let LocalHistoryId = 0;

let members = new Map();

let loadedMessages = new Map();  // messageSt objects
let visibleMessages = new Map();  // HTMLElement objects

let anchoredMsg = -1;
let visibleMsgSegStart = -1;
let visibleMsgSegEnd = -2;
let offsetOfAnchor = 500;
let highestPoint = null;
let lowestPoint = null;

let lastMsgId = -1;
let myRoleHere = null;  // Dung local state updates should be updated first

// Would start with true if opened `/chat/<>`
let bumpedAtTheBottom = false;

// Hidden variable. When deletion window popup is active
// Persists from popup activation until popup deactivation
let storeHiddenMsgIdForDeletionWin = -1;

// Positive in production, negative for debug
let softZoneSz = -150;
let chatPadding = 300;

function genSentBase(){
    return {
        'chatUpdReq': {
            'LocalHistoryId': LocalHistoryId,
            'chatId': openedchat.id
        }
    };
}

function genSentBaseGMN(){
    let Sent = genSentBase();
    Sent.amount = 1;
    return Sent;
}

function updateOffsetOfVisibleMsg(msgId, offset){
    visibleMessages.get(msgId).style.bottom = String(offset) + "px";
}

function updateOffsetsUpToTop(){
    let offset = offsetOfAnchor;
    for (let curMsg = anchoredMsg; curMsg >= visibleMsgSegStart; curMsg--){
        updateOffsetOfVisibleMsg(curMsg, offset);
        let height = visibleMessages.get(curMsg).offsetHeight;
        offset += height + 5;
    }
    return offset;
}

function updateOffsetsDown(){
    let offset = offsetOfAnchor;
    for (let curMsg = anchoredMsg + 1; curMsg <= visibleMsgSegEnd; curMsg++){
        let height = visibleMessages.get(curMsg).offsetHeight;
        offset -= (height + 5);
        updateOffsetOfVisibleMsg(curMsg, offset);
    }
    return offset;
}

function updateOffsetsSane(){
    if (anchoredMsg < 0)
        return;
    highestPoint = updateOffsetsUpToTop();
    lowestPoint = updateOffsetsDown();
}

function updateOffsets(){
    if (anchoredMsg < 0)
        return;
    updateOffsetsSane()
    let winTop = document.getElementById("chat-widget").offsetHeight;
    if (lowestPoint > chatPadding || (highestPoint - lowestPoint) <= winTop){
        bumpedAtTheBottom = true;
        anchoredMsg = visibleMsgSegEnd;
        offsetOfAnchor = chatPadding;
        updateOffsetsSane();
    } else if (highestPoint < winTop - chatPadding) {
        console.log("Advancing by " + (winTop - chatPadding - highestPoint))
        offsetOfAnchor += (winTop - chatPadding - highestPoint);
        updateOffsetsSane();
    }
}

function shouldShowDeleteMesgBtn(messageSt){
    return !messageSt.isSystem && messageSt.exists && (
        messageSt.myRoleHere === userChatRoleAdmin || messageSt.senderUserId === userinfo.uid);
}

function getMsgTypeClassSenderBased(messageSt){
    if (messageSt.isSystem)
        return "message-box-system"
    if (messageSt.senderUserId === userinfo.uid)
        return "message-box-mine"
    return "message-box-alien";
}

function getMsgFullTypeClassName(messageSt){
    return getMsgTypeClassSenderBased(messageSt) + (messageSt.exists ? "" : " message-box-deleted");
}

/* Two things can be updated: messages existance and delete button visibility */
function updateMessageBox(id, box, messageSt){
    box.querySelector(".message-box-button-delete").style.display = shouldShowDeleteMesgBtn(messageSt) ? "block" : "none";
    box.className = getMsgFullTypeClassName(messageSt);
    // Notice, that no check of previous state is performed. Double loading is a rare event,
    // and I can afford to be slow
    if (!messageSt.exists)
        box.querySelector(".message-box-msg").innerText = msgErased;
}

function decodeSystemMessage(text){
    let [subject, verb, object] = text.split(',');
    let subjectId = Number(subject);
    let objectId = Number(object);
    let subjectRef = members.has(subjectId) ? members.get(subjectId).nickname : "???";
    let objectRef = members.has(objectId) ? members.get(objectId).nickname : "???";
    if (verb === "kicked"){
        return subjectRef + " kicked " + objectRef;
    } else if (verb === "summoned"){
        return subjectRef + " summoned " + objectId;
    } else if (verb === "left"){
        return subjectRef + " left chat";
    } else if (verb === "joined"){
        return subjectId + " joined chat";
    } else if (verb === "created"){
        return subjectId + " created this chat";
    }
    return "... Bad log ...";
}

function convertMessageStToBox(messageSt){
    let box = document.createElement("div");
    box.className = getMsgFullTypeClassName(messageSt);

    let ID = messageSt.id;

    let topPart = document.createElement("div");
    box.appendChild(topPart);
    topPart.className = "message-box-top";

