using EasyDevCore.Common;
using EasyDevCore.Configuration.Configuration;
using Microsoft.Extensions.Configuration;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Linq;

namespace EasyDevCore.Configuration
{
    /// <summary>
    /// 
    /// </summary>
    public static class ConfigurationHelper
    {
        /// <summary>
        /// Adds the constant variables (constant declare in "AppSettings:Constants" section).
        /// </summary>
        /// <param name="builder">The builder.</param>
        /// <param name="configurationRoot">The configuration root.</param>
        /// <returns></returns>
        public static IConfigurationBuilder AddConstantVariables(this IConfigurationBuilder builder, IConfigurationRoot configurationRoot = null)
        {            
            builder.Add(new SubstitutingConfigurationSource(configurationRoot ?? builder.Build(), "AppSettings:Constants"));
            return builder;
        }

        /// <summary>
        /// Adds the decrypting data.
        /// </summary>
        /// <param name="builder">The builder.</param>
        /// <param name="decryptFunc">The decrypt function.</param>
        /// <param name="configurationRoot">The configuration root.</param>
        /// <returns></returns>
        public static IConfigurationBuilder AddDecryptingData(this IConfigurationBuilder builder, Func<string, string, string> decryptFunc, IConfigurationRoot configurationRoot = null)
        {
            builder.Add(new ProtectDataConfigurationSource(configurationRoot ?? builder.Build(), encryptFunc: null,  decryptFunc));
            return builder;
        }

        /// <summary>
        /// Adds the protect data.
        /// </summary>
        /// <param name="builder">The builder.</param>
        /// <param name="encryptFunc">The encrypt function.</param>
        /// <param name="decryptFunc">The decrypt function.</param>
        /// <param name="configurationRoot">The configuration root.</param>
        /// <returns></returns>
        public static IConfigurationBuilder AddProtectData(this IConfigurationBuilder builder, Func<string, string, string> encryptFunc, Func<string, string, string> decryptFunc, IConfigurationRoot configurationRoot = null)
        {
            builder.Add(new ProtectDataConfigurationSource(configurationRoot ?? builder.Build(), encryptFunc, decryptFunc));
            return builder;
        }

        /// <summary>
        /// Gets the configuation root.
        /// </summary>
        /// <param name="section">The section.</param>
        /// <returns></returns>
        public static IConfigurationRoot GetConfiguationRoot(this IConfiguration section)
        {
            if (section is IConfigurationRoot)
            {
                return (IConfigurationRoot)section;
            }
            else
            {
                var fieldInfo = section.GetType().GetField("_root", BindingFlags.NonPublic | BindingFlags.Instance);
                var root = fieldInfo.GetValue(section);
                return (IConfigurationRoot)root;
            }
        }

        /// <summary>
        /// Binds the specified section.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="section">The section.</param>
        /// <returns></returns>
        /// <exception cref="ConfigurationErrorsException">
        /// </exception>
        public static T Bind<T>(this IConfigurationSection section)
        {
            try
            {
                if (section.Value != null)
                    return section.Value.ConvertTo<T>();

                if (typeof(T).HasInterface<IEnumerable>()
                    && !typeof(T).HasInterface<IDictionary>())
                {
                    var values = section.GetChildren().Map(GetValue);
                    return values.ConvertTo<T>();
                }
            }
            catch (Exception ex)
            {
                var message = $"The {section.Key} setting had an invalid format. " +
                              $"The value \"{section.Value}\" could not be cast to type {typeof(T).FullName}";
                throw new ConfigurationErrorsException(message, ex);
            }

            try
            {
                var to = typeof(T).CreateInstance();
                section.Bind(to);
                return (T)to;
            }
            catch (InvalidOperationException ex)
            {
                throw new ConfigurationErrorsException(ex.Message, ex);
            }
        }

        /// <summary>
        /// Binds the specified section name.
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="config">The configuration.</param>
        /// <param name="sectionName">Name of the section.</param>
        /// <returns></returns>
        public static T Bind<T>(this IConfiguration config, string sectionName = null) => Bind<T>(config.GetSection(sectionName ?? typeof(T).Name));

        /// <summary>
        /// Existses the specified key.
        /// </summary>
        /// <param name="section">The section.</param>
        /// <param name="key">The key.</param>
        /// <returns></returns>
        public static bool Exists(this IConfigurationSection section, string key) => section.GetChildren().Any(x => x.Key == key) || section.GetSection(key).Exists();

        /// <summary>
        /// Existses the specified key.
        /// </summary>
        /// <param name="config">The configuration.</param>
        /// <param name="key">The key.</param>
        /// <returns></returns>
        public static bool Exists(this IConfiguration config, string key) => config.GetChildren().Any(x => x.Key == key) || config.GetSection(key).Exists();

        private static void GetAllChildren(List<IConfigurationSection> list, IConfiguration config)
        {
            foreach(var item in config.GetChildren())
            {
                if (item is IConfigurationSection) list.Add(item);
                GetAllChildren(list, item);
            }
        }

        /// <summary>
        /// Gets all children.
        /// </summary>
        /// <param name="configuration">The configuration.</param>
        /// <returns></returns>
        public static IEnumerable<IConfigurationSection> GetAllChildren(this IConfiguration configuration)
        {
            List<IConfigurationSection> list = new();
            GetAllChildren(list, configuration);
            return list;
        }

        /// <summary>Gets the value.</summary>
        /// <param name="section">The section.</param>
        /// <returns>
        ///   <br />
        /// </returns>
        static object GetValue(this IConfigurationSection section)
        {
            if (section == null)
                return null;
            if (section.Value != null)
                return section.Value;

            var children = section.GetChildren();
            var first = children.FirstOrDefault();
            if (first == null)
                return null;

            if (first.Key == "0")
            {
                var to = children.Select(GetValue).ToList();
                if (to.Count > 0)
                    return to;
            }
            else
            {
                var to = new Dictionary<string, object>();
                foreach (var child in children)
                {
                    to[child.Key] = GetValue(child);
                }
                if (to.Count > 0)
                    return to;
            }

            return null;
        }
    }
}