/*
    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>
*/
#![feature(iterator_try_collect)]
pub mod fragment;
pub mod hls;
pub mod jhls;
pub mod webvtt;

use anyhow::{anyhow, Context, Result};
use jellybase::common::{
    stream::{
        StreamContainer, StreamFormatInfo, StreamInfo, StreamSegmentInfo, StreamSpec,
        StreamTrackInfo, TrackKind,
    },
    LocalTrack, Node,
};
use jellyremuxer::metadata::{matroska_metadata, MatroskaMetadata};
use std::{collections::BTreeSet, io::SeekFrom, ops::Range, path::PathBuf, sync::Arc};
use tokio::{
    fs::File,
    io::{duplex, AsyncReadExt, AsyncSeekExt, AsyncWriteExt, DuplexStream},
    task::spawn_blocking,
};
use tokio_util::io::SyncIoBridge;

#[derive(Debug)]
pub struct SMediaInfo {
    pub info: Arc<Node>,
    pub files: BTreeSet<PathBuf>,
}

pub struct StreamHead {
    pub content_type: &'static str,
    pub range_supported: bool,
}

pub fn stream_head(spec: &StreamSpec) -> StreamHead {
    let cons = |ct: &'static str, rs: bool| StreamHead {
        content_type: ct,
        range_supported: rs,
    };
    let container_ct = |x: StreamContainer| match x {
        StreamContainer::WebM => "video/webm",
        StreamContainer::Matroska => "video/x-matroska",
        StreamContainer::WebVTT => "text/vtt",
        StreamContainer::JVTT => "application/jellything-vtt+json",
    };
    match spec {
        StreamSpec::Whep { .. } => cons("application/x-todo", false),
        StreamSpec::WhepControl { .. } => cons("application/x-todo", false),
        StreamSpec::Remux { container, .. } => cons(container_ct(*container), true),
        StreamSpec::Original { .. } => cons("video/x-matroska", true),
        StreamSpec::HlsSuperMultiVariant { .. } => cons("application/vnd.apple.mpegurl", false),
        StreamSpec::HlsMultiVariant { .. } => cons("application/vnd.apple.mpegurl", false),
        StreamSpec::HlsVariant { .. } => cons("application/vnd.apple.mpegurl", false),
        StreamSpec::Info { .. } => cons("application/jellything-stream-info+json", false),
        StreamSpec::FragmentIndex { .. } => cons("application/jellything-frag-index+json", false),
        StreamSpec::Fragment { container, .. } => cons(container_ct(*container), false),
    }
}

pub async fn stream(
    info: Arc<SMediaInfo>,
    spec: StreamSpec,
    range: Range<usize>,
) -> Result<DuplexStream> {
    let (a, b) = duplex(4096);

    match spec {
        StreamSpec::Whep { track, seek } => todo!(),
        StreamSpec::WhepControl { token } => todo!(),
        StreamSpec::Remux { tracks, container } => todo!(),
        StreamSpec::Original { track } => original_stream(info, track, range, b).await?,
        StreamSpec::HlsSuperMultiVariant { container } => todo!(),
        StreamSpec::HlsMultiVariant { segment, container } => todo!(),
        StreamSpec::HlsVariant {
            segment,
            track,
            container,
            format,
        } => todo!(),
        StreamSpec::Info { segment } => write_stream_info(info, b).await?,
        StreamSpec::FragmentIndex { segment, track } => todo!(),
        StreamSpec::Fragment {
            segment,
            track,
            index,
            container,
            format,
        } => todo!(),
    }

    Ok(a)
}

async fn async_matroska_metadata(path: PathBuf) -> Result<Arc<MatroskaMetadata>> {
    Ok(spawn_blocking(move || matroska_metadata(&path)).await??)
}

pub(crate) struct InternalStreamInfo {
    pub paths: Vec<PathBuf>,
    pub metadata: Vec<Arc<MatroskaMetadata>>,
    pub track_to_file: Vec<usize>,
}

async fn stream_info(info: Arc<SMediaInfo>) -> Result<(InternalStreamInfo, StreamInfo)> {
    let mut metadata = Vec::new();
    let mut paths = Vec::new();
    for path in &info.files {
        metadata.push(async_matroska_metadata(path.clone()).await?);
        paths.push(path.clone());
    }

    let mut tracks = Vec::new();
    let mut track_to_file = Vec::new();

    for (i, m) in metadata.iter().enumerate() {
        if let Some(t) = &m.tracks {
            for t in &t.entries {
                let mut formats = Vec::new();
                formats.push(StreamFormatInfo {
                    codec: t.codec_id.to_string(),
                    remux: true,
                    byterate: 10., // TODO
                    containers: [StreamContainer::Matroska].to_vec(),
                    bit_depth: t.audio.as_ref().and_then(|a| a.bit_depth.map(|e| e as u8)),
                    samplerate: t.audio.as_ref().map(|a| a.sampling_frequency),
                    channels: t.audio.as_ref().map(|a| a.channels as usize),
                    pixel_count: t.video.as_ref().map(|v| v.pixel_width * v.pixel_height),
                    ..Default::default()
                });
                tracks.push(StreamTrackInfo {
                    name: None,
                    kind: match t.track_type {
                        1 => TrackKind::Video,
                        2 => TrackKind::Audio,
                        17 => TrackKind::Subtitle,
                        _ => todo!(),
                    },
                    formats,
                });
                track_to_file.push(i);
            }
        }
    }

    let segment = StreamSegmentInfo {
        name: None,
        duration: 0,
        tracks,
    };
    Ok((
        InternalStreamInfo {
            metadata,
            paths,
            track_to_file,
        },
        StreamInfo {
            name: info.info.title.clone(),
            segments: vec![segment],
        },
    ))
}

async fn write_stream_info(info: Arc<SMediaInfo>, mut b: DuplexStream) -> Result<()> {
    let (_, info) = stream_info(info).await?;
    b.write_all(&serde_json::to_vec(&info)?).await?;
    Ok(())
}

async fn remux_stream(
    node: Arc<Node>,
    local_tracks: Vec<LocalTrack>,
    spec: StreamSpec,
    range: Range<usize>,
    b: DuplexStream,
) -> Result<()> {
    let b = SyncIoBridge::new(b);

    // tokio::task::spawn_blocking(move || {
    //     jellyremuxer::remux_stream_into(
    //         b,
    //         range,
    //         CONF.media_path.to_owned(),
    //         &node,
    //         local_tracks,
    //         spec.track,
    //         spec.webm.unwrap_or(false),
    //     )
    // });

    Ok(())
}

async fn original_stream(
    info: Arc<SMediaInfo>,
    track: usize,
    range: Range<usize>,
    b: DuplexStream,
) -> Result<()> {
    let (iinfo, _info) = stream_info(info).await?;

    let file_index = *iinfo
        .track_to_file
        .get(track)
        .ok_or(anyhow!("unknown track"))?;
    let mut file = File::open(&iinfo.paths[file_index])
        .await
        .context("opening source")?;
    file.seek(SeekFrom::Start(range.start as u64))
        .await
        .context("seek source")?;

    tokio::task::spawn(copy_stream(file, b, range.end - range.start));

    Ok(())
}

async fn copy_stream(mut inp: File, mut out: DuplexStream, mut amount: usize) -> Result<()> {
    let mut buf = [0u8; 4096];
    loop {
        let size = inp.read(&mut buf[..amount.min(4096)]).await?;
        if size == 0 {
            break Ok(());
        }
        out.write_all(&buf[..size]).await?;
        amount -= size;
    }
}