import { beforeEach, describe, expect, it, vi } from "vitest";
import type { Mock } from "vitest";
import type { Session } from "next-auth";

// The route handlers call auth() (src/auth.ts) directly to gate access (see
// src/app/api/requests/route.ts). That auth() reads cookies via
// next/headers under the hood, which only works inside Next.js's own
// request-handling machinery — not when these tests import and call
// GET()/POST() directly, bypassing Next entirely (the same reason
// middleware.ts itself isn't tested here; see CLAUDE.md's task notes).
// Mocking @/auth sidesteps next/headers altogether and lets each test
// control the session directly: a valid session by default (so the
// existing business-logic tests below are unaffected), and no session for
// the dedicated "returns 401" tests.
vi.mock("@/auth", () => ({ auth: vi.fn() }));

import { GET, POST } from "@/app/api/requests/route";
import { prisma } from "@/lib/prisma";
import { auth } from "@/auth";

// auth's real type is next-auth's overloaded call signature (RSC helper,
// middleware wrapper, API-route form, ...) — vi.mocked() picks the wrong
// overload to infer mock*Value's parameter type from, so cast to the one
// shape actually used here: the no-arg session-helper call the route
// handlers make.
const mockedAuth = auth as unknown as Mock<() => Promise<Session | null>>;

const testSession: Session = {
  user: { id: "test-user-id" },
  expires: new Date(Date.now() + 60 * 60 * 1000).toISOString(),
};

function postRequest(body: unknown): Request {
  return new Request("http://localhost/api/requests", {
    method: "POST",
    headers: { "content-type": "application/json" },
    body: JSON.stringify(body),
  });
}

// Request.employeeId is a real FK to Employee (see schema.prisma /
// src/lib/requests.ts) — tests that need a valid employee_id create a real
// Employee row first and use its id, rather than an arbitrary string.
function createTestEmployee(overrides: { name?: string; department?: string } = {}) {
  return prisma.employee.create({
    data: {
      name: overrides.name ?? "Test Employee",
      department: overrides.department ?? "IT",
    },
  });
}

beforeEach(async () => {
  // Each test starts from empty tables so listing/order assertions are
  // deterministic. requests must be cleared before employees since
  // requests.employee_id has an FK (ON DELETE RESTRICT) to employees.
  await prisma.request.deleteMany();
  await prisma.employee.deleteMany();
  // Default to a logged-in session — the tests below exercise request
  // business logic, not auth gating (that's covered by the "auth gating"
  // describe block further down).
  mockedAuth.mockResolvedValue(testSession);
});

describe("POST /api/requests", () => {
  it("creates a request in Draft status on valid input", async () => {
    const employee = await createTestEmployee();
    const res = await POST(
      postRequest({ employee_id: employee.id, type: "asset", reason: "New laptop for onboarding" })
    );

    expect(res.status).toBe(201);
    const body = await res.json();

    expect(body).toMatchObject({
      employee_id: employee.id,
      type: "asset",
      reason: "New laptop for onboarding",
      status: "Draft",
    });
    expect(typeof body.id).toBe("string");
    expect(body.id.length).toBeGreaterThan(0);
    expect(typeof body.created_at).toBe("string");
    expect(Number.isNaN(Date.parse(body.created_at))).toBe(false);
  });

  it("rejects requests with missing required fields", async () => {
    const res = await POST(postRequest({ employee_id: "", type: "asset", reason: "" }));

    expect(res.status).toBe(400);
    const body = await res.json();
    expect(typeof body.error).toBe("string");
    expect(body.error.length).toBeGreaterThan(0);
  });

  it("rejects requests missing the reason field entirely", async () => {
    const employee = await createTestEmployee();
    const res = await POST(postRequest({ employee_id: employee.id, type: "asset" }));

    expect(res.status).toBe(400);
    const body = await res.json();
    expect(typeof body.error).toBe("string");
  });

  it("rejects an invalid type value", async () => {
    const employee = await createTestEmployee();
    const res = await POST(
      postRequest({ employee_id: employee.id, type: "not-a-real-type", reason: "Something" })
    );

    expect(res.status).toBe(400);
    const body = await res.json();
    expect(body.error).toMatch(/type/i);
  });

  it("rejects an employee_id that is not a valid UUID", async () => {
    const res = await POST(
      postRequest({ employee_id: "emp-1", type: "asset", reason: "Something" })
    );

    expect(res.status).toBe(400);
    const body = await res.json();
    expect(body.error).toMatch(/employee_id/i);
  });

  it("rejects an employee_id that is a well-formed UUID but doesn't reference an existing employee", async () => {
    const res = await POST(
      postRequest({
        employee_id: "00000000-0000-0000-0000-000000000000",
        type: "asset",
        reason: "Something",
      })
    );

    expect(res.status).toBe(400);
    const body = await res.json();
    expect(body.error).toMatch(/employee_id/i);
    expect(body.error).toMatch(/does not reference an existing employee/i);

    // And it must not have created anything.
    const remaining = await prisma.request.findMany();
    expect(remaining).toHaveLength(0);
  });
});

describe("GET /api/requests", () => {
  it("lists created requests, newest first", async () => {
    const employee1 = await createTestEmployee({ name: "Employee One" });
    const employee2 = await createTestEmployee({ name: "Employee Two" });

    await POST(
      postRequest({ employee_id: employee1.id, type: "asset", reason: "First request" })
    );
    // Ensure a distinct created_at ordering even on fast filesystems/clocks.
    await new Promise((resolve) => setTimeout(resolve, 5));
    await POST(
      postRequest({ employee_id: employee2.id, type: "license", reason: "Second request" })
    );

    const res = await GET();
    expect(res.status).toBe(200);

    const body = await res.json();
    expect(Array.isArray(body)).toBe(true);
    expect(body).toHaveLength(2);

    // newest first
    expect(body[0]).toMatchObject({
      employee_id: employee2.id,
      type: "license",
      status: "Draft",
    });
    expect(body[1]).toMatchObject({
      employee_id: employee1.id,
      type: "asset",
      status: "Draft",
    });
  });

  it("returns an empty list when there are no requests", async () => {
    const res = await GET();
    expect(res.status).toBe(200);
    const body = await res.json();
    expect(body).toEqual([]);
  });
});

describe("auth gating on /api/requests", () => {
  // Route-level coverage for the "logged in or not" gate added alongside
  // middleware.ts (src/middleware.ts) — see that file's comment for why
  // page routes are gated via middleware but API routes gate themselves.
  // No role/permission logic here, per the flat permission model (any
  // logged-in user can do anything) — this only checks session presence.
  it("POST /api/requests returns 401 without a session", async () => {
    const employee = await createTestEmployee();
    mockedAuth.mockResolvedValue(null);

    const res = await POST(
      postRequest({
        employee_id: employee.id,
        type: "asset",
        reason: "New laptop for onboarding",
      })
    );

    expect(res.status).toBe(401);
    const body = await res.json();
    expect(body).toEqual({ error: "Unauthorized" });

    // And it must not have created anything.
    const remaining = await prisma.request.findMany();
    expect(remaining).toHaveLength(0);
  });

  it("GET /api/requests returns 401 without a session", async () => {
    mockedAuth.mockResolvedValue(null);

    const res = await GET();

    expect(res.status).toBe(401);
    const body = await res.json();
    expect(body).toEqual({ error: "Unauthorized" });
  });
});