using Microsoft.AspNetCore.WebUtilities;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http.Json;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;


internal class CapitalbusMile
{
    const string urlFormat = "http://ecar.capitalbusgroup.com.tw:8081/GetLastKM/{0}/{1}";
    const string key = "35505603";

    public static async Task<decimal?> GetMile(string carNumber, ILogger? logger = null)
    {
        try
        {
            HttpClient client = new HttpClient();
            string token = GetToken();
            string url = string.Format(urlFormat, carNumber, token);
            var result = await client.GetAsync(url);
            if (result.IsSuccessStatusCode)
            {
                Stream contentStream = await result.Content.ReadAsStreamAsync();
                var body = await new StreamReader(contentStream).ReadToEndAsync();
                //result.Headers.Add("Content-Type");
                //var body = await result.Content.ReadAsStringAsync();

                JObject jo = JObject.Parse(body);

                string resultString = jo.Value<string>("Result");// jo["State"].Value<int>();
                if (resultString == "Success" &&
                    jo.ContainsKey("DR_MILE"))
                {
                    decimal mileage = jo.Value<decimal>("DR_MILE");
                    return mileage;
                }

                return 1;
            }
        }
        catch(Exception e)
        {

        }
        return -1;
    }

    private static string GetToken()
    {
        return GetToken(DateTime.UtcNow, key);
    }

    private static string GetToken(DateTime DateTimeNow, string key)
    {
        DateTime baseTime = DateTime.Parse("1970/01/01 00:00:00Z").ToUniversalTime();
        TimeSpan time = DateTimeNow - baseTime;
        return GetToken((decimal)time.TotalSeconds, key);
    }

    private static string GetToken(decimal seconds, string key)
    {
        var ts_str = (seconds + 3600).ToString("0.0000000");
        var ts_byte = Encoding.UTF8.GetBytes(ts_str);

        var hasher = new HMACSHA1(Encoding.UTF8.GetBytes(key));
        var hashResult = hasher.ComputeHash(ts_byte);
        var sha1_tshexstr = BitConverter.ToString(hashResult).Replace("-", "").ToLower();

        var token = string.Format("{0}:{1}", ts_str, sha1_tshexstr);
        var b64_token = Base64UrlTextEncoder.Encode(Encoding.UTF8.GetBytes(token));
        return b64_token + '=';
    }
}