using System;
using System.Runtime.CompilerServices;
using System.Text.RegularExpressions;
using Microsoft.AspNetCore.Http;
using Microsoft.Net.Http.Headers;
using Nop.Core.Configuration;
using Nop.Core.Infrastructure;

namespace Nop.Services.Helpers
{
    /// <summary>
    /// User agent helper
    /// </summary>
    public partial class UserAgentHelper : IUserAgentHelper
    {
        #region Fields

        private static readonly object _locker = new object();
        private static readonly Regex _firstMobileDeviceRegex;
        private static readonly Regex _secondMobileDeviceRegex;

        private readonly IHttpContextAccessor _httpContextAccessor;
        private readonly INopFileProvider _fileProvider;
        private readonly NopConfig _nopConfig;

        #endregion

        #region Ctor

        public UserAgentHelper(IHttpContextAccessor httpContextAccessor,
            INopFileProvider fileProvider,
            NopConfig nopConfig)
        {
            _httpContextAccessor = httpContextAccessor;
            _fileProvider = fileProvider;
            _nopConfig = nopConfig;
        }

        static UserAgentHelper()
        {
            _firstMobileDeviceRegex = new Regex(@"(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|lge |maemo|midp|mmp|mobile.+firefox|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows ce|xda|xiino", RegexOptions.IgnoreCase | RegexOptions.Multiline | RegexOptions.Compiled);
            _secondMobileDeviceRegex = new Regex(@"1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-", RegexOptions.IgnoreCase | RegexOptions.Multiline| RegexOptions.Compiled);
        }

        #endregion

        #region Utilities

        /// <summary>
        /// Get BrowscapXmlHelper
        /// </summary>
        /// <returns>BrowscapXmlHelper</returns>
        [MethodImpl(MethodImplOptions.Synchronized)]
        protected virtual BrowscapXmlHelper GetBrowscapXmlHelper()
        {
            if (Singleton<BrowscapXmlHelper>.Instance != null)
                return Singleton<BrowscapXmlHelper>.Instance;

            //no database created
            if (string.IsNullOrEmpty(_nopConfig.UserAgentStringsPath))
                return null;

            //prevent multi loading data
            lock (_locker)
            {
                //data can be loaded while we waited
                if (Singleton<BrowscapXmlHelper>.Instance != null)
                    return Singleton<BrowscapXmlHelper>.Instance;

                var userAgentStringsPath = _fileProvider.MapPath(_nopConfig.UserAgentStringsPath);
                var crawlerOnlyUserAgentStringsPath = !string.IsNullOrEmpty(_nopConfig.CrawlerOnlyUserAgentStringsPath)
                    ? _fileProvider.MapPath(_nopConfig.CrawlerOnlyUserAgentStringsPath)
                    : string.Empty;

                var browscapXmlHelper = new BrowscapXmlHelper(userAgentStringsPath, crawlerOnlyUserAgentStringsPath, _fileProvider);
                Singleton<BrowscapXmlHelper>.Instance = browscapXmlHelper;

                return Singleton<BrowscapXmlHelper>.Instance;
            }
        }

        #endregion

        #region Methods

        /// <summary>
        /// Get a value indicating whether the request is made by search engine (web crawler)
        /// </summary>
        /// <returns>Result</returns>
        public virtual bool IsSearchEngine()
        {
            if (_httpContextAccessor?.HttpContext == null)
                return false;

            //we put required logic in try-catch block
            //more info: https://www.nopcommerce.com/boards/t/17711/unhandled-exception-request-is-not-available-in-this-context.aspx
            try
            {
                var browscapXmlHelper = GetBrowscapXmlHelper();

                //we cannot load parser
                if (browscapXmlHelper == null)
                    return false;

                var userAgent = _httpContextAccessor.HttpContext.Request.Headers[HeaderNames.UserAgent];
                return !string.IsNullOrWhiteSpace(userAgent) && browscapXmlHelper.IsCrawler(userAgent);
            }
            catch
            {
                // ignored
            }

            return false;
        }

        /// <summary>
        /// Get a value indicating whether the request is made by mobile device
        /// </summary>
        /// <returns></returns>
        public virtual bool IsMobileDevice()
        {
            if (_httpContextAccessor?.HttpContext == null)
                return false;

            //we put required logic in try-catch block
            //more info: https://www.nopcommerce.com/boards/t/17711/unhandled-exception-request-is-not-available-in-this-context.aspx
            try
            {
                //we don't parse browscap library here
                //in 99% of cases it's enough to use the approach suggested by http://detectmobilebrowsers.com/

                var userAgent = _httpContextAccessor.HttpContext.Request.Headers[HeaderNames.UserAgent].ToString();
                var mobile = _firstMobileDeviceRegex.IsMatch(userAgent) || _secondMobileDeviceRegex.IsMatch(userAgent.Substring(0, 4));
                return mobile;
            }
            catch
            {
                // ignored
            }

            return false;
        }

        /// <summary>
        /// Get a value indicating whether the request is made by IE8 browser
        /// </summary>
        /// <returns></returns>
        public virtual bool IsIe8()
        {
            if (_httpContextAccessor?.HttpContext == null)
                return false;

            //https://blogs.msdn.microsoft.com/ie/2009/01/09/the-internet-explorer-8-user-agent-string-updated-edition/

            var userAgent = _httpContextAccessor.HttpContext.Request.Headers[HeaderNames.UserAgent].ToString();
            return !string.IsNullOrEmpty(userAgent) && userAgent.IndexOf("MSIE 8.0", StringComparison.InvariantCultureIgnoreCase) >= 0;
        }

        #endregion
    }
}