using System.Collections.Specialized;
using System.Text;
using Newtonsoft.Json.Linq;

namespace JNPF.Extras.CollectiveOAuth.Utils;

/// <summary>
/// 配置管理.
/// </summary>
public class ConfigurationManager
{
    /// <summary>
    /// 配置内容.
    /// </summary>
    private static NameValueCollection _configurationCollection = new NameValueCollection();

    /// <summary>
    /// 配置监听响应链堆栈.
    /// </summary>
    private static Stack<KeyValuePair<string, FileSystemWatcher>> FileListeners = new Stack<KeyValuePair<string, FileSystemWatcher>>();

    /// <summary>
    /// 默认路径.
    /// </summary>
    private static string _defaultPath = Directory.GetCurrentDirectory() + "\\appsettings.json";

    /// <summary>
    /// 最终配置文件路径.
    /// </summary>
    private static string _configPath = null;

    /// <summary>
    /// 配置节点关键字.
    /// </summary>
    private static string _configSection = "AppSettings";

    /// <summary>
    /// 配置外连接的后缀.
    /// </summary>
    private static string _configUrlPostfix = "Url";

    /// <summary>
    /// 最终修改时间戳.
    /// </summary>
    private static long _timeStamp = 0L;

    /// <summary>
    /// 配置外链关键词，例如：AppSettings.Url.
    /// </summary>
    private static string _configUrlSection { get { return _configSection + "." + _configUrlPostfix; } }

    static ConfigurationManager()
    {
        ConfigFinder(_defaultPath);
    }

    /// <summary>
    /// 确定配置文件路径.
    /// </summary>
    private static void ConfigFinder(string Path)
    {
        _configPath = Path;
        JObject config_json = new JObject();
        while (config_json != null)
        {
            config_json = null;
            FileInfo config_info = new FileInfo(_configPath);
            if (!config_info.Exists) break;

            FileListeners.Push(CreateListener(config_info));
            config_json = LoadJsonFile(_configPath);
            if (config_json[_configUrlSection] != null)
                _configPath = config_json[_configUrlSection].ToString();
            else break;
        }

        if (config_json == null || config_json[_configSection] == null) return;

        LoadConfiguration();
    }

    /// <summary>
    /// 读取配置文件内容.
    /// </summary>
    private static void LoadConfiguration()
    {
        FileInfo config = new FileInfo(_configPath);
        var configColltion = new NameValueCollection();
        JObject config_object = LoadJsonFile(_configPath);
        if (config_object == null || !(config_object is JObject)) return;

        if (config_object[_configSection] != null)
        {
            foreach (JProperty prop in config_object[_configSection])
            {
                configColltion[prop.Name] = prop.Value.ToString();
            }
        }

        _configurationCollection = configColltion;
    }

    /// <summary>
    /// 解析Json文件.
    /// </summary>
    /// <param name="FilePath">文件路径</param>
    /// <returns></returns>
    private static JObject LoadJsonFile(string FilePath)
    {
        JObject config_object = null;
        try
        {
            StreamReader sr = new StreamReader(FilePath, Encoding.Default);
            config_object = JObject.Parse(sr.ReadToEnd());
            sr.Close();
        }
        catch { }
        return config_object;
    }

    /// <summary>
    /// 添加监听树节点.
    /// </summary>
    /// <param name="info"></param>
    /// <returns></returns>
    private static KeyValuePair<string, FileSystemWatcher> CreateListener(FileInfo info)
    {

        FileSystemWatcher watcher = new FileSystemWatcher();
        watcher.BeginInit();
        watcher.Path = info.DirectoryName;
        watcher.Filter = info.Name;
        watcher.IncludeSubdirectories = false;
        watcher.EnableRaisingEvents = true;
        watcher.NotifyFilter = NotifyFilters.Attributes | NotifyFilters.CreationTime | NotifyFilters.DirectoryName | NotifyFilters.FileName | NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.Size;
        watcher.Changed += new FileSystemEventHandler(ConfigChangeListener);
        watcher.EndInit();

        return new KeyValuePair<string, FileSystemWatcher>(info.FullName, watcher);

    }

    /// <summary>
    /// 配置改变监听器.
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private static void ConfigChangeListener(object sender, FileSystemEventArgs e)
    {
        long time = TimeStamp();
        lock (FileListeners)
        {
            if (time > _timeStamp)
            {
                _timeStamp = time;
                if (e.FullPath != _configPath || e.FullPath == _defaultPath)
                {
                    while (FileListeners.Count > 0)
                    {
                        var listener = FileListeners.Pop();
                        listener.Value.Dispose();
                        if (listener.Key == e.FullPath) break;
                    }
                    ConfigFinder(e.FullPath);
                }
                else
                {
                    LoadConfiguration();
                }
            }
        }
    }

    private static long TimeStamp()
    {
        return (long)((DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds * 100);
    }

    private static string c_configSection = null;

    public static string ConfigSection
    {
        get { return _configSection; }
        set { c_configSection = value; }
    }

    private static string c_configUrlPostfix = null;

    public static string ConfigUrlPostfix
    {
        get { return _configUrlPostfix; }
        set { c_configUrlPostfix = value; }
    }

    private static string c_defaultPath = null;
    public static string DefaultPath
    {
        get { return _defaultPath; }
        set { c_defaultPath = value; }
    }

    public static NameValueCollection AppSettings
    {
        get { return _configurationCollection; }
    }

    /// <summary>
    /// 手动刷新配置，修改配置后，请手动调用此方法，以便更新配置参数
    /// </summary>
    public static void RefreshConfiguration()
    {
        lock (FileListeners)
        {
            // 修改配置
            if (c_configSection != null) { _configSection = c_configSection; c_configSection = null; }
            if (c_configUrlPostfix != null) { _configUrlPostfix = c_configUrlPostfix; c_configUrlPostfix = null; }
            if (c_defaultPath != null) { _defaultPath = c_defaultPath; c_defaultPath = null; }

            // 释放掉全部监听响应链
            while (FileListeners.Count > 0)
                FileListeners.Pop().Value.Dispose();
            ConfigFinder(_defaultPath);
        }
    }
}