let gl;
let defaultProgram,
	waterProgram;

let objects = [];

let viewMatrix,
	projectionMatrix;

let eye,
	target,
	up;

let keyPressed = {
	KeyW: false,
	KeyA: false,
	KeyS: false,
	KeyD: false
};

const speed = 0.005;


function main() {

	// Get canvas and setup WebGL context
	const canvas = document.getElementById("gl-canvas");
	gl = canvas.getContext('webgl2');

	// Configure viewport
	gl.viewport(0,0,canvas.width,canvas.height);
	gl.clearColor(0.75,0.8,1.0,1.0);

	gl.enable(gl.DEPTH_TEST);

	// Init shader program via additional function and bind it
	defaultProgram = initShaders(gl, "vertex-shader", "fragment-shader");
	waterProgram = initShaders(gl, "vertex-shader-water", "fragment-shader-water");

	// Create object instances
	let island = new Island();
	objects.push(island);

	let tree1 = new Tree();
	tree1.SetModelMatrix([1.3, 0, 0.6], [0, 45, 0], [0.3, 0.3, 0.3]);
	objects.push(tree1);

	let tree2 = new Tree();
	tree2.SetModelMatrix([0.9, 0, 0.3], [0, 33, 0], [0.45, 0.45, 0.45]);
	objects.push(tree2);

	let tree3 = new Tree();
	tree3.SetModelMatrix([0.45, 0, 0.75], [0, 0, 0], [0.4, 0.4, 0.4]);
	objects.push(tree3);

	let tree4 = new Tree();
	tree4.SetModelMatrix([-1.1, 0, 0.5], [0, 222, 0], [0.42, 0.42, 0.42]);
	objects.push(tree4);

	let tree5 = new Tree();
	tree5.SetModelMatrix([-0.65, 0, 0.7], [0, 79, 0], [0.32, 0.32, 0.32]);
	objects.push(tree5);

	let cloud1 = new Cloud();
	cloud1.SetModelMatrix([-0.4, 1, -0.9], [0, 0, 0], [0.32, 0.32, 0.32]);
	objects.push(cloud1);

	let cloud2 = new Cloud();
	cloud2.SetModelMatrix([0, 1.4, -1.6], [0, -90, 0], [0.2, 0.2, 0.2]);
	objects.push(cloud2);

	let cloud3 = new Cloud();
	cloud3.SetModelMatrix([0.7, 0.9, -0.8], [0, 100, 0], [0.25, 0.25, 0.25]);
	objects.push(cloud3);

	let river = new River();
	river.SetModelMatrix([0, 0.04, 1.8], [0, 185, 0], [0.11, 0.11, 0.11]);
	objects.push(river);

	let sea = new Sea();
	objects.push(sea);

	// Compute view matrix
	eye = vec3.fromValues(0.0, 0.3, 4.0);
	target = vec3.fromValues(0.0, 0.3, 0.0);
	up = vec3.fromValues(0.0, 1.0, 0.0);

	viewMatrix = mat4.create();
	mat4.lookAt(viewMatrix, eye, target, up);

	// Compute projection matrix
	projectionMatrix = mat4.create();
	mat4.perspective(projectionMatrix, Math.PI * 0.25, canvas.width / canvas.height, 0.5, 100);

	for(let object of objects) {

		gl.useProgram(object.shader);

		// Set view and projection matrix
		gl.uniformMatrix4fv(object.viewMatrixLoc, false, viewMatrix);
		gl.uniformMatrix4fv(object.projectionMatrixLoc, false, projectionMatrix);

		// Set position und intensity of the light source
		gl.uniform3fv(object.lightPositionLoc, [1.0, 2.0, 1.0]);
		gl.uniform4fv(object.IaLoc, [0.4, 0.4, 0.4, 1.0]);
		gl.uniform4fv(object.IdLoc, [0.8, 0.8, 0.8, 1.0]);
		gl.uniform4fv(object.IsLoc, [1.0, 1.0, 1.0, 1.0]);
	}

	document.addEventListener("keydown", keydown);
	document.addEventListener("keyup", keyup);
	document.addEventListener("mousemove", changeView);

	canvas.onmousedown = function() {
		canvas.requestPointerLock();
	}

	gameLoop();
};

function update() 
{
	let look = vec3.create();
	vec3.sub(look, target, eye);
	vec3.scale(look, look, speed);

	if(keyPressed.KeyW) {
		eye[0] += look[0];
		eye[2] += look[2];
		target[0] += look[0];
		target[2] += look[2];
	}
	if(keyPressed.KeyS) {
		eye[0] -= look[0];
		eye[2] -= look[2];
		target[0] -= look[0];
		target[2] -= look[2];
	}
	if(keyPressed.KeyA) {
		eye[0] += look[2];
		eye[2] -= look[0];
		target[0] += look[2];
		target[2] -= look[0];
	}
	if(keyPressed.KeyD) {
		eye[0] -= look[2];
		eye[2] += look[0];
		target[0] -= look[2];
		target[2] += look[0];
	}
	mat4.lookAt(viewMatrix, eye, target, up);
	for(let object of objects) {
		gl.useProgram(object.shader);
		gl.uniformMatrix4fv(object.viewMatrixLoc, false, viewMatrix);
	}
}

function render() {
	
	// Only clear once
	gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

	// Call render function of each scene object
	for(let object of objects) {
		object.Render();
	};
}

function gameLoop() 
{
	update();
	render();
	requestAnimationFrame(gameLoop);
}

function keydown(e) 
{
	keyPressed[e.code] = true;
}

function keyup(e) 
{
	keyPressed[e.code] = false;
}

function changeView(e) 
{
	vec3.rotateY(target, target, eye, -e.movementX * speed);
	mat4.lookAt(viewMatrix, eye, target, up);
	for(let object of objects) {
		gl.useProgram(object.shader);
		gl.uniformMatrix4fv(object.viewMatrixLoc, false, viewMatrix);
	}
}

main();