using JdeScoping.ConfigManager.Core.Services;

namespace JdeScoping.ConfigManager.Core.Tests.Services;

public class AutoDiscoveryServiceTests : IDisposable
{
    private readonly IFileSystem _fileSystem;
    private readonly AutoDiscoveryService _sut;
    private readonly string? _originalEnvVar;

    public AutoDiscoveryServiceTests()
    {
        _fileSystem = Substitute.For<IFileSystem>();
        _sut = new AutoDiscoveryService(_fileSystem);
        // Save original env var to restore later
        _originalEnvVar = Environment.GetEnvironmentVariable("JDESCOPING_CONFIG_PATH");

        // Set up default Combine behavior to work like Path.Combine
        _fileSystem.Combine(Arg.Any<string[]>()).Returns(callInfo =>
        {
            var paths = callInfo.Arg<string[]>();
            return Path.Combine(paths);
        });
    }

    public void Dispose()
    {
        // Restore original env var
        Environment.SetEnvironmentVariable("JDESCOPING_CONFIG_PATH", _originalEnvVar);
    }

    [Fact]
    public async Task FindConfigFolderAsync_WhenEnvVarSet_ReturnsEnvPath()
    {
        // Arrange
        Environment.SetEnvironmentVariable("JDESCOPING_CONFIG_PATH", "/custom/config");
        _fileSystem.DirectoryExists("/custom/config").Returns(true);
        _fileSystem.FileExists(Arg.Is<string>(s => s.Contains("appsettings.json") && s.Contains("/custom/config"))).Returns(true);

        // Act
        var result = await _sut.FindConfigFolderAsync();

        // Assert
        result.ShouldBe("/custom/config");
    }

    [Fact]
    public async Task FindConfigFolderAsync_WhenEnvVarSetButDirectoryInvalid_SearchesOtherLocations()
    {
        // Arrange
        Environment.SetEnvironmentVariable("JDESCOPING_CONFIG_PATH", "/invalid/config");
        _fileSystem.DirectoryExists(Arg.Any<string>()).Returns(false);
        _fileSystem.FileExists(Arg.Any<string>()).Returns(false);

        // Act
        var result = await _sut.FindConfigFolderAsync();

        // Assert
        result.ShouldBeNull();
    }

    [Fact]
    public async Task FindConfigFolderAsync_WhenEnvVarSetButNoAppSettings_SearchesOtherLocations()
    {
        // Arrange
        Environment.SetEnvironmentVariable("JDESCOPING_CONFIG_PATH", "/custom/config");
        // Directory exists but no appsettings.json
        _fileSystem.DirectoryExists("/custom/config").Returns(true);
        _fileSystem.FileExists(Arg.Any<string>()).Returns(false);
        // All other locations also don't have config
        _fileSystem.DirectoryExists(Arg.Is<string>(s => s != "/custom/config")).Returns(false);

        // Act
        var result = await _sut.FindConfigFolderAsync();

        // Assert
        result.ShouldBeNull();
    }

    [Fact]
    public async Task FindConfigFolderAsync_WhenNotFound_ReturnsNull()
    {
        // Arrange
        Environment.SetEnvironmentVariable("JDESCOPING_CONFIG_PATH", null);
        _fileSystem.DirectoryExists(Arg.Any<string>()).Returns(false);
        _fileSystem.FileExists(Arg.Any<string>()).Returns(false);

        // Act
        var result = await _sut.FindConfigFolderAsync();

        // Assert
        result.ShouldBeNull();
    }

    [Fact]
    public async Task FindConfigFolderAsync_WhenExeDirectoryHasConfig_ReturnsExeDirectory()
    {
        // Arrange
        Environment.SetEnvironmentVariable("JDESCOPING_CONFIG_PATH", null);
        var exeDir = AppContext.BaseDirectory;

        _fileSystem.DirectoryExists(exeDir).Returns(true);
        _fileSystem.FileExists(Arg.Is<string>(s => s.Contains(exeDir) && s.Contains("appsettings.json"))).Returns(true);

