import { NextRequest, NextResponse } from "next/server";
import { requireAdmin } from "@/lib/api-auth";
import { auth } from "@/lib/auth/server";
import { db, users, auditLogs, eq } from "@epicure/db";
import { createInvite, consumeInvite, INVITE_COOKIE } from "@/lib/invites";
import { randomBytes, randomUUID } from "crypto";
import { APIError } from "better-auth";

const VALID_ROLES = ["user", "moderator", "admin"] as const;
const VALID_TIERS = ["free", "pro", "family"] as const;

export async function POST(req: NextRequest) {
  const { session, response } = await requireAdmin();
  if (response) return response;

  const body = (await req.json()) as {
    email?: string;
    name?: string;
    role?: string;
    tier?: string;
  };

  const email = body.email?.trim().toLowerCase();
  const name = body.name?.trim();
  const role = body.role ?? "user";
  const tier = body.tier ?? "free";

  if (!email || !name) {
    return NextResponse.json({ error: "email and name are required" }, { status: 400 });
  }
  if (!VALID_ROLES.includes(role as (typeof VALID_ROLES)[number])) {
    return NextResponse.json({ error: "Invalid role" }, { status: 400 });
  }
  if (!VALID_TIERS.includes(tier as (typeof VALID_TIERS)[number])) {
    return NextResponse.json({ error: "Invalid tier" }, { status: 400 });
  }

  const [existing] = await db.select({ id: users.id }).from(users).where(eq(users.email, email));
  if (existing) {
    return NextResponse.json({ error: "A user with this email already exists" }, { status: 409 });
  }

  // Route creation through the same invite gate the public signup flow uses,
  // so it works identically whether signups are currently open or closed —
  // and so role/tier assignment goes through the one audited code path.
  const invite = await createInvite({
    createdById: session!.user.id,
    email,
    role: role as (typeof VALID_ROLES)[number],
    tier: tier as (typeof VALID_TIERS)[number],
    expiresInDays: 1,
  });

  const temporaryPassword = randomBytes(24).toString("base64url");

  try {
    await auth.api.signUpEmail({
      body: { email, name, password: temporaryPassword },
      headers: new Headers({ cookie: `${INVITE_COOKIE}=${invite!.token}` }),
    });
  } catch (err) {
    if (err instanceof APIError) {
      return NextResponse.json({ error: err.message }, { status: err.statusCode ?? 400 });
    }
    throw err;
  }

  const [created] = await db
    .update(users)
    .set({ emailVerified: true })
    .where(eq(users.email, email))
    .returning();

  if (!created) {
    return NextResponse.json({ error: "User creation failed" }, { status: 500 });
  }

  // The invite gate only consumes on the databaseHooks "after" path when a
  // cookie is present on a real request; belt-and-suspenders it here too.
  await consumeInvite(invite!.id, created.id);

  // Let the new user set their own password instead of the admin knowing it.
  await auth.api.requestPasswordReset({
    body: { email, redirectTo: "/reset-password" },
  });

  await db.insert(auditLogs).values({
    id: randomUUID(),
    userId: session!.user.id,
    action: "admin.user.create",
    targetType: "user",
    targetId: created.id,
    metadata: JSON.stringify({ email, role, tier }),
    createdAt: new Date(),
  });

  return NextResponse.json({
    user: { id: created.id, email: created.email, name: created.name, role: created.role, tier: created.tier },
  });
}