#[cfg(test)]
mod tests;

use crate::{
    config::{AudioCodec, ImageFormat, MediaConfiguration, VideoCodec},
    formats::InternalVideoFormat,
    magick::{Details, ParseDetailsError, ValidInputType, ValidateDetailsError},
    process::{Process, ProcessError},
    store::{Store, StoreError},
};
use actix_web::web::Bytes;
use once_cell::sync::OnceCell;
use std::collections::HashSet;
use tokio::io::{AsyncRead, AsyncReadExt};

#[derive(Debug)]
pub(crate) struct TranscodeOptions {
    input_format: VideoFormat,
    output: TranscodeOutputOptions,
}

#[derive(Debug)]
enum TranscodeOutputOptions {
    Gif,
    Video {
        video_codec: VideoCodec,
        audio_codec: Option<AudioCodec>,
    },
}

#[derive(Clone, Copy, Debug)]
pub(crate) enum VideoFormat {
    Gif,
    Mp4,
    Webm,
}

#[derive(Clone, Copy, Debug)]
pub(crate) enum OutputFormat {
    Mp4,
    Webm,
}

#[derive(Clone, Copy, Debug)]
pub(crate) enum ThumbnailFormat {
    Jpeg,
    // Webp,
}

#[derive(Clone, Copy, Debug)]
pub(crate) enum FileFormat {
    Image(ImageFormat),
    Video(VideoFormat),
}

#[derive(serde::Deserialize)]
struct PixelFormatOutput {
    pixel_formats: Vec<PixelFormat>,
}

#[derive(serde::Deserialize)]
struct PixelFormat {
    name: String,
    flags: Flags,
}

#[derive(serde::Deserialize)]
struct Flags {
    alpha: usize,
}

#[derive(Debug, thiserror::Error)]
pub(crate) enum FfMpegError {
    #[error("Error in ffmpeg process")]
    Process(#[source] ProcessError),

    #[error("Error reading output")]
    Read(#[source] std::io::Error),

    #[error("Error writing bytes")]
    Write(#[source] std::io::Error),

    #[error("Invalid output format")]
    Json(#[source] serde_json::Error),

    #[error("Error creating parent directory")]
    CreateDir(#[source] crate::store::file_store::FileError),

    #[error("Error reading file to stream")]
    ReadFile(#[source] crate::store::file_store::FileError),

    #[error("Error opening file")]
    OpenFile(#[source] std::io::Error),

    #[error("Error creating file")]
    CreateFile(#[source] std::io::Error),

    #[error("Error closing file")]
    CloseFile(#[source] std::io::Error),

    #[error("Error removing file")]
    RemoveFile(#[source] std::io::Error),

    #[error("Error parsing details")]
    Details(#[source] ParseDetailsError),

    #[error("Media details are invalid")]
    ValidateDetails(#[source] ValidateDetailsError),

    #[error("Error in store")]
    Store(#[source] StoreError),

    #[error("Invalid file path")]
    Path,
}

impl FfMpegError {
    pub(crate) fn is_client_error(&self) -> bool {
        // Failing validation or ffmpeg bailing probably means bad input
        matches!(self, Self::ValidateDetails(_))
            || matches!(self, Self::Process(ProcessError::Status(_)))
    }

    pub(crate) fn is_not_found(&self) -> bool {
        if let Self::Store(e) = self {
            return e.is_not_found();
        }

        false
    }
}

impl TranscodeOptions {
    pub(crate) fn new(
        media: &MediaConfiguration,
        details: &Details,
        input_format: VideoFormat,
    ) -> Self {
        if let VideoFormat::Gif = input_format {
            if details.width <= media.gif.max_width
                && details.height <= media.gif.max_height
                && details.width * details.height <= media.gif.max_area
                && details.frames.unwrap_or(1) <= media.gif.max_frame_count
            {
                return Self {
                    input_format,
                    output: TranscodeOutputOptions::gif(),
                };
            }
        }

