unit TestSignals_Latch;

interface

uses
  DUnitX.TestFramework,
  Myc.Signals, // Unit under test, using TMycLatch static members
  System.SysUtils,
  System.StrUtils;

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]
  TTestMycLatch = 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')] // TMycLatch.CreateLatch(0) will return TMycLatch.Null
    [TestCase('InitialNegative', '-1,True')] // TMycLatch.CreateLatch(-1) will return TMycLatch.Null
    [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_IsNotifiedWhenLatchSet;
    [Test]
    procedure TestSubscriber_Multiple_AreNotifiedWhenLatchSet;
    [Test]
    procedure TestSubscriber_NotNotified_BeforeLatchSet;
    [Test]
    procedure TestSubscriber_NotifiedOnlyOnce_AfterLatchSet;
    [Test]
    procedure TestSubscribe_ToAlreadySetLatch_NotifiesImmediately;

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

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

{ TTestMycLatch }

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

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

procedure TTestMycLatch.TestCreate_InitialState(InitialCount: Integer; ExpectedIsSet: Boolean);
var
  latch: IMycLatch;
begin
  latch := TMycLatch.CreateLatch(InitialCount); // Changed to use TMycLatch.CreateLatch
  Assert.AreEqual(ExpectedIsSet, latch.State.IsSet, 'Latch initial IsSet state mismatch.');
end;

procedure TTestMycLatch.TestNotify_ReturnValueAndState_AfterOneNotify(InitialCount: Integer; ExpectedReturn: Boolean; ExpectedIsSet: Boolean);
var
  latch: IMycLatch;
  returnedValue: Boolean;
begin
  latch := TMycLatch.CreateLatch(InitialCount); // Changed to use TMycLatch.CreateLatch
  returnedValue := latch.Notify;

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

procedure TTestMycLatch.TestNotify_DecrementsCounter_StateChanges;
var
  latch: IMycLatch;
begin
  latch := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  Assert.IsFalse(latch.State.IsSet, 'Latch should initially not be set.');
  latch.Notify;
  Assert.IsTrue(latch.State.IsSet, 'Latch should be set after Notify.');
end;

procedure TTestMycLatch.TestNotify_MultipleNotifies_CounterBecomesNegativeAndStaysSet;
var
  latch: IMycLatch;
begin
  latch := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  latch.Notify;
  Assert.IsTrue(latch.State.IsSet, 'Latch should be set after first Notify.');
  latch.Notify;
  Assert.IsTrue(latch.State.IsSet, 'Latch should remain set after second Notify.');
end;

procedure TTestMycLatch.TestSubscriber_Single_IsNotifiedWhenLatchSet;
var
  latch: IMycLatch;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  latch := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  mockSub := TMockSubscriber.Create;
  subscription := latch.State.Subscribe(mockSub);

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

  latch.Notify;

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

procedure TTestMycLatch.TestSubscriber_Multiple_AreNotifiedWhenLatchSet;
var
  latch: IMycLatch;
  mockSub1, mockSub2, mockSub3: TMockSubscriber;
  sub1, sub2, sub3: TMycSubscription;
begin
  latch := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  mockSub1 := TMockSubscriber.Create;
  mockSub2 := TMockSubscriber.Create;
  mockSub3 := TMockSubscriber.Create;

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

  latch.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 TTestMycLatch.TestSubscriber_NotNotified_BeforeLatchSet;
var
  latch: IMycLatch;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  latch := TMycLatch.CreateLatch(2); // Changed to use TMycLatch.CreateLatch
  mockSub := TMockSubscriber.Create;
  subscription := latch.State.Subscribe(mockSub);

  Assert.AreEqual(0, mockSub.NotifyCount, 'MockSub should not be notified upon subscription if latch is not set.');
  latch.Notify;
  Assert.AreEqual(0, mockSub.NotifyCount, 'MockSub should still not be notified as latch is not yet set.');
end;

procedure TTestMycLatch.TestSubscriber_NotifiedOnlyOnce_AfterLatchSet;
var
  latch: IMycLatch;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  latch := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  mockSub := TMockSubscriber.Create;
  subscription := latch.State.Subscribe(mockSub);

  latch.Notify;
  Assert.AreEqual(1, mockSub.NotifyCount, 'MockSub notify count should be 1 after latch set.');

  latch.Notify;
  Assert.AreEqual(1, mockSub.NotifyCount, 'MockSub notify count should remain 1 (not notified again as it was unadvised).');
end;

procedure TTestMycLatch.TestSubscribe_ToAlreadySetLatch_NotifiesImmediately;
var
  latch: IMycLatch;
  mockSub1, mockSub2: TMockSubscriber;
  subscription1, subscription2: TMycSubscription;
begin
  latch := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  mockSub1 := TMockSubscriber.Create;
  subscription1 := latch.State.Subscribe(mockSub1);
  latch.Notify;

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

  mockSub2 := TMockSubscriber.Create;
  subscription2 := latch.State.Subscribe(mockSub2);

