feat: impl database structure

packages/core/database/indexer.js

@@ -0,0 +1,33 @@
+import Storage from "./storage";
+
+export default class Indexer extends Storage {
+  constructor(context, type) {
+    super(context);
+    this.type = type;
+    this.indices = [];
+  }
+
+  async initIndexer() {
+    this.indices = (await this.read(this.type)) || [];
+  }
+
+  async index(key) {
+    if (this.indices.length <= 0) {
+      this.indices = (await this.read(this.type)) || [];
+    }
+    this.indices[this.indices.length] = key;
+    await this.write(this.type, this.indices);
+  }
+
+  async getIndices() {
+    if (this.indices.length <= 0) {
+      this.indices = (await this.read(this.type)) || [];
+    }
+    return this.indices;
+  }
+
+  async deindex(key) {
+    this.indices.splice(this.indices.indexOf(key), 1);
+    await this.write(this.type, this.indices);
+  }
+}