use std::io::{Read, Seek};

use serde::Serialize;

use crate::mp4box::hdlr::HdlrBox;
use crate::mp4box::ilst::IlstBox;
use crate::mp4box::*;

#[derive(Debug, Clone, PartialEq, Eq, Serialize)]
#[serde(tag = "hdlr")]
#[serde(rename_all = "lowercase")]
pub enum MetaBox {
    Mdir {
        #[serde(skip_serializing_if = "Option::is_none")]
        ilst: Option<IlstBox>,
    },

    #[serde(skip)]
    Unknown {
        #[serde(skip)]
        hdlr: HdlrBox,

        #[serde(skip)]
        data: Vec<(BoxType, Vec<u8>)>,
    },
}

const MDIR: FourCC = FourCC { value: *b"mdir" };

impl MetaBox {
    pub fn get_type(&self) -> BoxType {
        BoxType::MetaBox
    }

    pub fn get_size(&self) -> u64 {
        let mut size = HEADER_SIZE + HEADER_EXT_SIZE;
        match self {
            Self::Mdir { ilst } => {
                size += HdlrBox::default().box_size();
                if let Some(ilst) = ilst {
                    size += ilst.box_size();
                }
            }
            Self::Unknown { hdlr, data } => {
                size += hdlr.box_size()
                    + data
                        .iter()
                        .map(|(_, data)| data.len() as u64 + HEADER_SIZE)
                        .sum::<u64>()
            }
        }
        size
    }
}

impl Mp4Box for MetaBox {
    fn box_type(&self) -> BoxType {
        self.get_type()
    }

    fn box_size(&self) -> u64 {
        self.get_size()
    }

    fn to_json(&self) -> Result<String> {
        Ok(serde_json::to_string(&self).unwrap())
    }

    fn summary(&self) -> Result<String> {
        let s = match self {
            Self::Mdir { .. } => "hdlr=ilst".to_string(),
            Self::Unknown { hdlr, data } => {
                format!("hdlr={} data_len={}", hdlr.handler_type, data.len())
            }
        };
        Ok(s)
    }
}

impl Default for MetaBox {
    fn default() -> Self {
        Self::Unknown {
            hdlr: Default::default(),
            data: Default::default(),
        }
    }
}

impl<R: Read + Seek> ReadBox<&mut R> for MetaBox {
    fn read_box(reader: &mut R, size: u64) -> Result<Self> {
        let start = box_start(reader)?;

        let extended_header = reader.read_u32::<BigEndian>()?;
        if extended_header != 0 {
            // ISO mp4 requires this header (version & flags) to be 0. Some
            // files skip the extended header and directly start the hdlr box.
            let possible_hdlr = BoxType::from(reader.read_u32::<BigEndian>()?);
            if possible_hdlr == BoxType::HdlrBox {
                // This file skipped the extended header! Go back to start.
                reader.seek(SeekFrom::Current(-8))?;
            } else {
                // Looks like we actually have a bad version number or flags.
                let v = (extended_header >> 24) as u8;
                return Err(Error::UnsupportedBoxVersion(BoxType::MetaBox, v));
            }
        }

        let mut current = reader.stream_position()?;
        let end = start + size;

        let content_start = current;

        // find the hdlr box
        let mut hdlr = None;
        while current < end {
            // Get box header.
            let header = BoxHeader::read(reader)?;
            let BoxHeader { name, size: s } = header;

            match name {
                BoxType::HdlrBox => {
                    hdlr = Some(HdlrBox::read_box(reader, s)?);
                }
                _ => {
                    // XXX warn!()
                    skip_box(reader, s)?;
                }
            }

            current = reader.stream_position()?;
        }

        let Some(hdlr) = hdlr else {
            return Err(Error::BoxNotFound(BoxType::HdlrBox));
        };

        // rewind and handle the other boxes
        reader.seek(SeekFrom::Start(content_start))?;
        current = reader.stream_position()?;

        let mut ilst = None;

        match hdlr.handler_type {
            MDIR => {
                while current < end {
                    // Get box header.
                    let header = BoxHeader::read(reader)?;
                    let BoxHeader { name, size: s } = header;

                    match name {
                        BoxType::IlstBox => {
                            ilst = Some(IlstBox::read_box(reader, s)?);
                        }
                        _ => {
                            // XXX warn!()
                            skip_box(reader, s)?;
                        }
                    }

                    current = reader.stream_position()?;
                }

                Ok(MetaBox::Mdir { ilst })
            }
            _ => {
                let mut data = Vec::new();

                while current < end {
                    // Get box header.
                    let header = BoxHeader::read(reader)?;
                    let BoxHeader { name, size: s } = header;

                    match name {
                        BoxType::HdlrBox => {
                            skip_box(reader, s)?;
                        }
                        _ => {
                            let mut box_data = vec![0; (s - HEADER_SIZE) as usize];
                            reader.read_exact(&mut box_data)?;

