use crate::{gdt, hlt_loop, kprint, kprintln};
use lazy_static::lazy_static;
use pic8259_simple::ChainedPics;
use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame, PageFaultErrorCode};

pub const PIC_1_OFFSET: u8 = 32;
pub const PIC_2_OFFSET: u8 = PIC_1_OFFSET + 8;

pub static PICS: spin::Mutex<ChainedPics> =
    spin::Mutex::new(unsafe { ChainedPics::new(PIC_1_OFFSET, PIC_2_OFFSET) });

lazy_static! {
    static ref IDT: InterruptDescriptorTable = {
        let mut idt = InterruptDescriptorTable::new();
        idt.breakpoint.set_handler_fn(breakpoint_handler);
        unsafe {
            idt.double_fault
                .set_handler_fn(double_fault_handler)
                .set_stack_index(gdt::DOUBLE_FAULT_IST_INDEX);
        }

        idt[InterruptIndex::Timer.as_usize()].set_handler_fn(timer_interrupt_handler);
        idt[InterruptIndex::Keyboard.as_usize()].set_handler_fn(keyboard_interrupt_handler);

        idt.page_fault.set_handler_fn(page_fault_handler);

        idt
    };
}

extern "x86-interrupt" fn page_fault_handler(
    stack_frame: &mut InterruptStackFrame,
    error_code: PageFaultErrorCode,
) {
    use x86_64::registers::control::Cr2;

    kprintln!("EXCEPTION: PAGE FAULT");
    kprintln!("Accessed Address: {:?}", Cr2::read());
    kprintln!("Error Code: {:?}", error_code);
    kprintln!("{:#?}", stack_frame);
    hlt_loop();
}

extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: &mut InterruptStackFrame) {
    use pc_keyboard::{layouts, DecodedKey, HandleControl, Keyboard, ScancodeSet1};
    use spin::Mutex;
    use x86_64::instructions::port::Port;

    lazy_static! {
        static ref KEYBOARD: Mutex<Keyboard<layouts::Us104Key, ScancodeSet1>> = Mutex::new(
            Keyboard::new(layouts::Us104Key, ScancodeSet1, HandleControl::Ignore)
        );
    }

    let mut keyboard = KEYBOARD.lock();
    let mut port = Port::new(0x60);

    // TODO: Handle a backspace
    let scancode: u8 = unsafe { port.read() };
    if let Ok(Some(key_event)) = keyboard.add_byte(scancode) {
        if let Some(key) = keyboard.process_keyevent(key_event) {
            match key {
                DecodedKey::Unicode(character) => kprint!("{}", character),
                DecodedKey::RawKey(key) => kprint!("{:?}", key),
            }
        }
    }

    unsafe {
        PICS.lock()
            .notify_end_of_interrupt(InterruptIndex::Keyboard.as_u8());
    }
}

extern "x86-interrupt" fn timer_interrupt_handler(_stack_frame: &mut InterruptStackFrame) {
    kprint!(".");
    unsafe {
        PICS.lock()
            .notify_end_of_interrupt(InterruptIndex::Timer.as_u8());
    }
}

#[derive(Debug, Clone, Copy)]
#[repr(u8)]
pub enum InterruptIndex {
    Timer = PIC_1_OFFSET,
    Keyboard,
}

impl InterruptIndex {
    fn as_u8(self) -> u8 {
        self as u8
    }

    fn as_usize(self) -> usize {
        usize::from(self.as_u8())
    }
}

/// Initialize and load an Interrupt Descriptor Table
///
/// The IDT is a lazy static and this is meant to be the first access
/// which initializes it with callbacks. After initialization, load is
/// called.
pub fn init_idt() {
    IDT.load();
}

extern "x86-interrupt" fn breakpoint_handler(stack_frame: &mut InterruptStackFrame) {
    kprintln!("EXCEPTION: BREAKPOINT\n{:#?}", stack_frame);
}

// TODO: This is diverging?
extern "x86-interrupt" fn double_fault_handler(
    stack_frame: &mut InterruptStackFrame,
    _error_code: u64,
) -> ! {
    panic!("EXCEPTION: DOUBLE FAULT\n{:#?}", stack_frame);
}

#[test_case]
fn test_breakpoint_exception() {
    x86_64::instructions::interrupts::int3();
}