export default class Entanglement {
    constructor({ options, server }) {
        this.event = {}
        this.options = options
        this.server = server
        this.channels = {}
        this.client = {}

        this.store = {}
        this.users = []
        this.account = {}
        this.ws = this.__create_websocket()
    }
    // 当创建一个对象时，会调用这个方法
    // 当创建一个对象时，所有连接在一起的终端都会同步这个对象
    // 并不是所有的终端都会监听全局变化, 因此需要在这里注册监听(频道)

    async __create_websocket() {
        const host = window.location.host
        const protocol = window.location.protocol === 'https:' ? 'wss' : 'ws'
        const ws = new WebSocket(`${protocol}://${host}/entanglement?name=sato&channel=chat`)
        ws.onopen = async () => {
            console.log('websocket 连接成功')
            if (this.ws instanceof Promise) {
                this.ws = await this.ws
            }
        }
        ws.onclose = async () => {
            console.log('websocket 连接关闭, 3s后尝试重新连接...')
            await new Promise(resolve => setTimeout(resolve, 3000))
            this.ws = await this.__create_websocket()
        }
        ws.onerror = async () => {
            console.log('websocket 连接错误, 3s后尝试重新连接...')
            await new Promise(resolve => setTimeout(resolve, 3000))
            this.ws = await this.__create_websocket()
        }
        ws.onmessage = async event => {
            const data = JSON.parse(event.data)
            if (data.type === 'list') {
                console.debug('收到在线列表', data.list)
                this.users = await Promise.all(data.list.map(async user => {
                    console.debug('发送给', user.name, 'offer')
                    const pc = await this.__create_webrtc(user)
                    const offer = await pc.createOffer()
                    pc.setLocalDescription(offer)
                    this.ws.send(JSON.stringify({ type: 'offer', user, offer }))
                    return { ...user, webrtc: pc }
                }))
                return
            }
            if (data.type === 'push') {
                console.debug(data.user.name, '上线', data)
                return
            }
            if (data.type === 'pull') {
                console.debug(data.user.name, '下线', data)
                return
            }
            if (data.type === 'offer') {
                console.debug(data.user.name, '发来 offer')
                const pc = await this.__create_webrtc(data.user)
                pc.setRemoteDescription(data.offer)
                const answer = await pc.createAnswer()
                await pc.setLocalDescription(answer)
                this.ws.send(JSON.stringify({ type: 'answer', user: data.user, answer }))
                this.users.push({ ...data.user, webrtc: pc })
                return
            }
            if (data.type === 'answer') {
                console.debug(data.user.name, '发来 answer')
                const pc = this.users.find(user => user.id === data.user.id).webrtc
                await pc.setRemoteDescription(data.answer)
                return
            }
            if (data.type === 'candidate') {
                console.debug(data.user.name, '发来 candidate 候选通道')
                const pc = this.users.find(user => user.id === data.user.id).webrtc
                await pc.addIceCandidate(data.candidate)
                return
            }
            console.error('收到未知数据:', data)
        }
        return ws
    }

    async __create_webrtc(user) {
        const pc = new RTCPeerConnection(this.options)
        // 当有新的媒体流加入时触发
        pc.onicecandidate = (event) => {
            if (event.candidate) {
                console.debug(user.name, '发出 candidate 候选通道')
                this.ws.send(JSON.stringify({ type: 'candidate', user, candidate: event.candidate }))
            }
        }
        // 当连接状态发生改变时触发
        pc.oniceconnectionstatechange = (event) => {
            if (webrtc.iceConnectionState === 'disconnected' || webrtc.iceConnectionState === 'failed') {
                console.error(data.name, '需要添加新的 candidate')
            } else if (webrtc.iceConnectionState === 'connected' || webrtc.iceConnectionState === 'completed') {
                console.debug(data.name, 'WebRTC 连接已经建立成功')
            }
        }
        // 协商新的会话, 建立初始连接或在网络条件发生变化后重新协商连接
        pc.onnegotiationneeded = async (event) => {
            console.log('onnegotiationneeded', event)
            const offer = await pc.createOffer()
            await pc.setLocalDescription(offer)
            this.ws.send(JSON.stringify({ type: 'offer', user, offer }))
        }
        // 当有新的媒体流加入时触发
        pc.ontrack = (event) => {
            console.log('ontrack', event)
        }
        // 当有新的数据通道加入时触发
        pc.ondatachannel = event => {
            console.log(data.user.name, '建立', event.channel.label, '通道')
            event.channel.onmessage = event => {
                console.log(data.user.name, '收到', event.channel.label, '通道消息', event.data)
            }
            event.channel.onopen = () => {
                console.log(data.user.name, '打开', event.channel.label, '通道')
                event.channel.send('hello')
            }
            event.channel.onclose = () => {
                console.log(data.user.name, '关闭', event.channel.label, '通道')
            }
            event.channel.onerror = () => {
                console.log(data.user.name, '通道', event.channel.label, '发生错误')
            }
        }
        return pc
    }

    // 向所有在线的用户广播消息(webrtc)
    send_all(channel_name, data) {
        console.log('向', channel_name, '频道广播消息:', data)
        this.users.filter(user => {
            const status = user.webrtc.iceConnectionState
            return status === 'connected' || status === 'completed'
        }).forEach(user => {
            console.log('向', user.name, '发送', channel_name, '频道消息:', data)
            const channel = user.webrtc.createDataChannel(channel_name)
            channel.onopen = () => channel.send(JSON.stringify(data))
        })
    }

    // 数据被修改时触发
    set(name, data) {
        // 递归创建代理对象
        const createDeepProxy = (obj, path = []) => {
            const proxy = new Proxy(obj, {
                set: (target, key, value) => {
                    if (!Array.isArray(target) || key !== 'length') {
                        console.log('对象被修改', [...path, key], value)
                        this.send_all(name, this.store[name]) // 向所有在线的用户广播消息
                    }
                    return Reflect.set(target, key, value)
                },
                get: (target, key) => {
                    return target[key]
                }
            })
            Object.keys(obj).forEach(key => {
                if (typeof obj[key] === 'object') {
                    obj[key] = createDeepProxy(obj[key], [...path, key])
                }
            })
            return proxy
        }
        return Reflect.set(this.store, name, createDeepProxy(data))
    }

    // 读取一个通道
    get(name) {
        return this.store[name]
    }
}