width);
        if wrapped.is_empty() {
            lines.push(Line::from(""));
        } else {
            lines.extend(wrapped.into_iter().map(|line| {
                Line::from(Span::styled(line.into_owned(), Style::default().fg(color)))
            }));
        }
    }
}