feat: add endpoint for entitlement events

package.json

@@ -23,6 +23,8 @@
 	},
 	"dependencies": {
 		"fastify": "5.2.1",
-		"nodemailer": "6.10.0"
+		"fastify-raw-body": "5.0.0",
+		"nodemailer": "6.10.0",
+		"tweetnacl": "1.0.3"
 	}
 }

pnpm-lock.yaml

@@ -11,9 +11,15 @@ importers:
       fastify:
         specifier: 5.2.1
         version: 5.2.1
+      fastify-raw-body:
+        specifier: 5.0.0
+        version: 5.0.0
       nodemailer:
         specifier: 6.10.0
         version: 6.10.0
+      tweetnacl:
+        specifier: 1.0.3
+        version: 1.0.3
     devDependencies:
       '@nhcarrigan/eslint-config':
         specifier: 5.1.0
@@ -711,6 +717,10 @@ packages:
     resolution: {integrity: sha512-zhaCDicdLuWN5UbN5IMnFqNMhNfo919sH85y2/ea+5Yg9TsTkeZxpL+JLbp6cgYFS4sRLp3YV4S6yDuqVWHYOw==}
     engines: {node: '>=6'}
 
+  bytes@3.1.2:
+    resolution: {integrity: sha512-/Nf7TyzTx6S3yRJObOAV7956r8cr2+Oj8AC5dt8wSP3BQAoeX58NoHyCU8P8zGkNXStjTSi6fzO6F0pBdcYbEg==}
+    engines: {node: '>= 0.8'}
+
   cac@6.7.14:
     resolution: {integrity: sha512-b6Ilus+c3RrdDk+JhLKUAQfzzgLEPy6wcXqS7f/xe1EETvsDP6GORG7SFuOs6cID5YkqchW/LXZbX5bc8j7ZcQ==}
     engines: {node: '>=8'}
@@ -823,6 +833,10 @@ packages:
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     engines: {node: '>= 0.4'}
 
+  depd@2.0.0:
+    resolution: {integrity: sha512-g7nH6P6dyDioJogAAGprGpCtVImJhpPk/roCzdb3fIh61/s/nPsfR6onyMwkCAR/OlC3yBC0lESvUoQEAssIrw==}
+    engines: {node: '>= 0.8'}
+
   dequal@2.0.3:
     resolution: {integrity: sha512-0je+qPKHEMohvfRTCEo3CrPG6cAzAYgmzKyxRiYSSDkS6eGJdyVJm7WaYA5ECaAD9wLB2T4EEeymA5aFVcYXCA==}
     engines: {node: '>=6'}
@@ -1050,6 +1064,13 @@ packages:
   fast-uri@3.0.6:
     resolution: {integrity: sha512-Atfo14OibSv5wAp4VWNsFYE1AchQRTv9cBGWET4pZWHzYshFSS9NQI6I57rdKn9croWVMbYFbLhJ+yJvmZIIHw==}
 
+  fastify-plugin@5.0.1:
+    resolution: {integrity: sha512-HCxs+YnRaWzCl+cWRYFnHmeRFyR5GVnJTAaCJQiYzQSDwK9MgJdyAsuL3nh0EWRCYMgQ5MeziymvmAhUHYHDUQ==}
+
+  fastify-raw-body@5.0.0:
+    resolution: {integrity: sha512-2qfoaQ3BQDhZ1gtbkKZd6n0kKxJISJGM6u/skD9ljdWItAscjXrtZ1lnjr7PavmXX9j4EyCPmBDiIsLn07d5vA==}
+    engines: {node: '>= 10'}
+
   fastify@5.2.1:
     resolution: {integrity: sha512-rslrNBF67eg8/Gyn7P2URV8/6pz8kSAscFL4EThZJ8JBMaXacVdVE4hmUcnPNKERl5o/xTiBSLfdowBRhVF1WA==}
 
@@ -1184,6 +1205,14 @@ packages:
   hosted-git-info@2.8.9:
     resolution: {integrity: sha512-mxIDAb9Lsm6DoOJ7xH+5+X4y1LU/4Hi50L9C5sIswK3JzULS4bwk1FvjdBgvYR4bzT4tuUQiC15FE2f5HbLvYw==}
 
