cityservice.ts

// import { cities } from './cities.ts'
import { DistanceCalculator } from "https://deno.land/x/distancecalculator/distance-calculator.ts"
import { cities } from 'https://deno.land/x/cities/cities.ts'
import { ICityInfo } from "https://deno.land/x/cities/interfaces.ts"


export class CityService {

    private static minimumPopulation = 40000


    public static getCityInfo(countryCode: string, cityName: string): ICityInfo {
        return cities.filter((city) => city.country === countryCode && city.name.toLowerCase() === cityName.toLowerCase())[0]
    }


    public static getCitiesByCountryCode(countryCode: string, minimumPopulation: number = CityService.minimumPopulation, maximumPopulation: number = 10000000000): ICityInfo[] { 

        if (minimumPopulation < CityService.minimumPopulation) {
            throw new Error(`This service includes only cities with at least ${CityService.minimumPopulation} inhabitants`)
        }

        return cities.filter((city) => city.country.toLowerCase() === countryCode.toLowerCase() && city.population >= minimumPopulation && city.population <= maximumPopulation)
    }


    public static getCitiesByPopulation(minimumPopulation: number, maximumPopulation: number = 10000000000): ICityInfo[] {

        if (minimumPopulation < CityService.minimumPopulation) {
            throw new Error(`This service includes only cities with at least ${CityService.minimumPopulation} inhabitants`)
        }

        return cities.filter((city) => city.population >= minimumPopulation && city.population <= maximumPopulation)
    }


    public static getClosestCity(latitude: number, longitude: number, minimumPopulation: number = CityService.minimumPopulation, maximumPopulation: number = 10000000000): ICityInfo {

        if (minimumPopulation < CityService.minimumPopulation) {
            throw new Error(`This service includes only cities with at least ${CityService.minimumPopulation} inhabitants`)
        }

        let cityWithLowestDistance
        let lowestDistance = 10000000000
        for (const city of cities.filter((entry: any) => entry.population >= minimumPopulation && entry.population <= maximumPopulation)){
            const distance = DistanceCalculator.getDistanceInKilometers(latitude, longitude, city.lat, city.lon)
            if (distance < lowestDistance) {
                lowestDistance = distance
                cityWithLowestDistance = city
            }
        }
        
        return cityWithLowestDistance as ICityInfo
    }
}