mod metadata;
pub use self::metadata::*;

use crate::constants::{SAMPLE_RATE, SAMPLE_RATE_RAW};

use std::io::{Seek, SeekFrom};
use symphonia::core::{
    codecs::{CodecParameters, CODEC_TYPE_OPUS},
    errors::{self as symph_err, Error as SymphError, Result as SymphResult, SeekErrorKind},
    formats::prelude::*,
    io::{MediaSource, MediaSourceStream, ReadBytes, SeekBuffered},
    meta::{Metadata as SymphMetadata, MetadataBuilder, MetadataLog, StandardTagKey, Tag, Value},
    probe::{Descriptor, Instantiate, QueryDescriptor},
    sample::SampleFormat,
};

impl QueryDescriptor for DcaReader {
    fn query() -> &'static [Descriptor] {
        &[symphonia_core::support_format!(
            "dca",
            "DCA[0/1] Opus Wrapper",
            &["dca"],
            &[],
            &[b"DCA1"]
        )]
    }

    fn score(_context: &[u8]) -> u8 {
        255
    }
}

struct SeekAccel {
    frame_offsets: Vec<(TimeStamp, u64)>,
    seek_index_fill_rate: u16,
    next_ts: TimeStamp,
}

impl SeekAccel {
    fn new(options: FormatOptions, first_frame_byte_pos: u64) -> Self {
        let per_s = options.seek_index_fill_rate;
        let next_ts = (per_s as u64) * (SAMPLE_RATE_RAW as u64);

        Self {
            frame_offsets: vec![(0, first_frame_byte_pos)],
            seek_index_fill_rate: per_s,
            next_ts,
        }
    }

    fn update(&mut self, ts: TimeStamp, pos: u64) {
        if ts >= self.next_ts {
            self.next_ts += (self.seek_index_fill_rate as u64) * (SAMPLE_RATE_RAW as u64);
            self.frame_offsets.push((ts, pos));
        }
    }

    fn get_seek_pos(&self, ts: TimeStamp) -> (TimeStamp, u64) {
        let index = self.frame_offsets.partition_point(|&(o_ts, _)| o_ts <= ts) - 1;
        self.frame_offsets[index]
    }
}

/// [DCA\[0/1\]](https://github.com/bwmarrin/dca) Format reader for Symphonia.
pub struct DcaReader {
    source: MediaSourceStream,
    track: Option<Track>,
    metas: MetadataLog,
    seek_accel: SeekAccel,
    curr_ts: TimeStamp,
    max_ts: Option<TimeStamp>,
    held_packet: Option<Packet>,
}

impl FormatReader for DcaReader {
    fn try_new(mut source: MediaSourceStream, options: &FormatOptions) -> SymphResult<Self> {
        // Read in the magic number to verify it's a DCA file.
        let magic = source.read_quad_bytes()?;

        // FIXME: make use of the new options.enable_gapless to apply the opus coder delay.

        let read_meta = match &magic {
            b"DCA1" => true,
            _ if &magic[..3] == b"DCA" => {
                return symph_err::unsupported_error("unsupported DCA version");
            },
            _ => {
                source.seek_buffered_rel(-4);
                false
            },
        };

        let mut codec_params = CodecParameters::new();

        codec_params
            .for_codec(CODEC_TYPE_OPUS)
            .with_max_frames_per_packet(1)
            .with_sample_rate(SAMPLE_RATE_RAW as u32)
            .with_time_base(TimeBase::new(1, SAMPLE_RATE_RAW as u32))
            .with_sample_format(SampleFormat::F32);

        let mut metas = MetadataLog::default();

        if read_meta {
            let size = source.read_u32()?;

            // Sanity check
            if (size as i32) < 2 {
                return symph_err::decode_error("missing DCA1 metadata block");
            }

            let raw_json = source.read_boxed_slice_exact(size as usize)?;

            let metadata: DcaMetadata = serde_json::from_slice::<DcaMetadata>(&raw_json)
                .map_err(|_| SymphError::DecodeError("malformed DCA1 metadata block"))?;

            let mut revision = MetadataBuilder::new();

            if let Some(info) = metadata.info {
                if let Some(t) = info.title {
                    revision.add_tag(Tag::new(
                        Some(StandardTagKey::TrackTitle),
                        "title",
                        Value::String(t),
                    ));
                }
                if let Some(t) = info.album {
                    revision.add_tag(Tag::new(
                        Some(StandardTagKey::Album),
                        "album",
                        Value::String(t),
                    ));
                }
                if let Some(t) = info.artist {
                    revision.add_tag(Tag::new(
                        Some(StandardTagKey::Artist),
                        "artist",
                        Value::String(t),
                    ));
                }
                if let Some(t) = info.genre {
                    revision.add_tag(Tag::new(
                        Some(StandardTagKey::Genre),
                        "genre",
                        Value::String(t),
                    ));
                }
                if let Some(t) = info.comments {
                    revision.add_tag(Tag::new(
                        Some(StandardTagKey::Comment),
                        "comments",
                        Value::String(t),
                    ));
                }
                if let Some(_t) = info.cover {
                    // TODO: Add visual, figure out MIME types.
                }
            }

            if let Some(origin) = metadata.origin {
                if let Some(t) = origin.url {
                    revision.add_tag(Tag::new(Some(StandardTagKey::Url), "url", Value::String(t)));
                }
            }

            metas.push(revision.metadata());
        }

        let bytes_read = source.pos();

