import { describe, it, expect, beforeEach, vi } from "vitest";
import { ExecutionContext, UnauthorizedException } from "@nestjs/common";

// Mock better-auth modules before importing AuthGuard (which imports AuthService)
vi.mock("better-auth/node", () => ({
  toNodeHandler: vi.fn().mockReturnValue(vi.fn()),
}));

vi.mock("better-auth", () => ({
  betterAuth: vi.fn().mockReturnValue({
    handler: vi.fn(),
    api: { getSession: vi.fn() },
  }),
}));

vi.mock("better-auth/adapters/prisma", () => ({
  prismaAdapter: vi.fn().mockReturnValue({}),
}));

vi.mock("better-auth/plugins", () => ({
  genericOAuth: vi.fn().mockReturnValue({ id: "generic-oauth" }),
}));

import { AuthGuard } from "./auth.guard";
import type { AuthService } from "../auth.service";

describe("AuthGuard", () => {
  let guard: AuthGuard;

  const mockAuthService = {
    verifySession: vi.fn(),
  };

  beforeEach(() => {
    // Directly construct the guard with the mock to avoid NestJS DI issues
    guard = new AuthGuard(mockAuthService as unknown as AuthService);

    vi.clearAllMocks();
  });

  const createMockExecutionContext = (
    headers: Record<string, string> = {},
    cookies: Record<string, string> = {}
  ): ExecutionContext => {
    const mockRequest = {
      headers,
      cookies,
    };

    return {
      switchToHttp: () => ({
        getRequest: () => mockRequest,
      }),
    } as ExecutionContext;
  };

  describe("canActivate", () => {
    const mockSessionData = {
      user: {
        id: "user-123",
        email: "test@example.com",
        name: "Test User",
      },
      session: {
        id: "session-123",
        token: "session-token",
        expiresAt: new Date(Date.now() + 86400000),
      },
    };

    describe("Bearer token authentication", () => {
      it("should return true for valid Bearer token", async () => {
        mockAuthService.verifySession.mockResolvedValue(mockSessionData);

        const context = createMockExecutionContext({
          authorization: "Bearer valid-token",
        });

        const result = await guard.canActivate(context);

        expect(result).toBe(true);
        expect(mockAuthService.verifySession).toHaveBeenCalledWith("valid-token");
      });

      it("should throw UnauthorizedException for invalid Bearer token", async () => {
        mockAuthService.verifySession.mockResolvedValue(null);

        const context = createMockExecutionContext({
          authorization: "Bearer invalid-token",
        });

        await expect(guard.canActivate(context)).rejects.toThrow(UnauthorizedException);
        await expect(guard.canActivate(context)).rejects.toThrow("Invalid or expired session");
      });
    });

    describe("Cookie-based authentication", () => {
      it("should return true for valid session cookie", async () => {
        mockAuthService.verifySession.mockResolvedValue(mockSessionData);

        const context = createMockExecutionContext(
          {},
          {
            "better-auth.session_token": "cookie-token",
          }
        );

        const result = await guard.canActivate(context);

        expect(result).toBe(true);
        expect(mockAuthService.verifySession).toHaveBeenCalledWith("cookie-token");
      });

      it("should prefer cookie over Bearer token when both present", async () => {
        mockAuthService.verifySession.mockResolvedValue(mockSessionData);

        const context = createMockExecutionContext(
          {
            authorization: "Bearer bearer-token",
          },
          {
            "better-auth.session_token": "cookie-token",
          }
        );

        const result = await guard.canActivate(context);

        expect(result).toBe(true);
        expect(mockAuthService.verifySession).toHaveBeenCalledWith("cookie-token");
      });

      it("should fallback to Bearer token if no cookie", async () => {
        mockAuthService.verifySession.mockResolvedValue(mockSessionData);

        const context = createMockExecutionContext(
          {
            authorization: "Bearer bearer-token",
          },
          {}
        );

        const result = await guard.canActivate(context);

        expect(result).toBe(true);
        expect(mockAuthService.verifySession).toHaveBeenCalledWith("bearer-token");
      });
    });

    describe("Error handling", () => {
      it("should throw UnauthorizedException if no token provided", async () => {
        const context = createMockExecutionContext({}, {});

        await expect(guard.canActivate(context)).rejects.toThrow(UnauthorizedException);
        await expect(guard.canActivate(context)).rejects.toThrow(
          "No authentication token provided"
        );
      });

      it("should propagate non-auth errors as-is (not wrap as 401)", async () => {
        const infraError = new Error("connect ECONNREFUSED 127.0.0.1:5432");
        mockAuthService.verifySession.mockRejectedValue(infraError);

