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

namespace AxCopilot.Services;

public static class AgentPerformanceLogService
{
    private static readonly string PerfDir;
    private static readonly object _lock = new();
    private static readonly JsonSerializerOptions _jsonOptions = new()
    {
        WriteIndented = false,
        Encoder = System.Text.Encodings.Web.JavaScriptEncoder.UnsafeRelaxedJsonEscaping,
    };

    static AgentPerformanceLogService()
    {
        PerfDir = Path.Combine(
            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
            "AxCopilot",
            "perf");
        try { Directory.CreateDirectory(PerfDir); } catch { }
    }

    public static void LogMetric(
        string area,
        string name,
        string conversationId,
        string tab,
        long durationMs,
        object? detail = null)
    {
        try
        {
            var fileName = $"performance-{DateTime.Now:yyyy-MM-dd}.json";
            var filePath = Path.Combine(PerfDir, fileName);
            var json = JsonSerializer.Serialize(new AgentPerformanceEntry
            {
                Timestamp = DateTime.Now,
                Area = area,
                Name = name,
                ConversationId = conversationId ?? "",
                Tab = tab ?? "",
                DurationMs = durationMs,
                Detail = detail == null ? "" : JsonSerializer.Serialize(detail, _jsonOptions),
            }, _jsonOptions);

            lock (_lock)
            {
                File.AppendAllText(filePath, json + Environment.NewLine, Encoding.UTF8);
            }
        }
        catch
        {
            // 성능 로그 실패는 런타임에 영향 주지 않음
        }
    }

    public static string GetPerformanceFolder() => PerfDir;
}

public sealed class AgentPerformanceEntry
{
    public DateTime Timestamp { get; init; }
    public string Area { get; init; } = "";
    public string Name { get; init; } = "";
    public string ConversationId { get; init; } = "";
    public string Tab { get; init; } = "";
    public long DurationMs { get; init; }
    public string Detail { get; init; } = "";
}