use anyhow::{anyhow, bail, Result};
use jellycommon::{ItemInfo, SourceTrack, SourceTrackKind};
use jellymatroska::{
    block::Block,
    matroska::MatroskaTag,
    read::EbmlReader,
    unflatten::{Unflat, Unflatten},
};
use log::{debug, error, info, trace, warn};

pub fn import_read(input: &mut EbmlReader, iteminfo: &mut ItemInfo) -> Result<()> {
    // TODO dont traverse the entire file, if the tracks are listed at the end
    while let Some(item) = input.next() {
        let item = match item {
            Ok(item) => item,
            Err(e) => {
                warn!("{e}");
                break;
            }
        };
        match item {
            MatroskaTag::Ebml(_) => {
                let mut iter = Unflatten::new_with_end(input, item);
                while let Some(Ok(Unflat { children: _, item })) = iter.next() {
                    match item {
                        MatroskaTag::DocType(t) => {
                            if !matches!(t.as_str(), "matroska" | "webm") {
                                error!("file is neither matroska nor webm but {:?}", t)
                            }
                        }
                        _ => debug!("(re) tag ignored: {item:?}"),
                    }
                }
            }
            MatroskaTag::Segment(_) => {
                info!("segment start");
                let mut children = Unflatten::new_with_end(input, item);
                import_read_segment(&mut children, iteminfo)?;
                info!("segment end");
            }
            _ => debug!("(r) tag ignored: {item:?}"),
        }
    }

    Ok(())
}

fn import_read_segment(children: &mut Unflatten, iteminfo: &mut ItemInfo) -> Result<()> {
    let (mut timestamp_scale, mut duration) = (None, None);
    while let Some(Ok(Unflat { children, item })) = children.next() {
        match item {
            MatroskaTag::SeekHead(_) => {}
            MatroskaTag::Info(_) => {
                let mut children = children.unwrap();
                while let Some(Ok(Unflat { children: _, item })) = children.next() {
                    match item {
                        MatroskaTag::TimestampScale(v) => timestamp_scale = Some(v),
                        MatroskaTag::Duration(v) => duration = Some(v),
                        _ => debug!("(rsi) tag ignored: {item:?}"),
                    }
                }
            }
            MatroskaTag::Cluster(_) => {
                info!("start of cluster found");
                let mut children = children.unwrap();
                while let Some(Ok(Unflat { children, item })) = children.next() {
                    match item {
                        MatroskaTag::BlockGroup(_) => {
                            debug!("group");
                            let mut children = children.unwrap();
                            while let Some(Ok(Unflat { children: _, item })) = children.next() {
                                match item {
                                    MatroskaTag::Block(buf) => {
                                        let block = Block::parse(&buf)?;
                                        debug!(
                                            "block: track={} tso={}",
                                            block.track, block.timestamp_off
                                        )
                                    }
                                    _ => trace!("{item:?}"),
                                }
                            }
                        }
                        MatroskaTag::SimpleBlock(buf) => {
                            let block = Block::parse(&buf)?;
                            debug!(
                                "simple block: track={} tso={}",
                                block.track, block.timestamp_off
                            )
                        }
                        _ => debug!("(rsc) tag ignored: {item:?}"),
                    }
                }
            }
            MatroskaTag::Tags(_) => {}
            MatroskaTag::Cues(_) => {
                let mut children = children.unwrap();
                while let Some(Ok(Unflat { children, item })) = children.next() {
                    match item {
                        MatroskaTag::CuePoint(_) => {
                            let mut children = children.unwrap();
                            while let Some(Ok(Unflat { children: _, item: _ })) = children.next() {
                                // error!("{item:?}")
                            }
                        }
                        _ => (),
                    }
                }
            }
            MatroskaTag::Chapters(_) => {}
            MatroskaTag::Tracks(_) => {
                let mut children = children.unwrap();
                while let Some(Ok(Unflat { children, item })) = children.next() {
                    match item {
                        MatroskaTag::TrackEntry(_) => {
                            let mut children = children.unwrap();
                            let (
                                mut index,
                                mut language,
                                mut codec,
                                mut kind,
                                mut sample_rate,
                                mut channels,
                                mut width,
                                mut height,
                                mut name,
                                mut fps,
                                mut bit_depth,
                                mut codec_private,
                                mut default_duration,
                            ) = (
                                None, None, None, None, None, None, None, None, None, None, None,
                                None, None,
                            );
                            while let Some(Ok(Unflat { children, item })) = children.next() {
                                match item {
                                    MatroskaTag::CodecID(b) => codec = Some(b),
                                    MatroskaTag::Language(v) => language = Some(v),
                                    MatroskaTag::TrackNumber(v) => index = Some(v),
                                    MatroskaTag::TrackType(v) => kind = Some(v),
                                    MatroskaTag::Name(v) => name = Some(v),
                                    MatroskaTag::CodecPrivate(v) => codec_private = Some(v),
                                    MatroskaTag::DefaultDuration(v) => default_duration = Some(v),
                                    MatroskaTag::Audio(_) => {
                                        let mut children = children.unwrap();
                                        while let Some(Ok(Unflat { item, .. })) = children.next() {
                                            match item {
                                                MatroskaTag::Channels(v) => {
                                                    channels = Some(v as usize)
                                                }
                                                MatroskaTag::SamplingFrequency(v) => {
                                                    sample_rate = Some(v)
                                                }
                                                MatroskaTag::BitDepth(v) => bit_depth = Some(v),
                                                _ => (),
                                            }
                                        }
                                    }
                                    MatroskaTag::Video(_) => {
                                        let mut children = children.unwrap();
                                        while let Some(Ok(Unflat { item, .. })) = children.next() {
                                            match item {
                                                MatroskaTag::PixelWidth(v) => width = Some(v),
                                                MatroskaTag::PixelHeight(v) => height = Some(v),
                                                MatroskaTag::FrameRate(v) => fps = Some(v),
                                                _ => (),
                                            }
                                        }
                                    }
                                    _ => (),
                                }
                            }
                            // let itrack_index = iteminfo.tracks.len();
                            let mtrack_index = index.unwrap();
                            let kind = match kind.ok_or(anyhow!("track type required"))? {
                                1 => SourceTrackKind::Video {
                                    fps: fps.unwrap_or(0.0), // TODO
                                    width: width.unwrap(),
                                    height: height.unwrap(),
                                },
                                2 => SourceTrackKind::Audio {
                                    bit_depth: bit_depth.unwrap_or(0) as usize, // TODO
                                    channels: channels.unwrap(),
                                    sample_rate: sample_rate.unwrap(),
                                },
                                17 => SourceTrackKind::Subtitles,
                                _ => bail!("invalid track type"),
                            };
                            // track_mapping.insert(mtrack_index, itrack_index);
                            iteminfo.tracks.insert(
                                mtrack_index,
                                SourceTrack {
                                    default_duration,
                                    codec_private,
                                    name: name.unwrap_or_else(|| "unnamed".to_string()),
                                    codec: codec.unwrap(),
                                    language: language.unwrap_or_else(|| "none".to_string()),
                                    kind,
                                },
                            );
                        }
                        _ => debug!("(rst) tag ignored: {item:?}"),
                    }
                }
            }
            _ => debug!("(rs) tag ignored: {item:?}"),
        }
    }
    iteminfo.duration =
        (duration.unwrap() * timestamp_scale.unwrap() as f64) as f64 / 1_000_000_000 as f64;
    Ok(())
}