using System;
using System.IO;
using System.Text;

namespace AlicizaX
{
    public static partial class Utility
    {
        /// <summary>
        /// 哈希计算相关的实用函数。
        /// </summary>
        public static partial class Hash
        {
            /// <summary>
            /// Md5
            /// </summary>
            public static class MD5
            {
                private static readonly System.Security.Cryptography.MD5 MD5Cryptography = System.Security.Cryptography.MD5.Create();

                /// <summary>
                /// 获取字符串的Md5值
                /// </summary>
                /// <param name="input"></param>
                /// <returns></returns>
                public static string Hash(string input)
                {
                    var data = MD5Cryptography.ComputeHash(Encoding.UTF8.GetBytes(input));
                    return ToHash(data);
                }

                /// <summary>
                /// 获取流的Md5值
                /// </summary>
                /// <param name="input"></param>
                /// <returns></returns>
                public static string Hash(Stream input)
                {
                    var data = MD5Cryptography.ComputeHash(input);
                    return ToHash(data);
                }

                /// <summary>
                /// 验证Md5值是否一致
                /// </summary>
                /// <param name="input"></param>
                /// <param name="hash"></param>
                /// <returns></returns>
                public static bool IsVerify(string input, string hash)
                {
                    var comparer = StringComparer.OrdinalIgnoreCase;
                    return 0 == comparer.Compare(input, hash);
                }

                static string ToHash(byte[] data)
                {
                    var sb = new StringBuilder();
                    foreach (var t in data)
                    {
                        sb.Append(t.ToString("x2"));
                    }

                    return sb.ToString();
                }

                /// <summary>
                /// 获取指定文件路径的Md5值
                /// </summary>
                /// <param name="filePath"></param>
                /// <returns></returns>
                public static string FileHash(string filePath)
                {
                    using (FileStream file = new FileStream(filePath, FileMode.Open))
                    {
                        return Hash(file);
                    }
                }
            }
        }
    }
}