use std::fmt;

use data_encoding::HEXLOWER_PERMISSIVE;

use crate::IdError;

#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct FileId(pub [u8; 20]);

impl FileId {
    pub fn from_raw(src: &[u8]) -> Result<FileId, IdError> {
        let mut dst = [0u8; 20];
        if src.len() != 20 {
            return Err(IdError::InvalidId);
        }
        dst.clone_from_slice(src);
        Ok(FileId(dst))
    }

    pub fn from_base16(src: &str) -> Result<FileId, IdError> {
        let mut dst = [0u8; 20];
        HEXLOWER_PERMISSIVE
            .decode_mut(src.as_bytes(), &mut dst)
            .map_err(|_| IdError::InvalidId)?;
        Ok(FileId(dst))
    }

    pub fn base16(&self) -> String {
        HEXLOWER_PERMISSIVE.encode(&self.0)
    }
}

impl fmt::Debug for FileId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_tuple("FileId").field(&self.base16()).finish()
    }
}

impl fmt::Display for FileId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(&self.base16())
    }
}

impl TryFrom<&[u8]> for FileId {
    type Error = IdError;

    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
        Self::from_raw(value)
    }
}