//! A live status indicator that shows the *latest* log line emitted by the
//! application while the agent is processing a long‑running task.

use std::time::Duration;
use std::time::Instant;

use codex_core::protocol::Op;
use crossterm::event::KeyCode;
use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::style::Stylize;
use ratatui::text::Line;
use ratatui::widgets::WidgetRef;

use crate::app_event::AppEvent;
use crate::app_event_sender::AppEventSender;
use crate::exec_cell::spinner;
use crate::key_hint;
use crate::shimmer::shimmer_spans;
use crate::tui::FrameRequester;

pub(crate) struct StatusIndicatorWidget {
    /// Animated header text (defaults to "Working").
    header: String,
    show_interrupt_hint: bool,

    elapsed_running: Duration,
    last_resume_at: Instant,
    is_paused: bool,
    app_event_tx: AppEventSender,
    frame_requester: FrameRequester,
}

// Format elapsed seconds into a compact human-friendly form used by the status line.
// Examples: 0s, 59s, 1m 00s, 59m 59s, 1h 00m 00s, 2h 03m 09s
pub fn fmt_elapsed_compact(elapsed_secs: u64) -> String {
    if elapsed_secs < 60 {
        return format!("{elapsed_secs}s");
    }
    if elapsed_secs < 3600 {
        let minutes = elapsed_secs / 60;
        let seconds = elapsed_secs % 60;
        return format!("{minutes}m {seconds:02}s");
    }
    let hours = elapsed_secs / 3600;
    let minutes = (elapsed_secs % 3600) / 60;
    let seconds = elapsed_secs % 60;
    format!("{hours}h {minutes:02}m {seconds:02}s")
}

impl StatusIndicatorWidget {
    pub(crate) fn new(app_event_tx: AppEventSender, frame_requester: FrameRequester) -> Self {
        Self {
            header: String::from("Working"),
            show_interrupt_hint: true,
            elapsed_running: Duration::ZERO,
            last_resume_at: Instant::now(),
            is_paused: false,

            app_event_tx,
            frame_requester,
        }
    }

    pub fn desired_height(&self, _width: u16) -> u16 {
        1
    }

    pub(crate) fn interrupt(&self) {
        self.app_event_tx.send(AppEvent::CodexOp(Op::Interrupt));
    }

    /// Update the animated header label (left of the brackets).
    pub(crate) fn update_header(&mut self, header: String) {
        self.header = header;
    }

    pub(crate) fn set_interrupt_hint_visible(&mut self, visible: bool) {
        self.show_interrupt_hint = visible;
    }

    #[cfg(test)]
    pub(crate) fn header(&self) -> &str {
        &self.header
    }

    #[cfg(test)]
    pub(crate) fn interrupt_hint_visible(&self) -> bool {
        self.show_interrupt_hint
    }

    pub(crate) fn pause_timer(&mut self) {
        self.pause_timer_at(Instant::now());
    }

    pub(crate) fn resume_timer(&mut self) {
        self.resume_timer_at(Instant::now());
    }

    pub(crate) fn pause_timer_at(&mut self, now: Instant) {
        if self.is_paused {
            return;
        }
        self.elapsed_running += now.saturating_duration_since(self.last_resume_at);
        self.is_paused = true;
    }

    pub(crate) fn resume_timer_at(&mut self, now: Instant) {
        if !self.is_paused {
            return;
        }
        self.last_resume_at = now;
        self.is_paused = false;
        self.frame_requester.schedule_frame();
    }

    fn elapsed_duration_at(&self, now: Instant) -> Duration {
        let mut elapsed = self.elapsed_running;
        if !self.is_paused {
            elapsed += now.saturating_duration_since(self.last_resume_at);
        }
        elapsed
    }

    fn elapsed_seconds_at(&self, now: Instant) -> u64 {
        self.elapsed_duration_at(now).as_secs()
    }

    pub fn elapsed_seconds(&self) -> u64 {
        self.elapsed_seconds_at(Instant::now())
    }
}

impl WidgetRef for StatusIndicatorWidget {
    fn render_ref(&self, area: Rect, buf: &mut Buffer) {
        if area.is_empty() {
            return;
        }

