// TestSignals_Semapore.pas
unit TestSignals_Semapore;

interface

uses
  DUnitX.TestFramework,
  Myc.Signals, // Unit under test
  System.SysUtils,
  System.StrUtils; // For BoolToStr (though not used in asserts anymore)

type
  // Helper class to mock a subscriber.
  TMockSubscriber = class(TInterfacedObject, IMycSubscriber)
  public
    NotifyCount: Integer;
    NotifyShouldReturn: Boolean;
    WasCalled: Boolean;

    constructor Create(ShouldReturn: Boolean = True);
    function Notify: Boolean; // IMycSubscriber implementation.
  end;

  [TestFixture]
  TTestMycSemaphore = class(TObject)
  public
    [Setup]
    procedure Setup;
    [TearDown]
    procedure TearDown;

    // --- Category 1: Basic Counter and State Functionality (Parameterized) ---
    [TestCase('InitialPositive', '1,False')]
    [TestCase('InitialZero', '0,True')]
    [TestCase('InitialNegative', '-1,True')]
    [TestCase('InitialLargePositive', '5,False')]
    procedure TestCreate_InitialState(InitialCount: Integer; ExpectedIsSet: Boolean);

    [TestCase('DecrementPositiveToZero', '1,False,True')]
    [TestCase('DecrementPositiveToPositive', '2,True,False')]
    [TestCase('DecrementZeroToNegative', '0,False,True')]
    [TestCase('DecrementNegativeToNegative', '-1,False,True')]
    procedure TestNotify_ReturnValueAndState_AfterOneNotify(InitialCount: Integer; ExpectedReturn: Boolean; ExpectedIsSet: Boolean);

    [Test]
    procedure TestNotify_DecrementsCounter_StateChanges;
    [Test]
    procedure TestNotify_MultipleNotifies_CounterBecomesNegativeAndStaysSet;

    // --- Category 2: Notification to Subscribers ---
    [Test]
    procedure TestSubscriber_Single_IsNotifiedWhenSet;
    [Test]
    procedure TestSubscriber_Multiple_AreNotifiedWhenSet;
    [Test]
    procedure TestSubscriber_NotNotified_BeforeSet;
    [Test]
    procedure TestSubscriber_NotifiedOnlyOnce_AfterFinalization;
    [Test]
    procedure TestSubscribe_AfterFinalization_SubscriberNotNotified;

    // --- Category 3: Chaining and Cascading ---
    [Test]
    procedure TestChaining_A_Notifies_B;
    [Test]
    procedure TestCascade_A_Notifies_B_Notifies_C;
    [Test]
    procedure TestChaining_B_NeedsMultipleSignalsFromA_WithSubscriberOnB;

    // --- Category 4: Special Cases ---
    [Test]
    procedure TestInitiallySet_NotifiesNewSubscriberImmediately;

    [Test]
    procedure TestUnsubscribe_SubscriberNotNotified;

    // --- Category 5: Signal Loss / Counter Integrity ---
    [Test]
    procedure TestMultipleTriggersNoSubscriber_StateCorrectForLaterSubscriber;
  end;

implementation

{ TMockSubscriber }

constructor TMockSubscriber.Create(ShouldReturn: Boolean = True);
begin
  inherited Create;
  NotifyCount := 0;
  NotifyShouldReturn := ShouldReturn;
  WasCalled := False;
end;

function TMockSubscriber.Notify: Boolean;
begin
  Inc(NotifyCount);
  WasCalled := True;
  Result := NotifyShouldReturn;
end;

{ TTestMycSemaphore }

procedure TTestMycSemaphore.Setup;
begin
  // Per-test setup code can go here (if any).
end;

procedure TTestMycSemaphore.TearDown;
begin
  // Per-test teardown code can go here (if any).
end;

procedure TTestMycSemaphore.TestCreate_InitialState(InitialCount: Integer; ExpectedIsSet: Boolean);
var
  semaphore: IMycSemaphore;
begin
  semaphore := Signals.CreateSemaphore(InitialCount);
  Assert.AreEqual(ExpectedIsSet, semaphore.State.IsSet, 'Semaphore initial IsSet state mismatch.');
end;

procedure TTestMycSemaphore.TestNotify_ReturnValueAndState_AfterOneNotify(InitialCount: Integer; ExpectedReturn: Boolean; ExpectedIsSet: Boolean);
var
  semaphore: IMycSemaphore;
  returnedValue: Boolean;
begin
  semaphore := Signals.CreateSemaphore(InitialCount);
  returnedValue := semaphore.Notify;