+  http-errors@2.0.0:
+    resolution: {integrity: sha512-FtwrG/euBzaEjYeRqOgly7G0qviiXoJWnvEH2Z1plBdXgbyjv34pHTSb9zoeHMyDy33+DWy5Wt9Wo+TURtOYSQ==}
+    engines: {node: '>= 0.8'}
+
+  iconv-lite@0.6.3:
+    resolution: {integrity: sha512-4fCk79wshMdzMp2rH06qWrJE4iolqLhCUH+OiuIgU++RB0+94NlDL81atO7GX55uUKueo0txHNtvEyI6D7WdMw==}
+    engines: {node: '>=0.10.0'}
+
   ignore@5.3.2:
     resolution: {integrity: sha512-hsBTNUqQTDwkWtcdYI2i06Y/nUBEsNEDJKjWdigLvegy8kDuJAS8uRlpkkcQpyEXL0Z/pjDy5HBmMjRCJ2gq+g==}
     engines: {node: '>= 4'}
@@ -1200,6 +1229,9 @@ packages:
     resolution: {integrity: sha512-EdDDZu4A2OyIK7Lr/2zG+w5jmbuk1DVBnEwREQvBzspBJkCEbRa8GxU1lghYcaGJCnRWibjDXlq779X1/y5xwg==}
     engines: {node: '>=8'}
 
+  inherits@2.0.4:
+    resolution: {integrity: sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ==}
+
   internal-slot@1.1.0:
     resolution: {integrity: sha512-4gd7VpWNQNB4UKKCFFVcp1AVv+FMOgs9NKzjHKusc8jTMhd5eL1NqQqOpE0KzMds804/yHlglp3uxgluOqAPLw==}
     engines: {node: '>= 0.4'}
@@ -1609,6 +1641,10 @@ packages:
   quick-format-unescaped@4.0.4:
     resolution: {integrity: sha512-tYC1Q1hgyRuHgloV/YXs2w15unPVh8qfu/qCTfhTYamaw7fyhumKa2yGpdSo87vY32rIclj+4fWYQXUMs9EHvg==}
 
+  raw-body@3.0.0:
+    resolution: {integrity: sha512-RmkhL8CAyCRPXCE28MMH0z2PNWQBNk2Q09ZdxM9IOOXwxwZbN+qbWaatPkdkWIKL2ZVDImrN/pK5HTRz2PcS4g==}
+    engines: {node: '>= 0.8'}
+
   react-is@16.13.1:
     resolution: {integrity: sha512-24e6ynE2H+OKt4kqsOvNd8kBpV65zoxbA4BVsEOB3ARVWQki/DHzaUoC5KuON/BiccDaCCTZBuOcfZs70kR8bQ==}
 
@@ -1703,6 +1739,12 @@ packages:
     resolution: {integrity: sha512-b3rppTKm9T+PsVCBEOUR46GWI7fdOs00VKZ1+9c1EWDaDMvjQc6tUwuFyIprgGgTcWoVHSKrU8H31ZHA2e0RHA==}
     engines: {node: '>=10'}
 
+  safer-buffer@2.1.2:
+    resolution: {integrity: sha512-YZo3K82SD7Riyi0E1EQPojLz7kpepnSQI9IyPbHHg1XXXevb5dJI7tpyN2ADxGcQbHG7vcyRHk0cbwqcQriUtg==}
+
+  secure-json-parse@2.7.0:
+    resolution: {integrity: sha512-6aU+Rwsezw7VR8/nyvKTx8QpWH9FrcYiXXlqC4z5d5XQBDRqtbfsRjnwGyqbi3gddNtWHuEk9OANUotL26qKUw==}
+
   secure-json-parse@3.0.2:
     resolution: {integrity: sha512-H6nS2o8bWfpFEV6U38sOSjS7bTbdgbCGU9wEM6W14P5H0QOsz94KCusifV44GpHDTu2nqZbuDNhTzu+mjDSw1w==}
 
@@ -1734,6 +1776,9 @@ packages:
     resolution: {integrity: sha512-RJRdvCo6IAnPdsvP/7m6bsQqNnn1FCBX5ZNtFL98MmFF/4xAIJTIg1YbHW5DC2W5SKZanrC6i4HsJqlajw/dZw==}
     engines: {node: '>= 0.4'}
 
