using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Primitives;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using EasyDevCore.Common;

namespace EasyDevCore.Configuration
{
    /// <summary>
    /// 
    /// </summary>
    /// <seealso cref="Microsoft.Extensions.Configuration.ConfigurationProvider" />
    public class ProtectDataConfigurationProvider : ConfigurationProvider
    {
        private readonly IConfigurationRoot _configurationRoot;
        private readonly Func<string, string, string> _decryptFunc;
        private readonly Func<string, string, string> _encryptFunc;

        /// <summary>
        /// Initializes a new instance of the <see cref="ProtectDataConfigurationProvider" /> class.
        /// </summary>
        /// <param name="configurationRoot">The configuration root.</param>
        /// <param name="decryptFunc">The decrypt function.</param>
        /// <param name="encryptFunc">The encrypt function.</param>
        public ProtectDataConfigurationProvider(IConfigurationRoot configurationRoot, Func<string, string, string> encryptFunc, Func<string, string, string> decryptFunc)
        {
            _configurationRoot = configurationRoot;
            _decryptFunc = decryptFunc;
            _encryptFunc = encryptFunc;
        }


        /// <summary>
        /// Attempts to find a value with the given key, returns true if one is found, false otherwise.
        /// </summary>
        /// <param name="key">The key to lookup.</param>
        /// <param name="value">The value found at key if one is found.</param>
        /// <returns>True if key has a value, false otherwise.</returns>
        public override bool TryGet(string key, out string value)
        {
            try
            {
                foreach (var provider in _configurationRoot.Providers.Reverse())
                {
                    if (provider != this)
                    {
                        if (_decryptFunc != null && provider.TryGet(key, out value))
                        {
                            if (value != null)
                            {
                                value = _decryptFunc(key, value);
                            }
                        }
                    }
                }
            }
            catch { }
            value = null;
            return false;
        }

        /// <summary>
        /// Sets a value for a given key.
        /// </summary>
        /// <param name="key">The configuration key to set.</param>
        /// <param name="value">The value to set.</param>
        public override void Set(string key, string value)
        {
            foreach (var provider in _configurationRoot.Providers)
            {
                if (provider != this)
                {
                    if (_encryptFunc != null && value != null)
                    {
                        provider.Set(key, _encryptFunc(key, value));

                    }
                }
            }
        }
    }
}