import { log } from './../logger/Logger';
import { IframeMessageRequest } from '../message/IframeMessageRequest'
import { IframeMessageResponse } from '../message/IframeMessageResponse'
import { nanoid } from "nanoid"
import { EventEmitter } from 'events'
/**
 * send message to sub iframe page and revice messge
 * 
 */
export class IframeMessageService extends EventEmitter {

    //target window to send Message
    subWindow: Window

    //all promise resolves
    resolves: Map<string, Function> = new Map()

    constructor(target: Window) {
        super()
        this.subWindow = target
        globalThis.addEventListener('message', (event) => this.reciveMessage(event), false)
    }



    async sendMessage(payload: IframeMessageRequest): Promise<IframeMessageResponse> {
        return new Promise((resolve) => {
            let requestId = nanoid()
            log("send message", { requestId, payload })
            this.subWindow.postMessage({ requestId, payload }, "*")
            this.resolves.set(requestId, resolve)
        })
    }

    /**
     * 接收子页面返回的消息
     */
    reciveMessage({ data }: MessageEvent): void {
        log("recive data", data)
        if (data !== undefined) {
            let { requestId, payload } = data
            if (requestId !== undefined) {
                let resolve = this.resolves.get(requestId)
                if (resolve !== undefined) {
                    log("promise back")
                    //处理异步返回
                    this.resolves.delete(requestId)
                    resolve(payload)
                } else {
                    log("pop event ")
                    //直接上报消息
                    let { type, data } = payload
                    this.emit(type, data)
                }
            }
        }
    }
}