feat: feature flags

apps/web/src/helpers/get-feature-flag.ts

@@ -0,0 +1,79 @@
+import { z } from 'zod';
+
+import { LOCAL_FEATURE_FLAGS, isFeatureFlagEnabled } from '@documenso/lib/constants/feature-flags';
+
+import { FeatureFlagValue } from '~/providers/feature-flag';
+
+/**
+ * Evaluate whether a flag is enabled for the current user.
+ *
+ * @param flag The flag to evaluate.
+ * @param options See `GetFlagOptions`.
+ * @returns Whether the flag is enabled, or the variant value of the flag.
+ */
+export const getFlag = async (
+  flag: string,
+  options?: GetFlagOptions,
+): Promise<FeatureFlagValue> => {
+  const requestHeaders = options?.requestHeaders ?? {};
+
+  if (!isFeatureFlagEnabled()) {
+    return LOCAL_FEATURE_FLAGS[flag] ?? true;
+  }
+
+  const url = new URL(`${process.env.NEXT_PUBLIC_SITE_URL}/api/feature-flag/get`);
+  url.searchParams.set('flag', flag);
+
+  const response = await fetch(url, {
+    headers: {
+      ...requestHeaders,
+    },
+    next: {
+      revalidate: 60,
+    },
+  })
+    .then((res) => res.json())
+    .then((res) => z.union([z.boolean(), z.string()]).parse(res))
+    .catch(() => false);
+
+  return response;
+};
+
+/**
+ * Get all feature flags for the current user if possible.
+ *
+ * @param options See `GetFlagOptions`.
+ * @returns A record of flags and their values for the user derived from the headers.
+ */
+export const getAllFlags = async (
+  options?: GetFlagOptions,
+): Promise<Record<string, FeatureFlagValue>> => {
+  const requestHeaders = options?.requestHeaders ?? {};
+
+  if (!isFeatureFlagEnabled()) {
+    return LOCAL_FEATURE_FLAGS;
+  }
+
+  const url = new URL(`${process.env.NEXT_PUBLIC_SITE_URL}/api/feature-flag/all`);
+
+  return fetch(url, {
+    headers: {
+      ...requestHeaders,
+    },
+    next: {
+      revalidate: 60,
+    },
+  })
+    .then((res) => res.json())
+    .then((res) => z.record(z.string(), z.union([z.boolean(), z.string()])).parse(res))
+    .catch(() => LOCAL_FEATURE_FLAGS);
+};
+
+interface GetFlagOptions {
+  /**
+   * The headers to attach to the request to evaluate flags.
+   *
+   * The authenticated user will be derived from the headers if possible.
+   */
+  requestHeaders: Record<string, string>;
+}