/**
 * Tracks one-shot request/response pairs over the `postMessage` bridge. Each `allocate` reserves a
 * unique `requestId` and stores its resolver. `resolve` finds the pending resolver by `requestId`
 * and calls it, then removes the entry so the same `requestId` cannot be resolved twice.
 */
export class PendingRequests<T> {
	private nextId = 1
	private readonly entries = new Map<string, (value: T) => void>()

	constructor(private readonly prefix: string) {}

	allocate(resolver: (value: T) => void): string {
		const requestId = `${this.prefix}-${this.nextId}`
		this.nextId += 1
		this.entries.set(requestId, resolver)
		return requestId
	}

	resolve(requestId: string, value: T): boolean {
		const resolver = this.entries.get(requestId)
		if (resolver === undefined) {
			return false
		}
		this.entries.delete(requestId)
		resolver(value)
		return true
	}
}