using FluentAssertions;
using Microsoft.Extensions.Configuration;
using StellaOps.FeatureFlags.Providers;
using Xunit;

namespace StellaOps.FeatureFlags.Tests;

[Trait("Category", "Unit")]
public class ConfigurationFeatureFlagProviderTests : IDisposable
{
    private readonly ConfigurationFeatureFlagProvider _sut;
    private readonly IConfigurationRoot _configuration;

    public ConfigurationFeatureFlagProviderTests()
    {
        var configData = new Dictionary<string, string?>
        {
            { "FeatureFlags:SimpleFlag", "true" },
            { "FeatureFlags:DisabledFlag", "false" },
            { "FeatureFlags:ComplexFlag:Enabled", "true" },
            { "FeatureFlags:ComplexFlag:Variant", "blue" },
            { "FeatureFlags:ComplexFlag:Description", "A complex feature flag" },
            { "FeatureFlags:VariantOnlyFlag:Enabled", "false" },
            { "FeatureFlags:VariantOnlyFlag:Variant", "control" },
            { "CustomSection:MyFlag", "true" }
        };

        _configuration = new ConfigurationBuilder()
            .AddInMemoryCollection(configData)
            .Build();

        _sut = new ConfigurationFeatureFlagProvider(_configuration);
    }

    public void Dispose()
    {
        _sut.Dispose();
    }

    [Fact]
    public void Name_ReturnsConfiguration()
    {
        _sut.Name.Should().Be("Configuration");
    }

    [Fact]
    public void Priority_ReturnsDefaultValue()
    {
        _sut.Priority.Should().Be(50);
    }

    [Fact]
    public void SupportsWatch_ReturnsTrue()
    {
        _sut.SupportsWatch.Should().BeTrue();
    }

    [Fact]
    public async Task TryGetFlagAsync_ReturnsTrueForEnabledSimpleFlag()
    {
        // Act
        var result = await _sut.TryGetFlagAsync("SimpleFlag", FeatureFlagEvaluationContext.Empty);

        // Assert
        result.Should().NotBeNull();
        result!.Enabled.Should().BeTrue();
        result.Key.Should().Be("SimpleFlag");
    }

    [Fact]
    public async Task TryGetFlagAsync_ReturnsFalseForDisabledSimpleFlag()
    {
        // Act
        var result = await _sut.TryGetFlagAsync("DisabledFlag", FeatureFlagEvaluationContext.Empty);

        // Assert
        result.Should().NotBeNull();
        result!.Enabled.Should().BeFalse();
    }

    [Fact]
    public async Task TryGetFlagAsync_ReturnsNullForUnknownFlag()
    {
        // Act
        var result = await _sut.TryGetFlagAsync("UnknownFlag", FeatureFlagEvaluationContext.Empty);

        // Assert
        result.Should().BeNull();
    }

    [Fact]
    public async Task TryGetFlagAsync_ParsesComplexFlagWithVariant()
    {
        // Act
        var result = await _sut.TryGetFlagAsync("ComplexFlag", FeatureFlagEvaluationContext.Empty);

        // Assert
        result.Should().NotBeNull();
        result!.Enabled.Should().BeTrue();
        result.Variant.Should().Be("blue");
    }

    [Fact]
    public async Task TryGetFlagAsync_ParsesComplexFlagWithEnabledFalse()
    {
        // Act
        var result = await _sut.TryGetFlagAsync("VariantOnlyFlag", FeatureFlagEvaluationContext.Empty);

        // Assert
        result.Should().NotBeNull();
        result!.Enabled.Should().BeFalse();
        result.Variant.Should().Be("control");
    }

    [Fact]
    public async Task ListFlagsAsync_ReturnsAllDefinedFlags()
    {
        // Act
        var result = await _sut.ListFlagsAsync();

        // Assert
        result.Should().HaveCount(4);
        result.Select(f => f.Key).Should().Contain([
            "SimpleFlag", "DisabledFlag", "ComplexFlag", "VariantOnlyFlag"
        ]);
    }

    [Fact]
    public async Task ListFlagsAsync_ParsesDefaultValuesCorrectly()
    {
        // Act
        var result = await _sut.ListFlagsAsync();

        // Assert
        var simpleFlag = result.Single(f => f.Key == "SimpleFlag");
        simpleFlag.DefaultValue.Should().BeTrue();

        var disabledFlag = result.Single(f => f.Key == "DisabledFlag");
        disabledFlag.DefaultValue.Should().BeFalse();

        var complexFlag = result.Single(f => f.Key == "ComplexFlag");
        complexFlag.DefaultValue.Should().BeTrue();
        complexFlag.Description.Should().Be("A complex feature flag");
    }

    [Fact]
    public void Constructor_WithCustomSection_ReadsFromThatSection()
    {
        // Arrange
        using var provider = new ConfigurationFeatureFlagProvider(_configuration, "CustomSection");

        // Act & Assert
        var result = provider.TryGetFlagAsync("MyFlag", FeatureFlagEvaluationContext.Empty).Result;
        result.Should().NotBeNull();
        result!.Enabled.Should().BeTrue();
    }

    [Fact]
    public void Constructor_WithCustomPriority_SetsCorrectPriority()
    {
        // Arrange
        using var provider = new ConfigurationFeatureFlagProvider(_configuration, priority: 25);

        // Assert
        provider.Priority.Should().Be(25);
    }

    [Theory]
    [InlineData("TRUE", true)]
    [InlineData("True", true)]
    [InlineData("true", true)]
    [InlineData("FALSE", false)]
    [InlineData("False", false)]
    [InlineData("false", false)]
    public async Task TryGetFlagAsync_HandlesCaseInsensitiveBooleanValues(string configValue, bool expected)
    {
        // Arrange
        var configData = new Dictionary<string, string?>
        {
            { "FeatureFlags:CaseFlag", configValue }
        };

        var configuration = new ConfigurationBuilder()
            .AddInMemoryCollection(configData)
            .Build();

        using var provider = new ConfigurationFeatureFlagProvider(configuration);

        // Act
        var result = await provider.TryGetFlagAsync("CaseFlag", FeatureFlagEvaluationContext.Empty);

        // Assert
        result.Should().NotBeNull();
        result!.Enabled.Should().Be(expected);
    }
}