+  setprototypeof@1.2.0:
+    resolution: {integrity: sha512-E5LDX7Wrp85Kil5bhZv46j8jOeboKq5JMmYM3gVGdGH8xFpPWXUMsNrlODCrkoxMEeNi/XZIwuRvY4XNwYMJpw==}
+
   shebang-command@2.0.0:
     resolution: {integrity: sha512-kHxr2zZpYtdmrN1qDjrrX/Z1rR1kG8Dx+gkpK1G4eXmvXswmcE1hTWBWYUzlraYw1/yZp6YuDY77YtvbN0dmDA==}
     engines: {node: '>=8'}
@@ -1797,6 +1842,10 @@ packages:
   stackback@0.0.2:
     resolution: {integrity: sha512-1XMJE5fQo1jGH6Y/7ebnwPOBEkIEnT4QF32d5R1+VXdXveM0IBMJt8zfaxX1P3QhVwrYe+576+jkANtSS2mBbw==}
 
+  statuses@2.0.1:
+    resolution: {integrity: sha512-RwNA9Z/7PrK06rYLIzFMlaF+l73iwpzsqRIFgbMLbTcLD6cOao82TaWefPXQvB2fOC4AjuYSEndS7N/mTCbkdQ==}
+    engines: {node: '>= 0.8'}
+
   std-env@3.8.0:
     resolution: {integrity: sha512-Bc3YwwCB+OzldMxOXJIIvC6cPRWr/LxOp48CdQTOkPyk/t4JWWJbrilwBd7RJzKV8QW7tJkcgAmeuLLJugl5/w==}
 
@@ -1872,6 +1921,10 @@ packages:
     resolution: {integrity: sha512-/m8M+2BJUpoJdgAHoG+baCwBT+tf2VraSfkBgl0Y00qIWt41DJ8R5B8nsEw0I58YwF5IZH6z24/2TobDKnqSWw==}
     engines: {node: '>=12'}
 
+  toidentifier@1.0.1:
+    resolution: {integrity: sha512-o5sSPKEkg/DIQNmH43V0/uerLrpzVedkUh8tGNvaeXpfpuwjKenlSox/2O/BTlZUtEe+JG7s5YhEz608PlAHRA==}
+    engines: {node: '>=0.6'}
+
   ts-api-utils@1.4.3:
     resolution: {integrity: sha512-i3eMG77UTMD0hZhgRS562pv83RC6ukSAC2GMNWc+9dieh/+jDM5u5YG+NHX6VNDRHQcHwmsTHctP9LhbC3WxVw==}
     engines: {node: '>=16'}
@@ -1890,6 +1943,9 @@ packages:
   tslib@2.8.1:
     resolution: {integrity: sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==}
 
+  tweetnacl@1.0.3:
+    resolution: {integrity: sha512-6rt+RN7aOi1nGMyC4Xa5DdYiukl2UWCbcJft7YhxReBGQD7OAM8Pbxw6YMo4r2diNEA8FEmu32YOn9rhaiE5yw==}
+
   type-check@0.4.0:
     resolution: {integrity: sha512-XleUoc9uwGXqjWwXaUTZAmzMcFZ5858QA2vvx1Ur5xIcixXIP+8LnFDgRplU30us6teqdlskFfu+ae4K79Ooew==}
     engines: {node: '>= 0.8.0'}
@@ -1934,6 +1990,10 @@ packages:
   undici-types@6.20.0:
     resolution: {integrity: sha512-Ny6QZ2Nju20vw1SRHe3d9jVu6gJ+4e3+MMpqu7pqE5HT6WsTSlce++GQmK5UXS8mzV8DSYHrQH+Xrf2jVcuKNg==}
 