  Assert.AreEqual(ExpectedReturn, returnedValue, 'Unexpected return value after one Notify call.');
  Assert.AreEqual(ExpectedIsSet, semaphore.State.IsSet, 'Unexpected IsSet state after one Notify call.');
end;

procedure TTestMycSemaphore.TestNotify_DecrementsCounter_StateChanges;
var
  semaphore: IMycSemaphore;
begin
  semaphore := Signals.CreateSemaphore(1);
  Assert.IsFalse(semaphore.State.IsSet, 'Semaphore should initially not be set.');
  semaphore.Notify;
  Assert.IsTrue(semaphore.State.IsSet, 'Semaphore should be set after Notify.');
end;

procedure TTestMycSemaphore.TestNotify_MultipleNotifies_CounterBecomesNegativeAndStaysSet;
var
  semaphore: IMycSemaphore;
begin
  semaphore := Signals.CreateSemaphore(1);
  semaphore.Notify;
  Assert.IsTrue(semaphore.State.IsSet, 'Semaphore should be set after first Notify.');
  semaphore.Notify;
  Assert.IsTrue(semaphore.State.IsSet, 'Semaphore should remain set after second Notify.');
end;

procedure TTestMycSemaphore.TestSubscriber_Single_IsNotifiedWhenSet;
var
  semaphore: IMycSemaphore;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  semaphore := Signals.CreateSemaphore(1);
  mockSub := TMockSubscriber.Create;
  subscription := semaphore.State.Subscribe(mockSub);

  Assert.IsFalse(semaphore.State.IsSet, 'Semaphore should initially not be set.');
  Assert.AreEqual(0, mockSub.NotifyCount, 'MockSub should not have been notified yet (before set).');

  semaphore.Notify;

  Assert.IsTrue(semaphore.State.IsSet, 'Semaphore should be set after its Notify is called.');
  Assert.AreEqual(1, mockSub.NotifyCount, 'MockSub should have been notified once when semaphore becomes set.');
end;

procedure TTestMycSemaphore.TestSubscriber_Multiple_AreNotifiedWhenSet;
var
  semaphore: IMycSemaphore;
  mockSub1, mockSub2, mockSub3: TMockSubscriber;
  sub1, sub2, sub3: TMycSubscription;
begin
  semaphore := Signals.CreateSemaphore(1);
  mockSub1 := TMockSubscriber.Create;
  mockSub2 := TMockSubscriber.Create;
  mockSub3 := TMockSubscriber.Create;

  sub1 := semaphore.State.Subscribe(mockSub1);
  sub2 := semaphore.State.Subscribe(mockSub2);
  sub3 := semaphore.State.Subscribe(mockSub3);

  semaphore.Notify;

  Assert.AreEqual(1, mockSub1.NotifyCount, 'MockSub1 notification count mismatch.');
  Assert.AreEqual(1, mockSub2.NotifyCount, 'MockSub2 notification count mismatch.');
  Assert.AreEqual(1, mockSub3.NotifyCount, 'MockSub3 notification count mismatch.');
end;

procedure TTestMycSemaphore.TestSubscriber_NotNotified_BeforeSet;
var
  semaphore: IMycSemaphore;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  semaphore := Signals.CreateSemaphore(2);
  mockSub := TMockSubscriber.Create;
  subscription := semaphore.State.Subscribe(mockSub);

  Assert.AreEqual(0, mockSub.NotifyCount, 'MockSub should not be notified upon subscription if semaphore is not set.');
  semaphore.Notify; // Count becomes 1, still not set for subscriber notification (unless Subscribe was changed to notify if count becomes 0 internally).
  Assert.AreEqual(0, mockSub.NotifyCount, 'MockSub should still not be notified as semaphore is not yet set for subscribers.');
end;

procedure TTestMycSemaphore.TestSubscriber_NotifiedOnlyOnce_AfterFinalization;
var
  semaphore: IMycSemaphore;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  semaphore := Signals.CreateSemaphore(1);
  mockSub := TMockSubscriber.Create;
  subscription := semaphore.State.Subscribe(mockSub);

