Fis-SearchUtility/services/query.service.ts

import * as fs from 'fs'
import { filter, isMatch } from 'lodash'
import { Observable, Subject, interval, map, of } from 'rxjs'

export class queryService {
    private dataFromStorage: Subject<any> = new Subject()
    private filteredResult: Subject<any> = new Subject()

    public query(storageAddress: Storage, ...conditions: Entries[]) : Observable<any> {
        this.loadObsData(storageAddress.address)
        this.filterFromObs(...conditions)
        return this.filteredResult.pipe()
    }

    // Data preparations: Purely Observables
    private loadObsData(location: string) {
        let data = fs.readFileSync(location, 'utf-8')
        let dataJson = JSON.parse(data)
        let count = 0
        const intervalId = setInterval(() => {
            this.dataFromStorage.next(dataJson[count]);
            count++;
            if (count >= 100) {
                clearInterval(intervalId);
                this.dataFromStorage.complete();
            }
        }, 1000)
    }

    // Search and Filter: Pure Observables. To be moved out to become a separate library again.
    private filterFromObs(...conditions: Entries[]) {
        this.dataFromStorage.subscribe({
            next: element => {
                if(isMatch(element, conditions)){
                    // Logic to check if data meets the conditions, if so, put it into result.next{}
                    this.filteredResult.next(element)
                }
            }
        })
    }

}

// Entries that client will use. Subject to be improved later on
export interface Entries {
    _id?: string,
    appLogLocId?: string,
    msgId?: string,
    msgLogDateTime?: Date | string,
    msgDateTime?: Date | string,
    msgTag?: string[],
    msgPayload?: string
}

export interface Storage {
    type: string,
    address: string
}