samples-js/functions/weatherMonitor.js

const { output } = require("@azure/functions");
const df = require("durable-functions");
const { DateTime } = require("luxon");
const axios = require("axios").default;

const clearWeatherConditions = ["clear sky", "few clouds", "scattered clouds", "broken clouds"];

const getIsClearActivity = "getIsClear";
const sendGoodWeatherAlertActivity = "sendGoodWeatherAlert";

df.app.orchestration("weatherMonitor", function* (context) {
    // get input
    const input = context.df.getInput();
    context.log(`Received monitor request. Location: ${input.location}. Phone: ${input.phone}`);
    verifyRequest(input);

    // set expiry time to 6 hours from now
    const endTime = DateTime.fromJSDate(context.df.currentUtcDateTime).plus({ hours: 6 });
    const locationString = `${input.location.city}${
        input.location.state ? `, ${input.location.state}` : ""
    }, ${input.location.country}`;
    context.log(`Instantiating monitor for ${locationString}. Expires: ${endTime.toString()}.`);

    // until the expiry time
    while (DateTime.fromJSDate(context.df.currentUtcDateTime) < endTime) {
        // Check the weather
        context.log(
            `Checking current weather conditions for ${locationString} at ${context.df.currentUtcDateTime}.`
        );
        const isClear = yield context.df.callActivity(getIsClearActivity, input.location);

        if (isClear) {
            // It's not raining! Or snowing. Or misting. Tell our user to take advantage of it.
            context.log(`Detected clear weather for ${locationString}. Notifying ${input.phone}.`);
            yield context.df.callActivity(sendGoodWeatherAlertActivity, input.phone);
            break;
        } else {
            // Wait for the next checkpoint
            const nextCheckpoint = DateTime.fromJSDate(context.df.currentUtcDateTime).plus({
                seconds: 30,
            });

            context.log(`Next check for ${locationString} at ${nextCheckpoint.toString()}`);

            yield context.df.createTimer(nextCheckpoint.toJSDate());
        }
    }

    context.log("Monitor expiring.");
});

function verifyRequest(request) {
    if (!request) {
        throw new Error("An input object is required.");
    }
    if (!request.location) {
        throw new Error("A location input is required.");
    }
    if (!request.location.city) {
        throw new Error("A city is required on the location input.");
    }
    if (!request.location.country) {
        throw new Error("A country code is required on location input.");
    }
    if (
        (request.location.country === "USA" || request.location.country === "US") &&
        !request.location.state
    ) {
        throw new Error("A state code is required on location input for US locations.");
    }
    if (!request.phone) {
        throw new Error("A phone number input is required.");
    }
}

df.app.activity(getIsClearActivity, {
    handler: async function (location, context) {
        try {
            // get current conditions from OpenWeatherMap API
            const currentConditions = await getCurrentConditions(location);
            // compare against known clear conditions
            return clearWeatherConditions.includes(currentConditions.description);
        } catch (err) {
            context.log(`${getIsClearActivity} encountered an error: ${err}`);
            throw err;
        }
    },
});

async function getCurrentConditions(location) {
    try {
        // get current conditions from OpenWeatherMap API
        const url = location.state
            ? `https://api.openweathermap.org/data/2.5/weather?q=${location.city},${location.state},${location.country}&appid=${process.env.OpenWeatherMapApiKey}`
            : `https://api.openweathermap.org/data/2.5/weather?q=${location.city},${location.country}&appid=${process.env.OpenWeatherMapApiKey}`;

        const response = await axios.get(url);
        return response.data.weather[0];
    } catch (err) {
        throw err;
    }
}

// configure twilio output
const twilioOutput = output.generic({
    type: "twilioSms",
    from: "%TwilioPhoneNumber%",
    accountSidSetting: "TwilioAccountSid",
    authTokenSetting: "TwilioAuthToken",
});

df.app.activity(sendGoodWeatherAlertActivity, {
    extraOutputs: [twilioOutput], // register twilio output
    handler: function (phoneNumber, context) {
        // send message to phone number
        context.extraOutputs.set(twilioOutput, {
            body: "The weather's clear outside! Go talk a walk!",
            to: phoneNumber,
        });
    },
});