serman/front/DAL/systemInfo.ts

import $ from "jquery"
import { SystemInfoDescription, SystemInfo as ModelSystemInfo, HostnameLiveSystemInfoDescription } from "../../src/models/systemInfo";
import { HostnameServiceDescription } from "../../src/models/service";

export interface TimedLiveSystemInfo {
    time: Date;
    data: HostnameLiveSystemInfoDescription;
}

export namespace DAL {
    export class SystemInfo {
        private static lastCachedData: SystemInfoDescription|null = null;
        private static liveData: TimedLiveSystemInfo[] = [];
        private static liveHandler: ReturnType<typeof setTimeout>|boolean = false;

        private static getData(): Promise<void> {
            return new Promise(ok => {
                $.get("/api/sysinfo", response => {
                    this.lastCachedData = response;
                    ok();
                });
            });
        }

        private static getDataWithCache(): Promise<void> {
            if (this.lastCachedData)
                return Promise.resolve();
            return this.getData();
        }

        public static async getInfo(hostname: string): Promise<ModelSystemInfo|undefined> {
            await this.getDataWithCache();
            return this.lastCachedData?.systemInfo[hostname];
        }

        public static async listHosts(): Promise<Array<string>> {
            await this.getDataWithCache();
            return Object.keys(this.lastCachedData?.systemInfo ?? {});
        }

        private static pushLiveData(data: HostnameLiveSystemInfoDescription): TimedLiveSystemInfo {
            let result: TimedLiveSystemInfo = { data: data, time: new Date() };
            this.liveData.push(result);
            return result;
        }

        private static pollNow(): Promise<TimedLiveSystemInfo> {
            return new Promise(ok => {
                $.get("/api/sysinfo/live", response => {
                    ok(this.pushLiveData(response.liveSystemInfo));
                });
            });
        }

        private static async pollTick(): Promise<TimedLiveSystemInfo> {
            let result = await this.pollNow();
            this.liveHandler = setTimeout(this.pollTick.bind(this), 10000);
            return result;
        }

        public static async startLivePolling(): Promise<TimedLiveSystemInfo> {
            if (this.liveHandler !== false)
                return this.liveData[this.liveData.length-1]!;
            this.liveHandler = true;
            await this.getDataWithCache();
            return await this.pollTick();
        }

        public static async getLive(): Promise<TimedLiveSystemInfo> {
            return await this.startLivePolling();
        }

        public static async getServices(): Promise<HostnameServiceDescription> {
            return new Promise(ok => {
                $.get("/api/services/list", response => {
                    ok(response.services);
                });
            });
        }
    }
}