namespace WaitingRoom.Test;

public sealed class WaitingRoomTests
{
    private const string Name = "Susi";
    private readonly DateTime _arrivalTime = DateTime.Now;
    private readonly WaitingRoom _waitingRoom = new();

    [Fact]
    public void Empty()
    {
        CheckCounts(0, 0);
        _waitingRoom.ToString().Should().Be("0 Emergency 0 Normal");
    }

    [Fact]
    public void Add_Single_Normal()
    {
        var p = new Patient(Name, _arrivalTime);
        
        _waitingRoom.AddPatient(p);
        
        CheckCounts(1, 0);
        _waitingRoom.ToString().Should().Be("0 Emergency 1 Normal");
    }

    [Fact]
    public void NextPatient()
    {
        var p = new Patient(Name, _arrivalTime);
        _waitingRoom.AddPatient(p);

        CheckCounts(1, 0);
        var next = _waitingRoom.Next();

        next.Should()
            .NotBeNull("patient was waiting");
        next?.Name.Should().Be(Name);
        next?.Arrival.Should().Be(_arrivalTime);
        next?.IsEmergency.Should().BeFalse();
        CheckCounts(0, 0);
    }

    [Fact]
    public void Add_Multiple_Normal()
    {
        var p1 = new Patient(Name, _arrivalTime);
        _waitingRoom.AddPatient(p1);

        var p2 = new Patient("BeforeFirst", _arrivalTime.AddMinutes(-5));
        _waitingRoom.AddPatient(p2);

        var p3 = new Patient("AfterFirst", _arrivalTime.AddMinutes(15));
        _waitingRoom.AddPatient(p3);

        CheckCounts(3, 0);

        var next = _waitingRoom.Next();
        next.Should().NotBeNull()
            .And.BeSameAs(p2, "patients are ordered by arrival time");
        CheckCounts(2, 0);

        next = _waitingRoom.Next();
        next.Should().NotBeNull()
            .And.BeSameAs(p1);
        CheckCounts(1, 0);

        next = _waitingRoom.Next();
        next.Should().NotBeNull()
            .And.BeSameAs(p3);
        CheckCounts(0, 0);
    }

    [Fact]
    public void Add_Multiple_Emergency()
    {
        var p1 = new Patient("FirstEmergency", _arrivalTime, true);
        _waitingRoom.AddPatient(p1);

        var p2 = new Patient("BeforeFirst", _arrivalTime.AddMinutes(-5));
        _waitingRoom.AddPatient(p2);

        var p3 = new Patient("AfterFirst", _arrivalTime.AddMinutes(15));
        _waitingRoom.AddPatient(p3);

        var p4 = new Patient("AnotherEmergency", _arrivalTime.AddMinutes(20), true);
        _waitingRoom.AddPatient(p4);

        CheckCounts(2, 2);

        var next = _waitingRoom.Next();
        next.Should().NotBeNull()
            .And.BeSameAs(p1, "first arrived emergency");
        CheckCounts(2, 1);

        next = _waitingRoom.Next();
        next.Should().NotBeNull()
            .And.BeSameAs(p4, "second emergency - treated before normal patients");
        CheckCounts(2, 0);

        next = _waitingRoom.Next();
        next.Should().NotBeNull()
            .And.BeSameAs(p2, "first arrived normal patient");
        CheckCounts(1, 0);
    }

    [Fact]
    public void ChangeToEmergency()
    {
        var p1 = new Patient("FirstEmergency", _arrivalTime, true);
        _waitingRoom.AddPatient(p1);

        var p2 = new Patient("BeforeFirst", _arrivalTime.AddMinutes(-5));
        _waitingRoom.AddPatient(p2);

        var p3 = new Patient("AfterFirst", _arrivalTime.AddMinutes(15));
        _waitingRoom.AddPatient(p3);

        var p4 = new Patient("VeryLatePatient", _arrivalTime.AddMinutes(20));
        _waitingRoom.AddPatient(p4);

        CheckCounts(3, 1);

        var next = _waitingRoom.Next();
        next.Should().NotBeNull()
            .And.BeSameAs(p1, "first emergency");
        CheckCounts(3, 0);

        _waitingRoom.SetPatientToEmergency(p4);
        p4.IsEmergency.Should().BeTrue("changed");
        CheckCounts(2, 1);

        next = _waitingRoom.Next();
        next.Should().NotBeNull()
            .And.BeSameAs(p4, "promoted to emergency");
        CheckCounts(2, 0);

        next = _waitingRoom.Next();
        next.Should().NotBeNull()
            .And.BeSameAs(p2, "regular next normal patient");
        CheckCounts(1, 0);
        
        next = _waitingRoom.Next();
        next.Should().NotBeNull()
            .And.BeSameAs(p3, "final patient");
        CheckCounts(0, 0);
    }
    
    private void CheckCounts(int normal, int emergency)
    {
        _waitingRoom.CountNormal.Should().Be(normal);
        _waitingRoom.CountEmergency.Should().Be(emergency);
        _waitingRoom.CountAll.Should().Be(normal + emergency);
    }
}