// https://stackoverflow.com/questions/25612452/html5-canvas-game-loop-delta-time-calculations
// TODO: Need to fully figure out a 60FPS and also display FPS on top right
let game = {
	 fps	: 60 // ??
	,time	: 0.0
	,start	: Date.now()
	,frameDuration	: 1000 / 60 // Target FPS 60?
	,lagOffset	: 0
	,player		: false
}

startGame();

function startGame(){

	// Create player
	createPlayerEntity(canvas.width/2, canvas.height/2);

	// Start game loop
	gameLoop();

}

function gameLoop(){

	// Check player exists (not dead/undefined by OOB)
	if(entities[game.player] === undefined || game.player === false){
		console.log('gome');
		return false;
	}

	setTimeout(() => {
		requestAnimationFrame(gameLoop, canvas);
	}, game.frameDuration);

	// Calcuate the time that has elapsed since the last frame
	let current = Date.now();
	let elapsed = current - game.start;
	game.start = current;
	game.lagOffset += elapsed;

	// Update the frame if the lag counter is greater than or
	// equal to the frame duration
	while (game.lagOffset >= game.frameDuration){  
		
		gameUpdate();
		game.lagOffset -= game.frameDuration;

	}

	// Calculate the lag offset and use it to render the sprites
	// var lagOffset = Math.round(game.lagOffset / game.frameDuration);
	// drawEntities(); // May need to pass lagOffset here to attempt to correct positions, etc.
	drawGame();

	// Print the game version above everything
	printText(GAME_VERSION,
		20,
		canvas.height - 20,
		'left', 'alphabetic', 'normal', 'bold', '10', 'Arial', '#00000050'
	);

	printText(elapsed,
		canvas.width - 20 - (ctx.measureText(elapsed).width),
		20 + 10, // + 10 is pt font-size to get in right pos
		'left', 'alphabetic', 'normal', 'bold', '10', 'Arial', '#00000090'
	);

}

// All the game update logic
function gameUpdate(){

	calculatePlayerMovement();
	calculateDirectionToPlayer();

	updateMovement();
	updateOOB();

	if(MOUSE.down){
		createBulkEntities(MOUSE.x, MOUSE.y);
	}

	
}

function calculatePlayerMovement(){
	
	let speedNow = speed[game.player];
	if(KEYPRESS.shift){ speedNow = speedNow * 5; }

	if(KEYPRESS.w){ position[game.player].y -= (1*speedNow); }
	if(KEYPRESS.s){ position[game.player].y += (1*speedNow); }

	if(KEYPRESS.a){ position[game.player].x -= (1*speedNow); }
	if(KEYPRESS.d){ position[game.player].x += (1*speedNow); }

}

function updateMovement(){
	// Use the direction currently, but likely 'velocity' in the future
	for (const [entity] of Object.entries(direction)) {
		if(position[entity] === undefined){ continue; }

		if(direction[entity].x !== undefined){
			if(direction[entity].x == 1){
				position[entity].x += (1 * speed[entity]);
			}
			else if(direction[entity].x == -1){
				position[entity].x -= (1 * speed[entity]);
			}
		}

		if(direction[entity].y !== undefined){
			if(direction[entity].y == 1){
				position[entity].y += (1 * speed[entity]);
			}
			else if(direction[entity].y == -1){
				position[entity].y -= (1 * speed[entity]);
			}
		}

	}
}
function calculateDirectionToPlayer(){

	// Enemies will W key towards the player as a hoard
	for (const [entity] of Object.entries(position)) {

		if(entity == game.player){ continue; }

		if(position[game.player].x > position[entity].x){ direction[entity].x = 1; }
		else{ direction[entity].x = -1; }

		if(position[game.player].y > position[entity].y){ direction[entity].y = 1; }
		else{ direction[entity].y = -1; }

	}

}

function updateOOB(){
	for (const [entity] of Object.entries(position)) {
		// Remove the entity if it goes out of bounds
		if(
			position[entity].y >= canvas.height-50 || position[entity].y <= 50
			||
			position[entity].x >= canvas.width-50 || position[entity].x <= 50
		){
			deleteEntity(entity);
		}
	}
}
function deleteEntity(entity){

	// Remove from each component
	// Definitely the most inefficient and janky way, but it does it
	if(position[entity] !== null){ delete position[entity]; }
	if(size[entity] !== null){ delete size[entity]; }
	if(team.good[entity] !== null){ delete team.good[entity]; }
	if(team.bad[entity] !== null){ delete team.bad[entity]; }
	if(team.allied[entity] !== null){ delete team.allied[entity]; }
	if(direction[entity] !== null){ delete direction[entity]; }

	// Finally remove the entity itself
	delete entities[entity];
	entityLive--; // To keep track of how many active entities there are (just a count)
	
}


function drawGame(){

	// Reset/clear all prior draws
	ctx.clearRect(0, 0, canvas.width, canvas.height);

	drawEntities();

	// Draw 'temp' hitbox area (to visualise entity removal)
	drawRectangle(50,50,canvas.width-100,canvas.height-100,null,'#FFF');

}

// Draw the game's entities
function drawEntities(){

	// Draw all entities (with size/position)
	for (const entity in size) {
		
		// If there's no position (or size), skip
		if(position[entity] === undefined){ continue; }

		// TEMP z-index draw to ensure player, etc. are drawn atop enemies (for now)
		// 0,1,2 TODO: WHY ISN'T IT WOKRIINNNGG
		for(let i = 0; i < 2; i++){

			// JANK IF. Change to defensive when I can be bothered
			if((zindex[entity] === undefined && i === 0) || zindex[entity] === i){

				// console.log(zindex[entity]);

				if(team.bad[entity] !== undefined){
					// Draw pixels from imageCanvas 
					drawEnemy(entity);
				}
				if(team.allied[entity] !== undefined){
					// Draw pixels from imageCanvas 
					drawAlly(entity);
				}
		
				// Player, temp
				if(team.good[entity] !== undefined){
					// Draw pixels from imageCanvas 
					drawPlayer(entity);
				}

			}

		}
		
	}

}


function createTestEntity(x,y){

	entityCount++;
	entityLive++; // To keep track of how many active entities there are (just a count)
	entities[entityCount] = entityCount;

	position[entityCount] = {x: x, y: y};
	size[entityCount] = {width: 16, height: 16};

	if(MOUSE.button[0]){
		team.bad[entityCount] = true;
	}
	else if(MOUSE.button[1]){
		team.allied[entityCount] = true;
	}
	else if(MOUSE.button[2]){
		// 
	}
	
	direction[entityCount] = {x: 0, y: 0}; // 0,1 left,right/up,down
	zindex[entityCount] = 0;
	speed[entityCount] = .75;

}
function createBulkEntities(x,y){
	let amount = 90;
	for(let i = 0; i < amount; i++){
		createTestEntity(
			 x+(Math.floor(Math.random() * 45)+1)
			,y+Math.floor(Math.random() * 35)+1
		);
	}
}


function createPlayerEntity(x,y){

	entityCount++;
	game.player = entityCount; // Set game.player to the player entity. TEMP

	entityLive++; // To keep track of how many active entities there are (just a count)
	entities[entityCount] = entityCount;

	position[entityCount] = {x: x, y: y};
	size[entityCount] = {width: 16, height: 16};

	team.good[entityCount] = true;

	direction[entityCount] = {x: 0, y: 0}; // 0,1 left,right/up,down

	zindex[entityCount] = 1;
	speed[entityCount] = 1.6;

}