1 files changed, 52 insertions, 0 deletions
diff --git a/pbt/ts/src/levelbank.ts b/pbt/ts/src/levelbank.ts
new file mode 100644
index 0000000..ead4e38
--- /dev/null
+++ b/pbt/ts/src/levelbank.ts
@@ -0,0 +1,52 @@
+// Specify types of keys and values (any, in the case of json).
+
+import {Level} from 'level';
+import {Account, Bank} from './bank';
+import {Option, fromNullable} from 'fp-ts/lib/Option';
+
+export class LevelBank implements Bank {
+  db: Level<string, number>;
+  file: string;
+
+  constructor(file: string) {
+    this.file = file;
+    this.db = new Level<Account, number>(file, {
+      valueEncoding: 'json',
+    });
+  }
+
+  async populateWith(
+    initialAccounts: Map<Account, number>,
+  ): Promise<LevelBank> {
+    await this.db.open({createIfMissing: true});
+
+    const puts: Promise<void>[] = [];
+
+    initialAccounts.forEach((v, k) => {
+      puts.push(this.db.put(k, v));
+    });
+
+    await Promise.all(puts);
+
+    return this;
+  }
+
+  async balance(account: string): Promise<Option<number>> {
+    const result = await this.db.get(account);
+    return fromNullable(result);
+  }
+
+  async deposit(account: string, amt: number): Promise<void> {
+    const current = await this.db.get(account);
+    if (current) {
+      await this.db.put(account, current + amt);
+    }
+  }
+
+  async withdraw(account: string, amt: number): Promise<void> {
+    const current = await this.db.get(account);
+    if (current) {
+      await this.db.put(account, current + amt);
+    }
+  }
+}