/*
    This file is part of jellything (https://codeberg.org/metamuffin/jellything)
    which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
    Copyright (C) 2024 metamuffin <metamuffin.org>
*/
use crate::seek_index::get_seek_index;
use anyhow::{anyhow, bail};
use jellycommon::LocalTrack;
use jellymatroska::{block::Block, read::EbmlReader, unflatten::IterWithPos, Master, MatroskaTag};
use log::{debug, info};
use std::{fs::File, io::BufReader, path::PathBuf};

pub fn extract_track(
    path_base: PathBuf,
    track_info: LocalTrack,
) -> anyhow::Result<Vec<(u64, u64, Vec<u8>)>> {
    let source_path = path_base.join(track_info.path);
    let file = File::open(&source_path)?;
    let mut reader = EbmlReader::new(BufReader::new(file));
    let index = get_seek_index(&source_path)?;
    let index = index
        .get(&(track_info.track as u64))
        .ok_or(anyhow!("track missing 4"))?;

    let mut out = Vec::new();
    for b in &index.blocks {
        reader.seek(b.source_off, MatroskaTag::Cluster(Master::Start))?;
        let (duration, block) = read_group(&mut reader)?;
        out.push((b.pts, duration, block.data))
    }
    Ok(out)
}

pub fn read_group(segment: &mut EbmlReader) -> anyhow::Result<(u64, Block)> {
    let (mut dur, mut block) = (None, None);
    loop {
        let item = segment.next().ok_or(anyhow!("eof"))??;
        match item {
            MatroskaTag::Void(_) => (),
            MatroskaTag::Crc32(_) => (),
            MatroskaTag::Cluster(_) => (),
            MatroskaTag::Timestamp(_) => (),
            MatroskaTag::SimpleBlock(_buf) => {
                // bail!("unexpected simpleblock, where a group was expected")
            }
            MatroskaTag::BlockGroup(Master::Start) => (),
            MatroskaTag::BlockGroup(Master::End) => return Ok((dur.unwrap(), block.unwrap())),
            MatroskaTag::BlockDuration(duration) => dur = Some(duration),
            MatroskaTag::Block(buf) => block = Some(Block::parse(&buf)?),
            MatroskaTag::Cues(_) => bail!("reached cues, this is the end"),
            MatroskaTag::Segment(Master::End) => info!("extractor reached segment end"),
            _ => debug!("(rs) tag ignored: {item:?}"),
        }
    }
}