{% extends "_layout.html" %}
{% block title %}ChatBox{% endblock %}
{% block pagestylesheet %}
<link rel="stylesheet" href="/static/index.css" />
{% endblock %}
{% block content %}
<div id="app">
    <div id="message-list">

    </div>
    <div id="inputs">
        <select id="peers">

        </select>
        <input id="message-input" />
        <input type="file" id="sendfile" disabled/>
    </div>
</div>
{% endblock %}
{% block pagescripts %}
<script>
(() => {
    let message_list = document.getElementById("message-list")
    let peers = document.getElementById("peers")
    let inputbox = document.getElementById("message-input")
    let sendfile = document.getElementById("sendfile")

    let search = new URLSearchParams(location.search);
    let sender = search.get("name") || "";
    
    let room = search.get("room") || "public";

    let peerMap = new Map();
    let channelMap = new Map();

    let ws;
    let wsReconnectInterval = 5000;

    const MessageBootstrap = "Bootstrap";
    const MessageDiscoverRequest = "DiscoverRequest";
    const MessageDiscoverResponse = "DiscoverResponse";
    const MessageSessionOffer = "SessionOffer";
    const MessageSessionAnswer = "SessionAnswer";
    const MessageICECandidate = "IceCandidate";

    let updateSendfile = () => {
        if (peers.value != "") {
            sendfile.removeAttribute("disabled")
        } else {
            sendfile.setAttribute("disabled", "")
        }
    }
    peers.addEventListener("change", updateSendfile)
    sendfile.addEventListener("change", async (ev) => {
        let file = sendfile.files[0]
        sendfile.value = ""

        let peer = peerMap.get(peers.value)
        if (!peer) {
            return
        }
        display(`你给 ${peers.value} 传了一个文件: ${file.name}。传输中...`)

        let reader = new FileReader()
        let dc = peer.createDataChannel(`file:${file.name}`)
        reader.addEventListener("load", (ev) => {
            dc.send(reader.result)
            dc.close()
        })
        dc.addEventListener("open", () => {
            reader.readAsArrayBuffer(file)
        })
    })

    const createNode = (tag, ...children) => {
        let node = document.createElement(tag)
        children.forEach(child => {
            if(typeof child === "string") {
                let inner = document.createElement("span")
                inner.innerHTML = child
                node.appendChild(inner)
            } else if (child instanceof HTMLElement) {
                node.appendChild(child)
            } else {
                console.log("child is not a node: ", child, typeof child)
            }
        })
        return node
    }

    const display = (...message) => {
        let scrollToBottom = Math.abs(message_list.scrollHeight - message_list.scrollTop - message_list.clientHeight) < 1;
        message_list.appendChild(createNode("div",
            `${new Date().toTimeString()}: `,
            ...message
        ))
        if(scrollToBottom) {
            message_list.scrollTo({
                top: message_list.scrollHeight
            })
        }
    }

    inputbox.addEventListener("keyup", (e) => {
        if (!(e.key === 'Enter' || e.keyCode === 13)) {
            return
        }
        if (!inputbox.value || inputbox.value.trim().length == 0) {
            return
        }
        let channel = channelMap.get(peers.value)
        if (!channel) {
            return
        }

        display(`你 -> ${peers.value}: ${inputbox.value}`)
        channel.send(inputbox.value)
        inputbox.value = ""
    })

    const addPeer = (peerName) => {
        display(`连接上了 ${peerName}`)

        let newNode = document.createElement("option")
        newNode.id = peerName
        newNode.setAttribute("value", peerName)
        newNode.innerHTML = peerName;
        peers.appendChild(newNode)

        updateSendfile()
    }
    const removePeer = (peerName) => {
        display(`${peerName} 走了...`)
        let el = document.getElementById(peerName);
        if(el) el.remove()

        updateSendfile()
    }

    let timeout;
    
    let reconnect = () => {
        if(ws && (ws.readyState == WebSocket.CONNECTING || ws.readyState == WebSocket.OPEN)) {
            return;
        }

        let protocol = "ws://";
        if (location.protocol === "https:") {
            protocol = "wss://"
        }
        
        ws = new WebSocket(protocol+location.host+"/ws");
        ws.addEventListener("error", reconnect)
        ws.addEventListener("close", reconnect)

        ws.addEventListener("message", ({data}) => {
            handle_ws_message(JSON.parse(data))
        })
        ws.addEventListener("open", () => {
            display("服务器连上啦。你等等，给你起个名字...")
            ws.send(JSON.stringify({
                message: {
                    type: MessageBootstrap,
                },
                room,
                sender,
            }))
        })
    }

    let handle_ws_message = (wsMessage) => {
        let recreateAndSetupPeer = async (peerName) => {
            if (!peerMap.has(peerName)) {

