using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using System;

using System.Linq;
using System.Net.Http;
using System.Net.Http.Json;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace GDZZ.Application.Help
{
    public class TencentCloudSmsService 
    {
        private static readonly HttpClient _httpClient =
            new HttpClient { BaseAddress = new Uri("https://yun.tim.qq.com") };
        private readonly string _appId;
        private readonly string _appKey;
        private const string SIGNATURE = "...";
        private const int DOMESTIC_TEMPLATE_ID = 1234;
        private const int OVERSEA_TEMPLATE_ID = 5678;
        private readonly ILogger _logger;

        public TencentCloudSmsService(IConfiguration conf,
            ILoggerFactory loggerFactory)
        {
            _appId = conf["tencentCloudSms:appId"];
            if (string.IsNullOrEmpty(_appId))
                throw new ArgumentException($"{nameof(_appId)} must have a value");

            _appKey = conf["tencentCloudSms:appKey"];
            if (string.IsNullOrEmpty(_appKey))
                throw new ArgumentException($"{nameof(_appKey)} must have a value");

            _logger = loggerFactory.CreateLogger<TencentCloudSmsService>();
        }

        /// <summary>
        /// 发送验证码
        /// </summary>
        /// <param name="countryCode">电话号码</param>
        /// <param name="mobile"></param>
        /// <param name="code"></param>
        /// <returns></returns>
        public async Task<bool> SendCode(string countryCode, long mobile, int code)
        {
            var random = GetRandom();
            var timestamp = DateTimeOffset.Now.ToUnixTimeSeconds();
            var data = new
            {
                tel = new { nationcode = countryCode.Replace("+", ""), mobile = mobile.ToString() },
                sign = SIGNATURE,
                tpl_id = countryCode == "+86" ? DOMESTIC_TEMPLATE_ID : OVERSEA_TEMPLATE_ID,
                @params = new[] { code.ToString() },
                sig = ComputeSignature(mobile, random, timestamp),
                time = timestamp,
                extend = "",
                ext = ""
            };

            var url = $"/v5/tlssmssvr/sendsms?sdkappid={_appId}&random={random}";
            _logger.LogDebug("Post to " + _httpClient.BaseAddress + url);
            var response = await _httpClient.PostAsJsonAsync<dynamic>(url, data);
            _logger.LogDebug("Post data:\n" + JsonConvert.SerializeObject(data));
            response.EnsureSuccessStatusCode();

            var result = await response.Content.ReadFromJsonAsync<decimal>();
            if (result != 0)
            {
                //_logger.LogError($"Failed to send message to {countryCode}-{mobile}: {result.errmsg}");
                return false;
            }

            return true;
        }

        private string ComputeSignature(long mobile, int random, long timestamp)
        {
            var input = $"appkey={_appKey}&random={random}&time={timestamp}&mobile={mobile}";
            var hasBytes = SHA256.Create().ComputeHash(Encoding.UTF8.GetBytes(input));
            return string.Join("", hasBytes.Select(b => b.ToString("x2")));
        }

        /// <summary>
        /// 随机数
        /// </summary>
        /// <returns></returns>
        private int GetRandom()
        {
            return new Random().Next(100000, 999999);
        }
    }
}