using ChatBot.Common.Constants;
using FluentAssertions;

namespace ChatBot.Tests.Common.Constants;

public class AIResponseConstantsTests
{
    [Fact]
    public void EmptyResponseMarker_ShouldHaveCorrectValue()
    {
        // Act & Assert
        AIResponseConstants.EmptyResponseMarker.Should().Be("{empty}");
    }

    [Fact]
    public void DefaultErrorMessage_ShouldHaveCorrectValue()
    {
        // Act & Assert
        AIResponseConstants
            .DefaultErrorMessage.Should()
            .Be("Извините, произошла ошибка при генерации ответа.");
    }

    [Fact]
    public void EmptyResponseMarker_ShouldNotBeNull()
    {
        // Act & Assert
        AIResponseConstants.EmptyResponseMarker.Should().NotBeNull();
    }

    [Fact]
    public void DefaultErrorMessage_ShouldNotBeNull()
    {
        // Act & Assert
        AIResponseConstants.DefaultErrorMessage.Should().NotBeNull();
    }

    [Fact]
    public void EmptyResponseMarker_ShouldNotBeEmpty()
    {
        // Act & Assert
        AIResponseConstants.EmptyResponseMarker.Should().NotBeEmpty();
    }

    [Fact]
    public void DefaultErrorMessage_ShouldNotBeEmpty()
    {
        // Act & Assert
        AIResponseConstants.DefaultErrorMessage.Should().NotBeEmpty();
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeReadOnly()
    {
        // Act & Assert
        AIResponseConstants.EmptyResponseMarker.Should().Be("{empty}");

        // Verify it's a constant by checking it doesn't change
        var firstValue = AIResponseConstants.EmptyResponseMarker;
        var secondValue = AIResponseConstants.EmptyResponseMarker;
        firstValue.Should().Be(secondValue);
    }

    [Fact]
    public void DefaultErrorMessage_ShouldBeReadOnly()
    {
        // Act & Assert
        AIResponseConstants
            .DefaultErrorMessage.Should()
            .Be("Извините, произошла ошибка при генерации ответа.");

        // Verify it's a constant by checking it doesn't change
        var firstValue = AIResponseConstants.DefaultErrorMessage;
        var secondValue = AIResponseConstants.DefaultErrorMessage;
        firstValue.Should().Be(secondValue);
    }

    [Fact]
    public void EmptyResponseMarker_ShouldContainBraces()
    {
        // Act & Assert
        AIResponseConstants.EmptyResponseMarker.Should().StartWith("{");
        AIResponseConstants.EmptyResponseMarker.Should().EndWith("}");
    }

    [Fact]
    public void DefaultErrorMessage_ShouldContainRussianText()
    {
        // Act & Assert
        AIResponseConstants.DefaultErrorMessage.Should().Contain("Извините");
        AIResponseConstants.DefaultErrorMessage.Should().Contain("ошибка");
        AIResponseConstants.DefaultErrorMessage.Should().Contain("генерации");
        AIResponseConstants.DefaultErrorMessage.Should().Contain("ответа");
    }

    [Fact]
    public void EmptyResponseMarker_ShouldHaveCorrectLength()
    {
        // Act & Assert
        AIResponseConstants.EmptyResponseMarker.Length.Should().Be(7);
    }

    [Fact]
    public void DefaultErrorMessage_ShouldHaveCorrectLength()
    {
        // Act & Assert
        AIResponseConstants.DefaultErrorMessage.Length.Should().Be(48);
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeImmutable()
    {
        // Act & Assert
        var value1 = AIResponseConstants.EmptyResponseMarker;
        var value2 = AIResponseConstants.EmptyResponseMarker;

        value1.Should().Be(value2);
        ReferenceEquals(value1, value2).Should().BeTrue();
    }

    [Fact]
    public void DefaultErrorMessage_ShouldBeImmutable()
    {
        // Act & Assert
        var value1 = AIResponseConstants.DefaultErrorMessage;
        var value2 = AIResponseConstants.DefaultErrorMessage;

        value1.Should().Be(value2);
        ReferenceEquals(value1, value2).Should().BeTrue();
    }

    [Fact]
    public void EmptyResponseMarker_ShouldNotContainSpaces()
    {
        // Act & Assert
        AIResponseConstants.EmptyResponseMarker.Should().NotContain(" ");
    }

    [Fact]
    public void DefaultErrorMessage_ShouldContainSpaces()
    {
        // Act & Assert
        AIResponseConstants.DefaultErrorMessage.Should().Contain(" ");
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeLowerCase()
    {
        // Act & Assert
        AIResponseConstants.EmptyResponseMarker.Should().BeLowerCased();
    }

    [Fact]
    public void DefaultErrorMessage_ShouldStartWithCapitalLetter()
    {
        // Act & Assert
        AIResponseConstants.DefaultErrorMessage.Should().StartWith("И");
    }

