/*
    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 anyhow::{anyhow, bail, Context, Result};
use bincode::{Decode, Encode};
use jellycommon::{Chapter, LocalTrack, SourceTrack, SourceTrackKind};
use jellymatroska::{
    matroska::MatroskaTag,
    read::EbmlReader,
    unflatten::{Unflat, Unflatten},
};
use log::{debug, error, info, warn};
use std::{path::PathBuf, time::Instant};

#[derive(Default, Clone, Debug, Encode, Decode)]
pub struct MatroskaMetadata {
    pub title: Option<String>,
    pub description: Option<String>,
    pub tagline: Option<String>,
    pub tracks: Vec<SourceTrack>,
    pub track_sources: Vec<LocalTrack>,
    pub cover: Option<(String, Vec<u8>)>,
    pub infojson: Option<String>,
    pub chapters: Vec<Chapter>,
    pub duration: f64,
}

pub fn import_metadata(input: &mut EbmlReader) -> Result<MatroskaMetadata> {
    while let Some(item) = input.next() {
        let item = match item {
            Ok((_, item)) => item,
            Err(e) => {
                if !matches!(e, jellymatroska::error::Error::Io(_)) {
                    warn!("{e}");
                }
                break;
            }
        };
        match item {
            MatroskaTag::Ebml(_) => {
                let mut iter = Unflatten::new_with_end(input, item);
                while let Some(Ok(Unflat {
                    children: _, item, ..
                })) = iter.n()
                {
                    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!("extracting metadata...");
                let mut children = Unflatten::new_with_end(input, item);
                let t = Instant::now();
                let r = import_read_segment(&mut children)?;
                info!("done in {:?}", t.elapsed());
                return Ok(r);
            }
            _ => debug!("(r) tag ignored: {item:?}"),
        }
    }
    Err(anyhow!("no segment found"))
}

fn import_read_segment(segment: &mut Unflatten) -> Result<MatroskaMetadata> {
    let (mut timestamp_scale, mut duration) = (None, None);
    let mut m = MatroskaMetadata::default();

    let (
        mut info_found,
        mut tags_found,
        mut attachments_found,
        mut tracks_found,
        mut found_chapters,
    ) = (false, false, false, false, false);

