UrlShortener.cs

/*
```c#
Input:

    {
        // [Required] The url you wish to have a short version for
        "url": "https://docs.microsoft.com/en-ca/azure/azure-functions/functions-create-your-first-function-visual-studio",

        // [Optional] Title of the page, or text description of your choice.
        "title": "Quickstart: Create your first function in Azure using Visual Studio"

        // [Optional] the end of the URL. If nothing one will be generated for you.
        "vanity": "azFunc"
    }

Output:
    {
        "ShortUrl": "http://c5m.ca/azFunc",
        "LongUrl": "https://docs.microsoft.com/en-ca/azure/azure-functions/functions-create-your-first-function-visual-studio"
    }
*/

using System;
using System.IO;
using System.Net;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using Cloud5mins.domain;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Http;
using Microsoft.Extensions.Logging;

namespace Cloud5mins.Function
{

	public class UrlShortener
	{
		private readonly ILogger _logger;
		//private readonly AdminApiSettings _adminApiSettings;
		private readonly ShortenerSettings _shortenerSettings;


		public UrlShortener(ILoggerFactory loggerFactory, ShortenerSettings shortenerSettings)
		{
			_logger = loggerFactory.CreateLogger<UrlShortener>();
			_shortenerSettings = shortenerSettings;
		}

		[Function("UrlShortener")]
		public async Task<HttpResponseData> Run(
		[HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)] HttpRequestData req,
			ExecutionContext context
		)
		{
			_logger.LogInformation($"__trace creating shortURL: {req}");
			string userId = string.Empty;
			ShortRequest input;
			var result = new ShortResponse();

			try
			{
				//var invalidCode = ClaimsUtility.CatchUnauthorize(req, _logger);
				//if (invalidCode != HttpStatusCode.Continue)
				//{
				//	return req.CreateResponse(invalidCode);
				//}

				// Validation of the inputs
				if (req == null)
				{
					return req.CreateResponse(HttpStatusCode.NotFound);
				}

				using (var reader = new StreamReader(req.Body))
				{
					var strBody = reader.ReadToEnd();
					input = JsonSerializer.Deserialize<ShortRequest>(strBody, new JsonSerializerOptions { PropertyNameCaseInsensitive = true });
					if (input == null)
					{
						return req.CreateResponse(HttpStatusCode.NotFound);
					}
				}

				// If the Url parameter only contains whitespaces or is empty return with BadRequest.
				if (string.IsNullOrWhiteSpace(input.Url))
				{
					var badResponse = req.CreateResponse(HttpStatusCode.BadRequest);
					await badResponse.WriteAsJsonAsync(new { Message = "The url parameter can not be empty." });
					return badResponse;
				}

				// Validates if input.url is a valid aboslute url, aka is a complete refrence to the resource, ex: http(s)://google.com
				if (!Uri.IsWellFormedUriString(input.Url, UriKind.Absolute))
				{
					var badResponse = req.CreateResponse(HttpStatusCode.BadRequest);
					await badResponse.WriteAsJsonAsync(new { Message = $"{input.Url} is not a valid absolute Url. The Url parameter must start with 'http://' or 'http://'." });
					return badResponse;
				}

				StorageTableHelper stgHelper = new StorageTableHelper(_shortenerSettings.UlsDataStorage);

				string longUrl = input.Url.Trim();
				string vanity = string.IsNullOrWhiteSpace(input.Vanity) ? "" : input.Vanity.Trim();
				string title = string.IsNullOrWhiteSpace(input.Title) ? "" : input.Title.Trim();


				ShortUrlEntity newRow;

				if (!string.IsNullOrEmpty(vanity))
				{
					newRow = new ShortUrlEntity(longUrl, vanity, title, input.Schedules);
					if (await stgHelper.IfShortUrlEntityExist(newRow))
					{
						var badResponse = req.CreateResponse(HttpStatusCode.Conflict);
						await badResponse.WriteAsJsonAsync(new { Message = "This Short URL already exist." });
						return badResponse;
					}
				}
				else
				{
					newRow = new ShortUrlEntity(longUrl, await Utility.GetValidEndUrl(vanity, stgHelper), title, input.Schedules);
				}

				await stgHelper.SaveShortUrlEntity(newRow);

				var host = "oneholt.io";// string.IsNullOrEmpty(_adminApiSettings.customDomain) ? req.Url.Host : _adminApiSettings.customDomain.ToString();
				result = new ShortResponse(host, newRow.Url, newRow.RowKey, newRow.Title);

				_logger.LogInformation("Short Url created.");
			}
			catch (Exception ex)
			{
				_logger.LogError(ex, "An unexpected error was encountered.");

				var badResponse = req.CreateResponse(HttpStatusCode.BadRequest);
				await badResponse.WriteAsJsonAsync(new { Message = ex.Message });
				return badResponse;
			}

			var response = req.CreateResponse(HttpStatusCode.OK);
			await response.WriteAsJsonAsync(result);

			return response;
		}
	}
}