using System;
using System.Diagnostics;
using System.IO;

namespace DRG.DRGInterfaceClient
{
    /// <summary>本地滚动日志：写 DRGInterfaceClient.log，并提供界面订阅、打开、清空。</summary>
    internal static class Logger
    {
        private static readonly string LogPath =
            Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "DRGInterfaceClient.log");
        private static readonly object _lock = new object();

        public static event Action<string> OnLog;

        public static void Info(string msg) { Write("INFO", msg); }
        public static void Warn(string msg) { Write("WARN", msg); }
        public static void Error(string msg, Exception ex = null)
        {
            string m = msg;
            if (ex != null) m += " | " + ex.GetType().Name + ": " + ex.Message;
            Write("ERROR", m);
        }

        private static void Write(string level, string msg)
        {
            string line = string.Format("[{0}] [{1}] {2}",
                DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"), level, msg);
            lock (_lock)
            {
                try
                {
                    RollIfNeeded();
                    File.AppendAllText(LogPath, line + Environment.NewLine);
                }
                catch { }
            }
            try { OnLog?.Invoke(line); } catch { }
        }

        private static void RollIfNeeded()
        {
            try
            {
                if (File.Exists(LogPath))
                {
                    long size = new FileInfo(LogPath).Length;
                    long max = (long)Config.Current.MaxLogSizeMB * 1024 * 1024;
                    if (size > max)
                    {
                        string bak = LogPath + ".1";
                        if (File.Exists(bak)) File.Delete(bak);
                        File.Move(LogPath, bak);
                    }
                }
            }
            catch { }
        }

        public static string ReadAll()
        {
            try { return File.Exists(LogPath) ? File.ReadAllText(LogPath) : ""; }
            catch { return ""; }
        }

        public static void OpenLogFile()
        {
            try { Process.Start(LogPath); }
            catch (Exception ex) { Error("打开日志文件失败", ex); }
        }

        public static void Clear()
        {
            lock (_lock)
            {
                try { if (File.Exists(LogPath)) File.WriteAllText(LogPath, ""); }
                catch { }
            }
        }
    }
}