// index.js

import { mat4 } from 'https://webgpufundamentals.org/3rdparty/wgpu-matrix.module.js';
import { initializeWebGPU } from './wgpu-device.js';
import { createState } from './wgpu-state.js';
import { initializeTiming } from './wgpu-timing.js';
import { createPipeline } from './wgpu-pipeline.js';
import { generateGlyphTextureAtlas, createTextureFromSource } from './wgpu-utility.js';
import { InitializeShaders } from './wgpu-shader.js';
import { GenerateVertexDataAndTexture } from './wgpu-texture.js';
import { generateGlyphVerticesForText } from './wgpu-text.js';
import { config } from './wgpu-config.js';
import { CANVAS, CTX, COLORS, RENDER_PASS_DESCRIPTOR } from './wgpu-constants.js';
import { CreateBuffers } from './wgpu-buffer.js';

const state = createState(config);

async function Main() {
    const adapter = await navigator.gpu?.requestAdapter();
    const { device, context, presentationFormat } = await initializeWebGPU(navigator, adapter, state.canvas);
    if (!device) return;

    state.webgpu.device = device;
    state.webgpu.context = context;
    state.webgpu.presentationFormat = presentationFormat;

    initializeTiming(state);

    await InitializeShaders(state);
    await InitializeResources(state);

    GameLoop(state);
}

async function InitializeResources(state) {
    const vertexSize = config.floatsPerVertex * 4;

    state.webgpu.pipeline = await createPipeline(state.webgpu.device, state.webgpu.presentationFormat, vertexSize, state.webgpu.shaderCode);

    const glyphCanvas = generateGlyphTextureAtlas(CANVAS, CTX, config);
    document.body.appendChild(glyphCanvas);
    glyphCanvas.style.backgroundColor = '#222';

    CreateBuffers(state, config);

    GenerateVertexDataAndTexture(state, glyphCanvas, generateGlyphVerticesForText, COLORS, config, createTextureFromSource);
}

function GameLoop(state) {
    function Tick(state) {
        state.timing.currentTime = performance.now();
        state.timing.frameTime = (state.timing.currentTime - state.timing.lastTime) / 1000;
        state.timing.lastTime = state.timing.currentTime;
        state.timing.deltaTime = Math.min(state.timing.frameTime, state.timing.maxFrameTime);
        state.timing.accumulator += state.timing.deltaTime;

        while (state.timing.accumulator >= state.timing.fixedDeltaTime) {
            FixedUpdate(state);
            state.timing.accumulator -= state.timing.fixedDeltaTime;
        }
        
        Render(state);

        setTimeout(() => Tick(state), state.timing.frameDuration);
    }

    Tick(state);
}

function FixedUpdate(state) {
    state.timing.time += state.timing.fixedDeltaTime;
}

function Render(state) {
    const fov = 60 * Math.PI / 180;
    const aspect = state.canvas.clientWidth / state.canvas.clientHeight;
    const projectionMatrix = mat4.perspective(fov, aspect, config.render.zNear, config.render.zFar);
    const viewMatrix = mat4.lookAt([0, 0, 5], [0, 0, 0], [0, 1, 0]);
    const viewProjectionMatrix = mat4.multiply(projectionMatrix, viewMatrix);
    RENDER_PASS_DESCRIPTOR.colorAttachments[0].view = state.webgpu.context.getCurrentTexture().createView();
    const encoder = state.webgpu.device.createCommandEncoder();
    const pass = encoder.beginRenderPass(RENDER_PASS_DESCRIPTOR);
    pass.setPipeline(state.webgpu.pipeline);
    mat4.rotateY(viewProjectionMatrix, state.timing.time, state.matrices.matrix);
    mat4.translate(state.matrices.matrix, [-state.glyphs.width / 2, -state.glyphs.height / 2, 0], state.matrices.matrix);
    state.webgpu.device.queue.writeBuffer(state.webgpu.uniformBuffer, 0, state.matrices.uniformValues);
    pass.setBindGroup(0, state.webgpu.bindGroup);
    pass.setVertexBuffer(0, state.webgpu.vertexBuffer);
    pass.setIndexBuffer(state.webgpu.indexBuffer, 'uint32');
    pass.drawIndexed(state.glyphs.numGlyphs * 6);
    pass.end();
    state.webgpu.device.queue.submit([encoder.finish()]);
}

Main();