//! # Kernel
//!
//! Kernel Start

#![no_std] // don't link the Rust standard library
#![no_main] // disable all Rust-level entry points
#![feature(const_mut_refs)]
#![feature(custom_test_frameworks)]
#![test_runner(crate::test_runner)]
#![reexport_test_harness_main = "test_main"]

mod sync;
mod vga;
mod serial;
use vga::*;
use serial::*;
use core::panic::PanicInfo;

pub trait Testable {
	fn run(&self) -> ();
}

impl<T> Testable for T
where
	T: Fn(),
{
	fn run(&self) {
		serial_print!("{}...\t", core::any::type_name::<T>());
		self();
		serial_println!("[ok]");
	}
}

/// This function is called on panic.
#[cfg(test)]
#[panic_handler]
fn panic(info: &PanicInfo) -> ! {
	serial_println!("[failed]\n");
	serial_println!("Error: {}\n", info);
	exit_qemu(QemuExitCode::Failed);
	loop {}
}

/// This function is called on panic.
#[cfg(not(test))]
#[panic_handler]
fn panic(info: &PanicInfo) -> ! {
	println!("{}", info);
	loop {}
}

fn kernel_init() {
	WRITER.init();
	SERIAL1.init();
}

#[no_mangle]
pub extern "C" fn _start() -> ! {
	kernel_init();

	#[cfg(not(test))]
	{
		WRITER.write_string("Hello World!");
		WRITER.write_string("\n\nHi\n");
		println!("{}", 5);
	}

	#[cfg(test)]
	test_main();

	loop {}
}

#[cfg(test)]
fn test_runner(tests: &[&dyn Testable]) {
	serial_println!("Running {} tests", tests.len());
	for test in tests {
		test.run();
	}
	exit_qemu(QemuExitCode::Success);
}

#[test_case]
fn trivial_assertion() {
	assert_eq!(1, 1);
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u32)]
pub enum QemuExitCode {
	Success = 0x10,
	Failed = 0x11,
}

pub fn exit_qemu(exit_code: QemuExitCode) {
	use x86_64::instructions::port::Port;

	unsafe {
		let mut port = Port::new(0xf4);
		port.write(exit_code as u32);
	}
}