        Self {
            input_format,
            output: TranscodeOutputOptions::video(media),
        }
    }

    pub(crate) const fn needs_reencode(&self) -> bool {
        !matches!(
            (self.input_format, &self.output),
            (VideoFormat::Gif, TranscodeOutputOptions::Gif)
        )
    }

    const fn input_file_extension(&self) -> &'static str {
        self.input_format.to_file_extension()
    }

    const fn output_ffmpeg_format(&self) -> &'static str {
        match self.output {
            TranscodeOutputOptions::Gif => "gif",
            TranscodeOutputOptions::Video { video_codec, .. } => {
                video_codec.to_output_format().to_ffmpeg_format()
            }
        }
    }

    const fn output_file_extension(&self) -> &'static str {
        match self.output {
            TranscodeOutputOptions::Gif => ".gif",
            TranscodeOutputOptions::Video { video_codec, .. } => {
                video_codec.to_output_format().to_file_extension()
            }
        }
    }

    const fn supports_alpha(&self) -> bool {
        matches!(
            self.output,
            TranscodeOutputOptions::Gif
                | TranscodeOutputOptions::Video {
                    video_codec: VideoCodec::Vp8 | VideoCodec::Vp9,
                    ..
                }
        )
    }

    fn execute(
        &self,
        input_path: &str,
        output_path: &str,
        alpha: bool,
    ) -> Result<Process, ProcessError> {
        match self.output {
            TranscodeOutputOptions::Gif => Process::run("ffmpeg", &[
                "-hide_banner",
                "-v",
                "warning",
                "-i",
                input_path,
                "-filter_complex",
                "[0:v] split [a][b]; [a] palettegen=stats_mode=single [p]; [b][p] paletteuse=new=1",
                "-an",
                "-f",
                self.output_ffmpeg_format(),
                output_path
            ]),
            TranscodeOutputOptions::Video {
                video_codec,
                audio_codec: None,
            } => Process::run(
                "ffmpeg",
                &[
                    "-hide_banner",
                    "-v",
                    "warning",
                    "-i",
                    input_path,
                    "-pix_fmt",
                    video_codec.pix_fmt(alpha),
                    "-vf",
                    "scale=trunc(iw/2)*2:trunc(ih/2)*2",
                    "-an",
                    "-c:v",
                    video_codec.to_ffmpeg_codec(),
                    "-f",
                    self.output_ffmpeg_format(),
                    output_path,
                ],
            ),
            TranscodeOutputOptions::Video {
                video_codec,
                audio_codec: Some(audio_codec),
            } => Process::run(
                "ffmpeg",
                &[
                    "-hide_banner",
                    "-v",
                    "warning",
                    "-i",
                    input_path,
                    "-pix_fmt",
                    video_codec.pix_fmt(alpha),
                    "-vf",
                    "scale=trunc(iw/2)*2:trunc(ih/2)*2",
                    "-c:a",
                    audio_codec.to_ffmpeg_codec(),
                    "-c:v",
                    video_codec.to_ffmpeg_codec(),
                    "-f",
                    self.output_ffmpeg_format(),
                    output_path,
                ],
            ),
        }
    }

    pub(crate) const fn output_type(&self) -> ValidInputType {
        match self.output {
            TranscodeOutputOptions::Gif => ValidInputType::Gif,
            TranscodeOutputOptions::Video { video_codec, .. } => {
                ValidInputType::from_video_codec(video_codec)
            }
        }
    }
}

impl TranscodeOutputOptions {
    fn video(media: &MediaConfiguration) -> Self {
        Self::Video {
            video_codec: media.video_codec,
            audio_codec: if media.enable_full_video {
                Some(
                    media
                        .audio_codec
                        .unwrap_or(media.video_codec.to_output_format().default_audio_codec()),
                )
            } else {
                None
            },
        }
    }

    const fn gif() -> Self {
        Self::Gif
    }
}

impl ValidInputType {
    pub(crate) fn to_file_format(self) -> FileFormat {
        match self {
            Self::Gif => FileFormat::Video(VideoFormat::Gif),
            Self::Mp4 => FileFormat::Video(VideoFormat::Mp4),
            Self::Webm => FileFormat::Video(VideoFormat::Webm),
            Self::Avif => FileFormat::Image(ImageFormat::Avif),
            Self::Jpeg => FileFormat::Image(ImageFormat::Jpeg),
            Self::Jxl => FileFormat::Image(ImageFormat::Jxl),
            Self::Png => FileFormat::Image(ImageFormat::Png),
            Self::Webp => FileFormat::Image(ImageFormat::Webp),
        }
    }
}

impl VideoFormat {
    const fn to_file_extension(self) -> &'static str {
        match self {
            Self::Gif => ".gif",
            Self::Mp4 => ".mp4",
            Self::Webm => ".webm",
        }
    }

    fn to_mime(self) -> mime::Mime {
        match self {
            Self::Gif => mime::IMAGE_GIF,
            Self::Mp4 => crate::magick::video_mp4(),
            Self::Webm => crate::magick::video_webm(),
        }
    }
}

