use rand::random;
use gemma::chip8::stack::Chip8Stack;

#[test]
#[should_panic]
fn stack_overflow_test() {
    let mut x = Chip8Stack::new();
    for i in 0..17 {
        x.push(&i);
    }
}

#[test]
#[should_panic]
fn stack_underflow_test() {
    let mut x = Chip8Stack::new();
    x.pop();
}

#[test]
fn stack_lots_of_subs() {
    let mut x = Chip8Stack::new();
    let stack_contents = [
        0x123, 0x321, 0xabc, 0xdef, 0xbad, 0xbef, 0xfed, 0xcab, 0xbed, 0xcad, 0xfeb, 0xcab, 0xfff,
        0x000, 0x001,
    ];
    for i in stack_contents {
        x.push(&i);
    }

    assert_eq!(x.depth(), 15);

    // up to 50 random loops
    let num_loops: u8 = random::<u8>() % 50;
    for i in 0..num_loops {
        let start_count = x.depth();
        let num_pop = random::<u8>() % x.depth() as u8;
        for current_pop in 0..num_pop {
            x.pop();
        }

        let post_pop_count = x.depth();
        assert_eq!(post_pop_count as u8, start_count as u8 - num_pop);
        for current_push in 0..num_pop {
            x.push(&stack_contents[(current_push + post_pop_count as u8) as usize]);
        }
        assert_eq!(x.depth(), 15);
    }
}