+  unpipe@1.0.0:
+    resolution: {integrity: sha512-pjy2bYhSsufwWlKwPc+l3cN7+wuJlK6uz0YdJEOlQDbl6jo/YlPi4mb8agUkVC8BF7V8NuzeyPNqRksA3hztKQ==}
+    engines: {node: '>= 0.8'}
+
   update-browserslist-db@1.1.2:
     resolution: {integrity: sha512-PPypAm5qvlD7XMZC3BujecnaOxwhrtoFR+Dqkk5Aa/6DssiH0ibKoketaj9w8LP7Bont1rYeoV5plxD7RTEPRg==}
     hasBin: true
@@ -2719,6 +2779,8 @@ snapshots:
 
   builtin-modules@3.3.0: {}
 
+  bytes@3.1.2: {}
+
   cac@6.7.14: {}
 
   call-bind-apply-helpers@1.0.1:
@@ -2827,6 +2889,8 @@ snapshots:
       has-property-descriptors: 1.0.2
       object-keys: 1.1.1
 
+  depd@2.0.0: {}
+
   dequal@2.0.3: {}
 
   dir-glob@3.0.1:
@@ -3224,6 +3288,14 @@ snapshots:
 
   fast-uri@3.0.6: {}
 
+  fastify-plugin@5.0.1: {}
+
+  fastify-raw-body@5.0.0:
+    dependencies:
+      fastify-plugin: 5.0.1
+      raw-body: 3.0.0
+      secure-json-parse: 2.7.0
+
   fastify@5.2.1:
     dependencies:
       '@fastify/ajv-compiler': 4.0.2
@@ -3382,6 +3454,18 @@ snapshots:
 
   hosted-git-info@2.8.9: {}
 
+  http-errors@2.0.0:
+    dependencies:
+      depd: 2.0.0
+      inherits: 2.0.4
+      setprototypeof: 1.2.0
+      statuses: 2.0.1
+      toidentifier: 1.0.1
+
+  iconv-lite@0.6.3:
+    dependencies:
+      safer-buffer: 2.1.2
+
   ignore@5.3.2: {}
 
   import-fresh@3.3.1:
@@ -3393,6 +3477,8 @@ snapshots:
 
   indent-string@4.0.0: {}
 
+  inherits@2.0.4: {}
+
   internal-slot@1.1.0:
     dependencies:
       es-errors: 1.3.0
@@ -3801,6 +3887,13 @@ snapshots:
 
   quick-format-unescaped@4.0.4: {}
 
+  raw-body@3.0.0:
+    dependencies:
+      bytes: 3.1.2
+      http-errors: 2.0.0
+      iconv-lite: 0.6.3
+      unpipe: 1.0.0
+
   react-is@16.13.1: {}
 
   react@19.0.0: {}
@@ -3924,6 +4017,10 @@ snapshots:
 
   safe-stable-stringify@2.5.0: {}
 
+  safer-buffer@2.1.2: {}
+
+  secure-json-parse@2.7.0: {}
+
   secure-json-parse@3.0.2: {}
 
   semver@5.7.2: {}
@@ -3956,6 +4053,8 @@ snapshots:
       es-errors: 1.3.0
       es-object-atoms: 1.1.1
 
+  setprototypeof@1.2.0: {}
+
   shebang-command@2.0.0:
     dependencies:
       shebang-regex: 3.0.0
@@ -4025,6 +4124,8 @@ snapshots:
 
   stackback@0.0.2: {}
 
+  statuses@2.0.1: {}
+
   std-env@3.8.0: {}
 
   string.prototype.matchall@4.0.12:
@@ -4110,6 +4211,8 @@ snapshots:
 
   toad-cache@3.7.0: {}
 
+  toidentifier@1.0.1: {}
+
   ts-api-utils@1.4.3(typescript@5.7.3):
     dependencies:
       typescript: 5.7.3
@@ -4127,6 +4230,8 @@ snapshots:
 
   tslib@2.8.1: {}
 
+  tweetnacl@1.0.3: {}
+
   type-check@0.4.0:
     dependencies:
       prelude-ls: 1.2.1
@@ -4181,6 +4286,8 @@ snapshots:
 
   undici-types@6.20.0: {}
 
+  unpipe@1.0.0: {}
+
   update-browserslist-db@1.1.2(browserslist@4.24.4):
     dependencies:
       browserslist: 4.24.4

