use std::fmt;

pub struct Chunk {
    data: *const [u8],
    patch_uri: String,
    offset: u64,
}

impl fmt::Debug for Chunk {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Chunk")
            .field("patch_uri", &self.patch_uri)
            .field("offset", &self.offset)
            .field("data_len", &self.data.len())
            .finish_non_exhaustive()
    }
}

impl Chunk {
    pub fn new(data: &[u8], patch_uri: String, offset: u64) -> Self {
        let data: *const [u8] = data as *const [u8];

        Self {
            data,
            patch_uri,
            offset,
        }
    }

    pub unsafe fn get_data(&self) -> &[u8] {
        unsafe { &*self.data }
    }

    pub fn get_length(&self) -> u64 {
        let len = self.data.len();

        // BOOKMARK this might **panic** on platforms where `usize` has more than 64 bit.
        // Also, you've allocated more than 2 EiB ... in ONE chunk.
        // Whoa! Maybe just chill?
        u64::try_from(len).unwrap_or_else(|e| panic!("usize={len} did not fit into u64: {e}"))
    }

    pub fn get_patch_uri(&self) -> &str {
        &self.patch_uri
    }

    pub fn get_offset(&self) -> u64 {
        self.offset
    }
}