    [Fact]
    public void EmptyResponseMarker_ShouldEndWithPeriod()
    {
        // Act & Assert
        AIResponseConstants.EmptyResponseMarker.Should().EndWith("}");
    }

    [Fact]
    public void DefaultErrorMessage_ShouldEndWithPeriod()
    {
        // Act & Assert
        AIResponseConstants.DefaultErrorMessage.Should().EndWith(".");
    }

    [Fact]
    public void EmptyResponseMarker_ShouldNotContainSpecialCharacters()
    {
        // Act & Assert
        AIResponseConstants.EmptyResponseMarker.Should().NotContain("@");
        AIResponseConstants.EmptyResponseMarker.Should().NotContain("#");
        AIResponseConstants.EmptyResponseMarker.Should().NotContain("$");
        AIResponseConstants.EmptyResponseMarker.Should().NotContain("%");
        AIResponseConstants.EmptyResponseMarker.Should().NotContain("^");
        AIResponseConstants.EmptyResponseMarker.Should().NotContain("&");
        AIResponseConstants.EmptyResponseMarker.Should().NotContain("*");
    }

    [Fact]
    public void DefaultErrorMessage_ShouldContainPunctuation()
    {
        // Act & Assert
        AIResponseConstants.DefaultErrorMessage.Should().Contain(",");
        AIResponseConstants.DefaultErrorMessage.Should().Contain(".");
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeValidForComparison()
    {
        // Act & Assert
        (AIResponseConstants.EmptyResponseMarker == "{empty}")
            .Should()
            .BeTrue();
        (AIResponseConstants.EmptyResponseMarker != "empty").Should().BeTrue();
    }

    [Fact]
    public void DefaultErrorMessage_ShouldBeValidForComparison()
    {
        // Act & Assert
        (
            AIResponseConstants.DefaultErrorMessage
            == "Извините, произошла ошибка при генерации ответа."
        )
            .Should()
            .BeTrue();
        (AIResponseConstants.DefaultErrorMessage != "Some other message").Should().BeTrue();
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeUsableInStringOperations()
    {
        // Act & Assert
        var testString = "Response: " + AIResponseConstants.EmptyResponseMarker;
        testString.Should().Be("Response: {empty}");

        var containsMarker = testString.Contains(AIResponseConstants.EmptyResponseMarker);
        containsMarker.Should().BeTrue();
    }

    [Fact]
    public void DefaultErrorMessage_ShouldBeUsableInStringOperations()
    {
        // Act & Assert
        var testString = "Error: " + AIResponseConstants.DefaultErrorMessage;
        testString.Should().Be("Error: Извините, произошла ошибка при генерации ответа.");

        var containsMessage = testString.Contains(AIResponseConstants.DefaultErrorMessage);
        containsMessage.Should().BeTrue();
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeUsableInConditionalLogic()
    {
        // Act & Assert
        var isMarker = AIResponseConstants.EmptyResponseMarker == "{empty}";
        isMarker.Should().BeTrue();

        var isNotMarker = AIResponseConstants.EmptyResponseMarker != "empty";
        isNotMarker.Should().BeTrue();
    }

    [Fact]
    public void DefaultErrorMessage_ShouldBeUsableInConditionalLogic()
    {
        // Act & Assert
        var isErrorMessage = AIResponseConstants.DefaultErrorMessage.Contains("ошибка");
        isErrorMessage.Should().BeTrue();

        var isNotEmpty = !string.IsNullOrEmpty(AIResponseConstants.DefaultErrorMessage);
        isNotEmpty.Should().BeTrue();
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeUsableInSwitchStatements()
    {
        // Act & Assert
        var result = AIResponseConstants.EmptyResponseMarker switch
        {
            "{empty}" => "IsEmptyMarker",
            _ => "NotEmptyMarker",
        };

        result.Should().Be("IsEmptyMarker");
    }

    [Fact]
    public void DefaultErrorMessage_ShouldBeUsableInSwitchStatements()
    {
        // Act & Assert
        var result = AIResponseConstants.DefaultErrorMessage switch
        {
            "Извините, произошла ошибка при генерации ответа." => "IsDefaultError",
            _ => "NotDefaultError",
        };

        result.Should().Be("IsDefaultError");
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeUsableInDictionaryKeys()
    {
        // Arrange
        var dictionary = new Dictionary<string, string>
        {
            { AIResponseConstants.EmptyResponseMarker, "Empty response value" },
        };

        // Act & Assert
        dictionary.ContainsKey(AIResponseConstants.EmptyResponseMarker).Should().BeTrue();
        dictionary[AIResponseConstants.EmptyResponseMarker].Should().Be("Empty response value");
    }