impl ThumbnailFormat {
    const fn as_ffmpeg_codec(self) -> &'static str {
        match self {
            Self::Jpeg => "mjpeg",
            // Self::Webp => "webp",
        }
    }

    const fn to_file_extension(self) -> &'static str {
        match self {
            Self::Jpeg => ".jpeg",
            // Self::Webp => ".webp",
        }
    }

    const fn as_ffmpeg_format(self) -> &'static str {
        match self {
            Self::Jpeg => "image2",
            // Self::Webp => "webp",
        }
    }
}

impl OutputFormat {
    const fn to_ffmpeg_format(self) -> &'static str {
        match self {
            Self::Mp4 => "mp4",
            Self::Webm => "webm",
        }
    }

    const fn default_audio_codec(self) -> AudioCodec {
        match self {
            Self::Mp4 => AudioCodec::Aac,
            Self::Webm => AudioCodec::Opus,
        }
    }

    const fn to_file_extension(self) -> &'static str {
        match self {
            Self::Mp4 => ".mp4",
            Self::Webm => ".webm",
        }
    }
}

impl VideoCodec {
    const fn to_output_format(self) -> OutputFormat {
        match self {
            Self::H264 | Self::H265 => OutputFormat::Mp4,
            Self::Av1 | Self::Vp8 | Self::Vp9 => OutputFormat::Webm,
        }
    }

    const fn to_ffmpeg_codec(self) -> &'static str {
        match self {
            Self::Av1 => "av1",
            Self::H264 => "h264",
            Self::H265 => "hevc",
            Self::Vp8 => "vp8",
            Self::Vp9 => "vp9",
        }
    }

    const fn pix_fmt(&self, alpha: bool) -> &'static str {
        match (self, alpha) {
            (VideoCodec::Vp8 | VideoCodec::Vp9, true) => "yuva420p",
            _ => "yuv420p",
        }
    }
}

impl AudioCodec {
    const fn to_ffmpeg_codec(self) -> &'static str {
        match self {
            Self::Aac => "aac",
            Self::Opus => "libopus",
            Self::Vorbis => "vorbis",
        }
    }
}

const FORMAT_MAPPINGS: &[(&str, VideoFormat)] = &[
    ("gif", VideoFormat::Gif),
    ("mp4", VideoFormat::Mp4),
    ("webm", VideoFormat::Webm),
];

pub(crate) async fn input_type_bytes(
    input: Bytes,
) -> Result<Option<(Details, ValidInputType)>, FfMpegError> {
    if let Some(details) = details_bytes(input).await? {
        let input_type = details
            .validate_input()
            .map_err(FfMpegError::ValidateDetails)?;

        return Ok(Some((details, input_type)));
    }

    Ok(None)
}

pub(crate) async fn details_store<S: Store>(
    store: &S,
    identifier: &S::Identifier,
) -> Result<Option<Details>, FfMpegError> {
    details_file(move |mut tmp_one| async move {
        let stream = store
            .to_stream(identifier, None, None)
            .await
            .map_err(FfMpegError::Store)?;
        tmp_one
            .write_from_stream(stream)
            .await
            .map_err(FfMpegError::Write)?;
        Ok(tmp_one)
    })
    .await
}

pub(crate) async fn details_bytes(input: Bytes) -> Result<Option<Details>, FfMpegError> {
    details_file(move |mut tmp_one| async move {
        tmp_one
            .write_from_bytes(input)
            .await
            .map_err(FfMpegError::Write)?;
        Ok(tmp_one)
    })
    .await
}

async fn alpha_pixel_formats() -> Result<HashSet<String>, FfMpegError> {
    let process = Process::run(
        "ffprobe",
        &[
            "-v",
            "0",
            "-show_entries",
            "pixel_format=name:flags=alpha",
            "-of",
            "compact=p=0",
            "-print_format",
            "json",
        ],
    )
    .map_err(FfMpegError::Process)?;

    let mut output = Vec::new();
    process
        .read()
        .read_to_end(&mut output)
        .await
        .map_err(FfMpegError::Read)?;

    let formats: PixelFormatOutput = serde_json::from_slice(&output).map_err(FfMpegError::Json)?;

    Ok(parse_pixel_formats(formats))
}

fn parse_pixel_formats(formats: PixelFormatOutput) -> HashSet<String> {
    formats
        .pixel_formats
        .into_iter()
        .filter_map(|PixelFormat { name, flags }| {
            if flags.alpha == 0 {
                return None;
            }