  semaphore.Notify; // Sets semaphore, notifies MockSub. Assumed TMycSignal's list is finalized by this action.
  Assert.AreEqual(1, mockSub.NotifyCount, 'MockSub notify count should be 1 after first signal set.');

  semaphore.Notify; // Trigger again.
  Assert.AreEqual(1, mockSub.NotifyCount, 'MockSub notify count should remain 1 after re-triggering finalized signal.');
end;

procedure TTestMycSemaphore.TestSubscribe_AfterFinalization_SubscriberNotNotified;
var
  semaphore: IMycSemaphore;
  mockSub1, mockSub2: TMockSubscriber;
  subscription1, subscription2: TMycSubscription;
begin
  semaphore := Signals.CreateSemaphore(1);

  mockSub1 := TMockSubscriber.Create;
  subscription1 := semaphore.State.Subscribe(mockSub1);

  semaphore.Notify; // Triggers semaphore. It becomes set.
                    // Its TMycSignal part notifies mockSub1.
                    // And its TMycSignal part is assumed to be finalized.

  Assert.IsTrue(semaphore.State.IsSet, 'Semaphore should be set after initial trigger.');
  Assert.AreEqual(1, mockSub1.NotifyCount, 'MockSub1 should have been notified once.');

  // Attempt to subscribe mockSub2 after the signal (TMycSignal part) has been finalized.
  mockSub2 := TMockSubscriber.Create;
  subscription2 := semaphore.State.Subscribe(mockSub2);

  // Current assertion in user-provided code expects mockSub2 to be notified.
  // This implies that Myc.Signals.Subscribe has specific logic to achieve this,
  // even if the underlying TMycNotifyList might have been finalized for mockSub1's notification.
  Assert.AreEqual(1, mockSub2.NotifyCount, 'MockSub2 should be notified upon subscribing to an already set signal.');

  semaphore.Notify; // Re-triggering the semaphore's count decrement.
  Assert.AreEqual(1, mockSub1.NotifyCount, 'MockSub1 notify count should remain 1 (not notified again).');
  // Current assertion in user-provided code expects mockSub2's count to also remain 1.
  Assert.AreEqual(1, mockSub2.NotifyCount, 'MockSub2 notify count should remain 1 after re-triggering.');
end;

procedure TTestMycSemaphore.TestChaining_A_Notifies_B;
var
  semaA, semaB: IMycSemaphore;
  mockSubForB: TMockSubscriber;
  subHandle_B_listens_A, subHandle_Mock_listens_B: TMycSubscription;
begin
  semaA := Signals.CreateSemaphore(1);
  semaB := Signals.CreateSemaphore(1);
  mockSubForB := TMockSubscriber.Create;

  subHandle_Mock_listens_B := semaB.State.Subscribe(mockSubForB);
  subHandle_B_listens_A := semaA.State.Subscribe(semaB);

  Assert.IsFalse(semaA.State.IsSet, 'SemaA initially not set.');
  Assert.IsFalse(semaB.State.IsSet, 'SemaB initially not set.');
  Assert.AreEqual(0, mockSubForB.NotifyCount, 'MockSubForB initially not notified.');

  semaA.Notify;

  Assert.IsTrue(semaA.State.IsSet, 'SemaA should be set after notify.');
  Assert.IsTrue(semaB.State.IsSet, 'SemaB should be set after being notified by SemaA.');
  Assert.AreEqual(1, mockSubForB.NotifyCount, 'MockSubForB should have been notified by SemaB.');
end;

procedure TTestMycSemaphore.TestCascade_A_Notifies_B_Notifies_C;
var
  semaA, semaB, semaC: IMycSemaphore;
  mockSubForC: TMockSubscriber;
  sub_Mock_C, sub_C_B, sub_B_A: TMycSubscription;
begin
  semaA := Signals.CreateSemaphore(1);
  semaB := Signals.CreateSemaphore(1);
  semaC := Signals.CreateSemaphore(1);
  mockSubForC := TMockSubscriber.Create;

  sub_Mock_C := semaC.State.Subscribe(mockSubForC);
  sub_C_B    := semaB.State.Subscribe(semaC);
  sub_B_A    := semaA.State.Subscribe(semaB);

  semaA.Notify;

