TwitterFavoritesReader.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Text;
using System.Threading.Tasks;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Host;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;

namespace TweetWhisperer.Function
{
    public static class TwitterFavoritesReader
    {
        static readonly HttpClient client = new HttpClient();

        [FunctionName("TwitterFavoritesReader")]
        public static async Task Run([TimerTrigger("0 */1 * * * *")]TimerInfo myTimer, ILogger log,
            ExecutionContext context)
        {
            var config = GetConfig(context);
            var token = config["TwitterAccessToken"] ?? await GetToken(config["TwitterKey"], config["TwitterSecret"]);
            var screenName = config["ScreenName"];
            //TODO: ONLY GET last minute of faves
            var uri = $"https://api.twitter.com/1.1/favorites/list.json?count=5&screen_name={screenName}";
            var authHeader = System.Convert.ToBase64String(
                new UTF8Encoding().GetBytes(token));
            try
            {
                client.DefaultRequestHeaders.Add("Authorization", $"Bearer {token}");
            }
            catch (Exception err)
            {
                log.LogError(err, "it happened");
            }
            var favoritesResponse = await client.GetAsync(uri);
            var favesJson = await favoritesResponse.Content.ReadAsStringAsync();
            var faves = JsonConvert.DeserializeObject<List<TwitterFave>>(favesJson);
            await CategorizeThem(config, faves, log);
            log.LogInformation(faves.Count()+" favorites found");
        }

        private static async Task CategorizeThem(IConfigurationRoot config, List<TwitterFave> faves, ILogger log)
        {
            var uri = config["CategorizeThemUrl"];
            var keepItResponse = await client.PostAsJsonAsync(uri, faves);
            var resp = await keepItResponse.Content.ReadAsStringAsync();
            log.LogTrace("Was it kept??? " + resp);
        }

        private static IConfigurationRoot GetConfig(ExecutionContext context)
        {
            var config = new ConfigurationBuilder()
            .SetBasePath(context.FunctionAppDirectory)
            .AddJsonFile("local.settings.json", optional: true, reloadOnChange: true)
            .AddEnvironmentVariables()
            .Build();   
            return config;     
        }

        private static async Task<string> GetToken(string key, string secret)
        {

            var uri = "https://api.twitter.com/oauth2/token";
            var bearerTokenCredentials = $"{key}:{secret}";
            var authHeader = "Basic "+System.Convert.ToBase64String(
                new UTF8Encoding().GetBytes(bearerTokenCredentials));
            client.DefaultRequestHeaders.Add("Authorization", authHeader);

            var nameValuePair = new KeyValuePair<string, string>("grant_type", "client_credentials");
            var encodedContent = new FormUrlEncodedContent(
                new List<KeyValuePair<string, string>>{nameValuePair});
            var result = await client.PostAsync(uri, encodedContent);
            var resultContent = await result.Content.ReadAsStringAsync();
            var e = JsonConvert.DeserializeObject<AccessTokenHolder>(resultContent);

            return e.access_token;
        }
    }

    public class AccessTokenHolder
    {
        public string token_type { get; set; }
        public string access_token { get; set; }
    }
}