//! Runs the `MediaPlayer` conformance suite against a real engine.
//!
//! A separate binary on purpose: it links libmpv and nothing else, so a wrapper
//! can be verified without building or launching the app — which is what made
//! the previous round of playback debugging so slow. Every failure here is a
//! wrapper bug, with no UI, no webview and no server in the way.
//!
//!     cargo run --features conformance --bin player-conformance -- <media-file>
//!
//! Audio and video are routed to null, so it is safe on a headless runner and
//! does not claim the speakers.
//!
//! TRACES: UR-081 | DR-244

use std::time::{Duration, Instant};

use crate::player::conformance::Harness;
use crate::player::legacy_player::LegacyPlayer;
use crate::player::media::MediaItem;
use crate::player::media_player::{MediaPlayer, OpenRequest, Phase};
use crate::player::mpv_backend::MpvBackend;
use crate::player::mpv_player::{MpvPlayer, Output};
use crate::repository::stream_selection::StreamSelection;

struct EngineHarness<P: MediaPlayer> {
    player: P,
    url: String,
}

impl<P: MediaPlayer> Harness for EngineHarness<P> {
    type Player = P;

    fn player(&mut self) -> &mut P {
        &mut self.player
    }

    fn request(&self, start: Duration) -> OpenRequest {
        let selection = StreamSelection::local_file(self.url.clone());
        let media = MediaItem::sample("conformance", &self.url);
        OpenRequest::new(media, selection).starting_at(start)
    }

    /// Wait for mpv to leave `Opening`.
    ///
    /// Polling a phase the engine publishes, not a fixed sleep: a suite whose
    /// result depends on how fast the machine is will eventually be ignored.
    fn settle(&mut self) {
        let deadline = Instant::now() + Duration::from_secs(15);
        while Instant::now() < deadline {
            if self.player.snapshot().phase != Phase::Opening {
                // Let the deferred seek land and one position tick arrive.
                std::thread::sleep(Duration::from_millis(300));
                return;
            }
            std::thread::sleep(Duration::from_millis(25));
        }
        eprintln!("  ! settle timed out - engine stayed in Opening");
    }

    /// mpv is on a null audio device here, so silence cannot be observed.
    /// Reporting `None` skips those assertions rather than passing them
    /// vacuously — an assertion that cannot fail is worse than an absent one.
    fn audible(&mut self) -> Option<bool> {
        None
    }

    /// Keyframe granularity: mpv lands on the nearest one, not on the request.
    fn seek_tolerance(&self) -> Duration {
        Duration::from_secs(10)
    }

    /// Poll until the decoder reports the new position, rather than assuming a
    /// seek is visible the instant it is accepted.
    fn await_seek(&mut self, target: Duration) {
        let deadline = Instant::now() + Duration::from_secs(10);
        while Instant::now() < deadline {
            let pos = self.player.snapshot().position;
            if pos.abs_diff(target) <= self.seek_tolerance() {
                return;
            }
            std::thread::sleep(Duration::from_millis(50));
        }
    }
}

macro_rules! run {
    ($failed:ident, $url:expr, $make:expr, $case:path) => {{
        let name = stringify!($case).rsplit("::").next().unwrap();
        print!("  {name:.<52}");
        let result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
            let mut h = EngineHarness {
                player: $make,
                url: $url.to_string(),
            };
            $case(&mut h);
            // Leave nothing playing behind for the next case.
            let _ = h.player.close();
        }));
        match result {
            Ok(()) => println!(" ok"),
            Err(_) => {
                println!(" FAILED");
                $failed += 1;
            }
        }
    }};
}

/// Which engine to interrogate.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Engine {
    /// The `MediaPlayer` implementation.
    Mpv,
    /// The old `PlayerBackend`, driven through `LegacyPlayer`.
    ///
    /// Present so the difference between the two designs can be *demonstrated*
    /// on the same engine and the same media, rather than argued.
    Legacy,
}

/// Run every conformance case against `engine`. Returns the failure count.
pub fn run_engine(url: &str, engine: Engine) -> u32 {
    println!("MediaPlayer conformance - {engine:?}");
    println!("media: {url}\n");

    let mut failed = 0u32;
    use crate::player::conformance as c;

    macro_rules! all_cases {
        ($make:expr) => {
            run!(failed, url, $make, c::opens_from_the_beginning);
            run!(failed, url, $make, c::opens_at_a_start_position);
            run!(failed, url, $make, c::seek_while_opening_is_honoured);
            run!(failed, url, $make, c::seek_while_opening_overrides_start);
            run!(failed, url, $make, c::seeks_after_open);
            run!(failed, url, $make, c::pause_and_play_are_observable);
            run!(failed, url, $make, c::close_is_silent_and_idempotent);
            run!(failed, url, $make, c::close_during_open_never_plays);
            run!(failed, url, $make, c::transport_settings_round_trip);
        };
    }

    match engine {
        Engine::Mpv => {
            all_cases!(MpvPlayer::new(Output::Null).expect("could not create mpv"));
        }
        Engine::Legacy => {
            all_cases!(LegacyPlayer::new(
                MpvBackend::new(
                    None,
                    std::sync::Arc::new(tokio::sync::Mutex::new(None)),
                    std::sync::Arc::new(crate::playback_reporting::throttle::EventThrottler::new()),
                )
                .expect("could not create the legacy backend"),
                crate::player::media_player::Capabilities::mpv(),
            ));
        }
    }

    if failed == 0 {
        println!("\nall cases passed");
    } else {
        println!("\n{failed} case(s) failed");
    }
    failed
}

/// Default entry point: the new engine.
pub fn run(url: &str) -> u32 {
    run_engine(url, Engine::Mpv)
}