meta-next/src/resources/Resources.js

class Resources 
{
	constructor() {
		this.resources = {}
		this.watchers = {}
		this.loading = false
		this.numToLoad = 0
	}

	load(config) 
	{
		const classes = this.Resource.__inherit

		for(let key in config) 
		{
			if(this.resources[key]) {
				console.warn(`(Resources.load) There is already resource with id: ${key}`)
				continue
			}

			const itemConfig = config[key]
			const cls = classes[itemConfig.type]
			if(!cls) {
				console.warn(`(Resources.load) No such resoruce type registered: ${itemConfig.type}`)
				continue
			}

			const resource = new cls(itemConfig)
			this.resources[key] = resource
		}
	}

	resourceLoading(resource) {
		if(this.numToLoad === 0) {
			this.loading = true
			this.emit("loading")
		}
		this.numToLoad++
	}

	resourceLoaded(resource) {
		this.numToLoad--
		if(this.numToLoad === 0) {
			this.loading = false
			this.emit("ready")
		}
	}

	get(id) {
		const resource = this.resources[id]
		return resource || null
	}

	on(event, func) 
	{
		const buffer = this.watchers[event]
		if(buffer) {
			buffer.push(func)
		}
		else {
			this.watchers[event] = [ func ]
		}
	}

	off(event, func) 
	{
		const buffer = this.watchers[event]
		if(!buffer) { return }

		const index = buffer.indexOf(func)
		if(index === -1) { return }

		buffer[index] = buffer[buffer.length - 1]
		buffer.pop()
	}

	emit(event) 
	{
		const buffer = this.watchers[event]
		if(!buffer) { return }

		for(let n = 0; n < buffer.length; n++) {
			buffer[n]()
		}
	}
}

const instance = new Resources()

export default instance