const ona = @import("ona");

const std = @import("std");

pub const Axis = struct {
	has_key_scancodes: ?[2]KeyScancode = null,
	has_mouse_buttons: ?[2]MouseButton = null,
};

pub const Event = union (enum) {
	key_up: KeyScancode,
	key_down: KeyScancode,
	mouse_up: MouseButton,
	mouse_down: MouseButton,
	mouse_motion: MouseMotion,
};

pub const KeyScancode = enum (u32) {
	no_event = 0x00,
	error_rollover = 0x01,
	post_fail = 0x02,
	error_undefined = 0x03,
	a = 0x04,
	b = 0x05,
	c = 0x06,
	d = 0x07,
	e = 0x08,
	f = 0x09,
	g = 0x0A,
	h = 0x0B,
	i = 0x0C,
	j = 0x0D,
	k = 0x0E,
	l = 0x0F,
	m = 0x10,
	n = 0x11,
	o = 0x12,
	p = 0x13,
	q = 0x14,
	r = 0x15,
	s = 0x16,
	t = 0x17,
	u = 0x18,
	v = 0x19,
	w = 0x1A,
	x = 0x1B,
	y = 0x1C,
	z = 0x1D,
	one = 0x1E,
	two = 0x1F,
	three = 0x20,
	four = 0x21,
	five = 0x22,
	six = 0x23,
	seven = 0x24,
	eight = 0x25,
	nine = 0x26,
	zero = 0x27,
	enter = 0x28,
	escape = 0x29,
	backspace = 0x2A,
	tab = 0x2B,
	space = 0x2C,
	minus = 0x2D,
	equal = 0x2E,
	left_bracket = 0x2F,
	right_bracket = 0x30,
	backslash = 0x31,
	non_us_pound = 0x32,
	semicolon = 0x33,
	quote = 0x34,
	grave = 0x35,
	comma = 0x36,
	period = 0x37,
	slash = 0x38,
	caps_lock = 0x39,
	f1 = 0x3A,
	f2 = 0x3B,
	f3 = 0x3C,
	f4 = 0x3D,
	f5 = 0x3E,
	f6 = 0x3F,
	f7 = 0x40,
	f8 = 0x41,
	f9 = 0x42,
	f10 = 0x43,
	f11 = 0x44,
	f12 = 0x45,
	print_screen = 0x46,
	scroll_lock = 0x47,
	pause = 0x48,
	insert = 0x49,
	home = 0x4A,
	page_up = 0x4B,
	delete = 0x4C,
	end = 0x4D,
	page_down = 0x4E,
	right_arrow = 0x4F,
	left_arrow = 0x50,
	down_arrow = 0x51,
	up_arrow = 0x52,
	num_lock = 0x53,
	keypad_slash = 0x54,
	keypad_asterisk = 0x55,
	keypad_minus = 0x56,
	keypad_plus = 0x57,
	keypad_enter = 0x58,
	keypad_one = 0x59,
	keypad_two = 0x5A,
	keypad_three = 0x5B,
	keypad_four = 0x5C,
	keypad_five = 0x5D,
	keypad_six = 0x5E,
	keypad_seven = 0x5F,
	keypad_eight = 0x60,
	keypad_nine = 0x61,
	keypad_zero = 0x62,
	keypad_period = 0x63,
	non_us_backslash = 0x64,
	application = 0x65,
	power = 0x66,
	keypad_equal = 0x67,
	f13 = 0x68,
	f14 = 0x69,
	f15 = 0x6A,
	f16 = 0x6B,
	f17 = 0x6C,
	f18 = 0x6D,
	f19 = 0x6E,
	f20 = 0x6F,
	f21 = 0x70,
	f22 = 0x71,
	f23 = 0x72,
	f24 = 0x73,
	execute = 0x74,
	help = 0x75,
	menu = 0x76,
	select = 0x77,
	stop = 0x78,
	again = 0x79,
	undo = 0x7A,
	cut = 0x7B,
	copy = 0x7C,
	paste = 0x7D,
	find = 0x7E,
	mute = 0x7F,
	volume_up = 0x80,
	volume_down = 0x81,
	lock_caps_lock = 0x82,
	lock_num_lock = 0x83,
	lock_scroll_lock = 0x84,
	keypad_comma = 0x85,
	keypad_equal_sign = 0x86,
	international1 = 0x87,
	international2 = 0x88,
	international3 = 0x89,
	international4 = 0x8A,
	international5 = 0x8B,
	international6 = 0x8C,
	international7 = 0x8D,
	international8 = 0x8E,
	international9 = 0x8F,
	lang1 = 0x90,
	lang2 = 0x91,
	lang3 = 0x92,
	lang4 = 0x93,
	lang5 = 0x94,
	lang6 = 0x95,
	lang7 = 0x96,
	lang8 = 0x97,
	lang9 = 0x98,
	alternate_erase = 0x99,
	sys_req_attention = 0x9A,
	cancel = 0x9B,
	clear = 0x9C,
	prior = 0x9D,
	return_key = 0x9E,
	separator = 0x9F,
	out = 0xA0,
	oper = 0xA1,
	clear_again = 0xA2,
	cr_sel_props = 0xA3,
	ex_sel = 0xA4,
	left_control = 0xE0,
	left_shift = 0xE1,
	left_alt = 0xE2,
	left_gui = 0xE3,
	right_control = 0xE4,
	right_shift = 0xE5,
	right_alt = 0xE6,
	right_gui = 0xE7,
	_,
};