        // Schedule next animation frame.
        self.frame_requester
            .schedule_frame_in(Duration::from_millis(32));
        let now = Instant::now();
        let elapsed_duration = self.elapsed_duration_at(now);
        let pretty_elapsed = fmt_elapsed_compact(elapsed_duration.as_secs());

        // Plain rendering: no borders or padding so the live cell is visually indistinguishable from terminal scrollback.
        let mut spans = Vec::with_capacity(5);
        spans.push(spinner(Some(self.last_resume_at)));
        spans.push(" ".into());
        spans.extend(shimmer_spans(&self.header));
        spans.push(" ".into());
        if self.show_interrupt_hint {
            spans.extend(vec![
                format!("({pretty_elapsed} • ").dim(),
                key_hint::plain(KeyCode::Esc).into(),
                " to interrupt)".dim(),
            ]);
        } else {
            spans.push(format!("({pretty_elapsed})").dim());
        }

        Line::from(spans).render_ref(area, buf);
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::app_event::AppEvent;
    use crate::app_event_sender::AppEventSender;
    use ratatui::Terminal;
    use ratatui::backend::TestBackend;
    use std::time::Duration;
    use std::time::Instant;
    use tokio::sync::mpsc::unbounded_channel;

    use pretty_assertions::assert_eq;

    #[test]
    fn fmt_elapsed_compact_formats_seconds_minutes_hours() {
        assert_eq!(fmt_elapsed_compact(0), "0s");
        assert_eq!(fmt_elapsed_compact(1), "1s");
        assert_eq!(fmt_elapsed_compact(59), "59s");
        assert_eq!(fmt_elapsed_compact(60), "1m 00s");
        assert_eq!(fmt_elapsed_compact(61), "1m 01s");
        assert_eq!(fmt_elapsed_compact(3 * 60 + 5), "3m 05s");
        assert_eq!(fmt_elapsed_compact(59 * 60 + 59), "59m 59s");
        assert_eq!(fmt_elapsed_compact(3600), "1h 00m 00s");
        assert_eq!(fmt_elapsed_compact(3600 + 60 + 1), "1h 01m 01s");
        assert_eq!(fmt_elapsed_compact(25 * 3600 + 2 * 60 + 3), "25h 02m 03s");
    }

    #[test]
    fn renders_with_working_header() {
        let (tx_raw, _rx) = unbounded_channel::<AppEvent>();
        let tx = AppEventSender::new(tx_raw);
        let w = StatusIndicatorWidget::new(tx, crate::tui::FrameRequester::test_dummy());

        // Render into a fixed-size test terminal and snapshot the backend.
        let mut terminal = Terminal::new(TestBackend::new(80, 2)).expect("terminal");
        terminal
            .draw(|f| w.render_ref(f.area(), f.buffer_mut()))
            .expect("draw");
        insta::assert_snapshot!(terminal.backend());
    }

    #[test]
    fn renders_truncated() {
        let (tx_raw, _rx) = unbounded_channel::<AppEvent>();
        let tx = AppEventSender::new(tx_raw);
        let w = StatusIndicatorWidget::new(tx, crate::tui::FrameRequester::test_dummy());

        // Render into a fixed-size test terminal and snapshot the backend.
        let mut terminal = Terminal::new(TestBackend::new(20, 2)).expect("terminal");
        terminal
            .draw(|f| w.render_ref(f.area(), f.buffer_mut()))
            .expect("draw");
        insta::assert_snapshot!(terminal.backend());
    }

    #[test]
    fn timer_pauses_when_requested() {
        let (tx_raw, _rx) = unbounded_channel::<AppEvent>();
        let tx = AppEventSender::new(tx_raw);
        let mut widget = StatusIndicatorWidget::new(tx, crate::tui::FrameRequester::test_dummy());

        let baseline = Instant::now();
        widget.last_resume_at = baseline;

        let before_pause = widget.elapsed_seconds_at(baseline + Duration::from_secs(5));
        assert_eq!(before_pause, 5);

        widget.pause_timer_at(baseline + Duration::from_secs(5));
        let paused_elapsed = widget.elapsed_seconds_at(baseline + Duration::from_secs(10));
        assert_eq!(paused_elapsed, before_pause);

        widget.resume_timer_at(baseline + Duration::from_secs(10));
        let after_resume = widget.elapsed_seconds_at(baseline + Duration::from_secs(13));
        assert_eq!(after_resume, before_pause + 3);
    }
}