                let peer = new RTCPeerConnection({
                    iceServers: [{ urls: ["stun:nhz.jeffthecoder.xyz:3478", "stun:nhz.jeffthecoder.xyz:3479", "stun:nhz.jeffthecoder.xyz:13478"] }]
                })
                peer.addEventListener("signalingstatechange", (ev) => {
                    console.log("signaling state changed: ", peer.signalingState)
                })
                peer.addEventListener("connectionstatechange", (ev) => {
                    console.log("peer connection state changed: ", peer.connectionState)
                    switch (peer.connectionState) {
                        case "closed":
                            break;
                        case "disconnected":
                        case "failed":
                            peer.restartIce()
                            break
                    }
                })
                peer.addEventListener("icecandidate", (ev) => {
                    if (!ev.candidate) {
                        console.log("gather end")
                        return
                    }
                    let candidate = ev.candidate.toJSON()
                    ws.send(JSON.stringify({
                        message: {
                            type: MessageICECandidate,
                            candidate: JSON.stringify(candidate),
                            sender,
                            kind: 3,
                        },
                        room,
                        sender,
                        receiver: wsMessage.sender,
                    }))
                })
                peer.addEventListener("icegatheringstatechange", ev => {
                    console.log("gather", peer.iceGatheringState)
                })
                peer.addEventListener("datachannel", ({channel}) => {
                    if(channel.label === "chat") {
                        channelMap.set(peerName, channel);
                        channel.addEventListener("open", (ev) => {
                            addPeer(peerName)
                        })
                        channel.addEventListener("message", (ev) => {
                            display(`${peerName} -> You: ${ev.data}`)
                        })
                        channel.addEventListener("close", () => {
                            removePeer(peerName)
                        })
                    } else if (channel.label.startsWith("file:")) {
                        let filename = channel.label.substr(5)
                        let buffers = [];
                        channel.addEventListener("open", ev => {
                            display(`${peerName} 给你发了一个文件: ${filename}。 接收中...`)
                        })
                        channel.addEventListener("message", ev => {
                            buffers.push(ev.data)
                        })
                        channel.addEventListener("close", () => {
                            var link = document.createElement('a');
                            link.href = window.URL.createObjectURL(new Blob(buffers));
                            link.download = filename;
                            link.innerHTML = filename
                            display(
                                "文件：",
                                link,
                            )
                        })
                    }
                })

                peerMap.set(peerName, peer);
            }
            let peer = peerMap.get(peerName);

            let resultSdp = null, resultMessageType;
            if(wsMessage.message.type === MessageDiscoverResponse) {
                let channel = peer.createDataChannel("chat");
                channel.addEventListener("open", (ev) => {
                    addPeer(peerName)
                })
                channel.addEventListener("message", (ev) => {
                    display(`${peerName} -> 你: ${ev.data}`)
                })
                channel.addEventListener("close", () => {
                    removePeer(peerName)
                })
                channelMap.set(peerName, channel);

                
                resultSdp = await peer.createOffer();
                resultMessageType = MessageSessionOffer;
                peer.setLocalDescription(resultSdp)
                console.log("set local offer")
            } else {
                peer.setRemoteDescription(JSON.parse(wsMessage.message.sdp))
                console.log("set remote offer")
                resultSdp = await peer.createAnswer();
                resultMessageType = MessageSessionAnswer;
                peer.setLocalDescription(resultSdp)
                console.log("set local answer")
            }

            ws.send(JSON.stringify({
                message: {
                    type: resultMessageType,
                    sdp: JSON.stringify(resultSdp),
                    sender,
                    kind: 3,
                },
                room,
                sender,
                receiver: wsMessage.sender,
            }))
        }

        let peer = peerMap.get(wsMessage.sender)
        
        switch (wsMessage.message.type) {
            case MessageBootstrap:
                sender = wsMessage.sender;
                ws.send(JSON.stringify({
                        message: {
                            type: MessageDiscoverRequest,
                        },
                        room,
                        sender: wsMessage.sender,
                    }))
                display(`决定了，就叫 ${sender}. 我们等等小伙伴吧...`)
                break;
            case MessageDiscoverRequest:
                display(`正在尝试连接 ${wsMessage.sender}`)
                ws.send(JSON.stringify({
                    message: {
                        type: MessageDiscoverResponse,
                    },
                    room,
                    sender,
                    receiver: wsMessage.sender,
                }))
                break
            case MessageDiscoverResponse:
                recreateAndSetupPeer(wsMessage.sender)
                break;
            case MessageSessionOffer:
                recreateAndSetupPeer(wsMessage.sender)
                break
            case MessageSessionAnswer:
                console.log("set remote answer")
                peer.setRemoteDescription(JSON.parse(wsMessage.message.sdp))
                peer.restartIce()
                break
            case MessageICECandidate:
                let candidate = JSON.parse(wsMessage.message.candidate);
                if(!peer) {
                    console.warn("candidate dropped", candidate)
                    return
                }
                peer.addIceCandidate(candidate)
        }
    }

    reconnect()
})()
</script>
{% endblock %}