import { NextRequest, NextResponse } from "next/server";
import { ZodError } from "zod";
import { requestOrigin } from "./request-origin";
import { getSessionUser } from "./session";

export class ApiError extends Error {
  constructor(public status: number, message: string, public code = "request_error") {
    super(message);
  }
}

export function requireSameOrigin(request: Request) {
  const origin = request.headers.get("origin");
  if (origin && origin !== requestOrigin(request)) throw new ApiError(403, "Cross-origin mutation rejected.", "origin_rejected");
}

export async function requireUser(request: NextRequest) {
  const session = await getSessionUser(request);
  if (!session) throw new ApiError(401, "Authentication required.", "authentication_required");
  if (!session.user.emailVerifiedAt) throw new ApiError(403, "Verify your email before continuing.", "email_unverified");
  return session.user;
}

export async function readJsonObject(request: Request) {
  let value: unknown;
  try {
    value = await request.json();
  } catch {
    throw new ApiError(400, "Request body must be valid JSON.", "invalid_json");
  }
  if (!value || typeof value !== "object" || Array.isArray(value)) {
    throw new ApiError(400, "Request body must be a JSON object.", "invalid_body");
  }
  return value;
}

export function apiResponseError(error: unknown) {
  if (error instanceof ApiError) {
    return NextResponse.json({ error: error.message, code: error.code }, { status: error.status });
  }
  if (error instanceof ZodError) {
    return NextResponse.json({ error: "Invalid request.", code: "validation_error", issues: error.flatten() }, { status: 400 });
  }
  console.error(error);
  return NextResponse.json({ error: "Unexpected server error.", code: "internal_error" }, { status: 500 });
}

export function parseLimit(value: string | null, fallback = 20, max = 50) {
  const limit = Number(value ?? fallback);
  if (!Number.isInteger(limit) || limit < 1 || limit > max) throw new ApiError(400, `limit must be between 1 and ${max}.`, "validation_error");
  return limit;
}