import * as _ from './utils'

export class CustomElementRegistry {
	/** Defines a new custom element using the given tag name and HTMLElement constructor. */
	define(name: string, constructor: Function, options?: ElementDefinitionOptions) {
		const internals = _.internalsOf<CustomElementRegistryInternals>(this, 'CustomElementRegistry', 'define')

		name = String(name)

		if (/[A-Z]/.test(name)) throw new SyntaxError('Custom element name cannot contain an uppercase ASCII letter')
		if (!/^[a-z]/.test(name)) throw new SyntaxError('Custom element name must have a lowercase ASCII letter as its first character')
		if (!/-/.test(name)) throw new SyntaxError('Custom element name must contain a hyphen')

		internals.constructorByName.set(name, constructor)
		internals.nameByConstructor.set(constructor, name)

		void options
	}

	/** Returns the constructor associated with the given tag name. */
	get(name: string) {
		const internals = _.internalsOf<CustomElementRegistryInternals>(this, 'CustomElementRegistry', 'get')

		name = String(name).toLowerCase()

		return internals.constructorByName.get(name)
	}

	getName(constructor: Function) {
		const internals = _.internalsOf<CustomElementRegistryInternals>(this, 'CustomElementRegistry', 'getName')

		return internals.nameByConstructor.get(constructor)
	}
}

_.allowStringTag(CustomElementRegistry)

interface CustomElementRegistryInternals {
	constructorByName: Map<string, Function>;
	nameByConstructor: Map<Function, string>;
}

interface ElementDefinitionOptions {
	extends?: string | undefined;
}

export const initCustomElementRegistry = (target: Record<any, any>, exclude: Set<string>) => {
	if (exclude.has('customElements')) return

	const CustomElementRegistry = target.CustomElementRegistry || globalThis.CustomElementRegistry

	const customElements: CustomElementRegistry = target.customElements = Object.create(CustomElementRegistry.prototype)

	_.INTERNALS.set(customElements, {
		constructorByName: new Map,
		nameByConstructor: new Map,
	} as CustomElementRegistryInternals)
}