            Some(name)
        })
        .collect()
}

#[derive(Debug, serde::Deserialize)]
struct DetailsOutput {
    streams: [Stream; 1],
    format: Format,
}

#[derive(Debug, serde::Deserialize)]
struct Stream {
    width: usize,
    height: usize,
    nb_read_frames: Option<String>,
}

#[derive(Debug, serde::Deserialize)]
struct Format {
    format_name: String,
}

#[tracing::instrument(skip(f))]
async fn details_file<F, Fut>(f: F) -> Result<Option<Details>, FfMpegError>
where
    F: FnOnce(crate::file::File) -> Fut,
    Fut: std::future::Future<Output = Result<crate::file::File, FfMpegError>>,
{
    let input_file = crate::tmp_file::tmp_file(None);
    let input_file_str = input_file.to_str().ok_or(FfMpegError::Path)?;
    crate::store::file_store::safe_create_parent(&input_file)
        .await
        .map_err(FfMpegError::CreateDir)?;

    let tmp_one = crate::file::File::create(&input_file)
        .await
        .map_err(FfMpegError::CreateFile)?;
    let tmp_one = (f)(tmp_one).await?;
    tmp_one.close().await.map_err(FfMpegError::CloseFile)?;

    let process = Process::run(
        "ffprobe",
        &[
            "-v",
            "quiet",
            "-select_streams",
            "v:0",
            "-count_frames",
            "-show_entries",
            "stream=width,height,nb_read_frames:format=format_name",
            "-of",
            "default=noprint_wrappers=1:nokey=1",
            "-print_format",
            "json",
            input_file_str,
        ],
    )
    .map_err(FfMpegError::Process)?;

    let mut output = Vec::new();
    process
        .read()
        .read_to_end(&mut output)
        .await
        .map_err(FfMpegError::Read)?;
    tokio::fs::remove_file(input_file_str)
        .await
        .map_err(FfMpegError::RemoveFile)?;

    let output: DetailsOutput = serde_json::from_slice(&output).map_err(FfMpegError::Json)?;

    parse_details(output)
}

fn parse_details(output: DetailsOutput) -> Result<Option<Details>, FfMpegError> {
    tracing::debug!("OUTPUT: {:?}", output);

    let [stream] = output.streams;
    let Format { format_name } = output.format;

    for (k, v) in FORMAT_MAPPINGS {
        if format_name.contains(k) {
            return parse_details_inner(
                stream.width,
                stream.height,
                stream.nb_read_frames.as_deref(),
                *v,
            )
            .map_err(FfMpegError::Details);
        }
    }

    Ok(None)
}

fn parse_details_inner(
    width: usize,
    height: usize,
    frames: Option<&str>,
    format: VideoFormat,
) -> Result<Option<Details>, ParseDetailsError> {
    let frames = frames
        .map(|frames| {
            frames
                .parse()
                .map_err(|_| ParseDetailsError::ParseFrames(String::from(frames)))
        })
        .transpose()?
        .unwrap_or(1);

    // Probably a still image. ffmpeg thinks AVIF is an mp4
    if frames == 1 {
        return Ok(None);
    }

    Ok(Some(Details {
        mime_type: format.to_mime(),
        width,
        height,
        frames: Some(frames),
    }))
}

async fn pixel_format(input_file: &str) -> Result<String, FfMpegError> {
    let process = Process::run(
        "ffprobe",
        &[
            "-v",
            "0",
            "-select_streams",
            "v:0",
            "-show_entries",
            "stream=pix_fmt",
            "-of",
            "compact=p=0:nk=1",
            input_file,
        ],
    )
    .map_err(FfMpegError::Process)?;

    let mut output = Vec::new();
    process
        .read()
        .read_to_end(&mut output)
        .await
        .map_err(FfMpegError::Read)?;
    Ok(String::from_utf8_lossy(&output).trim().to_string())
}