pub const Mapping = struct {
	key_scancodes: ActionSets(512) = .{},
	mouse_buttons: ActionSets(std.enums.values(MouseButton).len) = .{},
	mouse_position: MousePosition = @splat(0),

	fn ActionSets(comptime len: usize) type {
		const Set = std.bit_set.StaticBitSet(len);

		return struct {
			released: Set = Set.initEmpty(),
			pressed: Set = Set.initEmpty(),
			held: Set = Set.initEmpty(),

			const Self = @This();

			fn expire_frame(self: *Self) void {
				self.pressed = Set.initEmpty();
				self.released = Set.initEmpty();
			}
		};
	}

	pub fn axis_strength(self: Mapping, axis: Axis) f32 {
		if (axis.has_key_scancodes) |key_scancodes| {
			const neg_scancode, const pos_scancode = key_scancodes;
			const is_neg_held = self.key_scancodes.held.isSet(@intFromEnum(neg_scancode));
			const is_pos_held = self.key_scancodes.held.isSet(@intFromEnum(pos_scancode));

			if (is_neg_held or is_pos_held) {
				return
					@as(f32, @floatFromInt(@intFromBool(is_pos_held))) -
					@as(f32, @floatFromInt(@intFromBool(is_neg_held)));
			}
		}

		if (axis.has_mouse_buttons) |mouse_buttons| {
			const neg_button, const pos_button = mouse_buttons;
			const is_neg_held = self.mouse_buttons.held.isSet(@intFromEnum(neg_button));
			const is_pos_held = self.mouse_buttons.held.isSet(@intFromEnum(pos_button));

			if (is_neg_held or is_pos_held) {
				return
					@as(f32, @floatFromInt(@intFromBool(is_pos_held))) -
					@as(f32, @floatFromInt(@intFromBool(is_neg_held)));
			}
		}

		return 0;
	}
};

pub const MouseButton = enum {
	left,
	right,
	middle,
};

pub const MouseMotion = struct {
	relative_position: MousePosition,
	absolute_position: MousePosition,
};

pub const MousePosition = @Vector(2, f32);

test "mapping values" {
	const axis = Axis{
		.has_key_scancodes = .{.minus, .equal},
	};

	{
		var mapping = Mapping{};

		try std.testing.expectEqual(mapping.axis_strength(axis), 0);
	}

	{
		var mapping = Mapping{};

		mapping.key_scancodes.held.set(@intFromEnum(KeyScancode.equal));

		try std.testing.expectEqual(mapping.axis_strength(axis), 1);
	}

	{
		var mapping = Mapping{};

		mapping.key_scancodes.held.set(@intFromEnum(KeyScancode.minus));

		try std.testing.expectEqual(mapping.axis_strength(axis), -1);
	}

	{
		var mapping = Mapping{};

		mapping.key_scancodes.held.set(@intFromEnum(KeyScancode.minus));
		mapping.key_scancodes.held.set(@intFromEnum(KeyScancode.equal));

		try std.testing.expectEqual(mapping.axis_strength(axis), 0);
	}
}

pub fn setup(world: *ona.World, events: ona.App.Events) std.mem.Allocator.Error!void {
	try world.set_state(Mapping{});

	try world.on_event(events.pre_update, ona.system_fn(update), .{
		.label = "update actions",
	});
}

pub fn update(inputs: ona.Receive(Event), mapping: ona.Write(Mapping)) void {
	mapping.state.key_scancodes.expire_frame();
	mapping.state.mouse_buttons.expire_frame();

	for (inputs.messages()) |message| {
		switch (message) {
			.key_down => |scancode| {
				mapping.state.key_scancodes.pressed.set(@intFromEnum(scancode));
				mapping.state.key_scancodes.held.set(@intFromEnum(scancode));
			},

			.key_up => |scancode| {
				mapping.state.key_scancodes.held.unset(@intFromEnum(scancode));
				mapping.state.key_scancodes.released.set(@intFromEnum(scancode));
			},

			.mouse_down => |button|  {
				mapping.state.mouse_buttons.pressed.unset(@intFromEnum(button));
				mapping.state.mouse_buttons.held.set(@intFromEnum(button));
			},

			.mouse_up => |button| {
				mapping.state.key_scancodes.held.unset(@intFromEnum(button));
				mapping.state.key_scancodes.released.set(@intFromEnum(button));
			},

			.mouse_motion => |motion| {
				mapping.state.mouse_position = motion.absolute_position;
			},
		}
	}
}