    while let Some(Ok(Unflat { children, item, .. })) = segment.n() {
        match item {
            MatroskaTag::SeekHead(_) => {}
            MatroskaTag::Info(_) => {
                info_found = true;
                let mut children = children.unwrap();
                while let Some(Ok(Unflat {
                    children: _, item, ..
                })) = children.n()
                {
                    match item {
                        MatroskaTag::Title(t) => m.title = Some(t),
                        MatroskaTag::TimestampScale(v) => timestamp_scale = Some(v),
                        MatroskaTag::Duration(v) => duration = Some(v),
                        _ => debug!("(rsi) tag ignored: {item:?}"),
                    }
                }
            }
            MatroskaTag::Void(_) => {}
            MatroskaTag::Tags(_) => {
                tags_found = true;
                let mut children = children.unwrap();
                while let Some(Ok(Unflat { children, item, .. })) = children.n() {
                    match item {
                        MatroskaTag::Tag(_) => {
                            let mut children = children.unwrap();
                            while let Some(Ok(Unflat { children, item, .. })) = children.n() {
                                match item {
                                    MatroskaTag::SimpleTag(_) => {
                                        let (mut key, mut value) = (None, None);
                                        let mut children = children.unwrap();
                                        while let Some(Ok(Unflat {
                                            children: _, item, ..
                                        })) = children.n()
                                        {
                                            match item {
                                                MatroskaTag::TagName(k) => key = Some(k),
                                                MatroskaTag::TagString(v) => value = Some(v),
                                                _ => debug!("(rstts) tag ignored: {item:?}"),
                                            }
                                        }
                                        match (key, value) {
                                            (Some(key), Some(value)) => match key.as_str() {
                                                "DESCRIPTION" => m.description = Some(value),
                                                "COMMENT" => m.tagline = Some(value),
                                                _ => debug!("simple tag ignored: {key:?}"),
                                            },
                                            (None, None) => (),
                                            _ => warn!("simple tag with only one of name/string"),
                                        }
                                    }
                                    _ => debug!("(rstt) tag ignored: {item:?}"),
                                }
                            }
                        }
                        MatroskaTag::Crc32(_) => {}
                        _ => debug!("(rst) tag ignored: {item:?}"),
                    }
                }
            }
            MatroskaTag::Attachments(_) => {
                attachments_found = true;
                let mut children = children.unwrap();
                while let Some(Ok(Unflat { children, item, .. })) = children.n() {
                    match item {
                        MatroskaTag::AttachedFile(_) => {
                            let (mut name, mut data, mut mime) = Default::default();
                            let mut children = children.unwrap();
                            while let Some(Ok(Unflat {
                                children: _, item, ..
                            })) = children.n()
                            {
                                match item {
                                    MatroskaTag::FileName(n) => name = Some(n),
                                    MatroskaTag::FileData(d) => data = Some(d),
                                    MatroskaTag::FileMimeType(m) => mime = Some(m),
                                    _ => debug!("(rsaa) tag ignored: {item:?}"),
                                }
                            }
                            let (name, data, mime) = (
                                name.ok_or(anyhow!("attachment without name"))?,
                                data.ok_or(anyhow!("attachment without data"))?,
                                mime.ok_or(anyhow!("attachment without mime type"))?,
                            );
                            info!("attachment found: {name:?} type {mime:?}");
                            match (name.as_str(), mime.as_str()) {
                                ("info.json", "application/json") => {
                                    m.infojson =
                                        Some(String::from_utf8(data).context("info.json invalid")?)
                                }
                                (_, "image/jpeg" | "image/png" | "image/webp") => {
                                    m.cover = Some((mime, data))
                                }
                                _ => (),
                            }
                        }
                        _ => debug!("(rsa) tag ignored: {item:?}"),
                    }
                }
            }
            MatroskaTag::Cues(_) => {}
            MatroskaTag::Chapters(_) => {
                found_chapters = true;
                let mut children = children.unwrap();
                while let Some(Ok(Unflat { children, item, .. })) = children.n() {
                    match item {
                        MatroskaTag::EditionEntry(_) => {
                            let mut children = children.unwrap();
                            while let Some(Ok(Unflat { children, item, .. })) = children.n() {
                                match item {
                                    MatroskaTag::EditionUID(_)
                                    | MatroskaTag::EditionFlagHidden(_)
                                    | MatroskaTag::EditionFlagDefault(_) => {}
                                    MatroskaTag::ChapterAtom(_) => {
                                        let mut children = children.unwrap();
                                        let mut chap = Chapter::default();
                                        while let Some(Ok(Unflat { children, item, .. })) =
                                            children.n()
                                        {
                                            match item {
                                                MatroskaTag::ChapterFlagEnabled(_)
                                                | MatroskaTag::ChapterFlagHidden(_)
                                                | MatroskaTag::ChapterUID(_) => (),
                                                MatroskaTag::ChapterTimeStart(t) => {
                                                    chap.time_start = Some(t as f64 * 1e-9)
                                                }
                                                MatroskaTag::ChapterTimeEnd(t) => {
                                                    chap.time_end = Some(t as f64 * 1e-9)
                                                }
                                                MatroskaTag::ChapterDisplay(_) => {
                                                    let mut string = String::new();
                                                    let mut lang = String::new();
                                                    let mut children = children.unwrap();
                                                    while let Some(Ok(Unflat { item, .. })) =
                                                        children.n()
                                                    {
                                                        match item {
                                                            MatroskaTag::ChapString(s) => {
                                                                string = s
                                                            }
                                                            MatroskaTag::ChapLanguage(l) => {
                                                                lang = l
                                                            }
                                                            _ => warn!(
                                                                "(rscead) tag ignored: {item:?}"
                                                            ),
                                                        }
                                                    }
                                                    chap.labels.push((lang, string))
                                                }
                                                _ => warn!("(rscea) tag ignored: {item:?}"),
                                            }
                                        }
                                        m.chapters.push(chap);
                                    }
                                    _ => warn!("(rsce) tag ignored: {item:?}"),
                                }
                            }
                            if !m.chapters.is_empty() {
                                info!("{} chapters added", m.chapters.len());
                            }
                        }
                        _ => warn!("(rsc) tag ignored: {item:?}"),
                    }
                }
            }
            MatroskaTag::Tracks(_) => {
                tracks_found = true;
                let mut children = children.unwrap();
                while let Some(Ok(Unflat { children, item, .. })) = children.n() {
                    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 display_width,
                                mut display_height,
                                mut name,
                                mut fps,
                                mut bit_depth,
                                mut codec_private,
                                mut default_duration,
                                mut display_unit,
                            ) = (
                                None, None, None, None, None, None, None, None, None, None, None,
                                None, None, None, None, None,
                            );
                            while let Some(Ok(Unflat { children, item, .. })) = children.n() {
                                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.n() {
                                            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.n() {
                                            match item {
                                                MatroskaTag::PixelWidth(v) => width = Some(v),
                                                MatroskaTag::PixelHeight(v) => height = Some(v),
                                                MatroskaTag::DisplayWidth(v) => {
                                                    display_width = Some(v)
                                                }
                                                MatroskaTag::DisplayHeight(v) => {
                                                    display_height = Some(v)
                                                }
                                                MatroskaTag::DisplayUnit(v) => {
                                                    display_unit = Some(v)
                                                }
                                                MatroskaTag::FrameRate(v) => fps = Some(v),
                                                _ => (),
                                            }
                                        }
                                    }
                                    _ => (),
                                }
                            }
                            let track_index = index.unwrap();
                            let kind = match kind.ok_or(anyhow!("track type required"))? {
                                1 => SourceTrackKind::Video {
                                    fps,
                                    width: width.unwrap(),
                                    height: height.unwrap(),
                                    display_width,
                                    display_height,
                                    display_unit,
                                },
                                2 => SourceTrackKind::Audio {
                                    bit_depth: bit_depth.map(|x| x as usize),
                                    channels: channels.unwrap_or(1), // TODO
                                    sample_rate: sample_rate.unwrap_or(41_100.0), // TODO
                                },
                                17 => SourceTrackKind::Subtitles,
                                _ => bail!("invalid track type"),
                            };
                            m.tracks.push(SourceTrack {
                                federated: vec![],
                                default_duration,
                                name: name.unwrap_or_else(|| "unnamed".to_string()),
                                codec: codec.unwrap(),
                                language: language.unwrap_or_else(|| "none".to_string()),
                                kind,
                            });
                            m.track_sources.push(LocalTrack {
                                track: track_index as usize,
                                path: PathBuf::new(),
                                codec_private,
                            })
                        }
                        MatroskaTag::Crc32(_) => {}
                        _ => warn!("(rst) tag ignored: {item:?}"),
                    }
                }
            }
            MatroskaTag::Cluster(_) => {}

            _ => warn!("(rs) tag ignored: {item:?}"),
        };
        if info_found && tracks_found && attachments_found && tags_found && found_chapters {
            debug!("we found all we need, stopping read early");
            break;
        }
    }
    segment.exit_dirty();

    if let Some(duration) = duration {
        m.duration = (duration * timestamp_scale.unwrap_or(1_000_000) as f64) / 1_000_000_000_f64;
    }

    Ok(m)
}