using System;
using System.Collections.Generic;
using System.IO;
using System.Security.Cryptography;
using System.Text.RegularExpressions;
using Newtonsoft.Json.Linq;
using Microsoft.Extensions.Configuration;

namespace Settings
{
    public static class CustomConfigurationExtensions
    {
        public static IConfigurationBuilder AddEncryptedAndJsonFiles(this IConfigurationBuilder builder, string fileName, string basePath, bool optional, bool reloadOnChange = false)
        {
            string jsonFilePath = builder.GetFileProvider().GetFileInfo(fileName).PhysicalPath;
            var encryptedConfiguration = new EncryptedConfigurationSource(jsonFilePath, basePath);
            encryptedConfiguration.UpdateStoredSettings();

            return builder
                .AddJsonFile(fileName, optional, reloadOnChange)
                .Add(encryptedConfiguration);
        }
    }

    public class EncryptedConfigurationProvider : ConfigurationProvider
    {
        EncryptedConfigurationSource _source;
        public EncryptedConfigurationProvider(EncryptedConfigurationSource source)
        {
            _source = source;
        }

        public override void Load()
        {
            if (!File.Exists(_source.JsonFilePath))
                return;
            var jsonRoot = JObject.Parse(File.ReadAllText(_source.JsonFilePath));
            string keyPath = _source.GetEncryptionKeyPath(jsonRoot);
            if (String.IsNullOrEmpty(keyPath))
                return; // no encryption is to be done on this file
            Aes aes = _source.GetEncryptionAlgorithm(keyPath);

            if(!File.Exists(_source.EncryptedFilePath))
                throw new Exception("Encryption file not found at given path.");

            JObject encJsonRoot = _source.GetEncryptedContents(File.ReadAllBytes(_source.EncryptedFilePath), aes);
            foreach (JToken item in new JsonInOrderIterator(encJsonRoot))
            {
                if (item.Parent.Type != JTokenType.Property)
                    continue;
                var prop = item.Parent as JProperty;
                Data[prop.Name] = prop.Value.ToString(); // means that newer values will overwrite older ones.
            }
        }
    }
}