using System.IO;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace AxCopilot.Services.Agent;

internal static class WorktreeStateStore
{
    private const string StateRelativePath = ".ax/worktree_state.json";

    internal sealed class WorktreeState
    {
        [JsonPropertyName("root")]
        public string Root { get; set; } = "";

        [JsonPropertyName("active")]
        public string Active { get; set; } = "";

        [JsonPropertyName("updatedAt")]
        public DateTime UpdatedAt { get; set; } = DateTime.Now;
    }

    private static string GetPath(string root) => Path.Combine(root, StateRelativePath);

    internal static string ResolveRoot(string current)
    {
        try
        {
            var dir = new DirectoryInfo(Path.GetFullPath(current));
            while (dir != null)
            {
                var candidate = dir.FullName;
                var statePath = GetPath(candidate);
                if (File.Exists(statePath))
                {
                    var state = Load(candidate);
                    if (!string.IsNullOrWhiteSpace(state.Root))
                    {
                        var resolvedRoot = Path.GetFullPath(state.Root);
                        if (Directory.Exists(resolvedRoot))
                            return resolvedRoot;
                    }
                    return candidate;
                }

                dir = dir.Parent;
            }
        }
        catch
        {
            // ignore and fallback
        }

        return Path.GetFullPath(current);
    }

    internal static WorktreeState Load(string root)
    {
        var path = GetPath(root);
        if (!File.Exists(path))
            return new WorktreeState { Root = root, Active = root, UpdatedAt = DateTime.Now };

        try
        {
            var json = TextFileCodec.ReadAllText(path).Text;
            var state = JsonSerializer.Deserialize<WorktreeState>(json);
            return state ?? new WorktreeState { Root = root, Active = root, UpdatedAt = DateTime.Now };
        }
        catch
        {
            return new WorktreeState { Root = root, Active = root, UpdatedAt = DateTime.Now };
        }
    }

    internal static void Save(string root, WorktreeState state)
    {
        var path = GetPath(root);
        var dir = Path.GetDirectoryName(path);
        if (!string.IsNullOrWhiteSpace(dir) && !Directory.Exists(dir))
            Directory.CreateDirectory(dir);
        state.Root = root;
        state.UpdatedAt = DateTime.Now;
        File.WriteAllText(path, JsonSerializer.Serialize(state, new JsonSerializerOptions { WriteIndented = true }), TextFileCodec.Utf8NoBom);
    }
}