use core::panic;
use std::io;
use std::io::BufReader;
use std::io::prelude::*;
use std::fs::File;
use std::io::SeekFrom;

use libc::close;

pub const SECTORS_PER_TRACK : i32 = 32;
pub const NUM_TRACKS : i32 = 64;
pub const NUM_SECTORS : i32 = SECTORS_PER_TRACK * NUM_TRACKS;
pub const SECTOR_SIZE : i32 = 128;

pub struct Disk {
    pub last_selector : i32,
    pub active : bool
}

impl Disk {

    pub fn init_disk() -> Disk {
        Disk {
            last_selector : 0,
            active : false
        }
    }

    pub fn read_request(disk : &mut Disk, sector_number : i32, data : &mut Vec<u8>) -> io::Result<()> {
        if disk.active {
            panic!("Only one request at time");
        }

        if sector_number < 0 || sector_number >= NUM_SECTORS {
            panic!("sector_number isn't right");
        }

        let mut f = File::open("test/disk")?;
        f.seek(SeekFrom::Start((sector_number * SECTOR_SIZE) as u64))?;
        let mut reader = BufReader::new(f);

        match reader.read(data) {
            Ok(_) => println!("Data has been read successfully"),
            Err(e) => println!("{:?}", e),
                _ => ()
        }
        Ok(())
        
    }

    pub fn write_request(disk : &mut Disk, sector_number : i32, data : &mut Vec<u8>) -> io::Result<()> {
        if disk.active {
            panic!("Only one request at time");
        }
        if sector_number < 0 || sector_number >= NUM_SECTORS {
            panic!("sector_number isn't right");
        }
        
        let mut f = File::create("test/disk")?;
        f.seek(SeekFrom::Start((sector_number * SECTOR_SIZE) as u64))?;
        let res = f.write(data);
        match res {
            Ok(_) => println!("Data written successfully"),
            Err(e) => println!("{:?}", e),
                _ => ()
        }
        Ok(())
    }

}