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use std::convert::TryInto;

pub fn insert_document_mut(document_list: &mut Vec<u8>, document_id: &[u8; 16]) {
    let mut chunks: Vec<[u8; 16]> = document_list.chunks_exact(16).map(|v| v.try_into().unwrap()).collect();

    match chunks.binary_search(&document_id) {
        Ok(_) => {}
        Err(i) => {
            chunks.insert(i, document_id.clone());
        }
    }
    *document_list = chunks.concat()
}

pub fn insert_document_immut(document_list: &[u8], document_id: &[u8; 16]) -> Vec<u8> {
    let mut chunks: Vec<[u8; 16]> = document_list.chunks_exact(16).map(|v| v.try_into().unwrap()).collect();

    match chunks.binary_search(&document_id) {
        Ok(_) => {}
        Err(i) => {
            chunks.insert(i, document_id.clone());
        }
    }
    chunks.concat()
}

#[cfg(test)]
mod tests {
    #[test]
    fn insert_document_mut() {
        let mut document_list: Vec<u8> = Vec::new();

        super::insert_document_mut(&mut document_list, b"aaaaaaaaaaaaaaaa");
        super::insert_document_mut(&mut document_list, b"cccccccccccccccc");
        super::insert_document_mut(&mut document_list, b"aaaaaaaaaaaaaaaa");
        super::insert_document_mut(&mut document_list, b"bbbbbbbbbbbbbbbb");

        assert_eq!(&document_list[..], &b"aaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbcccccccccccccccc"[..]);
    }
    #[test]
    fn insert_document_immut() {
        let document_list = b"";

        let document_list = super::insert_document_immut(document_list, b"aaaaaaaaaaaaaaaa");
        let document_list = super::insert_document_immut(&document_list, b"cccccccccccccccc");
        let document_list = super::insert_document_immut(&document_list, b"aaaaaaaaaaaaaaaa");
        let document_list = super::insert_document_immut(&document_list, b"bbbbbbbbbbbbbbbb");

        assert_eq!(document_list, &b"aaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbcccccccccccccccc"[..]);
    }
}