        const context = createMockExecutionContext({
          authorization: "Bearer error-token",
        });

        await expect(guard.canActivate(context)).rejects.toThrow(infraError);
        await expect(guard.canActivate(context)).rejects.not.toBeInstanceOf(UnauthorizedException);
      });

      it("should propagate database errors so GlobalExceptionFilter returns 500", async () => {
        const dbError = new Error("PrismaClientKnownRequestError: Connection refused");
        mockAuthService.verifySession.mockRejectedValue(dbError);

        const context = createMockExecutionContext({
          authorization: "Bearer valid-token",
        });

        await expect(guard.canActivate(context)).rejects.toThrow(dbError);
        await expect(guard.canActivate(context)).rejects.not.toBeInstanceOf(UnauthorizedException);
      });

      it("should propagate timeout errors so GlobalExceptionFilter returns 503", async () => {
        const timeoutError = new Error("Connection timeout after 5000ms");
        mockAuthService.verifySession.mockRejectedValue(timeoutError);

        const context = createMockExecutionContext({
          authorization: "Bearer valid-token",
        });

        await expect(guard.canActivate(context)).rejects.toThrow(timeoutError);
        await expect(guard.canActivate(context)).rejects.not.toBeInstanceOf(UnauthorizedException);
      });
    });

    describe("user data validation", () => {
      const mockSession = {
        id: "session-123",
        token: "session-token",
        expiresAt: new Date(Date.now() + 86400000),
      };

      it("should throw UnauthorizedException when user is missing id", async () => {
        mockAuthService.verifySession.mockResolvedValue({
          user: { email: "a@b.com", name: "Test" },
          session: mockSession,
        });

        const context = createMockExecutionContext({
          authorization: "Bearer valid-token",
        });

        await expect(guard.canActivate(context)).rejects.toThrow(UnauthorizedException);
        await expect(guard.canActivate(context)).rejects.toThrow(
          "Invalid user data in session"
        );
      });

      it("should throw UnauthorizedException when user is missing email", async () => {
        mockAuthService.verifySession.mockResolvedValue({
          user: { id: "1", name: "Test" },
          session: mockSession,
        });

        const context = createMockExecutionContext({
          authorization: "Bearer valid-token",
        });

        await expect(guard.canActivate(context)).rejects.toThrow(UnauthorizedException);
        await expect(guard.canActivate(context)).rejects.toThrow(
          "Invalid user data in session"
        );
      });

      it("should throw UnauthorizedException when user is missing name", async () => {
        mockAuthService.verifySession.mockResolvedValue({
          user: { id: "1", email: "a@b.com" },
          session: mockSession,
        });

        const context = createMockExecutionContext({
          authorization: "Bearer valid-token",
        });

        await expect(guard.canActivate(context)).rejects.toThrow(UnauthorizedException);
        await expect(guard.canActivate(context)).rejects.toThrow(
          "Invalid user data in session"
        );
      });

      it("should throw UnauthorizedException when user is a string", async () => {
        mockAuthService.verifySession.mockResolvedValue({
          user: "not-an-object",
          session: mockSession,
        });

        const context = createMockExecutionContext({
          authorization: "Bearer valid-token",
        });

        await expect(guard.canActivate(context)).rejects.toThrow(UnauthorizedException);
        await expect(guard.canActivate(context)).rejects.toThrow(
          "Invalid user data in session"
        );
      });

      it("should reject when user is null (typeof null === 'object' causes TypeError on 'in' operator)", async () => {
        // Note: typeof null === "object" in JS, so the guard's typeof check passes
        // but "id" in null throws TypeError. The catch block propagates non-auth errors as-is.
        mockAuthService.verifySession.mockResolvedValue({
          user: null,
          session: mockSession,
        });

        const context = createMockExecutionContext({
          authorization: "Bearer valid-token",
        });

        await expect(guard.canActivate(context)).rejects.toThrow(TypeError);
        await expect(guard.canActivate(context)).rejects.not.toBeInstanceOf(
          UnauthorizedException
        );
      });
    });

    describe("request attachment", () => {
      it("should attach user and session to request on success", async () => {
        mockAuthService.verifySession.mockResolvedValue(mockSessionData);

        const mockRequest = {
          headers: {
            authorization: "Bearer valid-token",
          },
          cookies: {},
        };

        const context = {
          switchToHttp: () => ({
            getRequest: () => mockRequest,
          }),
        } as ExecutionContext;

        await guard.canActivate(context);

        expect(mockRequest).toHaveProperty("user", mockSessionData.user);
        expect(mockRequest).toHaveProperty("session", mockSessionData.session);
      });
    });
  });
});