use crate::gdt::{DPL, GdtSelector};

#[repr(C, packed)]
pub struct InterruptTableDescriptor {
    size: u16,
    offset: u64,
}

#[repr(transparent)]
pub struct IdtTableEntry {
    inner: u128,
}

pub type ISR = extern "x86-interrupt" fn(InterruptStackFrame) -> ();

#[repr(C)]
pub struct InterruptStackFrame {
    ip: usize,
    cs: usize,
    flags: usize,
    sp: usize,
    ss: usize,
}

#[repr(u8)]
pub enum Gate {
    Interrupt = 0b1110,
    Trap = 0b1111,
}

impl IdtTableEntry {
    pub fn new(isr: ISR, selector: GdtSelector, ist: u8, gate: Gate, priority: DPL) -> Self {
        let mut inner = 0b0;
        let offset = (isr as *const ()) as u64;

        let bytes = (offset >> 32) as u32;
        inner |= (bytes as u128) << 64;

        let bytes = (offset as u32) >> 16;
        inner |= (bytes as u128) << 48;

        let bytes = offset as u16;
        inner |= bytes as u128;

        inner |= (selector.raw() as u128) << 16;

        assert!(ist <= 0b111);

        inner |= (ist as u128) << 32;
        inner |= (gate as u128) << 40;
        inner |= (priority as u128) << 45;
        inner |= 1 << 47;

        Self { inner }
    }
}