    if (!members.has(messageSt.senderUserId))
        throw new Error("First - update members");
    let senderMemberSt = members.get(messageSt.senderUserId);
    let senderProfileURI = "/user/" + senderMemberSt.nickname;

    let inTopPartSenderName = document.createElement("a");
    topPart.appendChild(inTopPartSenderName);
    inTopPartSenderName.className = "message-box-sender-name";
    inTopPartSenderName.innerText = senderMemberSt.name;
    inTopPartSenderName.href = senderProfileURI;

    let inTopPartSenderNickname = document.createElement("a");
    topPart.appendChild(inTopPartSenderNickname);
    inTopPartSenderNickname.className = "message-box-sender-name message-box-sender-shortname"
    inTopPartSenderNickname.innerText = senderMemberSt.nickname;
    inTopPartSenderNickname.href = senderProfileURI;

    let inTopPartButtonDelete = document.createElement("img");
    topPart.appendChild(inTopPartButtonDelete);
    inTopPartButtonDelete.className = "message-box-button message-box-button-delete";
    inTopPartButtonDelete.src = "/assets/img/delete.svg";
    inTopPartButtonDelete.onclick = (ev) => {
        if (ev.button !== 0)
            return;
        let msgText = box.querySelector(".message-box-msg").innerText;
        let previewText = senderMemberSt.nickname + ":\n" + msgText;
        if (previewText.length > 1000)
            previewText = previewText.substring(0, 1000 - 3);
        document.getElementById("win-deletion-msg-preview").innerText = previewText;
        storeHiddenMsgIdForDeletionWin = ID;
        activatePopupWindowById("msg-deletion-win");
    };

    let inTopPartButtonGetLink = document.createElement("img");
    topPart.appendChild(inTopPartButtonGetLink);
    inTopPartButtonGetLink.className = "message-box-button";
    inTopPartButtonGetLink.src = "/assets/img/link.svg";
    inTopPartButtonGetLink.onclick = (ev) => {
        if (ev.button !== 0)
            return;
        let URI = window.location.host + "/chat/" + openedchat.nickname + "/m/" + String(ID);
        document.getElementById("message-input").innerText += (" " + URI + "");
        console.log("Tried to get link on message " + ID);
    };


    let msgPart = document.createElement("p");
    box.appendChild(msgPart);
    msgPart.className = "message-box-msg";
    if (messageSt.exists){
        if (messageSt.isSystem)
            msgPart.innerText = decodeSystemMessage(messageSt.text);
        else
            msgPart.innerText = messageSt.text;
    } else
        msgPart.innerText = msgErased;
    return box;
}

function makeVisible(msgId){
    let box = convertMessageStToBox(loadedMessages.get(msgId));
    const chatWin = document.getElementById("chat-widget");
    chatWin.appendChild(box);
    visibleMessages.set(msgId, box);
}

function opaNewMessageSt(messageSt){
    let msgId = messageSt.id;
    if (loadedMessages.has(msgId)){
        loadedMessages.set(msgId, messageSt);
        if (visibleMessages.has(msgId)){
            updateMessageBox(msgId, visibleMessages.get(msgId), messageSt);
        }
    } else {
        loadedMessages.set(msgId, messageSt);
        if (anchoredMsg < 0){
            anchoredMsg = msgId;
            visibleMsgSegStart = msgId;
            visibleMsgSegEnd = msgId;
            makeVisible(msgId);
        } else if (msgId + 1 === visibleMsgSegStart) {
            visibleMsgSegStart--;
            makeVisible(msgId);
            while (loadedMessages.has(visibleMsgSegStart - 1)){
                visibleMsgSegStart--;
                makeVisible(visibleMsgSegStart);
            }
        } else if (msgId - 1 === visibleMsgSegEnd){
            visibleMsgSegEnd++;
            makeVisible(msgId);
            while (loadedMessages.has(visibleMsgSegEnd + 1)){
                visibleMsgSegEnd++;
                makeVisible(visibleMsgSegEnd);
            }
        }
    }
}

function canISendMessages(){
    return myRoleHere === userChatRoleRegular || myRoleHere === userChatRoleAdmin;
}

function updateLocalStateFromChatUpdRespBlind(chatUpdResp){
    LocalHistoryId = chatUpdResp.HistoryId;
    for (let memberSt of chatUpdResp.members){
        let id = memberSt.userId;
        if (id === userinfo.uid && myRoleHere !== memberSt.roleHere) {
            myRoleHere = memberSt.roleHere;
            for (let [msgId, box] of visibleMessages){
                updateMessageBox(msgId, loadedMessages.get(msgId), box);
            }
            document.getElementById("message-input").style.display = (canISendMessages() ? "block" : "none");
        }
    }
    for (let memberSt of chatUpdResp.members){
        let id = memberSt.userId;
        members.set(id, memberSt);
    }
    lastMsgId = chatUpdResp.lastMsgId;
    for (let messageSt of chatUpdResp.messages){
        opaNewMessageSt(messageSt);
    }
    updateOffsets();
}

