import { WASM_MEMORY_PAGE_SIZE, appGlobals } from './globals.js'
import { loadWasmModule, wasmPntrToJsString, wasmPntrAndLengthToJsString } from './wasm_functions.js'
import { jsStdFunctions } from './std_functions.js'
import { jsGlFunctions } from './gl_functions.js'

function AcquireCanvas(canvasWidth, canvasHeight)
{
	var canvas = document.getElementsByTagName("canvas")[0];
	// console.log(canvas);
	
	// set the display size of the canvas.
	canvas.style.width = canvasWidth + "px";
	canvas.style.height = canvasHeight + "px";
	
	// set the size of the drawingBuffer
	var devicePixelRatio = window.devicePixelRatio || 1;
	canvas.width = canvasWidth * devicePixelRatio;
	canvas.height = canvasHeight * devicePixelRatio;
	
	// canvasContainer = document.getElementById("canvas_container");
	// console.assert(canvasContainer != null, "Couldn't find canvas container DOM element!");
	appGlobals.canvas = canvas;
	return canvas;
}

function CreateGlContext(canvas)
{
	var canvasContextGl = canvas.getContext("webgl2");
	if (canvasContextGl === null) { console.error("Unable to initialize WebGL render context. Your browser or machine may not support it :("); return null; }
	// console.dir(canvasContextGl);
	appGlobals.glContext = canvasContextGl;
	return canvasContextGl;
}

async function LoadWasmModule(wasmFilePath, initialWasmPageCount)
{
	appGlobals.textDecoder = new TextDecoder("utf-8");
	
	let wasmEnvironment =
	{
		...jsStdFunctions,
		...jsGlFunctions,
	};
	appGlobals.wasmModule = await loadWasmModule(wasmFilePath, wasmEnvironment);
	
	appGlobals.memDataView = new DataView(new Uint8Array(appGlobals.wasmModule.exports.memory.buffer).buffer);
	// let heapBaseAddress = appGlobals.wasmModule.exports.__heap_base.value;
	// console.log("__heap_base = " + heapBaseAddress);
	
	let memorySize = appGlobals.wasmModule.exports.memory.buffer.byteLength;
	let numMemoryPagesAfterLoad = memorySize / WASM_MEMORY_PAGE_SIZE;
	if ((memorySize % WASM_MEMORY_PAGE_SIZE) != 0)
	{
		console.warn("memorySize (" + memorySize + ") is not a multiple of WASM_MEMORY_PAGE_SIZE (" + WASM_MEMORY_PAGE_SIZE + ")");
		numMemoryPagesAfterLoad++;
	}
	appGlobals.wasmModule.exports.init_mem(numMemoryPagesAfterLoad);
}

async function MainLoop()
{
	console.log("Initializing WebGL Canvas...");
	var canvas = AcquireCanvas(600, 400);
	var glContext = CreateGlContext(canvas);
	
	console.log("Loading WASM Module...");
	await LoadWasmModule("app.wasm", 4);
	appGlobals.wasmModule.exports.App_Initialize();
	
	console.log("Running!");
	function renderFrame()
	{
		appGlobals.wasmModule.exports.App_UpdateAndRender();
		window.requestAnimationFrame(renderFrame);
	}
	window.requestAnimationFrame(renderFrame);
}

MainLoop();