import Imap, { Box } from "imap";
import { resolve } from "path";
import { getMailbox, getMailboxModseq, updateMailbox, updateMailboxModseq } from "../../db/imap/imap-db";
import { Attrs, AttrsWithEnvelope } from "../../interfaces/mail/attrs.interface";
import logger from "../../system/Logger";
import RegisterMessageInApp from "../message/saveMessage";
import { saveMessage } from "../message/storeMessage";
import updateMessage from "../message/updateMessage";

export interface ImapInfo {
    uid: number;
    modseq: string;
    flags: string[];
}

export default class Mailbox {
    imap: Imap;
    boxName: string;
    id: number;
    box: Box;
    msgToSync: number;
    syncing: boolean;

    constructor(_imap: Imap, _boxId: number, _boxName: string) {
        this.imap = _imap;
        this.boxName = _boxName;
        this.id = _boxId;
        this.box;
        this.msgToSync = 0;
        this.syncing = false;
        this.init();
    }

    async init() {
        // get mailbox from the database
        this.box = (await getMailbox(this.id))[0];
        const isReadOnly = false;
        this.imap.openBox(this.boxName, isReadOnly, (err, box) => {
            if (err) logger.err(err);

            // sync messages and flags
            this.initSync(box);

            // wait for new mails
            this.imap.on("mail", (numNewMsgs: number) => {
                if (!this.syncing) {
                    // if not syncing restart a sync
                    this.syncManager(this.box.uidnext - 1, this.box.uidnext + numNewMsgs - 1);
                } else {
                    // else save number of message to sync latter
                    this.msgToSync += numNewMsgs;
                }
            });

            // wait for flags update
            this.imap.on("update", (seqno: number, info: ImapInfo) => {
                logger.log(`Update message ${info.uid} with ${info.flags}`);
                const updateMsg = new updateMessage(info.uid, info.flags);
                updateMsg.updateFlags();
            });

            this.imap.on("expunge", (seqno: number) => {
                console.log("Message with sequence number " + seqno + " has been deleted from the server.");
            });
        });
    }

    async updateModseq(newModseq: number) {
        updateMailboxModseq(this.id, newModseq).then(() => {
            this.box.highestmodseq = newModseq.toString();
        });
    }

    async initSync(box: Box) {
        // sync mail only if has new messages
        if (this.box.uidnext < box.uidnext) {
            this.syncManager(this.box.uidnext, box.uidnext);
        } else {
            logger.log("Mail already up to date");
        }

        // sync flags
        const lastModseq = (await getMailboxModseq(this.id))[0]?.modseq ?? 0;
        if (parseInt(box.highestmodseq) > lastModseq) {
            const fetchStream = this.imap.fetch("1:*", { bodies: "", modifiers: { changedsince: lastModseq } });
            fetchStream.on("message", (message) => {
                message.once("attributes", (attrs) => {
                    const updateMsg = new updateMessage(attrs.uid, attrs.flags);
                    updateMsg.updateFlags();
                });
            });
            fetchStream.once("error", function (err) {
                logger.err("Fetch error when syncing flags: " + err);
            });
            fetchStream.once("end", function () {
                logger.log("Done fetching new flags");
            });
        } else {
            logger.log("Flags already up to date");
        }
        this.updateModseq(parseInt(box.highestmodseq));
    }

    syncManager = async (savedUid: number, currentUid: number) => {
        this.syncing = true;
        logger.log(`Fetching from ${savedUid} to ${currentUid} uid`);
        const nbMessageToSync = currentUid - savedUid;
        let STEP = nbMessageToSync > 300 ? Math.floor(nbMessageToSync / 7) : nbMessageToSync;
        let mails: AttrsWithEnvelope[] = [];

        for (let i = 0; i < nbMessageToSync; i += STEP) {
            mails = [];
            try {
                // fetch mails
                let secondUid = savedUid + STEP < currentUid ? savedUid + STEP : currentUid;
                await this.mailFetcher(savedUid, secondUid, mails)
                logger.log(`Fetched ${STEP} uids (${mails.length} messages)`);
                // save same in the database
                for (let k = 0; k < mails.length; k++) {
                    try {
                        const messageId = await saveMessage(mails[k], this.id, this.imap);
                        const register = new RegisterMessageInApp(messageId, mails[k], this.id);
                        await register.save();
                    } catch (error) {
                        logger.err("Failed to save a message: " + error);
                    }
                }
                savedUid = secondUid;
                this.box.uidnext += savedUid;

                updateMailbox(this.id, savedUid);
            } catch (error) {
                logger.err("Failed to sync message " + error);
            }
            logger.log(`Saved messages ${i + STEP > nbMessageToSync ? nbMessageToSync : i + STEP}/${nbMessageToSync}`);
        }

        // if has receive new msg during last sync then start a new sync
        if (this.msgToSync > 0) {
            const currentUid = this.box.uidnext;
            this.box.uidnext += this.msgToSync;
            // reset value to allow to detect new incoming message while syncing
            this.msgToSync = 0;
            await this.syncManager(currentUid, this.box.uidnext);
        }
        this.syncing = false;
        logger.log(`Finished syncing messages`);
    };

    async mailFetcher(startUid: number, endUid: number, mails: Attrs[]): Promise<any> {
        return new Promise((resolve, reject) => {
            const f = this.imap.seq.fetch(`${startUid}:${endUid}`, {
                size: true,
                envelope: true,
            });

            f.on("message", (msg, seqno) => {
                msg.once("attributes", (attrs: AttrsWithEnvelope) => {
                    mails.push(attrs);
                });
            });

            f.once("error", (err) => {
                logger.err("Fetch error: " + err);
                reject(1);
            });

            f.once("end", async () => {
                resolve(0);
            });
        });
    }

    addFlag(source: string, flags: string[]): Promise<void> {
        return new Promise((resolve, reject) => {
            this.imap.addFlags(source, flags, (err) => {
                if (err) {
                    reject(err);
                } else {
                    resolve();
                }
            });
        });
    }

    removeFlag(source: string, flags: string[]): Promise<void> {
        return new Promise((resolve, reject) => {
            this.imap.delFlags(source, flags, (err) => {
                if (err) {
                    reject(err);
                } else {
                    resolve();
                }
            });
        });
    }
}