"use strict";

var boardRatio = 1.5;
var ballRadius = 0.01, padWidth = 0.01, padHeight = 0.15, padX = 0.01;
var padBaseSpeed = 0.8;

var gameId;
var cvs, ctx, cvsW, cvsH, bdW, bdH, bdltX, bdltY;
var socket;
var playing = false, flip = false;
var ballX, ballY, ballVX, ballVY;
var padPos, padVel, pad2Pos, pad2Vel;

function redraw() {
	ctx.fillStyle = "#000000";
	ctx.fillRect(0, 0, cvsW, cvsH);

	redrawFast();
}

function calcBallX() {return bdltX + bdW * (flip ? 1 - ballX : ballX);}
function calcBallY() {return bdltY + bdH * ballY;}
function calcPadY() {return bdltY + bdH * ((flip ? pad2Pos : padPos) - padHeight / 2);}
function calcPad2Y() {return bdltY + bdH * ((flip ? padPos : pad2Pos) - padHeight / 2);}

function redrawFast() {
	ctx.strokeStyle = "#ffffff";
	ctx.lineWidth = 2;
	ctx.strokeRect(bdltX - 1, bdltY - 1, bdW + 2, bdH + 2);

	ctx.lineWidth = 1;
	ctx.beginPath();
	ctx.moveTo(bdltX + bdW / 2 | 0, bdltY);
	ctx.lineTo(bdltX + bdW / 2 | 0, bdltY + bdH);
	ctx.stroke();

	if (playing) {
		ctx.fillStyle = "#ffffff";
		ctx.beginPath();
		ctx.arc(calcBallX(), calcBallY(), ballRadius * bdW, 0, 2 * Math.PI);
		ctx.rect(bdltX + bdW * padX, calcPadY(), bdW * padWidth, bdH * padHeight);
		ctx.rect(bdltX + bdW * (1 - padX - padWidth), calcPad2Y(), bdW * padWidth, bdH * padHeight);
		ctx.fill();
	}
}

function undrawElements() {
	ctx.fillStyle = "#000000";
	ctx.beginPath();
	ctx.rect(
		calcBallX() - ballRadius * bdW - 2, calcBallY() - ballRadius * bdW - 2,
		2 * ballRadius * bdW + 4, 2 * ballRadius * bdW + 4);
	ctx.rect(
		bdltX + bdW * padX - 2, calcPadY() - 2,
		bdW * padWidth + 4, bdH * padHeight + 4);
	ctx.rect(
		bdltX + bdW * (1 - padX - padWidth) - 2, calcPad2Y() - 2,
		bdW * padWidth + 4, bdH * padHeight + 4);
	ctx.fill();
}

function resizeHandler() {
	var rect = cvs.getBoundingClientRect();
	cvsW = cvs.width = rect.width;
	cvsH = cvs.height = rect.height;
	// I believe this stuff is correct.
	if (cvsH * boardRatio > cvsW) {
		bdW = cvsW;
		bdH = bdW / boardRatio | 0;
		bdltX = 2;
		bdltY = (cvsH - bdH) / 2 + 2 | 0;
		bdW -= 4; bdH -= 4;
	} else {
		bdH = cvsH;
		bdW = boardRatio * bdH | 0;
		bdltX = (cvsW - bdW) / 2 + 2 | 0;
		bdltY = 2;
		bdW -= 4; bdH -= 4;
	}

	redraw();
}

function displayStatus(msg) {
	document.getElementById("status").innerHTML = msg;
}

function displayScore(score) {
	document.getElementById("score").classList.remove("invisible");
	document.getElementById("score-left").innerHTML = score[0];
	document.getElementById("score-right").innerHTML = score[1];

	setTimeout(function() {
		document.getElementById("score").classList.add("invisible");
	}, 2000);
}

function openGame() {
	socket = io();
	socket.on("redirect", function(url) {
		location.href = url;
	});

	socket.on("status", function(msg) {
		displayStatus(msg);
	});

	socket.on("score", function(score) {
		displayScore(score);
	});

	socket.on("serve", function(side, x, y) {
		playing = true;
		flip = side == "right";
		ballX = x; ballY = y;
		padPos = pad2Pos = 0.5;
		redraw();
	});

	socket.on("stop", function() {
		playing = false;
		stopPhysicsLoop();
		stopGraphicsLoop();
		redraw();
	});

