const { WEATHER_FIELDS, hasValue } = require("../constants");
const { createInfluxProvider } = require("./influxdb");
const { createOpenMeteoProvider } = require("./open-meteo");

function mergeWeather(target, addition, providerName) {
    let added = false;

    for (const field of WEATHER_FIELDS) {
        if (!hasValue(addition[field])) continue;
        if (hasValue(target[field])) continue;

        target[field] = addition[field];
        added = true;
    }

    if (added) {
        const existing = target.source || [];
        const nextSources = Array.from(new Set([...existing, ...(addition.source || [providerName])].filter(Boolean)));
        target.source = nextSources;
    }

    return added;
}

function buildProviders(config) {
    const providers = [];
    const influx = createInfluxProvider(config.providers?.influxdb, config);
    const openMeteo = createOpenMeteoProvider(config.providers?.openMeteo, config);

    if (influx) providers.push(influx);
    if (openMeteo) providers.push(openMeteo);

    return providers;
}

async function fetchWeather(targetDateTime, config) {
    const providers = buildProviders(config);
    const weather = {};

    for (const provider of providers) {
        const result = await provider.fetch({ target: targetDateTime });

        if (!result) continue;

        mergeWeather(weather, result, provider.name);

        const complete = WEATHER_FIELDS.every((field) => hasValue(weather[field]));
        if (complete) break;
    }

    return Object.keys(weather).length > 0 ? weather : null;
}

module.exports = {
    fetchWeather,
    hasConfiguredProvider: (config) => buildProviders(config).length > 0,
    mergeWeather,
};