dow/server/src/app/services/weather.ts

import { service } from '../service'
import { ForecastData, TimeseriesData } from './weather/types'

type WeatherItem = DetailedWeatherItem | SummaryWeatherItem

interface SummaryWeatherItem {
	date: string
	temperature: { min: number; max: number }
	summary: null | string
	precipitationAmount: number
}

interface DetailedWeatherItem {
	date: string

	summary: null | string
	precipitationAmount: null | number

	temperature: number

	windDirection: number
	windSpeed: number

	relativeHumidity: number

	airPressure: number
}

const API_URL = 'https://api.met.no/weatherapi'
const API_USER_AGENT = 'KamenWatch 1.0 jan@zipek.cz'

const API_PARAMS = {
	lat: '50.070219',
	lon: '14.414034',
}

const getSummaryItem = (date: string, item: TimeseriesData) => {
	if (item.next_6_hours) {
		return {
			date,
			temperature: {
				min: item.next_6_hours.details.air_temperature_min,
				max: item.next_6_hours.details.air_temperature_max,
			},
			summary: item.next_6_hours.summary.symbol_code,
			precipitationAmount: item.next_6_hours.details.precipitation_amount,
		} as SummaryWeatherItem
	}
}

const getDetailedItem = (date: string, item: TimeseriesData) => {
	const detail = item.instant?.details

	if (!detail) {
		return
	}

	const result: DetailedWeatherItem = {
		date,
		temperature: detail.air_temperature,
		airPressure: detail.air_pressure_at_sea_level,
		relativeHumidity: detail.relative_humidity,
		windDirection: detail.wind_from_direction,
		windSpeed: detail.wind_speed,
		precipitationAmount: null,
		summary: null,
	}

	if (item.next_1_hours) {
		result.summary = item.next_1_hours.summary.symbol_code
		result.precipitationAmount = item.next_1_hours.details.precipitation_amount
	} else if (item.next_6_hours) {
		result.summary = item.next_6_hours.summary.symbol_code
	} else if (item.next_12_hours) {
		result.summary = item.next_12_hours.summary.symbol_code
	}

	return result
}

export const weatherService = service(({ fetch }) => {
	return async () => {
		const forecast: ForecastData = JSON.parse(
			await fetch(
				`${API_URL}/locationforecast/2.0/complete?lat=${API_PARAMS.lat}&lon=${API_PARAMS.lon}`,
				{
					headers: {
						'User-agent': API_USER_AGENT,
					},
				},
			),
		)

		const result = {
			now: null as WeatherItem | null,
			hours: {} as Record<number, WeatherItem>,
			days: {} as Record<number, WeatherItem>,
		}

		let recordedHours = 0
		const nowDays = Math.floor(Date.now() / 1000 / 3600 / 24)
		const nowHours = Math.floor(Date.now() / 1000 / 3600)

		forecast.properties.timeseries.forEach((item, index) => {
			const date = new Date(item['time'])
			const converted = getDetailedItem(item.time, item.data)

			if (!converted) {
				return
			}

			if (index === 0) {
				result.now = converted
			}

			if (date.getHours() === 14) {
				const dayData = getSummaryItem(item.time, item.data)

				if (dayData) {
					const daysDiff =
						Math.floor(date.getTime() / 1000 / 3600 / 24) - nowDays

					result.days[daysDiff] = dayData
				}
			}

			if (recordedHours < 23) {
				const hoursDiff = Math.floor(date.getTime() / 1000 / 3600) - nowHours

				result.hours[hoursDiff] = converted
				recordedHours += 1
			}
		})

		return result
	}
})