	socket.on("startBall", function() {
		initPhysics();
		ballVX = -0.5 / boardRatio;
		ballVY = -0.5;
		startPhysicsLoop();
		startGraphicsLoop();
	});

	socket.on("start", function() {
		initPhysics();
		ballVX = 0.5 / boardRatio;
		ballVY = -0.5;
		startPhysicsLoop();
		startGraphicsLoop();
	});

	socket.on("padvec", function(pos, vel) {
		pad2Pos = pos;
		pad2Vel = vel;
	});

	socket.on("ballvec", function(x, y, vx, vy) {
		ballX = x; ballY = y;
		ballVX = vx; ballVY = vy;
	});

	socket.emit("open", gameId);
}

var graphicsLoopId = null, physicsLoopId = null;

function startGraphicsLoop() {
	// undrawElements();
	redraw();  // TODO: redrawFast
	graphicsLoopId = requestAnimationFrame(startGraphicsLoop);
}

function stopGraphicsLoop() {
	if (graphicsLoopId == null) return;
	cancelAnimationFrame(graphicsLoopId);
	graphicsLoopId = null;
}

function startPhysicsLoop() {
	var interval = 1 / 120;
	physicsLoopId = setInterval(function() {
		if (advancePhysics(interval)) {
			socket.emit("ballvec", ballX, ballY, ballVX, ballVY);
		}
		if (ballX < -ballRadius) {
			socket.emit("ballout");
			stopPhysicsLoop();
		}
	}, interval * 1000);
}

function stopPhysicsLoop() {
	if (physicsLoopId == null) return;
	clearInterval(physicsLoopId);
	physicsLoopId = null;
}

function initPhysics() {
	ballX = ballY = 0.5;
	ballVX = ballVY = 0;
	padPos = pad2Pos = 0.5;
	padVel = pad2Vel = 0;
}

// Returns whether a new ballvec should be sent
function advancePhysics(deltaT) {
	var sendBallvec = false;

	var newballX = ballX + ballVX * deltaT;
	var newballY = ballY + ballVY * deltaT;
	var newpadPos = padPos + padVel * deltaT;
	var newpad2Pos = pad2Pos + pad2Vel * deltaT;

	var t;
	if (newballY <= ballRadius) {
		t = (ballRadius - ballY) / ballVY;
	} else if (newballY >= 1 - ballRadius) {
		t = (1 - ballRadius - ballY) / ballVY;
	} else {
		t = -1;
	}
	if (t >= 0) {
		newballY = ballY + ballVY * (2 * t - deltaT);
		ballVY = -ballVY;
	}

	if (newballX <= padX + padWidth + ballRadius &&
				Math.abs(newballY - padPos) < padHeight / 2 + ballRadius) {
		t = (padX + padWidth + ballRadius - ballX) / ballVX;
		sendBallvec = true;  // rebound from *our* pad
	} else if (newballX >= 1 - (padX + padWidth + ballRadius) &&
				Math.abs(newballY - pad2Pos) < padHeight / 2 + ballRadius) {
		t = (1 - (padX + padWidth + ballRadius) - ballX) / ballVX;
	} else {
		t = -1;
	}
	if (t >= 0) {
		newballX = ballX + ballVX * (2 * t - deltaT);
		ballVX = -ballVX;
	}

	// If the ball has come to our side, send a ballvec
	if (ballX >= 0.5 && newballX < 0.5) {
		sendBallvec = true;
	}

	ballX = newballX;
	ballY = newballY;
	padPos = newpadPos;
	pad2Pos = newpad2Pos;

	return sendBallvec;
}

function setupBindings() {
	window.addEventListener("keydown", function(ev) {
		if (ev.key == "w" || ev.key == "ArrowUp") {
			padVel = -padBaseSpeed;
			socket.emit("padvec", padPos, padVel);
		} else if (ev.key == "s" || ev.key == "ArrowDown") {
			padVel = padBaseSpeed;
			socket.emit("padvec", padPos, padVel);
		}
	});

	window.addEventListener("keyup", function(ev) {
		if (ev.key == "w" || ev.key == "ArrowUp" ||
					ev.key == "s" || ev.key == "ArrowDown") {
			padVel = 0;
			socket.emit("padvec", padPos, padVel);
		}
	});
}

window.addEventListener("load", function() {
	gameId = document.location.href.replace(/.*\//, "");

	cvs = document.getElementById("cvs");
	ctx = cvs.getContext("2d");

	resizeHandler();

	setupBindings();

	openGame();
});

window.addEventListener("resize", resizeHandler);