/**
 * Tests for AppInitPage isSessionReady Logic
 *
 * These tests ensure the AppInitPage properly waits for session validation
 * before rendering protected routes. This prevents the ProtectedRoute from
 * making redirect decisions based on stale isAuthenticated state.
 *
 * The isSessionReady logic:
 * - Returns true immediately if autoLogin === true (auto-login mode handles its own timing)
 * - Returns isSessionFetched if autoLogin === false (wait for session validation)
 * - Returns false otherwise (initial state, wait for autoLogin to be determined)
 */

import { renderHook } from "@testing-library/react";
import { useMemo } from "react";

// Helper hook to test isSessionReady logic in isolation
function useIsSessionReady(
  autoLogin: boolean | undefined,
  isSessionFetched: boolean,
) {
  return useMemo(() => {
    if (autoLogin === true) {
      return true;
    }
    if (autoLogin === false) {
      return isSessionFetched;
    }
    return false;
  }, [autoLogin, isSessionFetched]);
}

describe("AppInitPage - isSessionReady Logic", () => {
  describe("Auto-Login Mode (autoLogin === true)", () => {
    it("should_return_true_immediately_when_autoLogin_is_true", () => {
      // Arrange
      const autoLogin = true;
      const isSessionFetched = false;

      // Act
      const { result } = renderHook(() =>
        useIsSessionReady(autoLogin, isSessionFetched),
      );

      // Assert: In auto-login mode, we don't wait for session validation
      // because auto-login handles its own retry logic
      expect(result.current).toBe(true);
    });

    it("should_return_true_regardless_of_isSessionFetched_when_autoLogin_is_true", () => {
      // Arrange
      const autoLogin = true;

      // Act & Assert: Both cases should return true
      const { result: result1 } = renderHook(() =>
        useIsSessionReady(autoLogin, false),
      );
      const { result: result2 } = renderHook(() =>
        useIsSessionReady(autoLogin, true),
      );

      expect(result1.current).toBe(true);
      expect(result2.current).toBe(true);
    });
  });

  describe("Manual Login Mode (autoLogin === false)", () => {
    it("should_return_false_when_session_not_yet_fetched", () => {
      // Arrange
      const autoLogin = false;
      const isSessionFetched = false;

      // Act
      const { result } = renderHook(() =>
        useIsSessionReady(autoLogin, isSessionFetched),
      );

      // Assert: Must wait for session validation before rendering routes
      expect(result.current).toBe(false);
    });

    it("should_return_true_when_session_has_been_fetched", () => {
      // Arrange
      const autoLogin = false;
      const isSessionFetched = true;

      // Act
      const { result } = renderHook(() =>
        useIsSessionReady(autoLogin, isSessionFetched),
      );

      // Assert: Session validated, safe to render routes
      expect(result.current).toBe(true);
    });

    it("should_block_rendering_until_session_validation_completes", () => {
      // This is the critical fix for the race condition
      // Old behavior: rendered immediately, ProtectedRoute saw isAuthenticated=false
      // New behavior: waits for isSessionFetched=true

      // Arrange: Session not yet validated
      const autoLogin = false;
      const isSessionFetched = false;

      // Act
      const { result } = renderHook(() =>
        useIsSessionReady(autoLogin, isSessionFetched),
      );

      // Assert: Should block rendering
      expect(result.current).toBe(false);
    });
  });

  describe("Initial State (autoLogin === undefined)", () => {
    it("should_return_false_when_autoLogin_is_undefined", () => {
      // Arrange
      const autoLogin = undefined;
      const isSessionFetched = false;

      // Act
      const { result } = renderHook(() =>
        useIsSessionReady(autoLogin, isSessionFetched),
      );

      // Assert: Wait for autoLogin to be determined
      expect(result.current).toBe(false);
    });

    it("should_return_false_even_if_session_fetched_when_autoLogin_undefined", () => {
      // Arrange: Session is fetched but autoLogin not yet determined
      const autoLogin = undefined;
      const isSessionFetched = true;

      // Act
      const { result } = renderHook(() =>
        useIsSessionReady(autoLogin, isSessionFetched),
      );

      // Assert: Still wait for autoLogin determination
      expect(result.current).toBe(false);
    });
  });

  describe("State Transitions", () => {
    it("should_transition_from_not_ready_to_ready_when_session_fetched", () => {
      // Arrange: Start with session not fetched
      const autoLogin = false;
      let isSessionFetched = false;

      // Act: Initial state
      const { result, rerender } = renderHook(
        ({ sessionFetched }) => useIsSessionReady(autoLogin, sessionFetched),
        { initialProps: { sessionFetched: isSessionFetched } },
      );

      expect(result.current).toBe(false);

      // Act: Session fetched
      isSessionFetched = true;
      rerender({ sessionFetched: isSessionFetched });

      // Assert: Now ready
      expect(result.current).toBe(true);
    });

    it("should_transition_from_not_ready_to_ready_when_autoLogin_becomes_true", () => {
      // Arrange
      let autoLogin: boolean | undefined = undefined;
      const isSessionFetched = false;

      // Act: Initial state
      const { result, rerender } = renderHook(
        ({ auto }) => useIsSessionReady(auto, isSessionFetched),
        { initialProps: { auto: autoLogin } },
      );

      expect(result.current).toBe(false);

      // Act: autoLogin determined to be true
      autoLogin = true;
      rerender({ auto: autoLogin });

