//! Overlay: Rewind / session history — shows recent messages and lets the user
//! pick a point to rewind the transcript back to.
//!
//! Flow: reads the last 8 messages from `state.transcript_cache.messages`,
//! renders each with a role tag and content preview; an overflow note is
//! appended when there are more than 8 messages. The input controller handles
//! ↑/↓ navigation and Enter to confirm the rewind point.

use ratatui::style::{Modifier, Style};
use ratatui::text::{Line, Span};
use ratatui::widgets::{Block, Paragraph};
use ratatui::Frame;
use crate::view::theme::Theme;
use tracing;

/// Render the Rewind overlay — message list with role tags and previews.
pub fn render(
    frame: &mut Frame,
    area: ratatui::layout::Rect,
    block: Block<'static>,
    state: &crate::app::state::rest::AppStateRest,
) {
    tracing::debug!("overlay: Rewind (messages={})", state.transcript_cache.messages.len());
    let block = block
        .title(Span::styled(
            " Rewind ",
            Style::default()
                .fg(Theme::ACCENT_ORANGE)
                .add_modifier(Modifier::BOLD),
        ))
        .border_style(Style::default().fg(Theme::ACCENT_ORANGE));
    let mut lines: Vec<Line> = vec![
        Line::from(Span::styled(
            "  Use ↑↓ to navigate, Enter to rewind to that point",
            Style::default().fg(Theme::TEXT_DIM),
        )),
        Line::from(Span::raw("")),
    ];
    let messages = &state.transcript_cache.messages;
    if messages.is_empty() {
        lines.push(Line::from(Span::styled(
            "  No messages in current session.",
            Style::default().fg(Theme::TEXT_DIM),
        )));
    } else {
        let start = if messages.len() > 8 {
            messages.len() - 8
        } else {
            0
        };
        for msg in &messages[start..] {
            let role_str = match msg.role {
                crate::dto::chat::message::Role::User => "User",
                crate::dto::chat::message::Role::Assistant => "Asst",
                crate::dto::chat::message::Role::System => "Sys",
                crate::dto::chat::message::Role::Tool => "Tool",
            };
            let preview: String = msg.content.chars().take(70).collect();
            lines.push(Line::from(Span::styled(
                format!("  [{role_str}] {preview}"),
                Style::default().fg(
                    if matches!(msg.role, crate::dto::chat::message::Role::User) {
                        Theme::INFO
                    } else {
                        Theme::TEXT
                    },
                ),
            )));
        }
        if messages.len() > 8 {
            lines.push(Line::from(Span::styled(
                format!("  ... and {} more messages", messages.len() - 8),
                Style::default().fg(Theme::TEXT_DIM),
            )));
        }
    }
    let paragraph = Paragraph::new(lines).block(block);
    frame.render_widget(paragraph, area);
}