using NewLife.Log;
using NewLife.Threading;

namespace NewLife.Configuration;

/// <summary>文件配置提供者</summary>
/// <remarks>
/// 每个提供者实例对应一个配置文件，支持热更新
/// </remarks>
public abstract class FileConfigProvider : ConfigProvider
{
    #region 属性
    /// <summary>文件名。最高优先级，优先于模型特性指定的文件名</summary>
    public String? FileName { get; set; }

    /// <summary>更新周期。默认5秒</summary>
    public Int32 Period { get; set; } = 5;
    #endregion

    #region 构造
    /// <summary>销毁</summary>
    /// <param name="disposing"></param>
    protected override void Dispose(Boolean disposing)
    {
        base.Dispose(disposing);

        _timer.TryDispose();
    }

    /// <summary>已重载。输出友好信息</summary>
    /// <returns></returns>
    public override String ToString() => $"{GetType().Name} FileName={FileName}";
    #endregion

    #region 方法
    /// <summary>初始化</summary>
    /// <param name="value"></param>
    public override void Init(String value)
    {
        base.Init(value);

        // 加上文件名
        if (FileName.IsNullOrEmpty() && !value.IsNullOrEmpty())
        {
            // 加上配置目录
            var str = value;
            if (!str.StartsWithIgnoreCase("Config/", "Config\\")) str = "Config".CombinePath(str);

            FileName = str;
        }
    }

    /// <summary>加载配置</summary>
    public override Boolean LoadAll()
    {
        // 准备文件名
        var fileName = FileName;
        if (fileName.IsNullOrEmpty()) throw new ArgumentNullException(nameof(FileName));

        fileName = fileName.GetBasePath();

        IsNew = true;

        //if (!File.Exists(fileName)) throw new FileNotFoundException("找不到文件", fileName);
        if (!File.Exists(fileName)) return false;

        // 读取文件，换个对象，避免数组元素在多次加载后重叠
        var section = new ConfigSection { };
        OnRead(fileName, section);
        Root = section;

        IsNew = false;
        _lastTime = fileName.AsFile().LastWriteTime;

        return true;
    }

    /// <summary>读取配置文件</summary>
    /// <param name="fileName">文件名</param>
    /// <param name="section">配置段</param>
    protected abstract void OnRead(String fileName, IConfigSection section);

    /// <summary>保存配置树到数据源</summary>
    public override Boolean SaveAll()
    {
        // 准备文件名
        var fileName = FileName;
        if (fileName.IsNullOrEmpty()) throw new ArgumentNullException(nameof(FileName));

        fileName = fileName.GetBasePath();
        fileName.EnsureDirectory(true);

        // 写入文件
        OnWrite(fileName, Root);
        _lastTime = fileName.AsFile().LastWriteTime;

        // 通知绑定对象，配置数据有改变
        NotifyChange();

        return true;
    }

    /// <summary>保存模型实例</summary>
    /// <typeparam name="T">模型</typeparam>
    /// <param name="model">模型实例</param>
    /// <param name="path">路径。配置树位置</param>
    public override Boolean Save<T>(T model, String? path = null)
    {
        if (model == null) return false;

        // 加锁，避免多线程冲突
        lock (this)
        {
            // 文件存储，直接覆盖Root
            Root.Childs?.Clear();
            Root.MapFrom(model);

            return SaveAll();
        }
    }

    /// <summary>写入配置文件</summary>
    /// <param name="fileName">文件名</param>
    /// <param name="section">配置段</param>
    protected virtual void OnWrite(String fileName, IConfigSection section)
    {
        var str = GetString(section);
        var old = "";
        if (File.Exists(fileName)) old = File.ReadAllText(fileName);

        if (str != old)
        {
            XTrace.WriteLine("保存配置 {0}", fileName);

            File.WriteAllText(fileName, str);
        }
    }

    /// <summary>获取字符串形式</summary>
    /// <param name="section">配置段</param>
    /// <returns></returns>
    public virtual String? GetString(IConfigSection? section = null) => null;
    #endregion

    #region 绑定
    /// <summary>绑定模型，使能热更新，配置存储数据改变时同步修改模型属性</summary>
    /// <typeparam name="T">模型</typeparam>
    /// <param name="model">模型实例</param>
    /// <param name="autoReload">是否自动更新。默认true</param>
    /// <param name="path">路径。配置树位置，配置中心等多对象混合使用时</param>
    public override void Bind<T>(T model, Boolean autoReload = true, String? path = null)
    {
        base.Bind<T>(model, autoReload, path);

        if (autoReload) InitTimer();
    }

    private TimerX? _timer;
    private void InitTimer()
    {
        if (_timer != null) return;
        lock (this)
        {
            if (_timer != null) return;

            var p = Period;
            if (p <= 0) p = 60;
            _timer = new TimerX(DoRefresh, null, p * 1000, p * 1000) { Async = true };
        }
    }

    private Boolean _reading;
    private DateTime _lastTime;
    private void DoRefresh(Object? state)
    {
        if (_reading) return;
        if (FileName.IsNullOrEmpty()) return;

        var fileName = FileName.GetBasePath();
        var fi = FileName.AsFile();
        if (!fi.Exists) return;

        fi.Refresh();
        if (_lastTime.Year > 2000 && fi.LastWriteTime <= _lastTime) return;
        _lastTime = fi.LastWriteTime;

        XTrace.WriteLine("配置文件改变，重新加载 {0}", fileName);

        _reading = true;
        try
        {
            var section = new ConfigSection { };
            OnRead(fileName, section);
            Root = section;

            NotifyChange();
        }
        catch (Exception ex)
        {
            XTrace.WriteException(ex);
        }
        finally
        {
            _reading = false;
        }
    }
    #endregion
}