src/config/applicationData.ts

@@ -0,0 +1,96 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+/* eslint-disable @typescript-eslint/naming-convention -- We are using the numerical ids as the keys.*/
+export const applicationData: Record<string, { name: string; key: string }> = {
+  "1235128719836712970": {
+    key:  "e255cd3a348ce604e18e2f2c0f5a59a9273a420ca732630d569ef5f839f2143e",
+    name: "Celestine",
+  },
+  "1338596130207957035": {
+    key:  "ef9d2a3c8e9a4d165a12ca798be93d719dd51cc7ff901ade8136cb992cd7fe3e",
+    name: "Aria Iuvo",
+  },
+  "1338664192714211459": {
+    key:  "a28c9c2683acb209341e04d5b43bd2a24bc81f5b263095a1bf487e94ca6a3ff9",
+    name: "Cordelia Taryne",
+  },
+  "1338753576583041074": {
+    key:  "62468252371a68791c650b5aaa599ef2b7b148a7169bb5fa9f56075705ac405e",
+    name: "Melody Iuvo",
+  },
+  "1343341112437248041": {
+    key:  "3ccf23b9c10dda9a7af434e0c5fc116d05aba66caf2ebd8c738c60ba9875436f",
+    name: "Becca Lyria",
+  },
+  "1343370633916059668": {
+    key:  "a9146e39ab5f69129e3c50db5d5848c56bc4a2cb90bba10e492e08355acd3d12",
+    name: "Maylin Taryne",
+  },
+  "1343413943447584819": {
+    key:  "6d95c7132ee9f28a4ea5fffbc8dd33ecaffe0f50add0c631d5ef51cc071bd2df",
+    name: "Gwen Abalise",
+  },
+  "1347642447643017289": {
+    key:  "091be058344e543e87baafeb9fe20b004bd170ca5ee57b17afff595271080a27",
+    name: "Mommy",
+  },
+  "1386862413936328796": {
+    key:  "831e3981135a4c9d30e8c02e6f8cba73436d30c36b1a14f1fb7bc7147cd4cb75",
+    name: "Maribelle",
+  },
+  "1391117878182281316": {
+    key:  "b182039c954ba57216bf53bdc4d5ba3d89efc2b41c850cbf7f3430fbb6cc0c56",
+    name: "Hikari",
+  },
+  "1391488058913718374": {
+    key:  "fc1a838c3102351602221f2db63d997f9e4495510044d5ec436844038b9a5bd5",
+    name: "Rosalia Nightsong",
+  },
+  "1391489982887362761": {
+    key:  "ef173a181d6fcf506b72795812fca8ecc3a81c2ff382bfd39564bab63fd90eee",
+    name: "Sorielle",
+  },
+  "1391491102657482863": {
+    key:  "a412583e5d5510aebb6d54eb49f36797e62f9567efd79108863adbb93cf00236",
+    name: "Verena",
+  },
+  "1391492296222179459": {
+    key:  "aab61af4411fc1dc710d5b5aba5d16fba9effaad9415b878a3f1595428dbebcd",
+    name: "Liora",
+  },
+  "1391493722176356434": {
+    key:  "3dc2abd018271a5a1f65c09597738a711b2fc619d34da59189279d6c2a1922f4",
+    name: "Thessalia",
+  },
+  "1391494389477412906": {
+    key:  "8d11517cf954779e4645b8c10432697a0572dcfcecc0bb14d0fe2397f5a03453",
+    name: "Callista",
+  },
+  "1391495288421879849": {
+    key:  "fb0894e2dcd3e736addd70a675b40d5681d39c133289cdfe4f7378006163e817",
+    name: "Eirene",
+  },
+  "1391497269177483405": {
+    key:  "0887f7e12053d559f8944a06ed323ec237d34f8e15860b672fb7abe6dc32d192",
+    name: "Sybil",
+  },
+  "1391503229287928000": {
+    key:  "8a4d4f18dae4e2d0ec610e3da47254a812c39cfac6ee986cfaa20eb848a2db92",
+    name: "Clarion",
+  },
+  "1391503834073006181": {
+    key:  "60ffe0a3503d5166c1e4b7370753793dff60d75a28ebf4ace8b6623ad5207821",
+    name: "Evangeline",
+  },
+  "1391504577811185744": {
+    key:  "33bb085873b46199facfbfae00b7d71ed04d55377deeaa2a0c8afa303c68a75d",
+    name: "Theodora",
+  },
+  "1391505285465509978": {
+    key:  "edce882890078d52c00c653b9e305565a909a0807abf86b36f1d7679434b80fa",
+    name: "Veluna",
+  },
+};