function updateLocalStateFromRecvBlind(Recv){
    updateLocalStateFromChatUpdRespBlind(Recv.chatUpdResp);
}

async function requestMessageNeighbours(fromMsg, direction){
    let Sent = genSentBaseGMN();
    Sent.msgId = fromMsg;
    Sent.direction = direction;
    let Recv = await apiRequest("getMessageNeighbours", Sent);
    updateLocalStateFromRecvBlind(Recv);  // Blind to non-loaded whitespaces
}

function needToLoadWhitespace(){
    let winTop = document.getElementById("chat-widget").offsetHeight;
    if (anchoredMsg === -1){
        if (lastMsgId >= 0)
            console.log("NEEDED 1", anchoredMsg, lastMsgId);
        return lastMsgId >= 0;
    } else if (highestPoint < winTop + softZoneSz && visibleMsgSegStart > 0){
        console.log("NEEDED 2", visibleMsgSegStart);
        return true;
    } else if (lowestPoint > 0 - softZoneSz && visibleMsgSegEnd < lastMsgId){
        console.log("NEEDED 3");
        return true;
    }
    return false;
}

async function tryLoadWhitespace(){
    let winTop = document.getElementById("chat-widget").offsetHeight;
    console.log(anchoredMsg, lastMsgId);
    if (anchoredMsg === -1){
        if (lastMsgId !== -1){
            await requestMessageNeighbours(-1, "backward");
        }
    } else if (highestPoint < winTop + softZoneSz && visibleMsgSegStart > 0){
        await requestMessageNeighbours(visibleMsgSegStart, "backward");
    } else if (lowestPoint > 0 - softZoneSz && visibleMsgSegEnd < lastMsgId){
        await requestMessageNeighbours(visibleMsgSegEnd, "forward");
    }
}

async function loadWhitespaceMultitry(){
    if (needToLoadWhitespace()){
        cancelMainloopTimeout();
        do {
            console.trace();
            console.log("Normalnie ludi ne spyat");
            try {
                await tryLoadWhitespace();
                await sleep(100);
            } catch (e) {
                console.error(e);
                await sleep(1500);
            }
        } while (needToLoadWhitespace());
        setMainloopTimeout();
    }
}

async function updateLocalStateFromRecv(Recv){
    updateLocalStateFromRecvBlind(Recv);
    await loadWhitespaceMultitry();
}

async function safeApiRequestWithLocalStUpdate(type, Sent, errMsg){
    try {
        let Recv = await apiRequest(type, Sent)
        await updateLocalStateFromRecv(Recv);
    } catch(e) {
        console.error(e);
        alert(errMsg);
    }
}

function configureMsgDeletionPopupButtons(){
    document.getElementById("msg-deletion-yes").onclick = function(ev){
        if (ev.button !== 0)
            return;
        deactivateActivePopup();
        let Sent = genSentBase();
        Sent.id = storeHiddenMsgIdForDeletionWin;
        safeApiRequestWithLocalStUpdate("deleteMessage", Sent, "Failed to delete message");
    };

    document.getElementById("msg-deletion-no").onclick = function (ev){
        if (ev.button !== 0)
            return;
        deactivateActivePopup();
    }
}

__mainloopDelayMs = 1000;
async function UPDATE(){
    let Recv = await apiRequest("chatPollEvents", genSentBase());
    await updateLocalStateFromRecv(Recv);
}
// __guestMainloopPollerAction = UPDATE();

window.onload = function (){
    console.log("Page was loaded");

    document.body.addEventListener("wheel", function (event) {
        // event.preventDefault();
        bumpedAtTheBottom = false;
        offsetOfAnchor += event.deltaY / 3;
        updateOffsets();
        loadWhitespaceMultitry().then(dopDopYesYes);
    });

    document.getElementById("message-input").addEventListener("keyup", function (event) {
        if (event.ctrlKey && event.key === 'Enter'){
            let textarea = document.getElementById("message-input");
            let text = String(textarea.innerText);
            console.log(text);
            textarea.innerText = "";
            let Sent = genSentBase();
            Sent.content = {};
            Sent.content.text = text;
            safeApiRequestWithLocalStUpdate("sendMessage", Sent, "Failed to send message");
        }
    });

    let chatWg = document.getElementById("chat-widget");
    let chatWgDebugLinesFnc = function (){
        let H = chatWg.offsetHeight;
        document.getElementById("debug-line-lowest").style.bottom = String(-softZoneSz) + "px";
        document.getElementById("debug-line-highest").style.bottom = String(H + softZoneSz) + "px";
    };
    window.addEventListener("resize", chatWgDebugLinesFnc);
    chatWgDebugLinesFnc();

    configureMsgDeletionPopupButtons();

    updateLocalStateFromChatUpdRespBlind(initial_chatUpdResp);

    setMainloopTimeout();

    loadWhitespaceMultitry();
}