  Assert.IsTrue(semaA.State.IsSet, 'SemaA state mismatch in cascade.');
  Assert.IsTrue(semaB.State.IsSet, 'SemaB state mismatch in cascade.');
  Assert.IsTrue(semaC.State.IsSet, 'SemaC state mismatch in cascade.');
  Assert.AreEqual(1, mockSubForC.NotifyCount, 'MockSubForC notification count mismatch in cascade.');
end;

procedure TTestMycSemaphore.TestChaining_B_NeedsMultipleSignalsFromA_WithSubscriberOnB;
var
  semaA, semaB: IMycSemaphore;
  mockSubForB: TMockSubscriber;
  sub_Mock_B, sub_B_A: TMycSubscription;
begin
  semaA := Signals.CreateSemaphore(2);
  semaB := Signals.CreateSemaphore(1);
  mockSubForB := TMockSubscriber.Create;

  sub_Mock_B := semaB.State.Subscribe(mockSubForB);
  sub_B_A    := semaA.State.Subscribe(semaB);

  semaA.Notify; // First trigger for SemaA
  Assert.IsFalse(semaA.State.IsSet, 'SemaA should not be set after first trigger of two.');
  Assert.IsFalse(semaB.State.IsSet, 'SemaB should not have been triggered yet by SemaA.');
  Assert.AreEqual(0, mockSubForB.NotifyCount, 'MockSubForB should not have been notified yet.');

  semaA.Notify; // Second trigger for SemaA
  Assert.IsTrue(semaA.State.IsSet, 'SemaA should be set after second trigger.');
  Assert.IsTrue(semaB.State.IsSet, 'SemaB should now be set by SemaA.');
  Assert.AreEqual(1, mockSubForB.NotifyCount, 'MockSubForB should have been notified by SemaB.');
end;

procedure TTestMycSemaphore.TestInitiallySet_NotifiesNewSubscriberImmediately;
var
  semaphore: IMycSemaphore;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  semaphore := Signals.CreateSemaphore(0); // Semaphore is created in 'IsSet' state but not finalized.
  mockSub := TMockSubscriber.Create;

  // Assumes TMycSignal.Subscribe is modified to implement immediate notification for set signals.
  subscription := semaphore.State.Subscribe(mockSub);

  Assert.IsTrue(semaphore.State.IsSet, 'Semaphore IsSet property mismatch after creation with count 0.');
  Assert.AreEqual(1, mockSub.NotifyCount, 'MockSub should be notified immediately upon subscribing to an already set semaphore.');
end;

procedure TTestMycSemaphore.TestUnsubscribe_SubscriberNotNotified;
var
  semaphore: IMycSemaphore;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  semaphore := Signals.CreateSemaphore(1);
  mockSub := TMockSubscriber.Create;

  subscription := semaphore.State.Subscribe(mockSub);
  subscription := Default(TMycSubscription); // Simulates leaving scope / destruction, calls Finalize for unsubscription.

  semaphore.Notify;

  Assert.AreEqual(0, mockSub.NotifyCount, 'Unsubscribed MockSub should not be notified.');
end;

procedure TTestMycSemaphore.TestMultipleTriggersNoSubscriber_StateCorrectForLaterSubscriber;
var
  semaphore: IMycSemaphore;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  semaphore := Signals.CreateSemaphore(3);

  semaphore.Notify; // Count -> 2
  semaphore.Notify; // Count -> 1
  Assert.IsFalse(semaphore.State.IsSet, 'Semaphore should not be set yet after partial triggers.');

  mockSub := TMockSubscriber.Create;
  subscription := semaphore.State.Subscribe(mockSub);
  // Assumes TMycSignal.Subscribe does not notify immediately if signal is not yet set.
  Assert.AreEqual(0, mockSub.NotifyCount, 'MockSub should not be notified on subscribe if semaphore not yet set.');


  semaphore.Notify; // Count -> 0, Semaphore becomes set and notifies mockSub
  Assert.IsTrue(semaphore.State.IsSet, 'Semaphore should now be set.');
  Assert.AreEqual(1, mockSub.NotifyCount, 'MockSub should have been notified when semaphore becomes set.');
end;

initialization
  // Optional: Register test cases if not using automatic registration.
  // TDUnitX.RegisterTestFixture(TTestMycSemaphore);
end.