src/interfaces/entitlement.ts

@@ -0,0 +1,31 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+/* eslint-disable @typescript-eslint/naming-convention -- Needs to match Discord's structure. */
+export interface Entitlement {
+  application_id: string;
+  event: {
+    data: {
+      application_id:  string;
+      consumed:        boolean;
+      deleted:         boolean;
+      ends_at:         string;
+      gift_code_flags: number;
+      guild_id:        string;
+      id:              string;
+      promotion_id:    string | null;
+      sku_id:          string;
+      starts_at:       string;
+      subscription_id: string;
+      type:            number;
+      user_id:         string;
+    };
+    timestamp: string;
+    type:      string;
+  };
+  type:    number;
+  version: number;
+}

src/modules/discord.ts

@@ -17,6 +17,7 @@ export const sendDiscord = async(
     body: JSON.stringify({
       components: [
         {
+          // eslint-disable-next-line @typescript-eslint/naming-convention -- Needs to match Discord's structure.
           accent_color: 15_418_782,
           components:   [
             {
@@ -40,6 +41,7 @@ export const sendDiscord = async(
       flags: 32_768,
     }),
     headers: {
+      // eslint-disable-next-line @typescript-eslint/naming-convention -- Needs to match Discord's structure.
       "Content-Type": "application/json",
     },
     method: "POST",

src/modules/validateWebhook.ts

@@ -0,0 +1,46 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+import nacl from "tweetnacl";
+import { applicationData } from "../config/applicationData.js";
+import type { Entitlement } from "../interfaces/entitlement.js";
+import type { FastifyRequest } from "fastify";
+
+/**
+ * Validates that the webhook request is from Discord by checking the signature.
+ * @param request - The Fastify request object containing the webhook data.
+ * @returns A boolean indicating whether the webhook signature is valid.
+ */
+export const validateWebhook = (
+  // eslint-disable-next-line @typescript-eslint/naming-convention -- Body must be capitalised for Fastify.
+  request: FastifyRequest<{ Body: Entitlement }>,
+): boolean => {
+  const { application_id: applicationId } = request.body;
+  const appData = applicationData[applicationId];
+  if (appData === undefined) {
+    return false;
+  }
+  const signature = request.headers["x-signature-ed25519"];
+  const timestamp = request.headers["x-signature-timestamp"];
+  const { rawBody } = request;
+  if (
+    signature === undefined
+    || timestamp === undefined
+    || rawBody === undefined
+  ) {
+    return false;
+  }
+  return nacl.sign.detached.verify(
+    // eslint-disable-next-line @typescript-eslint/restrict-template-expressions -- Being lazy here, tbh.
+    Buffer.from(`${timestamp}${rawBody}`),
+    Buffer.from(
+      Array.isArray(signature)
+        ? signature[0] ?? signature.join("")
+        : signature,
+      "hex",
+    ),
+    Buffer.from(process.env.DISCORD_PUBLIC_KEY ?? "", "hex"),
+  );
+};

src/server/serve.ts

@@ -5,12 +5,16 @@
  */
 
 import fastify from "fastify";
+import fastifyRawBody from "fastify-raw-body";
+import { applicationData } from "../config/applicationData.js";
 import { auth } from "../modules/auth.js";
 import { sendDiscord } from "../modules/discord.js";
 import { sendMail } from "../modules/sendMail.js";
+import { validateWebhook } from "../modules/validateWebhook.js";
 import { errorSchema } from "../schemas/errorSchema.js";
 import { logSchema } from "../schemas/logSchema.js";
 import { uptimeSchema } from "../schemas/uptimeSchema.js";
+import type { Entitlement } from "../interfaces/entitlement.js";
 import type { Error } from "../interfaces/error.js";
 import type { Log } from "../interfaces/log.js";
 import type { Uptime } from "../interfaces/uptime.js";
@@ -63,6 +67,15 @@ export const instantiateServer = (): void => {
       logger: false,
     });
 