      // Assert: Now ready (auto-login mode)
      expect(result.current).toBe(true);
    });
  });

  describe("Race Condition Prevention", () => {
    it("should_prevent_premature_route_rendering_in_new_tab_scenario", () => {
      // Scenario: User clicks MCP Server button, opens new tab
      // Initial state: autoLogin=undefined, isSessionFetched=false

      // Arrange: New tab initial state
      const autoLogin = undefined;
      const isSessionFetched = false;

      // Act
      const { result } = renderHook(() =>
        useIsSessionReady(autoLogin, isSessionFetched),
      );

      // Assert: Should NOT render routes yet
      // This prevents ProtectedRoute from redirecting based on stale state
      expect(result.current).toBe(false);
    });

    it("should_only_allow_rendering_after_proper_initialization_sequence", () => {
      // Arrange: Simulate the proper initialization sequence
      let autoLogin: boolean | undefined = undefined;
      let isSessionFetched = false;

      const { result, rerender } = renderHook(
        ({ auto, fetched }) => useIsSessionReady(auto, fetched),
        { initialProps: { auto: autoLogin, fetched: isSessionFetched } },
      );

      // Step 1: Initial state - not ready
      expect(result.current).toBe(false);

      // Step 2: autoLogin determined (manual mode)
      autoLogin = false;
      rerender({ auto: autoLogin, fetched: isSessionFetched });
      expect(result.current).toBe(false);

      // Step 3: Session validated - now ready
      isSessionFetched = true;
      rerender({ auto: autoLogin, fetched: isSessionFetched });
      expect(result.current).toBe(true);
    });
  });

  describe("Edge Cases", () => {
    it("should_handle_null_autoLogin_as_undefined", () => {
      // Arrange
      const autoLogin = null as unknown as undefined;
      const isSessionFetched = true;

      // Act
      const { result } = renderHook(() =>
        useIsSessionReady(autoLogin, isSessionFetched),
      );

      // Assert: Treat null same as undefined
      expect(result.current).toBe(false);
    });

    it("should_be_memoized_and_not_cause_unnecessary_rerenders", () => {
      // Arrange
      const autoLogin = false;
      const isSessionFetched = true;

      // Act
      const { result, rerender } = renderHook(() =>
        useIsSessionReady(autoLogin, isSessionFetched),
      );

      const firstValue = result.current;

      // Rerender with same values
      rerender();

      // Assert: Same reference
      expect(result.current).toBe(firstValue);
    });
  });
});

describe("AppInitPage - isReady Combined Logic", () => {
  // Helper to simulate the full isReady condition
  function useIsReady(
    isFetched: boolean,
    isExamplesFetched: boolean,
    isSessionReady: boolean,
  ) {
    return isFetched && isExamplesFetched && isSessionReady;
  }

  it("should_only_be_ready_when_all_conditions_are_true", () => {
    // All true
    expect(useIsReady(true, true, true)).toBe(true);

    // Any false
    expect(useIsReady(false, true, true)).toBe(false);
    expect(useIsReady(true, false, true)).toBe(false);
    expect(useIsReady(true, true, false)).toBe(false);
    expect(useIsReady(false, false, false)).toBe(false);
  });

  it("should_block_rendering_when_session_not_ready_even_if_other_fetches_complete", () => {
    // Arrange: Other fetches complete but session not ready
    const isFetched = true;
    const isExamplesFetched = true;
    const isSessionReady = false; // Session validation pending

    // Assert: Should not render
    expect(useIsReady(isFetched, isExamplesFetched, isSessionReady)).toBe(
      false,
    );
  });
});

describe("Integration: Full Initialization Flow", () => {
  // Standalone helper for integration tests
  function computeIsSessionReady(
    autoLogin: boolean | undefined,
    isSessionFetched: boolean,
  ): boolean {
    if (autoLogin === true) {
      return true;
    }
    if (autoLogin === false) {
      return isSessionFetched;
    }
    return false;
  }

  it("should_follow_correct_initialization_order_for_manual_login", () => {
    // This test documents the expected initialization flow

    // Step 1: Initial state
    const state1 = {
      autoLogin: undefined as boolean | undefined,
      isSessionFetched: false,
      isFetched: false,
      isExamplesFetched: false,
    };

    let isSessionReady = computeIsSessionReady(
      state1.autoLogin,
      state1.isSessionFetched,
    );
    expect(isSessionReady).toBe(false);

    // Step 2: useGetAutoLogin completes, determines manual login mode
    const state2 = { ...state1, autoLogin: false, isFetched: true };
    isSessionReady = computeIsSessionReady(
      state2.autoLogin,
      state2.isSessionFetched,
    );
    expect(isSessionReady).toBe(false); // Still waiting for session

    // Step 3: useGetAuthSession completes
    const state3 = { ...state2, isSessionFetched: true };
    isSessionReady = computeIsSessionReady(
      state3.autoLogin,
      state3.isSessionFetched,
    );
    expect(isSessionReady).toBe(true); // Now ready!
  });

  it("should_follow_correct_initialization_order_for_auto_login", () => {
    // Step 1: Initial state
    const state1 = {
      autoLogin: undefined as boolean | undefined,
      isSessionFetched: false,
    };

    let isSessionReady = computeIsSessionReady(
      state1.autoLogin,
      state1.isSessionFetched,
    );
    expect(isSessionReady).toBe(false);

    // Step 2: useGetAutoLogin completes, determines auto-login mode
    const state2 = { ...state1, autoLogin: true };
    isSessionReady = computeIsSessionReady(
      state2.autoLogin,
      state2.isSessionFetched,
    );
    expect(isSessionReady).toBe(true); // Ready immediately in auto-login mode!
  });
});
