const PrometheusClient = require("prom-client");
const { log } = require("../src/util");

const commonLabels = [
    "monitor_name",
    "monitor_type",
    "monitor_url",
    "monitor_hostname",
    "monitor_port",
    "monitor_tags"
];

const monitorCertDaysRemaining = new PrometheusClient.Gauge({
    name: "monitor_cert_days_remaining",
    help: "The number of days remaining until the certificate expires",
    labelNames: commonLabels
});

const monitorCertIsValid = new PrometheusClient.Gauge({
    name: "monitor_cert_is_valid",
    help: "Is the certificate still valid? (1 = Yes, 0= No)",
    labelNames: commonLabels
});
const monitorResponseTime = new PrometheusClient.Gauge({
    name: "monitor_response_time",
    help: "Monitor Response Time (ms)",
    labelNames: commonLabels
});

const monitorStatus = new PrometheusClient.Gauge({
    name: "monitor_status",
    help: "Monitor Status (1 = UP, 0= DOWN, 2= PENDING, 3= MAINTENANCE)",
    labelNames: commonLabels
});

class Prometheus {
    monitorLabelValues = {};

    /**
     * @param {object} monitor Monitor object to monitor
     * @param {Array<{name:string,value:?string}>} tags Tags to add to the monitor
     */
    constructor(monitor, tags) {
        let filteredValidAsciiTags = this.filterValidAsciiTags(tags);

        if (filteredValidAsciiTags.length <= 0) {
            filteredValidAsciiTags = "null";
        }

        this.monitorLabelValues = {
            monitor_name: monitor.name,
            monitor_type: monitor.type,
            monitor_url: monitor.url,
            monitor_hostname: monitor.hostname,
            monitor_port: monitor.port,
            monitor_tags: filteredValidAsciiTags
        };
    }

    /**
     * Filter tags to remove the ones that contain non-ASCII characters
     * See https://github.com/louislam/uptime-kuma/pull/4704#issuecomment-2366524692
     * @param {Array<{name: string, value:?string}>} tags The tags to filter
     * @returns {string[]} The filtered tags
     */
    filterValidAsciiTags(tags) {
        const asciiRegex = /^[a-zA-Z_][a-zA-Z0-9_]*$/;
        return tags.reduce((filteredTags, tag) => {
            if (asciiRegex.test(tag.name)) {
                if (tag.value !== "" && asciiRegex.test(tag.value)) {
                    filteredTags.push(`${tag.name}:${tag.value}`);
                } else {
                    filteredTags.push(tag.name);
                }
            }
            return filteredTags;
        }, []);
    }

    /**
     * Update the metrics page
     * @param {object} heartbeat Heartbeat details
     * @param {object} tlsInfo TLS details
     * @returns {void}
     */
    update(heartbeat, tlsInfo) {
        if (typeof tlsInfo !== "undefined") {
            try {
                let isValid;
                if (tlsInfo.valid === true) {
                    isValid = 1;
                } else {
                    isValid = 0;
                }
                monitorCertIsValid.set(this.monitorLabelValues, isValid);
            } catch (e) {
                log.error("prometheus", "Caught error");
                log.error("prometheus", e);
            }

            try {
                if (tlsInfo.certInfo != null) {
                    monitorCertDaysRemaining.set(this.monitorLabelValues, tlsInfo.certInfo.daysRemaining);
                }
            } catch (e) {
                log.error("prometheus", "Caught error");
                log.error("prometheus", e);
            }
        }

        if (heartbeat) {
            try {
                monitorStatus.set(this.monitorLabelValues, heartbeat.status);
            } catch (e) {
                log.error("prometheus", "Caught error");
                log.error("prometheus", e);
            }

            try {
                if (typeof heartbeat.ping === "number") {
                    monitorResponseTime.set(this.monitorLabelValues, heartbeat.ping);
                } else {
                    // Is it good?
                    monitorResponseTime.set(this.monitorLabelValues, -1);
                }
            } catch (e) {
                log.error("prometheus", "Caught error");
                log.error("prometheus", e);
            }
        }
    }

    /**
     * Remove monitor from prometheus
     * @returns {void}
     */
    remove() {
        try {
            monitorCertDaysRemaining.remove(this.monitorLabelValues);
            monitorCertIsValid.remove(this.monitorLabelValues);
            monitorResponseTime.remove(this.monitorLabelValues);
            monitorStatus.remove(this.monitorLabelValues);
        } catch (e) {
            console.error(e);
        }
    }
}

module.exports = {
    Prometheus
};