Add Postgres adapter

deno.json

@@ -11,7 +11,13 @@
     "nsec": "deno run scripts/nsec.ts"
   },
   "exclude": ["./public"],
-  "imports": { "@/": "./src/", "@soapbox/nspec": "jsr:@soapbox/nspec@^0.8.1", "~/fixtures/": "./fixtures/" },
+  "imports": {
+    "@/": "./src/",
+    "@nostrify/nostrify": "jsr:@nostrify/nostrify@^0.9.7",
+    "@soapbox/nspec": "jsr:@soapbox/nspec@^0.8.1",
+    "~/fixtures/": "./fixtures/",
+    "kysely": "npm:kysely@^0.26.3"
+  },
   "lint": {
     "include": ["src/", "scripts/"],
     "rules": {

src/db/DittoDB.ts

@@ -1,4 +1,5 @@
 import { Conf } from '@/config.ts';
+import { DittoPostgres } from '@/db/adapters/DittoPostgres.ts';
 import { DittoSQLite } from '@/db/adapters/DittoSQLite.ts';
 import { DittoTables } from '@/db/DittoTables.ts';
 import { Kysely } from '@/deps.ts';
@@ -10,6 +11,8 @@ export class DittoDB {
     switch (databaseUrl.protocol) {
       case 'sqlite:':
         return DittoSQLite.getInstance();
+      case 'postgres:':
+        return DittoPostgres.getInstance();
       default:
         throw new Error('Unsupported database URL.');
     }

src/db/adapters/DittoPostgres.ts

@@ -0,0 +1,35 @@
+import { Kysely, PostgresAdapter, PostgresIntrospector, PostgresQueryCompiler } from 'kysely';
+
+import { DittoTables } from '@/db/DittoTables.ts';
+import { PostgreSQLDriver } from 'https://deno.land/x/kysely_deno_postgres@v0.4.0/mod.ts';
+
+export class DittoPostgres {
+  static db: Kysely<DittoTables> | undefined;
+
+  // deno-lint-ignore require-await
+  static async getInstance(): Promise<Kysely<DittoTables>> {
+    if (!this.db) {
+      this.db = new Kysely({
+        dialect: {
+          createAdapter() {
+            return new PostgresAdapter();
+          },
+          // @ts-ignore mismatched kysely versions probably
+          createDriver() {
+            return new PostgreSQLDriver({
+              connectionString: Deno.env.get('DATABASE_URL'),
+            });
+          },
+          createIntrospector(db: Kysely<unknown>) {
+            return new PostgresIntrospector(db);
+          },
+          createQueryCompiler() {
+            return new PostgresQueryCompiler();
+          },
+        },
+      });
+    }
+
+    return this.db;
+  }
+}