var urlParamsForBackground = new URLSearchParams(window.location.search);
if (urlParamsForBackground.get('forward') == 'langstudy.tech-homepage.html') {
    throw new Error("Halting 3d background. A integration specified the current page should not have a 3d background.");
}

color = 0xffffff
pointcolor = 0x000000
if (window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches) {
    color = 0x000000
    pointcolor = 0xffffff

    var style = document.createElement('style');
    style.innerHTML = `
        body {
            --primary-color: #000000 !important;
            --secondary-color: #ffffff !important;
        }
    `;
    document.head.appendChild(style);
}

var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera( 75, window.innerWidth/window.innerHeight, 0.1, 1000 );

var renderer = new THREE.WebGLRenderer(antiAlias = true);
renderer.setSize( window.innerWidth, window.innerHeight);
rendererElement = renderer.domElement
rendererElement.style.position = 'absolute'
rendererElement.style.top = 0
rendererElement.style.left = 0
rendererElement.style.zIndex = -5
document.body.appendChild( rendererElement );

window.addEventListener("mousemove", function(event) {
    let mouseY = event.clientY
    let windowHeight = window.innerHeight
    targetCameraPosY = -((mouseY - windowHeight / 2) / 500) + 5
});

function lerp(a, b, t) {
    return a + (b - a) * t
}

// loop over a 2D grid of points
spheres = []
sphereHeightOffset = []
for ( var x = -40; x <= 40; x += 1 ) {
    for ( var z = -20; z <= 5; z += 1) {
        var geometry = new THREE.SphereGeometry( 0.05, 32, 32 );
        var material = new THREE.MeshBasicMaterial( {color: pointcolor} )
        var sphere = new THREE.Mesh( geometry, material );
        sphere.position.x = x
        sphere.position.z = z

        var height = Math.pow(z, 2) / 70
        // height = 0
        sphere.position.y = height

        sphereHeightOffset.push(height)
        spheres.push(sphere)
        scene.add( sphere );
    }
}

// set the skybox to white
scene.background = new THREE.Color( color );

camera.position.z = 10;
camera.position.y = 5;

time = 0
rate = 2
noise.seed(Math.random())

var animate = function () {
	requestAnimationFrame( animate );
	renderer.render( scene, camera );
    
    time_since_last_resize += 1;

    for (var i = 0; i < spheres.length; i++) {
        var sphere = spheres[i]
        var x = sphere.position.x
        var z = sphere.position.z
        var height = noise.simplex2(x/10 + (time / rate), z/10 + (time / rate)) * 0.5
        sphere.position.y = height + sphereHeightOffset[i]
        
        var color = new THREE.Color( 0xffffff );
        color.setHSL( 0, 0, height + 0.5 );
        sphere.material.color = color

        sphere.scale.x = 1 + height
        sphere.scale.y = 1 + height
        sphere.scale.z = 1 + height
    }

    camera.position.y = lerp(camera.position.y, targetCameraPosY, 0.1)

    time += 0.01

    if (time_since_last_resize > 5) {
        camera.aspect = window.innerWidth / window.innerHeight;
        camera.updateProjectionMatrix();

        renderer.setSize( window.innerWidth, window.innerHeight );

        window_needs_resize = false;
    }
};


var window_needs_resize = false;
var time_since_last_resize = 0;

window.addEventListener( 'resize', onWindowResize, false );

function onWindowResize(){
    time_since_last_resize = 0;
    window_needs_resize = true;
}

animate();