        Ok(Self {
            source,
            track: Some(Track {
                id: 0,
                language: None,
                codec_params,
            }),
            metas,
            seek_accel: SeekAccel::new(*options, bytes_read),
            curr_ts: 0,
            max_ts: None,
            held_packet: None,
        })
    }

    fn cues(&self) -> &[Cue] {
        // No cues in DCA...
        &[]
    }

    fn metadata(&mut self) -> SymphMetadata<'_> {
        self.metas.metadata()
    }

    fn seek(&mut self, _mode: SeekMode, to: SeekTo) -> SymphResult<SeekedTo> {
        let can_backseek = self.source.is_seekable();

        let track = if self.track.is_none() {
            return symph_err::seek_error(SeekErrorKind::Unseekable);
        } else {
            self.track.as_ref().unwrap()
        };

        let rate = track.codec_params.sample_rate;
        let ts = match to {
            SeekTo::Time { time, .. } =>
                if let Some(rate) = rate {
                    TimeBase::new(1, rate).calc_timestamp(time)
                } else {
                    return symph_err::seek_error(SeekErrorKind::Unseekable);
                },
            SeekTo::TimeStamp { ts, .. } => ts,
        };

        if let Some(max_ts) = self.max_ts {
            if ts > max_ts {
                return symph_err::seek_error(SeekErrorKind::OutOfRange);
            }
        }

        let backseek_needed = self.curr_ts > ts;

        if backseek_needed && !can_backseek {
            return symph_err::seek_error(SeekErrorKind::ForwardOnly);
        }

        let (accel_seek_ts, accel_seek_pos) = self.seek_accel.get_seek_pos(ts);

        if backseek_needed || accel_seek_pos > self.source.pos() {
            self.source.seek(SeekFrom::Start(accel_seek_pos))?;
            self.curr_ts = accel_seek_ts;
        }

        while let Ok(pkt) = self.next_packet() {
            let pts = pkt.ts;
            let dur = pkt.dur;
            let track_id = pkt.track_id();

            if (pts..pts + dur).contains(&ts) {
                self.held_packet = Some(pkt);
                return Ok(SeekedTo {
                    track_id,
                    required_ts: ts,
                    actual_ts: pts,
                });
            }
        }

        symph_err::seek_error(SeekErrorKind::OutOfRange)
    }

    fn tracks(&self) -> &[Track] {
        // DCA tracks can hold only one track by design.
        // Of course, a zero-length file is technically allowed,
        // in which case no track.
        if let Some(track) = self.track.as_ref() {
            std::slice::from_ref(track)
        } else {
            &[]
        }
    }

    fn default_track(&self) -> Option<&Track> {
        self.track.as_ref()
    }

    fn next_packet(&mut self) -> SymphResult<Packet> {
        if let Some(pkt) = self.held_packet.take() {
            return Ok(pkt);
        }

        let frame_pos = self.source.pos();

        let p_len = match self.source.read_u16() {
            Ok(len) => len as i16,
            Err(eof) => {
                self.max_ts = Some(self.curr_ts);
                return Err(eof.into());
            },
        };

        if p_len < 0 {
            return symph_err::decode_error("DCA frame header had a negative length.");
        }

        let buf = self.source.read_boxed_slice_exact(p_len as usize)?;

        let checked_buf = buf[..].try_into().or_else(|_| {
            symph_err::decode_error("Packet was not a valid Opus Packet: too large for audiopus.")
        })?;

        let sample_ct = audiopus::packet::nb_samples(checked_buf, SAMPLE_RATE).or_else(|_| {
            symph_err::decode_error(
                "Packet was not a valid Opus packet: couldn't read sample count.",
            )
        })? as u64;

        let out = Packet::new_from_boxed_slice(0, self.curr_ts, sample_ct, buf);

        self.seek_accel.update(self.curr_ts, frame_pos);

        self.curr_ts += sample_ct;

        Ok(out)
    }

    fn into_inner(self: Box<Self>) -> MediaSourceStream {
        self.source
    }
}

#[cfg(test)]
mod tests {
    use crate::input::input_tests::*;
    use crate::{constants::test_data::FILE_DCA_TARGET, input::File};

    // NOTE: this covers youtube audio in a non-copyright-violating way, since
    // those depend on an HttpRequest internally anyhow.
    #[tokio::test]
    #[ntest::timeout(10_000)]
    async fn dca_track_plays() {
        track_plays_passthrough(|| File::new(FILE_DCA_TARGET)).await;
    }

    #[tokio::test]
    #[ntest::timeout(10_000)]
    async fn dca_forward_seek_correct() {
        forward_seek_correct(|| File::new(FILE_DCA_TARGET)).await;
    }

    #[tokio::test]
    #[ntest::timeout(10_000)]
    async fn dca_backward_seek_correct() {
        backward_seek_correct(|| File::new(FILE_DCA_TARGET)).await;
    }

    #[tokio::test]
    #[ntest::timeout(10_000)]
    async fn opus_passthrough_when_other_tracks_paused() {
        track_plays_passthrough_when_is_only_active(|| File::new(FILE_DCA_TARGET)).await;
    }
}