const https = require("https");
const dayjs = require("dayjs");
const utc = require("dayjs/plugin/utc")
let timezone = require("dayjs/plugin/timezone")
dayjs.extend(utc)
dayjs.extend(timezone)
const axios = require("axios");
const { Prometheus } = require("../prometheus");
const { debug, UP, DOWN, PENDING, flipStatus } = require("../../src/util");
const { tcping, ping, checkCertificate } = require("../util-server");
const { R } = require("redbean-node");
const { BeanModel } = require("redbean-node/dist/bean-model");
const { Notification } = require("../notification")

/**
 * status:
 *      0 = DOWN
 *      1 = UP
 *      2 = PENDING
 */
class Monitor extends BeanModel {
    async toJSON() {

        let notificationIDList = {};

        let list = await R.find("monitor_notification", " monitor_id = ? ", [
            this.id,
        ])

        for (let bean of list) {
            notificationIDList[bean.notification_id] = true;
        }

        return {
            id: this.id,
            name: this.name,
            url: this.url,
            hostname: this.hostname,
            port: this.port,
            maxretries: this.maxretries,
            weight: this.weight,
            active: this.active,
            type: this.type,
            interval: this.interval,
            keyword: this.keyword,
            ignoreTls: this.getIgnoreTls(),
            upsideDown: this.isUpsideDown(),
            notificationIDList,
        };
    }

    /**
     * Parse to boolean
     * @returns {boolean}
     */
    getIgnoreTls() {
        return Boolean(this.ignoreTls)
    }

    /**
     * Parse to boolean
     * @returns {boolean}
     */
    isUpsideDown() {
        return Boolean(this.upsideDown);
    }

    start(io) {
        let previousBeat = null;
        let retries = 0;

        let prometheus = new Prometheus(this);

        const beat = async () => {

            if (! previousBeat) {
                previousBeat = await R.findOne("heartbeat", " monitor_id = ? ORDER BY time DESC", [
                    this.id,
                ])
            }

            const isFirstBeat = !previousBeat;

            let bean = R.dispense("heartbeat")
            bean.monitor_id = this.id;
            bean.time = R.isoDateTime(dayjs.utc());
            bean.status = DOWN;

            if (this.isUpsideDown()) {
                bean.status = flipStatus(bean.status);
            }

            // Duration
            if (! isFirstBeat) {
                bean.duration = dayjs(bean.time).diff(dayjs(previousBeat.time), "second");
            } else {
                bean.duration = 0;
            }

            try {
                if (this.type === "http" || this.type === "keyword") {
                    let startTime = dayjs().valueOf();

                    // Use Custom agent to disable session reuse
                    // https://github.com/nodejs/node/issues/3940
                    let res = await axios.get(this.url, {
                        headers: {
                            "User-Agent": "Uptime-Kuma",
                        },
                        httpsAgent: new https.Agent({
                            maxCachedSessions: 0,
                            rejectUnauthorized: ! this.getIgnoreTls(),
                        }),
                    });
                    bean.msg = `${res.status} - ${res.statusText}`
                    bean.ping = dayjs().valueOf() - startTime;

                    // Check certificate if https is used

                    let certInfoStartTime = dayjs().valueOf();
                    if (this.getUrl()?.protocol === "https:") {
                        try {
                            await this.updateTlsInfo(checkCertificate(res));
                        } catch (e) {
                            if (e.message !== "No TLS certificate in response") {
                                console.error(e.message)
                            }
                        }
                    }

                    debug("Cert Info Query Time: " + (dayjs().valueOf() - certInfoStartTime) + "ms")

                    if (this.type === "http") {
                        bean.status = UP;
                    } else {

                        let data = res.data;

                        // Convert to string for object/array
                        if (typeof data !== "string") {
                            data = JSON.stringify(data)
                        }

                        if (data.includes(this.keyword)) {
                            bean.msg += ", keyword is found"
                            bean.status = UP;
                        } else {
                            throw new Error(bean.msg + ", but keyword is not found")
                        }

                    }

                } else if (this.type === "port") {
                    bean.ping = await tcping(this.hostname, this.port);
                    bean.msg = ""
                    bean.status = UP;

                } else if (this.type === "ping") {
                    bean.ping = await ping(this.hostname);
                    bean.msg = ""
                    bean.status = UP;
                }

                if (this.isUpsideDown()) {
                    bean.status = flipStatus(bean.status);

                    if (bean.status === DOWN) {
                        throw new Error("Flip UP to DOWN");
                    }
                }

                retries = 0;

            } catch (error) {

                bean.msg = error.message;

                // If UP come in here, it must be upside down mode
                // Just reset the retries
                if (this.isUpsideDown() && bean.status === UP) {
                    retries = 0;

                } else if ((this.maxretries > 0) && (retries < this.maxretries)) {
                    retries++;
                    bean.status = PENDING;
                }
            }

            // * ? -> ANY STATUS = important [isFirstBeat]
            // UP -> PENDING = not important
            // * UP -> DOWN = important
            // UP -> UP = not important
            // PENDING -> PENDING = not important
            // * PENDING -> DOWN = important
            // PENDING -> UP = not important
            // DOWN -> PENDING = this case not exists
            // DOWN -> DOWN = not important
            // * DOWN -> UP = important
            let isImportant = isFirstBeat ||
                (previousBeat.status === UP && bean.status === DOWN) ||
                (previousBeat.status === DOWN && bean.status === UP) ||
                (previousBeat.status === PENDING && bean.status === DOWN);

