//! Writing an [OS] in Rust: [Double Faults]
//!
//! [os]: https://os.phil-opp.com
//! [double faults]: https://os.phil-opp.com/double-fault-exceptions/
#![no_std]
#![no_main]
#![feature(custom_test_frameworks)]
#![test_runner(rustos::test_runner)]
#![reexport_test_harness_main = "test_main"]
#![feature(abi_x86_interrupt)]
extern crate rustos;
extern crate x86_64;
use core::panic::PanicInfo;
use rustos::{print, println};

#[no_mangle]
pub extern "C" fn _start() -> ! {
    println!("Welcome to the real world!");
    init();
    #[cfg(test)]
    test_main();
    println!("It did not crash!!!");
    loop {
        x86_64::instructions::hlt();
    }
}

#[cfg(not(test))]
#[panic_handler]
fn panic(info: &PanicInfo) -> ! {
    println!("{}", info);
    loop {
        x86_64::instructions::hlt();
    }
}

#[cfg(test)]
#[panic_handler]
fn panic(info: &PanicInfo) -> ! {
    rustos::test_panic_handler(info)
}

extern crate lazy_static;
extern crate pc_keyboard;
extern crate pic8259_simple;
extern crate spin;
use lazy_static::lazy_static;
use pic8259_simple::ChainedPics;
use spin::Mutex;
use x86_64::structures::idt::{InterruptDescriptorTable, InterruptStackFrame};

fn init() {
    IDT.load();
    // Initialize the interrupt controller.
    unsafe { PICS.lock().initialize() };
    // Enable the hardware interrupts.
    x86_64::instructions::interrupts::enable();
}

lazy_static! {
    static ref IDT: InterruptDescriptorTable = {
        let mut idt = InterruptDescriptorTable::new();
        idt[InterruptIndex::Timer.as_usize()].set_handler_fn(timer_interrupt_handler);
        idt[InterruptIndex::Keyboard.as_usize()].set_handler_fn(keyboard_interrupt_handler);
        idt
    };
}

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

extern "x86-interrupt" fn keyboard_interrupt_handler(_stack_frame: &mut InterruptStackFrame) {
    use pc_keyboard::{layouts, DecodedKey, HandleControl, Keyboard, ScancodeSet1};
    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);
    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) => print!("{}", character),
                DecodedKey::RawKey(key) => print!("{:?}", key),
            }
        }
    }
    unsafe {
        PICS.lock()
            .notify_end_of_interrupt(InterruptIndex::Keyboard.as_u8());
    }
}

#[allow(dead_code)]
extern "x86-interrupt" fn tenkey_interrupt_handler(_stack_frame: &mut InterruptStackFrame) {
    use x86_64::instructions::port::Port;
    let mut port = Port::new(0x60);
    let scancode: u8 = unsafe { port.read() };
    let key = match scancode {
        0x02 => Some('1'),
        0x03 => Some('2'),
        0x04 => Some('3'),
        0x05 => Some('4'),
        0x06 => Some('5'),
        0x07 => Some('6'),
        0x08 => Some('7'),
        0x09 => Some('8'),
        0x0a => Some('9'),
        0x0b => Some('0'),
        _ => None,
    };
    if let Some(key) = key {
        print!("{}", key);
    }
    unsafe {
        PICS.lock()
            .notify_end_of_interrupt(InterruptIndex::Keyboard.as_u8());
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u8)]
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())
    }
}

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

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