use {
    crate::{Checksum, Error},
    md5::{Digest, Md5},
    sha1::Sha1,
    sha2::Sha256,
    std::io::{Read, Write},
};

#[derive(Debug)]
pub struct File {
    pub len: u64,
    pub checksum: Checksum,
    pub data: Vec<u8>,
}

impl File {
    pub fn read<T: Read>(reader: &mut T) -> Result<Self, Error> {
        let mut len = [0; 8];
        reader.read_exact(&mut len)?;
        let len = u64::from_le_bytes(len);
        let checksum = Checksum::read(reader)?;
        let mut data = Vec::with_capacity(len.try_into()?);
        let mut handle = reader.take(len);
        handle.read_exact(&mut data)?;
        match checksum {
            Checksum::Md5(sum) => {
                let mut hasher = Md5::new();
                hasher.update(&data);
                let res = hasher.finalize();
                if res == sum.into() {
                    Ok(Self {
                        len,
                        checksum,
                        data,
                    })
                } else {
                    Err(Error::InvalidChecksum)
                }
            }
            Checksum::Sha1(sum) => {
                let mut hasher = Sha1::new();
                hasher.update(&data);
                let res = hasher.finalize();
                if res == sum.into() {
                    Ok(Self {
                        len,
                        checksum,
                        data,
                    })
                } else {
                    Err(Error::InvalidChecksum)
                }
            }
            Checksum::Sha256(sum) => {
                let mut hasher = Sha256::new();
                hasher.update(&data);
                let res = hasher.finalize();
                if res == sum.into() {
                    Ok(Self {
                        len,
                        checksum,
                        data,
                    })
                } else {
                    Err(Error::InvalidChecksum)
                }
            }
            _ => Ok(Self {
                len,
                checksum,
                data,
            }),
        }
    }

    pub fn write<T: Write>(&self, writer: &mut T) -> Result<(), Error> {
        writer.write_all(&self.len.to_be_bytes())?;
        Checksum::write(&self.checksum, writer)?;
        writer.write_all(&self.data)?;
        Ok(())
    }
}