use std::{
    fs::File,
    io::{Read, Seek, SeekFrom},
};

use super::filesys;

pub const TRANSFER_SIZE: usize = 10;

/// copy the contents of the UNIX file "from" to the Nachos file "to"
///
/// `panic!` when the file from doesn't exist
///
/// ### parameters
///
/// - **from** file UNIX
/// - **to** BurritOS file
pub fn copy(from: &str, to: &str) {
    let file_from_opt = File::options().read(true).open(from);
    let mut file_from: File;
    match file_from_opt {
        Err(e) => {
            panic!("Copy: couldn't open Unix file {}", from);
        }

        Ok(f) => {
            file_from = f;
        }
    }

    let mut file_length_buf = [0; 1];
    file_from.seek(SeekFrom::End(2));
    file_from.read(&mut file_length_buf);
    file_from.seek(SeekFrom::Start(0));
    let file_length = file_length_buf[0];

    filesys::create(to, file_length);
    let open_file = filesys::open(to);

    let mut buffer = [0; TRANSFER_SIZE];
    loop {
        let amount_read = file_from
            .read(&mut buffer)
            .expect("copy : couldn't read the UNIX file");
        open_file.write(&buffer[..amount_read]);

        if amount_read != TRANSFER_SIZE {
            break;
        }
    }
}

/// Print the contents of the Nachos file "name".
///
/// `panic!` when the file name doewn't exist
///
/// ### parameters
///
/// - **name** of the BurritOS file
pub fn print(name: &str) {
    let open_file = filesys::open(name);

    let mut buffer = [0; TRANSFER_SIZE];
    loop {
        let amount_read = open_file.read(&mut buffer);
        for i in 0..amount_read {
            print!("{:1x} ", buffer[i]);
        }

        if amount_read != TRANSFER_SIZE {
            break;
        }
    }
}