use indicatif::{MultiProgress, ProgressBar, ProgressStyle};
use std::io::Write;
use std::sync::LazyLock;
use std::time::Duration;
use tracing_subscriber::fmt::MakeWriter;

use crate::cli::render::{Icons, Theme};

static MULTI: LazyLock<MultiProgress> = LazyLock::new(MultiProgress::new);

pub fn multi() -> &'static MultiProgress {
    &MULTI
}

/// Stage spinner with icon prefix and elapsed time on the right.
///
/// Template: `{spinner:.cyan} {prefix} {wide_msg} {elapsed_style:.dim}`
pub fn stage_spinner_v2(icon: &str, label: &str, msg: &str, robot_mode: bool) -> ProgressBar {
    if robot_mode {
        return ProgressBar::hidden();
    }
    let pb = multi().add(ProgressBar::new_spinner());
    pb.set_style(
        ProgressStyle::default_spinner()
            .template("  {spinner:.cyan} {prefix} {wide_msg}")
            .expect("valid template"),
    );
    pb.enable_steady_tick(Duration::from_millis(60));
    pb.set_prefix(format!("{icon} {label}"));
    pb.set_message(msg.to_string());
    pb
}

/// Nested progress bar with count, throughput, and ETA.
///
/// Template: `    {spinner:.dim} {msg} {bar:30.cyan/dark_gray} {pos}/{len} {per_sec:.dim} {eta:.dim}`
pub fn nested_progress(msg: &str, len: u64, robot_mode: bool) -> ProgressBar {
    if robot_mode {
        return ProgressBar::hidden();
    }
    let pb = multi().add(ProgressBar::new(len));
    pb.set_style(
        ProgressStyle::default_bar()
            .template(
                "  {spinner:.dim} {msg} {bar:30.cyan/dark_gray} {pos}/{len} {per_sec:.dim} {eta:.dim}",
            )
            .expect("valid template")
            .progress_chars(Icons::progress_chars()),
    );
    pb.enable_steady_tick(Duration::from_millis(60));
    pb.set_message(msg.to_string());
    pb
}

/// Replace a spinner with a static completion line showing icon, label, summary, and elapsed.
///
/// Output: `  ✓ Label  summary  elapsed`
pub fn finish_stage(pb: &ProgressBar, icon: &str, label: &str, summary: &str, elapsed: Duration) {
    let line = format_stage_line(icon, label, summary, elapsed);
    pb.set_style(ProgressStyle::with_template("{msg}").expect("valid template"));
    pb.finish_with_message(line);
}

/// Build a static stage line showing icon, label, summary, and elapsed.
///
/// Output: `  ✓ Label  summary  elapsed`
pub fn format_stage_line(icon: &str, label: &str, summary: &str, elapsed: Duration) -> String {
    let elapsed_str = format_elapsed(elapsed);
    let styled_label = Theme::info().bold().render(&format!("{label:<12}"));
    let styled_elapsed = Theme::timing().render(&format!("{elapsed_str:>8}"));
    format!("  {icon} {styled_label}{summary:>40}  {styled_elapsed}")
}

/// Format a Duration as a compact human string (e.g. "1.2s", "42ms", "1m 5s").
fn format_elapsed(d: Duration) -> String {
    let ms = d.as_millis();
    if ms < 1000 {
        format!("{ms}ms")
    } else if ms < 60_000 {
        format!("{:.1}s", ms as f64 / 1000.0)
    } else {
        let secs = d.as_secs();
        let m = secs / 60;
        let s = secs % 60;
        format!("{m}m {s}s")
    }
}

#[derive(Clone)]
pub struct SuspendingWriter;

pub struct SuspendingWriterInner {
    buf: Vec<u8>,
}

impl Write for SuspendingWriterInner {
    fn write(&mut self, data: &[u8]) -> std::io::Result<usize> {
        self.buf.extend_from_slice(data);
        Ok(data.len())
    }

    fn flush(&mut self) -> std::io::Result<()> {
        Ok(())
    }
}

impl Drop for SuspendingWriterInner {
    fn drop(&mut self) {
        if !self.buf.is_empty() {
            let buf = std::mem::take(&mut self.buf);
            MULTI.suspend(|| {
                let _ = std::io::stderr().write_all(&buf);
                let _ = std::io::stderr().flush();
            });
        }
    }
}

impl<'a> MakeWriter<'a> for SuspendingWriter {
    type Writer = SuspendingWriterInner;

    fn make_writer(&'a self) -> Self::Writer {
        SuspendingWriterInner { buf: Vec::new() }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn multi_returns_same_instance() {
        let a = multi() as *const MultiProgress;
        let b = multi() as *const MultiProgress;
        assert!(std::ptr::eq(a, b));
    }

    #[test]
    fn added_bar_is_tracked() {
        let bar = multi().add(ProgressBar::new_spinner());
        bar.set_message("test");
        bar.finish_and_clear();
    }

    #[test]
    fn hidden_bar_works_with_multi() {
        let bar = multi().add(ProgressBar::hidden());
        bar.set_message("hidden");
        bar.finish_and_clear();
    }

    #[test]
    fn suspending_writer_buffers_and_flushes() {
        let writer = SuspendingWriter;
        let mut w = MakeWriter::make_writer(&writer);
        let n = w.write(b"test log line\n").unwrap();
        assert_eq!(n, 14);
        drop(w);
    }

    #[test]
    fn suspending_writer_empty_does_not_flush() {
        let writer = SuspendingWriter;
        let w = MakeWriter::make_writer(&writer);
        drop(w);
    }

    // ── Progress API tests ──

    #[test]
    fn stage_spinner_v2_robot_mode_returns_hidden() {
        let pb = stage_spinner_v2("\u{2714}", "Issues", "fetching...", true);
        assert!(pb.is_hidden());
    }

    #[test]
    fn stage_spinner_v2_human_mode_sets_properties() {
        let pb = stage_spinner_v2("\u{2714}", "Issues", "fetching...", false);
        assert!(pb.prefix().contains("Issues"));
        assert_eq!(pb.message(), "fetching...");
        pb.finish_and_clear();
    }

    #[test]
    fn nested_progress_robot_mode_returns_hidden() {
        let pb = nested_progress("Embedding...", 100, true);
        assert!(pb.is_hidden());
    }

    #[test]
    fn nested_progress_human_mode_sets_length() {
        let pb = nested_progress("Embedding...", 100, false);
        assert_eq!(pb.length(), Some(100));
        assert_eq!(pb.message(), "Embedding...");
        pb.finish_and_clear();
    }

    #[test]
    fn format_elapsed_sub_second() {
        assert_eq!(format_elapsed(Duration::from_millis(42)), "42ms");
        assert_eq!(format_elapsed(Duration::from_millis(999)), "999ms");
    }

    #[test]
    fn format_elapsed_seconds() {
        assert_eq!(format_elapsed(Duration::from_millis(1200)), "1.2s");
        assert_eq!(format_elapsed(Duration::from_millis(5000)), "5.0s");
    }

    #[test]
    fn format_elapsed_minutes() {
        assert_eq!(format_elapsed(Duration::from_secs(65)), "1m 5s");
        assert_eq!(format_elapsed(Duration::from_secs(120)), "2m 0s");
    }

    #[test]
    fn format_stage_line_includes_label_summary_and_elapsed() {
        let line = format_stage_line("✔", "Issues", "10 issues", Duration::from_millis(4200));
        assert!(line.contains("✔"));
        assert!(line.contains("Issues"));
        assert!(line.contains("10 issues"));
        assert!(line.contains("4.2s"));
    }
}