/*
    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) 2025 metamuffin <metamuffin.org>
*/

use anyhow::{anyhow, Result};
use jellycache::cache_memory;
use jellyremuxer::demuxers::create_demuxer_autodetect;
use serde::{Deserialize, Serialize};
use std::{collections::BTreeMap, fs::File, path::Path, sync::Arc};

#[derive(Serialize, Deserialize, Default)]
pub struct TrackStat {
    pub num_blocks: usize,
    pub total_size: u64,
}

#[derive(Clone, Copy, Serialize, Deserialize)]
pub struct GeneratedCue {
    pub position: u64,
    pub time: u64,
}

#[derive(Serialize, Deserialize)]
pub struct StatsAndCues {
    pub stats: BTreeMap<u64, TrackStat>,
    pub cues: Vec<GeneratedCue>,
}

pub fn generate_cues(path: &Path) -> Result<Arc<StatsAndCues>> {
    cache_memory("generated-cues", path, move || {
        let media = File::open(path)?;
        let mut media =
            create_demuxer_autodetect(Box::new(media))?.ok_or(anyhow!("media format unknown"))?;

        let info = media.info()?;
        media.seek_cluster(None)?;

        let mut stats = BTreeMap::<u64, TrackStat>::new();
        let mut cues = Vec::new();

        while let Some((position, cluster)) = media.read_cluster()? {
            cues.push(GeneratedCue {
                position,
                time: cluster.timestamp * info.timestamp_scale,
            });
            for block in cluster.simple_blocks {
                let e = stats.entry(block.track).or_default();
                e.num_blocks += 1;
                e.total_size += block.data.len() as u64;
            }
        }

        Ok(StatsAndCues { stats, cues })
    })
}