feat: improve form response experience

lib/form-answer-values.test.ts

@@ -0,0 +1,25 @@
+import { describe, expect, test } from "bun:test";
+
+import {
+  decodeCheckboxAnswer,
+  encodeAnswerValue,
+  formatStoredAnswer,
+} from "@/lib/form-answer-values";
+
+describe("form answer values", () => {
+  test("round-trips checkbox choices containing commas", () => {
+    const choices = ["Alpha, beta", "Gamma"];
+    const stored = encodeAnswerValue(choices);
+
+    expect(decodeCheckboxAnswer(stored)).toEqual(choices);
+    expect(formatStoredAnswer(stored, "checkbox")).toBe("Alpha, beta, Gamma");
+  });
+
+  test("continues to read legacy comma-separated checkbox answers", () => {
+    expect(decodeCheckboxAnswer("Alpha, Beta")).toEqual(["Alpha", "Beta"]);
+  });
+
+  test("does not decode JSON-looking text answers", () => {
+    expect(formatStoredAnswer('["plain text"]', "text")).toBe('["plain text"]');
+  });
+});

lib/form-answer-values.ts

@@ -0,0 +1,41 @@
+import type { QuestionType } from "@/db/schema/form";
+
+export type FormAnswerValue = string | string[];
+
+export function decodeCheckboxAnswer(value: FormAnswerValue | undefined): string[] {
+  if (Array.isArray(value)) {
+    return value.filter((item): item is string => typeof item === "string");
+  }
+
+  if (!value) {
+    return [];
+  }
+
+  try {
+    const parsed: unknown = JSON.parse(value);
+    if (Array.isArray(parsed) && parsed.every((item) => typeof item === "string")) {
+      return parsed;
+    }
+  } catch {
+    // Older checkbox answers were stored as comma-separated text.
+  }
+
+  return value.split(", ").filter(Boolean);
+}
+
+export function encodeAnswerValue(value: FormAnswerValue): string {
+  return Array.isArray(value) ? JSON.stringify(value) : value;
+}
+
+export function formatStoredAnswer(
+  value: string | undefined,
+  questionType: QuestionType | string
+): string {
+  if (!value) {
+    return "";
+  }
+
+  return questionType === "checkbox"
+    ? decodeCheckboxAnswer(value).join(", ")
+    : value;
+}