feature: Add webhook url overload for DiscordWebhookClient (#1260)

* Add webhook url overload for DiscordWebhookClient

Adds an overloaded constructor for `DiscordWebhookClient` which accepts the webhook URL. This URL is parsed using a regex for the id and token. If the token is invalid an `ArgumentException` is thrown.

* add null or whitespace check

* add some tests for the new DiscordWebhookClient constructor

* make the Regex static, specify flags

* update regex to look for "discordapp"

* specify reason why exception is thrown despite regex match

* move parsing logic into new function for testing

src/Discord.Net.Webhook/DiscordWebhookClient.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using Discord.Logging;
 using Discord.Rest;
@@ -26,6 +27,12 @@ namespace Discord.Webhook
         /// <summary> Creates a new Webhook Discord client. </summary>
         public DiscordWebhookClient(ulong webhookId, string webhookToken)
             : this(webhookId, webhookToken, new DiscordRestConfig()) { }
+        /// <summary> Creates a new Webhook Discord client. </summary>
+        public DiscordWebhookClient(string webhookUrl)
+            : this(webhookUrl, new DiscordRestConfig()) { }
+
+        // regex pattern to match webhook urls
+        private static Regex WebhookUrlRegex = new Regex(@"^.*discordapp\.com\/api\/webhooks\/([\d]+)\/([a-z0-9_-]+)$", RegexOptions.Compiled | RegexOptions.IgnoreCase);
 
         /// <summary> Creates a new Webhook Discord client. </summary>
         public DiscordWebhookClient(ulong webhookId, string webhookToken, DiscordRestConfig config)
@@ -43,6 +50,21 @@ namespace Discord.Webhook
             _webhookId = Webhook.Id;
         }
 
+        /// <summary>
+        ///     Creates a new Webhook Discord client.
+        /// </summary>
+        /// <param name="webhookUrl">The url of the webhook.</param>
+        /// <param name="config">The configuration options to use for this client.</param>
+        /// <exception cref="ArgumentException">Thrown if the <paramref name="webhookUrl"/> is an invalid format.</exception>
+        /// <exception cref="ArgumentNullException">Thrown if the <paramref name="webhookUrl"/> is null or whitespace.</exception>
+        public DiscordWebhookClient(string webhookUrl, DiscordRestConfig config) : this(config)
+        {
+            string token;
+            ParseWebhookUrl(webhookUrl, out _webhookId, out token);
+            ApiClient.LoginAsync(TokenType.Webhook, token).GetAwaiter().GetResult();
+            Webhook = WebhookClientHelper.GetWebhookAsync(this, _webhookId).GetAwaiter().GetResult();
+        }
+
         private DiscordWebhookClient(DiscordRestConfig config)
         {
             ApiClient = CreateApiClient(config);
@@ -94,5 +116,31 @@ namespace Discord.Webhook
         {
             ApiClient?.Dispose();
         }
+
+        internal static void ParseWebhookUrl(string webhookUrl, out ulong webhookId, out string webhookToken)
+        {
+            if (string.IsNullOrWhiteSpace(webhookUrl))
+                throw new ArgumentNullException(paramName: nameof(webhookUrl), message:
+                    "The given webhook Url cannot be null or whitespace.");
+
+            // thrown when groups are not populated/valid, or when there is no match
+            ArgumentException ex(string reason = null)
+                => new ArgumentException(paramName: nameof(webhookUrl), message:
+                $"The given webhook Url was not in a valid format. {reason}");
+            var match = WebhookUrlRegex.Match(webhookUrl);
+            if (match != null)
+            {
+                // ensure that the first group is a ulong, set the _webhookId
+                // 0th group is always the entire match, so start at index 1
+                if (!(match.Groups[1].Success && ulong.TryParse(match.Groups[1].Value, out webhookId)))
+                    throw ex("The webhook Id could not be parsed.");
+
+                if (!match.Groups[2].Success)
+                    throw ex("The webhook token could not be parsed.");
+                webhookToken = match.Groups[2].Value;
+            }
+            else
+                throw ex();
+        }
     }
 }

test/Discord.Net.Tests/Discord.Net.Tests.csproj

@@ -19,6 +19,7 @@
     <ProjectReference Include="../../src/Discord.Net.Core/Discord.Net.Core.csproj" />
     <ProjectReference Include="../../src/Discord.Net.Rest/Discord.Net.Rest.csproj" />
     <ProjectReference Include="../../src/Discord.Net.Analyzers/Discord.Net.Analyzers.csproj" />
+    <ProjectReference Include="..\..\src\Discord.Net.Webhook\Discord.Net.Webhook.csproj" />
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Akavache" Version="6.0.31" />

test/Discord.Net.Tests/Tests.DiscordWebhookClient.cs

@@ -0,0 +1,60 @@
+using Discord.Webhook;
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Xunit;
+
+namespace Discord
+{
+    /// <summary>
+    ///     Tests the <see cref="DiscordWebhookClient.ParseWebhookUrl(string, out ulong, out string)"/> function.
+    /// </summary>
+    public class DiscordWebhookClientTests
+    {
+        [Theory]
+        [InlineData("https://discordapp.com/api/webhooks/123412347732897802/_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK",
+            123412347732897802, "_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK")]
+        // ptb, canary, etc will have slightly different urls
+        [InlineData("https://ptb.discordapp.com/api/webhooks/123412347732897802/_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK",
+            123412347732897802, "_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK")]
+        [InlineData("https://canary.discordapp.com/api/webhooks/123412347732897802/_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK",
+            123412347732897802, "_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK")]
+        // don't care about https
+        [InlineData("http://canary.discordapp.com/api/webhooks/123412347732897802/_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK",
+            123412347732897802, "_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK")]
+        // this is the minimum that the regex cares about
+        [InlineData("discordapp.com/api/webhooks/123412347732897802/_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK",
+            123412347732897802, "_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK")]
+        public void TestWebhook_Valid(string webhookurl, ulong expectedId, string expectedToken)
+        {
+            DiscordWebhookClient.ParseWebhookUrl(webhookurl, out ulong id, out string token);
+
+            Assert.Equal(expectedId, id);
+            Assert.Equal(expectedToken, token);
+        }
+
+        [Theory]
+        [InlineData("")]
+        [InlineData("   ")]
+        [InlineData(null)]
+        public void TestWebhook_Null(string webhookurl)
+        {
+            Assert.Throws<ArgumentNullException>(() =>
+            {
+                DiscordWebhookClient.ParseWebhookUrl(webhookurl, out ulong id, out string token);
+            });
+        }
+
+        [Theory]
+        [InlineData("123412347732897802/_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK")]
+        // trailing slash
+        [InlineData("https://discordapp.com/api/webhooks/123412347732897802/_abcde123456789-ABCDEFGHIJKLMNOP12345678-abcdefghijklmnopABCDEFGHIJK/")]
+        public void TestWebhook_Invalid(string webhookurl)
+        {
+            Assert.Throws<ArgumentException>(() =>
+            {
+                DiscordWebhookClient.ParseWebhookUrl(webhookurl, out ulong id, out string token);
+            });
+        }
+    }
+}