feat: implement payload builder

Co-authored-by: imdudu1 <[email protected]>

Author: jbl428

lib/utils/payload-builder.ts

@@ -0,0 +1,92 @@
+import { TupleArrayBuilder } from "./tuple-array-builder";
+import {
+  type RequestBodyMetadata,
+  type RequestFormMetadata,
+} from "../decorators";
+
+export class PayloadBuilder {
+  constructor(
+    private readonly args: any[],
+    private readonly metadata: {
+      body?: RequestBodyMetadata;
+      form?: RequestFormMetadata;
+    } = {}
+  ) {}
+
+  contentType(): string | undefined {
+    if (this.metadata.form !== undefined) {
+      return "application/x-www-form-urlencoded";
+    }
+
+    if (this.metadata.body !== undefined) {
+      return "application/json";
+    }
+
+    return undefined;
+  }
+
+  build(): BodyInit | undefined {
+    if (this.metadata.form !== undefined) {
+      const form = new FormData();
+      this.data.forEach(([index, value]) => {
+        if (value !== undefined) {
+          form.append(value, this.args[index]);
+          return;
+        }
+
+        TupleArrayBuilder.of<string, string | Blob>(this.args[index]).forEach(
+          ([k, v]) => {
+            form.append(k, v);
+          }
+        );
+      });
+
+      return form;
+    }
+
+    if (this.metadata.body !== undefined) {
+      const payload = this.data.reduce(
+        (
+          acc: Record<string, unknown>,
+          [index, value]: [number, string | undefined]
+        ) => this.makePayload(acc, index, value),
+        {}
+      );
+
+      return JSON.stringify(payload);
+    }
+
+    return undefined;
+  }
+
+  private makePayload(
+    acc: Record<string, unknown>,
+    index: number,
+    value?: string
+  ): Record<string, unknown> {
+    if (value !== undefined) {
+      acc[value] = this.args[index];
+      return acc;
+    }
+
+    TupleArrayBuilder.of<string, unknown>(this.args[index]).forEach(
+      ([k, v]) => {
+        acc[k] = v;
+      }
+    );
+
+    return acc;
+  }
+
+  private get data(): Array<[number, string | undefined]> {
+    if (this.metadata.form !== undefined) {
+      return this.metadata.form.toArray();
+    }
+
+    if (this.metadata.body !== undefined) {
+      return this.metadata.body.toArray();
+    }
+
+    return [];
+  }
+}