  Assert.AreEqual(1, mockSub2.NotifyCount, 'MockSub2 should be notified immediately upon subscribing to an already set latch.');

  latch.Notify;
  Assert.AreEqual(1, mockSub1.NotifyCount, 'MockSub1 notify count should remain 1.');
  Assert.AreEqual(1, mockSub2.NotifyCount, 'MockSub2 notify count should remain 1 after re-triggering.');
end;

procedure TTestMycLatch.TestChaining_A_Notifies_B;
var
  latchA, latchB: IMycLatch;
  mockSubForB: TMockSubscriber;
  subHandle_B_listens_A, subHandle_Mock_listens_B: TMycSubscription;
begin
  latchA := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  latchB := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  mockSubForB := TMockSubscriber.Create;

  subHandle_Mock_listens_B := latchB.State.Subscribe(mockSubForB);
  subHandle_B_listens_A := latchA.State.Subscribe(latchB);

  Assert.IsFalse(latchA.State.IsSet, 'LatchA initially not set.');
  Assert.IsFalse(latchB.State.IsSet, 'LatchB initially not set.');
  Assert.AreEqual(0, mockSubForB.NotifyCount, 'MockSubForB initially not notified.');

  latchA.Notify;

  Assert.IsTrue(latchA.State.IsSet, 'LatchA should be set after notify.');
  Assert.IsTrue(latchB.State.IsSet, 'LatchB should be set after being notified by LatchA.');
  Assert.AreEqual(1, mockSubForB.NotifyCount, 'MockSubForB should have been notified by LatchB.');
end;

procedure TTestMycLatch.TestCascade_A_Notifies_B_Notifies_C;
var
  latchA, latchB, latchC: IMycLatch;
  mockSubForC: TMockSubscriber;
  sub_Mock_C, sub_C_B, sub_B_A: TMycSubscription;
begin
  latchA := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  latchB := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  latchC := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  mockSubForC := TMockSubscriber.Create;

  sub_Mock_C := latchC.State.Subscribe(mockSubForC);
  sub_C_B    := latchB.State.Subscribe(latchC);
  sub_B_A    := latchA.State.Subscribe(latchB);

  latchA.Notify;

  Assert.IsTrue(latchA.State.IsSet, 'LatchA state mismatch in cascade.');
  Assert.IsTrue(latchB.State.IsSet, 'LatchB state mismatch in cascade.');
  Assert.IsTrue(latchC.State.IsSet, 'LatchC state mismatch in cascade.');
  Assert.AreEqual(1, mockSubForC.NotifyCount, 'MockSubForC notification count mismatch in cascade.');
end;

procedure TTestMycLatch.TestChaining_B_NeedsMultipleNotifiesFromA_WithSubscriberOnB;
var
  latchA, latchB: IMycLatch;
  mockSubForB: TMockSubscriber;
  sub_Mock_B, sub_B_A: TMycSubscription;
begin
  latchA := TMycLatch.CreateLatch(2); // Changed to use TMycLatch.CreateLatch
  latchB := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  mockSubForB := TMockSubscriber.Create;

  sub_Mock_B := latchB.State.Subscribe(mockSubForB);
  sub_B_A    := latchA.State.Subscribe(latchB);

  latchA.Notify;
  Assert.IsFalse(latchA.State.IsSet, 'LatchA should not be set after first notify of two.');
  Assert.IsFalse(latchB.State.IsSet, 'LatchB should not have been triggered yet by LatchA.');
  Assert.AreEqual(0, mockSubForB.NotifyCount, 'MockSubForB should not have been notified yet.');

  latchA.Notify;
  Assert.IsTrue(latchA.State.IsSet, 'LatchA should be set after second notify.');
  Assert.IsTrue(latchB.State.IsSet, 'LatchB should now be set by LatchA.');
  Assert.AreEqual(1, mockSubForB.NotifyCount, 'MockSubForB should have been notified by LatchB.');
end;

procedure TTestMycLatch.TestInitiallySetLatch_NotifiesNewSubscriberImmediately;
var
  latch: IMycLatch;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  latch := TMycLatch.CreateLatch(0); // Changed to use TMycLatch.CreateLatch. Will return TMycLatch.Null.
  mockSub := TMockSubscriber.Create;

  subscription := latch.State.Subscribe(mockSub);

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

procedure TTestMycLatch.TestUnsubscribe_SubscriberNotNotified;
var
  latch: IMycLatch;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  latch := TMycLatch.CreateLatch(1); // Changed to use TMycLatch.CreateLatch
  mockSub := TMockSubscriber.Create;

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

  latch.Notify;

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

procedure TTestMycLatch.TestMultipleTriggersNoSubscriber_StateCorrectForLaterSubscriber;
var
  latch: IMycLatch;
  mockSub: TMockSubscriber;
  subscription: TMycSubscription;
begin
  latch := TMycLatch.CreateLatch(3); // Changed to use TMycLatch.CreateLatch

  latch.Notify;
  latch.Notify;
  Assert.IsFalse(latch.State.IsSet, 'Latch should not be set yet after partial notifies.');

  mockSub := TMockSubscriber.Create;
  subscription := latch.State.Subscribe(mockSub);
  Assert.AreEqual(0, mockSub.NotifyCount, 'MockSub should not be notified on subscribe if latch not yet set.');

  latch.Notify;
  Assert.IsTrue(latch.State.IsSet, 'Latch should now be set.');
  Assert.AreEqual(1, mockSub.NotifyCount, 'MockSub should have been notified when latch becomes set.');
end;

initialization
  TDUnitX.RegisterTestFixture(TTestMycLatch);
end.