use self::super::key::*;
use crate::machine::device_io::*;
use bitflags::bitflags;
use core::cmp;
use core::cmp::{Eq, PartialEq};
use core::ffi::c_uchar;
use num_enum::{IntoPrimitive, TryFromPrimitive};

// Driver for the PS/2 keybard/mouse controller
// beyound OOStuBS:
// The 'gather' field should NEVER have imcomplete state: it should either be a
// valid key, or nothing.
// TODO what if IO ops fails or timeout?
// TODO figure out how to abstract the "interrupt control" layer.
// Keyboard controller should not be arch dependent
#[cfg(target_arch = "x86_64")]
use crate::arch::x86_64::interrupt::{pic_8259, pic_8259::PicDeviceInt as PD};

use super::key::Modifiers;

// TODO
// reboot()
// set_led(char led,bool on)
// set_repeat_rate(int speed,int delay)

pub struct KeyboardController {
	leds: Led,
	keystate: KeyState,
	gather: Option<Key>, // if not collected timely it will be overwritten
	cport: IOPort,
	dport: IOPort,
}

struct KeyState {
	modi: Modifiers, // active modifiers
	prefix: Prefix,  // prefix state for some certain modifiers
	scan: Option<u8>,
}

#[derive(Clone, Copy, Eq, PartialEq)]
enum Prefix {
	PREFIX1,
	PREFIX2,
	NONE, // don't confuse Option None with Prefix enum NONE
}

impl Prefix {
	pub fn try_from_u8(val: u8) -> Option<Prefix> {
		match val {
			Defs::C_PREFIX1 => Some(Self::PREFIX1),
			Defs::C_PREFIX2 => Some(Self::PREFIX2),
			_ => None,
		}
	}
}

impl KeyState {
	pub fn new() -> Self {
		return Self {
			modi: Modifiers::NONE,
			prefix: Prefix::NONE,
			scan: None,
		};
	}

	pub fn toggle_capslock(&mut self) {
		self.modi.toggle(Modifiers::CAPSLOCK);
	}

	pub fn toggle_numlock(&mut self) {
		self.modi.toggle(Modifiers::NUMLOCK);
	}

	pub fn toggle_scroll_lock(&mut self) {
		self.modi.toggle(Modifiers::SCROLL_LOCK);
	}
}

impl KeyboardController {
	pub fn new() -> Self {
		Self {
			leds: Led::NONE,
			keystate: KeyState::new(),
			cport: IOPort::new(Defs::CTRL),
			dport: IOPort::new(Defs::DATA),
			gather: None,
		}
	}

	// Led and lock state are toggled together, to prevent out-of-sync
	// TODO: rollback lock state if setting led fails
	fn toggle_lock(&mut self, lock: Modifiers) {
		let led = match lock {
			Modifiers::SCROLL_LOCK => Some(Led::SCROLL_LOCK),
			Modifiers::CAPSLOCK => Some(Led::CAPS_LOCK),
			Modifiers::NUMLOCK => Some(Led::NUM_LOCk),
			_ => None,
		};
		if let Some(led) = led {
			self.keystate.modi.toggle(lock);
			self.toggle_led(led);
		}
	}

	fn toggle_led(&mut self, led: Led) {
		self.leds.toggle(led);
		todo!("toggle keyboard led: ");
	}

	pub fn update_state(&mut self, code: u8) {
		// TODO investigate this code pattern: is there much runtime cost??
		self.keystate.scan = Some(code);
		if let Some(p) = Prefix::try_from_u8(code) {
			self.keystate.prefix = p;
			return;
		}
		if code & Defs::BREAK_BIT == 0 {
			if self.press_event() {
				self.decode_key();
			}
		} else {
			self.release_event();
		}
		// the prefix should have been comsumed at this point so clear it
		self.keystate.prefix = Prefix::NONE;
	}

	fn press_event(&mut self) -> bool {
		let mut should_decode_ascii = false;
		let code = self.keystate.scan.unwrap();
		match code {
			Defs::C_SHIFT_L | Defs::C_SHIFT_R => self.keystate.modi.insert(Modifiers::SHIFT),
			Defs::C_ALT => match self.keystate.prefix {
				Prefix::PREFIX1 => self.keystate.modi.insert(Modifiers::ALT_RIGHT),
				_ => self.keystate.modi.insert(Modifiers::ALT_LEFT),
			},
			Defs::C_CTRL => match self.keystate.prefix {
				Prefix::PREFIX1 => self.keystate.modi.insert(Modifiers::CTRL_RIGHT),
				_ => self.keystate.modi.insert(Modifiers::CTRL_LEFT),
			},
			Defs::C_CAPSLOCK => self.toggle_lock(Modifiers::CAPSLOCK),
			Defs::C_NUM_P => {
				if !self.keystate.modi.contains(Modifiers::CTRL_LEFT) {
					self.toggle_lock(Modifiers::NUMLOCK);
				}
			}
			Defs::C_SCRLOCK => self.toggle_lock(Modifiers::SCROLL_LOCK),
			_ => {
				should_decode_ascii = true;
			}
		}
		should_decode_ascii
	}

	fn release_event(&mut self) {
		// we only care about release events for shift/alt/ctrl
		let code = self.keystate.scan.unwrap() & !Defs::BREAK_BIT;
		match code {
			Defs::C_SHIFT_L | Defs::C_SHIFT_R => self.keystate.modi.remove(Modifiers::SHIFT),
			Defs::C_ALT => match self.keystate.prefix {
				Prefix::PREFIX1 => self.keystate.modi.remove(Modifiers::ALT_RIGHT),
				_ => self.keystate.modi.remove(Modifiers::ALT_LEFT),
			},
			Defs::C_CTRL => match self.keystate.prefix {
				Prefix::PREFIX1 => self.keystate.modi.remove(Modifiers::CTRL_RIGHT),
				_ => self.keystate.modi.remove(Modifiers::CTRL_LEFT),
			},
			_ => {}
		}
	}