                            data.push((name, box_data));
                        }
                    }

                    current = reader.stream_position()?;
                }

                Ok(MetaBox::Unknown { hdlr, data })
            }
        }
    }
}

impl<W: Write> WriteBox<&mut W> for MetaBox {
    fn write_box(&self, writer: &mut W) -> Result<u64> {
        let size = self.box_size();
        BoxHeader::new(self.box_type(), size).write(writer)?;

        write_box_header_ext(writer, 0, 0)?;

        let hdlr = match self {
            Self::Mdir { .. } => HdlrBox {
                handler_type: MDIR,
                ..Default::default()
            },
            Self::Unknown { hdlr, .. } => hdlr.clone(),
        };
        hdlr.write_box(writer)?;

        match self {
            Self::Mdir { ilst } => {
                if let Some(ilst) = ilst {
                    ilst.write_box(writer)?;
                }
            }
            Self::Unknown { data, .. } => {
                for (box_type, data) in data {
                    BoxHeader::new(*box_type, data.len() as u64 + HEADER_SIZE).write(writer)?;
                    writer.write_all(data)?;
                }
            }
        }
        Ok(size)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::mp4box::BoxHeader;
    use std::io::Cursor;

    #[test]
    fn test_meta_mdir_empty() {
        let src_box = MetaBox::Mdir { ilst: None };

        let mut buf = Vec::new();
        src_box.write_box(&mut buf).unwrap();
        assert_eq!(buf.len(), src_box.box_size() as usize);

        let mut reader = Cursor::new(&buf);
        let header = BoxHeader::read(&mut reader).unwrap();
        assert_eq!(header.name, BoxType::MetaBox);
        assert_eq!(header.size, src_box.box_size());

        let dst_box = MetaBox::read_box(&mut reader, header.size).unwrap();
        assert_eq!(dst_box, src_box);
    }

    #[test]
    fn test_meta_mdir() {
        let src_box = MetaBox::Mdir {
            ilst: Some(IlstBox::default()),
        };

        let mut buf = Vec::new();
        src_box.write_box(&mut buf).unwrap();
        assert_eq!(buf.len(), src_box.box_size() as usize);

        let mut reader = Cursor::new(&buf);
        let header = BoxHeader::read(&mut reader).unwrap();
        assert_eq!(header.name, BoxType::MetaBox);
        assert_eq!(header.size, src_box.box_size());

        let dst_box = MetaBox::read_box(&mut reader, header.size).unwrap();
        assert_eq!(dst_box, src_box);
    }

    #[test]
    fn test_meta_hdrl_non_first() {
        let data = b"\x00\x00\x00\x7fmeta\x00\x00\x00\x00\x00\x00\x00Qilst\x00\x00\x00I\xa9too\x00\x00\x00Adata\x00\x00\x00\x01\x00\x00\x00\x00TMPGEnc Video Mastering Works 7 Version 7.0.15.17\x00\x00\x00\"hdlr\x00\x00\x00\x00\x00\x00\x00\x00mdirappl\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
        let mut reader = Cursor::new(data);
        let header = BoxHeader::read(&mut reader).unwrap();
        assert_eq!(header.name, BoxType::MetaBox);

        let meta_box = MetaBox::read_box(&mut reader, header.size).unwrap();

        // this contains \xa9too box in the ilst
        // it designates the tool that created the file, but is not yet supported by this crate
        assert_eq!(
            meta_box,
            MetaBox::Mdir {
                ilst: Some(IlstBox::default())
            }
        );
    }

    #[test]
    fn test_meta_unknown() {
        let src_hdlr = HdlrBox {
            handler_type: FourCC::from(*b"test"),
            ..Default::default()
        };
        let src_data = (BoxType::UnknownBox(0x42494241), b"123".to_vec());
        let src_box = MetaBox::Unknown {
            hdlr: src_hdlr,
            data: vec![src_data],
        };

        let mut buf = Vec::new();
        src_box.write_box(&mut buf).unwrap();
        assert_eq!(buf.len(), src_box.box_size() as usize);

        let mut reader = Cursor::new(&buf);
        let header = BoxHeader::read(&mut reader).unwrap();
        assert_eq!(header.name, BoxType::MetaBox);
        assert_eq!(header.size, src_box.box_size());

        let dst_box = MetaBox::read_box(&mut reader, header.size).unwrap();
        assert_eq!(dst_box, src_box);
    }
}