src/lib/api-route.ts

Linked repository file from this build.

import { NextResponse } from "next/server";
import { z } from "zod";
import { AccessError } from "@/lib/auth/scope";
import { DocumentError } from "@/lib/documents/server-storage";
import { NotFoundError, RuleError } from "@/lib/errors";
import { StaleReviewError } from "@/features/reviews/persistence";
import { ReviewStoreUnavailableError } from "@/features/reviews/review-store";

/**
 * Wrap an API handler so every route maps errors the same way:
 * typed errors keep their status and message, and anything else is logged
 * and returns 503 with `fallback`.
 */
export function apiRoute<Context = unknown>(
  fallback: string,
  handler: (request: Request, context: Context) => Promise<Response>,
) {
  return async (request: Request, context: Context) => {
    try {
      return await handler(request, context);
    } catch (error) {
      return errorResponse(error, fallback);
    }
  };
}

export function errorResponse(error: unknown, fallback: string): Response {
  if (error instanceof AccessError || error instanceof DocumentError)
    return NextResponse.json({ error: error.message }, { status: error.status });
  if (error instanceof NotFoundError)
    return NextResponse.json({ error: error.message }, { status: 404 });
  if (error instanceof StaleReviewError)
    return NextResponse.json({ error: error.message, current: error.current }, { status: 409 });
  if (error instanceof ReviewStoreUnavailableError)
    return NextResponse.json({ error: error.message }, { status: 503 });
  // The client turns serialized Zod issues into readable field messages.
  if (error instanceof RuleError || error instanceof z.ZodError)
    return NextResponse.json({ error: error.message }, { status: 400 });
  if (error instanceof SyntaxError)
    return NextResponse.json({ error: "The request body is not valid JSON." }, { status: 400 });
  return unavailableResponse(error, fallback);
}

/** Log the real failure and, off production, return it so Preview Network can show the cause. */
export function unavailableResponse(error: unknown, fallback: string) {
  console.error(fallback, {
    name: error instanceof Error ? error.name : typeof error,
    message: error instanceof Error ? error.message : String(error),
    databaseUrlConfigured: Boolean(process.env.DATABASE_URL),
    vercelEnv: process.env.VERCEL_ENV ?? "local",
  });
  if (error instanceof Error && error.stack) console.error(error.stack);
  return NextResponse.json(
    process.env.VERCEL_ENV === "production"
      ? { error: fallback }
      : {
          error: fallback,
          detail: error instanceof Error ? error.message : String(error),
        },
    { status: 503 },
  );
}