            // Mark as important if status changed, ignore pending pings,
            // Don't notify if disrupted changes to up
            if (isImportant) {
                bean.important = true;

                // Send only if the first beat is DOWN
                if (!isFirstBeat || bean.status === DOWN) {
                    let notificationList = await R.getAll("SELECT notification.* FROM notification, monitor_notification WHERE monitor_id = ? AND monitor_notification.notification_id = notification.id ", [
                        this.id,
                    ])

                    let text;
                    if (bean.status === UP) {
                        text = "✅ Up"
                    } else {
                        text = "🔴 Down"
                    }

                    let msg = `[${this.name}] [${text}] ${bean.msg}`;

                    for (let notification of notificationList) {
                        try {
                            await Notification.send(JSON.parse(notification.config), msg, await this.toJSON(), bean.toJSON())
                        } catch (e) {
                            console.error("Cannot send notification to " + notification.name)
                        }
                    }
                }

            } else {
                bean.important = false;
            }

            if (bean.status === UP) {
                console.info(`Monitor #${this.id} '${this.name}': Successful Response: ${bean.ping} ms | Interval: ${this.interval} seconds | Type: ${this.type}`)
            } else if (bean.status === PENDING) {
                console.warn(`Monitor #${this.id} '${this.name}': Pending: ${bean.msg} | Max retries: ${this.maxretries} | Type: ${this.type}`)
            } else {
                console.warn(`Monitor #${this.id} '${this.name}': Failing: ${bean.msg} | Type: ${this.type}`)
            }

            prometheus.update(bean)

            io.to(this.user_id).emit("heartbeat", bean.toJSON());

            await R.store(bean)
            Monitor.sendStats(io, this.id, this.user_id)

            previousBeat = bean;
        }

        beat();
        this.heartbeatInterval = setInterval(beat, this.interval * 1000);
    }

    stop() {
        clearInterval(this.heartbeatInterval)
    }

    /**
     * Helper Method:
     * returns URL object for further usage
     * returns null if url is invalid
     * @returns {null|URL}
     */
    getUrl() {
        try {
            return new URL(this.url);
        } catch (_) {
            return null;
        }
    }

    /**
     * Store TLS info to database
     * @param checkCertificateResult
     * @returns {Promise<void>}
     */
    async updateTlsInfo(checkCertificateResult) {
        let tls_info_bean = await R.findOne("monitor_tls_info", "monitor_id = ?", [
            this.id,
        ]);
        if (tls_info_bean == null) {
            tls_info_bean = R.dispense("monitor_tls_info");
            tls_info_bean.monitor_id = this.id;
        }
        tls_info_bean.info_json = JSON.stringify(checkCertificateResult);
        await R.store(tls_info_bean);
    }

    static async sendStats(io, monitorID, userID) {
        Monitor.sendAvgPing(24, io, monitorID, userID);
        Monitor.sendUptime(24, io, monitorID, userID);
        Monitor.sendUptime(24 * 30, io, monitorID, userID);
        Monitor.sendCertInfo(io, monitorID, userID);
    }

    /**
     *
     * @param duration : int Hours
     */
    static async sendAvgPing(duration, io, monitorID, userID) {
        let avgPing = parseInt(await R.getCell(`
            SELECT AVG(ping)
            FROM heartbeat
            WHERE time > DATETIME('now', ? || ' hours')
            AND ping IS NOT NULL
            AND monitor_id = ? `, [
            -duration,
            monitorID,
        ]));

        io.to(userID).emit("avgPing", monitorID, avgPing);
    }

    static async sendCertInfo(io, monitorID, userID) {
        let tls_info = await R.findOne("monitor_tls_info", "monitor_id = ?", [
            monitorID,
        ]);
        if (tls_info != null) {
            io.to(userID).emit("certInfo", monitorID, tls_info.info_json);
        }
    }

    /**
     * Uptime with calculation
     * Calculation based on:
     * https://www.uptrends.com/support/kb/reporting/calculation-of-uptime-and-downtime
     * @param duration : int Hours
     */
    static async sendUptime(duration, io, monitorID, userID) {
        let sec = duration * 3600;

        let heartbeatList = await R.getAll(`
            SELECT duration, time, status
            FROM heartbeat
            WHERE time > DATETIME('now', ? || ' hours')
            AND monitor_id = ? `, [
            -duration,
            monitorID,
        ]);

        let downtime = 0;
        let total = 0;
        let uptime;

        // Special handle for the first heartbeat only
        if (heartbeatList.length === 1) {

            if (heartbeatList[0].status === 1) {
                uptime = 1;
            } else {
                uptime = 0;
            }

        } else {
            for (let row of heartbeatList) {
                let value = parseInt(row.duration)
                let time = row.time

                // Handle if heartbeat duration longer than the target duration
                // e.g.   Heartbeat duration = 28hrs, but target duration = 24hrs
                if (value > sec) {
                    let trim = dayjs.utc().diff(dayjs(time), "second");
                    value = sec - trim;

                    if (value < 0) {
                        value = 0;
                    }
                }

                total += value;
                if (row.status === 0 || row.status === 2) {
                    downtime += value;
                }
            }

            uptime = (total - downtime) / total;

            if (uptime < 0) {
                uptime = 0;
            }
        }

        io.to(userID).emit("uptime", monitorID, duration, uptime);
    }
}

module.exports = Monitor;