    [Fact]
    public void DefaultErrorMessage_ShouldBeUsableInDictionaryKeys()
    {
        // Arrange
        var dictionary = new Dictionary<string, string>
        {
            { AIResponseConstants.DefaultErrorMessage, "Error response value" },
        };

        // Act & Assert
        dictionary.ContainsKey(AIResponseConstants.DefaultErrorMessage).Should().BeTrue();
        dictionary[AIResponseConstants.DefaultErrorMessage].Should().Be("Error response value");
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeUsableInListOperations()
    {
        // Arrange
        var list = new List<string> { AIResponseConstants.EmptyResponseMarker };

        // Act & Assert
        list.Contains(AIResponseConstants.EmptyResponseMarker).Should().BeTrue();
        list.Count.Should().Be(1);
        list[0].Should().Be(AIResponseConstants.EmptyResponseMarker);
    }

    [Fact]
    public void DefaultErrorMessage_ShouldBeUsableInListOperations()
    {
        // Arrange
        var list = new List<string> { AIResponseConstants.DefaultErrorMessage };

        // Act & Assert
        list.Contains(AIResponseConstants.DefaultErrorMessage).Should().BeTrue();
        list.Count.Should().Be(1);
        list[0].Should().Be(AIResponseConstants.DefaultErrorMessage);
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeUsableInStringFormatting()
    {
        // Act & Assert
        var formatted = string.Format("Response: {0}", AIResponseConstants.EmptyResponseMarker);
        formatted.Should().Be("Response: {empty}");
    }

    [Fact]
    public void DefaultErrorMessage_ShouldBeUsableInStringFormatting()
    {
        // Act & Assert
        var formatted = string.Format("Error: {0}", AIResponseConstants.DefaultErrorMessage);
        formatted.Should().Be("Error: Извините, произошла ошибка при генерации ответа.");
    }

    [Fact]
    public void EmptyResponseMarker_ShouldBeUsableInStringInterpolation()
    {
        // Act & Assert
        var interpolated = $"Response: {AIResponseConstants.EmptyResponseMarker}";
        interpolated.Should().Be("Response: {empty}");
    }

    [Fact]
    public void DefaultErrorMessage_ShouldBeUsableInStringInterpolation()
    {
        // Act & Assert
        var interpolated = $"Error: {AIResponseConstants.DefaultErrorMessage}";
        interpolated.Should().Be("Error: Извините, произошла ошибка при генерации ответа.");
    }

    [Fact]
    public void Constants_ShouldBeAccessibleFromDifferentAssemblies()
    {
        // Act & Assert
        // This test verifies that constants are public and accessible
        var emptyMarker = AIResponseConstants.EmptyResponseMarker;
        var errorMessage = AIResponseConstants.DefaultErrorMessage;

        emptyMarker.Should().NotBeNull();
        errorMessage.Should().NotBeNull();
    }

    [Fact]
    public void Constants_ShouldBeCompileTimeConstants()
    {
        // Act & Assert
        // This test verifies that constants can be used in switch expressions
        var emptyMarkerType = AIResponseConstants.EmptyResponseMarker switch
        {
            "{empty}" => typeof(string),
            _ => typeof(object),
        };

        emptyMarkerType.Should().Be(typeof(string));
    }

    [Fact]
    public void Constants_ShouldBeUsableInAttributeParameters()
    {
        // Act & Assert
        // This test verifies that constants can be used in attributes
        var testClass = typeof(AIResponseConstants);
        testClass.Should().NotBeNull();
        testClass.IsClass.Should().BeTrue();
        testClass.IsPublic.Should().BeTrue();
    }

    [Fact]
    public void Constants_ShouldBeUsableInDefaultParameterValues()
    {
        // Act & Assert
        // This test verifies that constants can be used as default parameter values
        var method = typeof(AIResponseConstants).GetMethod("EmptyResponseMarker");
        method.Should().BeNull(); // It's a field, not a method

        var field = typeof(AIResponseConstants).GetField("EmptyResponseMarker");
        field.Should().NotBeNull();
        field!.IsLiteral.Should().BeTrue();
        field.IsInitOnly.Should().BeFalse(); // Constants are not init-only
    }

    [Fact]
    public void Constants_ShouldBeUsableInReflection()
    {
        // Act & Assert
        var type = typeof(AIResponseConstants);
        var emptyMarkerField = type.GetField("EmptyResponseMarker");
        var errorMessageField = type.GetField("DefaultErrorMessage");

        emptyMarkerField.Should().NotBeNull();
        errorMessageField.Should().NotBeNull();

        emptyMarkerField!.GetValue(null).Should().Be("{empty}");
        errorMessageField!
            .GetValue(null)
            .Should()
            .Be("Извините, произошла ошибка при генерации ответа.");
    }
}