	#[inline(always)]
	pub fn read_status(&self) -> Option<StatusReg> {
		// TODO maybe there is a path which leads to invalid SR, e.g. timeout?
		Some(StatusReg::from_bits_truncate(self.cport.inb()))
	}
	
	// this should be called by the interrupt handler prologue
	pub fn fetch_key(&mut self) {
		// I'd like to see if this panics....
		let sr = self.read_status().unwrap();
		// ignore mouse events
		if !sr.contains(StatusReg::OUTB) || sr.contains(StatusReg::AUXB) {
			return;
		}
		self.update_state(self.dport.inb());
	}
	
	// this should be called by the "epilogue"
	pub fn consume_key(&mut self) -> Option<Key>{
		let res = self.gather.clone();
		self.gather = None;
		return res
	}

	pub fn decode_key(&mut self) {
		// the decode_key should not be called when there is no scancode.
		// mask the breakbit
		let s = self.keystate.scan.unwrap();
		let c = s & !Defs::BREAK_BIT;
		let m = self.keystate.modi;
		let p = self.keystate.prefix;

		if c == 53 && p == Prefix::PREFIX1 {
			self.gather = Some(Key {
				asc: b'/',
				modi: m,
				scan: s,
			});
			return;
		}

		let asc = if m.contains(Modifiers::NUMLOCK) && p == Prefix::NONE && c >= 71 && c <= 83 {
			ASC_NUM_TAB[c as usize - 71]
		} else if m.contains(Modifiers::ALT_RIGHT) {
			ALT_TAB[c as usize]
		} else if m.contains(Modifiers::SHIFT) {
			SHIFT_TAB[c as usize]
		} else if m.contains(Modifiers::CAPSLOCK) {
			if (c >= 16 && c <= 26) || (c >= 30 && c <= 40) || (c >= 44 && c <= 50) {
				SHIFT_TAB[c as usize]
			} else {
				NORMAL_TAB[c as usize]
			}
		} else {
			NORMAL_TAB[c as usize]
		};

		self.gather = Some(Key {
			asc,
			modi: m,
			scan: s,
		});
	}

	pub fn set_repeat_rate_delay() {
		todo!();
	}

	pub fn reboot(&mut self) {
		todo!();
	}
}

// x86 and arm has different interrupt controller
#[cfg(target_arch = "x86_64")]
impl KeyboardController {
	#[inline(always)]
	fn disable_keyboard_int() {
		pic_8259::forbid(PD::KEYBOARD);
	}

	#[inline(always)]
	fn enable_keyboard_int() {
		pic_8259::allow(PD::KEYBOARD);
	}

	#[inline(always)]
	fn toggle_keyboard_int(enable: bool) {
		if enable {
			Self::enable_keyboard_int()
		} else {
			Self::disable_keyboard_int()
		}
	}

	#[inline(always)]
	fn is_int_masked() -> bool {
		pic_8259::is_masked(PD::KEYBOARD)
	}
}

enum Cmd {
	// these commands are sent through DATA port
	SetLed = 0xed,
	ScanCode = 0xf0, // Get or set current scancode set
	SetSpeed = 0xf3,
}

bitflags! {
pub struct Led:u8 {
	const NONE			= 0;
	const SCROLL_LOCK	= 1<<0;
	const NUM_LOCk		= 1<<1;
	const CAPS_LOCK		= 1<<2;
}
}

bitflags! {
pub struct StatusReg:u8 {
	const NONE			= 0;
	const OUTB			= 1 << 0;	// output buffer full (can read)
	const INB			= 1 << 1;	// input buffer full (don't write yet)
	const SYS			= 1 << 2;	// System flag, self test success
	const CMD_DATA		= 1 << 3;	// 0: last write to input buffer was data (0x60)
									// 1: last write to input buffer was command (0x64)
	const NOT_LOCKED	= 1 << 4;	// Keyboard Lock. 1: not locked 0: locked
	const AUXB			= 1 << 5;	// AUXB: aux output buffer full.
									// on AT,	1: TIMEOUT
									// on PS/2, 0: keyboard		1: mouse
	const TIMEOUT		= 1 << 6;	// 0: OK 1: Timeout.
	const PARITY_ERR	= 1 << 7;
}
}

enum Msg {
	ACK = 0xfa,
}

pub struct Defs;
impl Defs {
	pub const CTRL: u16 = 0x64;
	pub const DATA: u16 = 0x60;
	pub const CPU_RESET: u8 = 0xfe;
	pub const BREAK_BIT: u8 = 1 << 7;
	// defs of special scan codes.
	pub const C_PREFIX1: u8 = 0xe0;
	pub const C_PREFIX2: u8 = 0xe1;
	pub const C_SHIFT_L: u8 = 0x2a;
	pub const C_SHIFT_R: u8 = 0x36;
	pub const C_ALT: u8 = 0x38;
	pub const C_CTRL: u8 = 0x1d;
	pub const C_CAPSLOCK: u8 = 0x3a;
	pub const C_SCRLOCK: u8 = 0x46;
	pub const C_NUM_P: u8 = 0x45; // NumLock or Pause
	pub const C_F1: u8 = 0x3b;
	pub const C_DEL: u8 = 0x53;
	pub const C_UP: u8 = 0x48;
	pub const C_DOWN: u8 = 0x50;
	pub const C_LEFT: u8 = 0x4b;
	pub const C_RIGHT: u8 = 0x4d;
	pub const C_DIV: u8 = 0x8;
}