import Imap, { ImapMessageAttributes, Box } from "imap";
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.syncMail(this.box.uidnext, this.box.uidnext + numNewMsgs);
                } 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();
            });
        });
    }

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

    async initSync(box: Box) {
        // sync mail only if has new messages
        if (this.box.uidnext < box.uidnext) {
            this.syncMail(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 (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(box.highestmodseq);
    }

    async syncMail(savedUid: number, currentUid: number) {
        this.syncing = true;
        const promises: Promise<unknown>[] = [];
        const mails: Attrs[] = [];
        logger.log(`Syncing from ${savedUid} to ${currentUid} uid`);
        const f = this.imap.seq.fetch(`${savedUid}:${currentUid}`, {
            size: true,
            envelope: true,
        });

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

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

        f.once("end", async () => {
            let step = 20;
            for (let i = 0; i < promises.length; i += step) {
                for (let j = i; j < (i + step && promises.length); j++) {
                    await new Promise((resolve, reject) => {
                        promises[j]
                            .then(async (res: number) => {
                                const register = new RegisterMessageInApp(res, mails[j], this.id);
                                await register.save();
                                resolve("");
                            })
                            .catch((err) => {
                                reject(err);
                            });
                    });
                }
                logger.log(`Saved messages ${i + step > promises.length ? promises.length : i + step}/${mails.length}`);
                updateMailbox(this.id, mails[i].uid);
            }
            updateMailbox(this.id, currentUid);
            this.syncing = false;

            // 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;
                this.syncMail(currentUid, this.box.uidnext);
            }
        });
    }

    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();
                }
            });
        });
    }
}