controlstadia.js

function main(){
	let config = null;
	window.addEventListener("startConfig", function(e) {
		config = e.detail;
		setupCS();
	}, false);
	const setupCS = function(){
		console.log("ControlStadia: Injected!");
		console.log(config);
		const buttonCount = 17;
		const axisCount = 4;

		const emulatedGamepad = {
			id: "ControlStadia emulated gamepad",
			index: 0,
			connected: true,
			timestamp: 0,
			mapping: "standard",
			axes: [0, 0, 0, 0],
			buttons: new Array(buttonCount).fill().map(m => ({pressed: false, touched: false, value: 0}))
		}

		let indicesFound = false;
		const findGamepadIndices = function(originalGamepads){
			for(let i = 0; i < buttonCount; i++){
				if(typeof config.buttons[i].dstID !== "undefined"){
					for(let gamepadIndex = 0; gamepadIndex < originalGamepads.length; gamepadIndex++){
						if(originalGamepads[gamepadIndex] !== null && originalGamepads[gamepadIndex].id === config.buttons[i].dstID){
							config.buttons[i].gamepadIndex = gamepadIndex;
							break;
						}
					}
				}
			}
			for(let i = 0; i < axisCount; i++){
				if(typeof config.axes[i].dstID !== "undefined"){
					for(let gamepadIndex = 0; gamepadIndex < originalGamepads.length; gamepadIndex++){
						if(originalGamepads[gamepadIndex] !== null && originalGamepads[gamepadIndex].id === config.axes[i].dstID){
							config.axes[i].gamepadIndex = gamepadIndex;
							break;
						}
					}
				}
			}
			console.log("ControlStadia: Gamepad indicies found!");
			indicesFound = true;
		}
		
		const originalGetGamepads = navigator.getGamepads;
		navigator.getGamepads = function(){ // The magic happens here
			if(typeof config.buttons !== "undefined"){
				const originalGamepads = originalGetGamepads.apply(navigator);
				if(!indicesFound){
					const gamepadFound = Array.from(originalGamepads).some(gamepad => gamepad !== null);
					if(gamepadFound) findGamepadIndices(originalGamepads);
				}
				
				for(let i = 0; i < 17; i++){
					if(typeof config.buttons[i] === "undefined" || typeof config.buttons[i].gamepadIndex === "undefined") continue;
					const selectedConfigButton = config.buttons[i];
					const gamepadIndex = selectedConfigButton.gamepadIndex;
					const dstIndex = selectedConfigButton.dstIndex;
					if(selectedConfigButton.dstType){ //Axis
						const button = emulatedGamepad.buttons[i];
						button.pressed = button.touched = (originalGamepads[gamepadIndex].axes[dstIndex] + selectedConfigButton.offset) !== 0;
						button.value = Math.min(Math.max((originalGamepads[gamepadIndex].axes[dstIndex] * selectedConfigButton.scale) + selectedConfigButton.offset, -1), 1);
					}else{ //Button
						emulatedGamepad.buttons[i] = originalGamepads[gamepadIndex].buttons[dstIndex];
					}
					emulatedGamepad.timestamp = originalGamepads[gamepadIndex].timestamp;
				}
				for(let i = 0; i < 4; i++){
					if(typeof config.axes[i] === "undefined" || typeof config.axes[i].gamepadIndex === "undefined") continue;
					const selectedConfigAxis = config.axes[i];
					const gamepadIndex = selectedConfigAxis.gamepadIndex;
					emulatedGamepad.axes[i] = Math.min(Math.max((originalGamepads[gamepadIndex].axes[selectedConfigAxis.dstIndex] * selectedConfigAxis.scale) + selectedConfigAxis.offset, -1), 1);
					emulatedGamepad.timestamp = originalGamepads[gamepadIndex].timestamp;
				}
			}
			return [emulatedGamepad, null, null, null];
		}
	}
} 

chrome.storage.sync.get([
	"axes",
	"buttons",
	"disableControlStadia"
], function(settings) {
	settings.extUrl = chrome.runtime.getURL("/");
	if(settings.disableControlStadia) return;
	const injScript = document.createElement("script");
	injScript.appendChild(document.createTextNode("(" + main + ")();"));
	(document.body || document.head || document.documentElement).appendChild(injScript);
	window.dispatchEvent(new CustomEvent("startConfig", {detail: settings}));
});