class Loader{
	constructor(callback){
		this.callback = callback
		this.loadedAssets = 0
		this.assetsDiv = document.getElementById("assets")
		this.canvasTest = new CanvasTest()
		p2 = new P2Connection()
		this.startTime = +new Date
		
		this.ajax("src/views/loader.html").then(this.run.bind(this))
	}
	run(page){
		this.promises = []
		this.screen = document.getElementById("screen")
		this.screen.innerHTML = page
		this.loaderPercentage = document.querySelector("#loader .percentage")
		this.loaderProgress = document.querySelector("#loader .progress")
		
		snd.buffer = new SoundBuffer()
		snd.musicGain = snd.buffer.createGain()
		snd.sfxGain = snd.buffer.createGain()
		snd.previewGain = snd.buffer.createGain()
		snd.sfxGainL = snd.buffer.createGain("left")
		snd.sfxGainR = snd.buffer.createGain("right")
		snd.sfxLoudGain = snd.buffer.createGain()
		snd.buffer.setCrossfade(
			[snd.musicGain, snd.previewGain],
			[snd.sfxGain, snd.sfxGainL, snd.sfxGainR],
			0.5
		)
		snd.sfxLoudGain.setVolume(1.2)
		
		snd.buffer.load("/assets/audio/" + assets.audioOgg).then(() => {
			this.oggNotSupported = false
		}, () => {
			this.oggNotSupported = true
		}).then(() => {
			
			assets.fonts.forEach(name => {
				var font = document.createElement("h1")
				font.style.fontFamily = name
				font.appendChild(document.createTextNode("I am a font"))
				this.assetsDiv.appendChild(font)
				this.promises.push(new Promise((resolve, reject) => {
					FontDetect.onFontLoaded(name, resolve, reject, {msTimeout: 90000})
				}))
			})
			var fontDetectDiv = document.getElementById("fontdetectHelper")
			fontDetectDiv.parentNode.removeChild(fontDetectDiv)
			
			assets.img.forEach(name => {
				var id = this.getFilename(name)
				var image = document.createElement("img")
				this.promises.push(pageEvents.load(image))
				image.id = name
				image.src = "/assets/img/" + name
				this.assetsDiv.appendChild(image)
				assets.image[id] = image
			})
			
			assets.audioSfx.forEach(name => {
				this.promises.push(this.loadSound(name, snd.sfxGain))
			})
			assets.audioMusic.forEach(name => {
				this.promises.push(this.loadSound(name, snd.musicGain))
			})
			assets.audioSfxLR.forEach(name => {
				this.promises.push(this.loadSound(name, snd.sfxGain).then(sound => {
					var id = this.getFilename(name)
					assets.sounds[id + "_p1"] = assets.sounds[id].copy(snd.sfxGainL)
					assets.sounds[id + "_p2"] = assets.sounds[id].copy(snd.sfxGainR)
				}))
			})
			assets.audioSfxLoud.forEach(name => {
				this.promises.push(this.loadSound(name, snd.sfxLoudGain))
			})
			
			this.promises.push(this.ajax("/api/songs").then(songs => {
				assets.songs = JSON.parse(songs)
			}))

			this.promises.push(this.ajax("/api/config").then(conf => {
				gameConfig = JSON.parse(conf)
			}))
			
			assets.views.forEach(name => {
				var id = this.getFilename(name)
				this.promises.push(this.ajax("src/views/" + name).then(page => {
					assets.pages[id] = page
				}))
			})
			
			this.promises.push(this.canvasTest.blurPerformance().then(result => {
				perf.blur = result
				if(result > 1000 / 50){
					// Less than 50 fps with blur enabled
					disableBlur = true
				}
			}))
			
			this.promises.forEach(promise => {
				promise.then(this.assetLoaded.bind(this))
			})
			
			Promise.all(this.promises).then(() => {
				this.canvasTest.drawAllImages().then(result => {
					perf.allImg = result
					perf.load = (+new Date) - this.startTime
					this.canvasTest.clean()
					this.clean()
					this.callback()
				})
			}, this.errorMsg.bind(this))
			
		})
	}
	loadSound(name, gain){
		if(this.oggNotSupported && name.endsWith(".ogg")){
			name = name.slice(0, -4) + ".wav"
		}
		var id = this.getFilename(name)
		return gain.load("/assets/audio/" + name).then(sound => {
			assets.sounds[id] = sound
		})
	}
	getFilename(name){
		return name.slice(0, name.lastIndexOf("."))
	}
	errorMsg(){
		this.error = true
		this.loaderPercentage.appendChild(document.createElement("br"))
		this.loaderPercentage.appendChild(document.createTextNode("An error occurred, please refresh"))
		this.clean()
	}
	assetLoaded(){
		if(!this.error){
			this.loadedAssets++
			var percentage = Math.floor(this.loadedAssets * 100 / this.promises.length)
			this.loaderProgress.style.width = percentage + "%"
			this.loaderPercentage.firstChild.data = percentage + "%"
		}
	}
	changePage(name){
		this.screen.innerHTML = assets.pages[name]
	}
	ajax(url, customRequest){
		return new Promise((resolve, reject) => {
			var request = new XMLHttpRequest()
			request.open("GET", url)
			pageEvents.load(request).then(() => {
				resolve(request.response)
			}, reject)
			if(customRequest){
				customRequest(request)
			}
			request.send()
		})
	}
	clean(){
		delete this.assetsDiv
		delete this.loaderPercentage
		delete this.loaderProgress
		delete this.promises
		pageEvents.remove(root, "touchstart")
	}
}