using System.Text.Json;
using ClawdDotNet.App.Services;
using ClawdDotNet.Core.Config;
using Shouldly;
using ClawdDotNet.Core.Instances;

namespace ClawdDotNet.App.Tests.Services;

/// <summary>
/// The other half of #375: existing instances carry <c>"logDirectory": "./Logs"</c>
/// in their <c>InstanceSettings.json</c> — <see cref="InstanceDirectoryManager.CreateInstance"/>
/// wrote it there. On loading it becomes "empty".
///
/// <para>Since #528 (stage 1) both spellings point to the same place anyway:
/// <c>&lt;Instanz&gt;/Logs</c>. The empty value says so without pinning it down — if
/// the instance moves, the log moves with it.</para>
///
/// Whoever deliberately entered a different path keeps it.
/// </summary>
public sealed class InstanceLogDirectoryMigrationTests : IDisposable
{
    private readonly string _instancesDir;
    private readonly InstanceDirectoryManager _manager;

    public InstanceLogDirectoryMigrationTests()
    {
        _instancesDir = Path.Combine(
            Path.GetTempPath(), "clawd-tests", Guid.NewGuid().ToString("N"), "Instances");
        _manager = new InstanceDirectoryManager(_instancesDir);
    }

    public void Dispose()
    {
        try { Directory.Delete(Path.GetDirectoryName(_instancesDir)!, recursive: true); }
        catch { /* Cleaning up is secondary */ }
    }

    /// <summary>Creates an instance and sets logDirectory in the file to the legacy value.</summary>
    private string InstanceWithLogDirectory(string value)
    {
        var dir = _manager.CreateInstance("Test");
        var path = Path.Combine(dir, "InstanceSettings.json");

        var config = JsonSerializer.Deserialize<InstanceConfig>(File.ReadAllText(path))!;
        config.LogDirectory = value;
        File.WriteAllText(path, JsonSerializer.Serialize(config));

        return dir;
    }

    [Theory]
    [InlineData("./Logs")]
    [InlineData(@".\Logs")]
    [InlineData("Logs")]
    public void The_old_default_becomes_no_value(string old)
    {
        var dir = InstanceWithLogDirectory(old);

        _manager.LoadInstanceConfig(dir).LogDirectory.ShouldBe("");
    }

    [Fact]
    public void A_deliberately_set_path_stays()
    {
        var own = Path.Combine(Path.GetTempPath(), "clawd-eigene-logs");
        var dir = InstanceWithLogDirectory(own);

        _manager.LoadInstanceConfig(dir).LogDirectory.ShouldBe(own);
    }

    [Fact]
    public void The_file_is_not_written_back_on_load()
    {
        // The migration only applies in memory. A load must not touch anything —
        // only the next save makes the legacy value disappear.
        var dir = InstanceWithLogDirectory("./Logs");
        var path = Path.Combine(dir, "InstanceSettings.json");

        _manager.LoadInstanceConfig(dir);

        File.ReadAllText(path).ShouldContain("./Logs");
    }

    [Fact]
    public void A_new_instance_gets_no_value_at_all()
    {
        var dir = _manager.CreateInstance("Frisch");
        var config = _manager.LoadInstanceConfig(dir);

        config.LogDirectory.ShouldBe("");
        config.BackupDirectory.ShouldBe("");

        File.ReadAllText(Path.Combine(dir, "InstanceSettings.json")).ShouldNotContain("./Logs");
    }

    /// <summary>
    /// The actual purpose of stage 1: two freshly created instances do not log
    /// and back up into the same folder.
    /// </summary>
    [Fact]
    public void Two_fresh_instances_do_not_end_up_in_the_same_folder()
    {
        var a = _manager.CreateInstance("Eins");
        var b = _manager.CreateInstance("Zwei");

        var configA = _manager.LoadInstanceConfig(a);
        var configB = _manager.LoadInstanceConfig(b);

        AppHost.ResolveLogDirectory(configA, a)
            .ShouldNotBe(AppHost.ResolveLogDirectory(configB, b));

        AppHost.ResolveBackupDirectory(configA, a)
            .ShouldNotBe(AppHost.ResolveBackupDirectory(configB, b));
    }
}