#[tracing::instrument(skip(input))]
pub(crate) async fn transcode_bytes(
    input: Bytes,
    transcode_options: TranscodeOptions,
) -> Result<impl AsyncRead + Unpin, FfMpegError> {
    let input_file = crate::tmp_file::tmp_file(Some(transcode_options.input_file_extension()));
    let input_file_str = input_file.to_str().ok_or(FfMpegError::Path)?;
    crate::store::file_store::safe_create_parent(&input_file)
        .await
        .map_err(FfMpegError::CreateDir)?;

    let output_file = crate::tmp_file::tmp_file(Some(transcode_options.output_file_extension()));
    let output_file_str = output_file.to_str().ok_or(FfMpegError::Path)?;
    crate::store::file_store::safe_create_parent(&output_file)
        .await
        .map_err(FfMpegError::CreateDir)?;

    let mut tmp_one = crate::file::File::create(&input_file)
        .await
        .map_err(FfMpegError::CreateFile)?;
    tmp_one
        .write_from_bytes(input)
        .await
        .map_err(FfMpegError::Write)?;
    tmp_one.close().await.map_err(FfMpegError::CloseFile)?;

    let alpha = if transcode_options.supports_alpha() {
        static ALPHA_PIXEL_FORMATS: OnceCell<HashSet<String>> = OnceCell::new();

        let format = pixel_format(input_file_str).await?;

        match ALPHA_PIXEL_FORMATS.get() {
            Some(alpha_pixel_formats) => alpha_pixel_formats.contains(&format),
            None => {
                let pixel_formats = alpha_pixel_formats().await?;
                let alpha = pixel_formats.contains(&format);
                let _ = ALPHA_PIXEL_FORMATS.set(pixel_formats);
                alpha
            }
        }
    } else {
        false
    };

    let process = transcode_options
        .execute(input_file_str, output_file_str, alpha)
        .map_err(FfMpegError::Process)?;

    process.wait().await.map_err(FfMpegError::Process)?;
    tokio::fs::remove_file(input_file)
        .await
        .map_err(FfMpegError::RemoveFile)?;

    let tmp_two = crate::file::File::open(&output_file)
        .await
        .map_err(FfMpegError::OpenFile)?;
    let stream = tmp_two
        .read_to_stream(None, None)
        .await
        .map_err(FfMpegError::ReadFile)?;
    let reader = tokio_util::io::StreamReader::new(stream);
    let clean_reader = crate::tmp_file::cleanup_tmpfile(reader, output_file);

    Ok(Box::pin(clean_reader))
}

#[tracing::instrument(skip(store))]
pub(crate) async fn thumbnail<S: Store>(
    store: S,
    from: S::Identifier,
    input_format: InternalVideoFormat,
    format: ThumbnailFormat,
) -> Result<impl AsyncRead + Unpin, FfMpegError> {
    let input_file = crate::tmp_file::tmp_file(Some(input_format.file_extension()));
    let input_file_str = input_file.to_str().ok_or(FfMpegError::Path)?;
    crate::store::file_store::safe_create_parent(&input_file)
        .await
        .map_err(FfMpegError::CreateDir)?;

    let output_file = crate::tmp_file::tmp_file(Some(format.to_file_extension()));
    let output_file_str = output_file.to_str().ok_or(FfMpegError::Path)?;
    crate::store::file_store::safe_create_parent(&output_file)
        .await
        .map_err(FfMpegError::CreateDir)?;

    let mut tmp_one = crate::file::File::create(&input_file)
        .await
        .map_err(FfMpegError::CreateFile)?;
    let stream = store
        .to_stream(&from, None, None)
        .await
        .map_err(FfMpegError::Store)?;
    tmp_one
        .write_from_stream(stream)
        .await
        .map_err(FfMpegError::Write)?;
    tmp_one.close().await.map_err(FfMpegError::CloseFile)?;

    let process = Process::run(
        "ffmpeg",
        &[
            "-hide_banner",
            "-v",
            "warning",
            "-i",
            input_file_str,
            "-frames:v",
            "1",
            "-codec",
            format.as_ffmpeg_codec(),
            "-f",
            format.as_ffmpeg_format(),
            output_file_str,
        ],
    )
    .map_err(FfMpegError::Process)?;

    process.wait().await.map_err(FfMpegError::Process)?;
    tokio::fs::remove_file(input_file)
        .await
        .map_err(FfMpegError::RemoveFile)?;

    let tmp_two = crate::file::File::open(&output_file)
        .await
        .map_err(FfMpegError::OpenFile)?;
    let stream = tmp_two
        .read_to_stream(None, None)
        .await
        .map_err(FfMpegError::ReadFile)?;
    let reader = tokio_util::io::StreamReader::new(stream);
    let clean_reader = crate::tmp_file::cleanup_tmpfile(reader, output_file);

    Ok(Box::pin(clean_reader))
}