+    server.register(fastifyRawBody, {
+      encoding:         "utf8",
+      field:            "rawBody",
+      global:           false,
+      jsonContentTypes: [],
+      routes:           [],
+      runFirst:         true,
+    });
+
     server.get("/", (_request, response) => {
       response.header("Content-Type", "text/html");
       response.send(html);
@@ -90,7 +103,10 @@ export const instantiateServer = (): void => {
           return;
         }
         const { application, context, stack, message } = request.body;
-        await sendMail(`[ERROR]: ${context} - ${application}`, `${message}\n\n${stack}`);
+        await sendMail(
+          `[ERROR]: ${context} - ${application}`,
+          `${message}\n\n${stack}`,
+        );
         await sendDiscord(
           `[ERROR]: ${context} - ${application}`,
           `${message}\n\n\`\`\`\n${stack}\n\`\`\``,
@@ -115,13 +131,68 @@ export const instantiateServer = (): void => {
       },
     );
 
+    // eslint-disable-next-line @typescript-eslint/naming-convention -- Body must be capitalised for Fastify.
+    server.post<{ Body: Entitlement }>(
+      "/entitlement",
+      { config: { rawBody: true } },
+      async(request, response) => {
+        if (!validateWebhook(request)) {
+          await response.status(401).send({ success: false });
+          void sendDiscord(
+            "[NOTIFICATION]: Entitlement Event",
+            "An invalid webhook signature was received.",
+          );
+          void sendMail(
+            "[NOTIFICATION]: Entitlement Event",
+            "An invalid webhook signature was received.",
+          );
+          return;
+        }
+        const { type } = request.body;
+        if (type === 0) {
+          await response.status(204).send();
+          void sendDiscord(
+            "[NOTIFICATION]: Entitlement Event",
+            "Received a ping from Discord.",
+          );
+          void sendMail(
+            "[NOTIFICATION]: Entitlement Event",
+            "Received a ping from Discord.",
+          );
+          return;
+        }
+        await response.status(204).send();
+        const { application_id: applicationId, event } = request.body;
+        const {
+          user_id: userId,
+          guild_id: guildId,
+          ends_at: endsAt,
+        } = event.data;
+        const appInfo = applicationData[applicationId];
+        await sendDiscord(
+          `[ENTITLEMENT]: ${appInfo?.name ?? applicationId}`,
+          `Entitlement purchased!\n- **User ID**: ${userId}\n- **Guild ID**: ${guildId}\n- **Ends At**: ${endsAt}`,
+        );
+        await sendMail(
+          `[ENTITLEMENT]: ${appInfo?.name ?? applicationId}`,
+          `Entitlement purchased!\n- **User ID**: ${userId}\n- **Guild ID**: ${guildId}\n- **Ends At**: ${endsAt}`,
+        );
+      },
+    );
+
     server.listen({ port: 5003 }, (error) => {
       const application = "Alert Server";
       if (error) {
         const { message, stack } = error;
         const context = "Server Startup";
-        void sendMail(`[ERROR]: ${context} - ${application}`, `${message}\n\n${String(stack)}`);
+        void sendMail(
-        void sendDiscord(`[ERROR]: ${context} - ${application}`, `${message}\n\n\`\`\`\n${String(stack)}\n\`\`\``);
+          `[ERROR]: ${context} - ${application}`,
+          `${message}\n\n${String(stack)}`,
+        );
+        void sendDiscord(
+          `[ERROR]: ${context} - ${application}`,
+          `${message}\n\n\`\`\`\n${String(stack)}\n\`\`\``,
+        );
         return;
       }
       const level = "debug";
@@ -134,7 +205,13 @@ export const instantiateServer = (): void => {
     const context = "Server Startup";
     // eslint-disable-next-line @typescript-eslint/consistent-type-assertions -- Totally being lazy.
     const { message, stack } = error as Error;
-    void sendMail(`[ERROR]: ${context} - ${application}`, `${message}\n\n${stack}`);
+    void sendMail(
-    void sendDiscord(`[ERROR]: ${context} - ${application}`, `${message}\n\n\`\`\`\n${stack}\n\`\`\``);
+      `[ERROR]: ${context} - ${application}`,
+      `${message}\n\n${stack}`,
+    );
+    void sendDiscord(
+      `[ERROR]: ${context} - ${application}`,
+      `${message}\n\n\`\`\`\n${stack}\n\`\`\``,
+    );
   }
 };