        // Act
        var result = await _sut.FindConfigFolderAsync();

        // Assert
        result.ShouldBe(exeDir);
    }

    [Fact]
    public async Task FindConfigFolderAsync_WhenHostDirectoryHasConfig_ReturnsHostDirectory()
    {
        // Arrange
        Environment.SetEnvironmentVariable("JDESCOPING_CONFIG_PATH", null);
        var exeDir = AppContext.BaseDirectory;
        var hostDir = Path.Combine(exeDir, "..", "JdeScoping.Host");

        // Exe directory doesn't have config
        _fileSystem.DirectoryExists(exeDir).Returns(false);

        // Host directory has config
        _fileSystem.DirectoryExists(hostDir).Returns(true);
        _fileSystem.FileExists(Arg.Is<string>(s => s.Contains("JdeScoping.Host") && s.Contains("appsettings.json"))).Returns(true);

        // Other directories don't have config
        _fileSystem.DirectoryExists(Arg.Is<string>(s => s != exeDir && s != hostDir)).Returns(false);

        // Act
        var result = await _sut.FindConfigFolderAsync();

        // Assert
        result.ShouldBe(hostDir);
    }

    [Fact]
    public async Task FindConfigFolderAsync_WhenUserConfigDirectoryHasConfig_ReturnsUserConfigDirectory()
    {
        // Arrange
        Environment.SetEnvironmentVariable("JDESCOPING_CONFIG_PATH", null);
        var exeDir = AppContext.BaseDirectory;
        var hostDir = Path.Combine(exeDir, "..", "JdeScoping.Host");

        // Determine user config path based on OS
        string userConfigDir;
        if (OperatingSystem.IsWindows())
        {
            var localAppData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
            userConfigDir = Path.Combine(localAppData, "JdeScoping");
        }
        else
        {
            var home = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
            userConfigDir = Path.Combine(home, ".jdescoping");
        }

        // Exe directory doesn't have config
        _fileSystem.DirectoryExists(exeDir).Returns(false);

        // Host directory doesn't have config
        _fileSystem.DirectoryExists(hostDir).Returns(false);

        // User config directory has config
        _fileSystem.DirectoryExists(userConfigDir).Returns(true);
        _fileSystem.FileExists(Arg.Is<string>(s => s.Contains(userConfigDir) && s.Contains("appsettings.json"))).Returns(true);

        // Act
        var result = await _sut.FindConfigFolderAsync();

        // Assert
        result.ShouldBe(userConfigDir);
    }

    [Fact]
    public async Task FindConfigFolderAsync_SearchesPrioritizedOrder()
    {
        // Arrange - all locations have config, but env var should be returned first
        Environment.SetEnvironmentVariable("JDESCOPING_CONFIG_PATH", "/env/config");
        var exeDir = AppContext.BaseDirectory;

        // Both env var path and exe dir have valid config
        _fileSystem.DirectoryExists("/env/config").Returns(true);
        _fileSystem.DirectoryExists(exeDir).Returns(true);
        _fileSystem.FileExists(Arg.Any<string>()).Returns(true);

        // Act
        var result = await _sut.FindConfigFolderAsync();

        // Assert - should return env var path, not exe dir
        result.ShouldBe("/env/config");
    }

    [Fact]
    public async Task FindConfigFolderAsync_WithCancellationToken_DoesNotThrow()
    {
        // Arrange
        Environment.SetEnvironmentVariable("JDESCOPING_CONFIG_PATH", "/custom/config");
        _fileSystem.DirectoryExists("/custom/config").Returns(true);
        _fileSystem.FileExists(Arg.Any<string>()).Returns(true);

        using var cts = new CancellationTokenSource();

        // Act
        var result = await _sut.FindConfigFolderAsync(cts.Token);

        // Assert
        result.ShouldBe("/custom/config");
    }
}