import { App } from "../Server/sifrr.server";
import { HttpRequest, HttpResponse } from "uWebSockets.js";
import { register, collectDefaultMetrics } from "prom-client";

interface IPrometheusValue {
    labels: { [label: string]: string };
    value: number;
}
interface IPrometheusMetric {
    name: string;
    help: string;
    type: string;
    values: Array<IPrometheusValue>;
}
export class PrometheusController {
    constructor(private App: App) {
        collectDefaultMetrics({
            gcDurationBuckets: [0.001, 0.01, 0.1, 1, 2, 5], // These are the default buckets.
        });

        this.App.get("/metrics", this.metrics.bind(this));
        this.App.get("/metrics.json", this.metricsAsJSON.bind(this));
    }

    private metrics(res: HttpResponse, req: HttpRequest): void {
        res.writeHeader("Content-Type", register.contentType);
        res.end(register.metrics());
    }
    private async getAllMetrics() : Promise<IPrometheusMetric[]> {
        return await Promise.all(
            (register.getMetricsAsArray() as any[])
                .map((metric) => metric.get() as Promise<IPrometheusMetric>));
    }
    private metricsAsJSON(res: HttpResponse, req: HttpRequest): void {
        this.getAllMetrics().then((items) => {
            let json : { [key : string] : number | { [label : string] : number } } = {};
            for (const item of items) {
                for (const value of item.values) {
                    if (value.labels && Object.keys(value.labels).length > 0) {
                        const key = Object.keys(value.labels)
                                    .map((label) => label + ':' + value.labels[label]).join('|');
                        const data : { [label : string] : number } = (json[item.name] as { [label : string] : number }) || { };
                        data[key] = value.value;
                        json[item.name] = data;
                    } else {
                        json[item.name] = value.value;
                    }
                }
            }
            res.writeHeader('Content-Type', 'application/json');
            res.end(JSON.stringify(json));
        });
    }
}