using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using MediaBrowser.Controller;
using MediaBrowser.Controller.Configuration;
using MediaBrowser.Model.IO;
using Microsoft.Extensions.Logging;

namespace MediaBrowser.WebDashboard.Api
{
    public class PackageCreator
    {
        private readonly IFileSystem _fileSystem;
        private readonly ILogger _logger;
        private readonly IServerConfigurationManager _config;
        private readonly string _basePath;
        private IResourceFileManager _resourceFileManager;

        public PackageCreator(string basePath, IFileSystem fileSystem, ILogger logger, IServerConfigurationManager config, IResourceFileManager resourceFileManager)
        {
            _fileSystem = fileSystem;
            _logger = logger;
            _config = config;
            _basePath = basePath;
            _resourceFileManager = resourceFileManager;
        }

        public async Task<Stream> GetResource(string virtualPath,
            string mode,
            string localizationCulture,
            string appVersion)
        {
            var resourceStream = GetRawResourceStream(virtualPath);

            if (resourceStream != null)
            {
                if (IsFormat(virtualPath, "html"))
                {
                    if (IsCoreHtml(virtualPath))
                    {
                        resourceStream = await ModifyHtml(virtualPath, resourceStream, mode, appVersion, localizationCulture).ConfigureAwait(false);
                    }
                }
            }

            return resourceStream;
        }

        /// <summary>
        /// Determines whether the specified path is HTML.
        /// </summary>
        /// <param name="path">The path.</param>
        /// <param name="format">The format.</param>
        /// <returns><c>true</c> if the specified path is HTML; otherwise, <c>false</c>.</returns>
        private static bool IsFormat(string path, string format)
        {
            return Path.GetExtension(path).EndsWith(format, StringComparison.OrdinalIgnoreCase);
        }

        public bool IsCoreHtml(string path)
        {
            if (path.IndexOf(".template.html", StringComparison.OrdinalIgnoreCase) != -1)
            {
                return false;
            }

            return IsFormat(path, "html");
        }

        /// <summary>
        /// Modifies the HTML by adding common meta tags, css and js.
        /// </summary>
        /// <returns>Task{Stream}.</returns>
        public async Task<Stream> ModifyHtml(string path, Stream sourceStream, string mode, string appVersion, string localizationCulture)
        {
            var isMainIndexPage = string.Equals(path, "index.html", StringComparison.OrdinalIgnoreCase);

            using (sourceStream)
            {
                string html;

                using (var memoryStream = new MemoryStream())
                {
                    await sourceStream.CopyToAsync(memoryStream).ConfigureAwait(false);

                    var originalBytes = memoryStream.ToArray();

                    html = Encoding.UTF8.GetString(originalBytes, 0, originalBytes.Length);

                    if (isMainIndexPage)
                    {
                        if (!string.IsNullOrWhiteSpace(localizationCulture))
                        {
                            var lang = localizationCulture.Split('-').FirstOrDefault();

                            html = html.Replace("<html", "<html data-culture=\"" + localizationCulture + "\" lang=\"" + lang + "\"");
                        }
                    }
                }

                if (isMainIndexPage)
                {
                    html = html.Replace("<head>", "<head>" + GetMetaTags(mode));
                }

                // Disable embedded scripts from plugins. We'll run them later once resources have loaded
                if (html.IndexOf("<script", StringComparison.OrdinalIgnoreCase) != -1)
                {
                    html = html.Replace("<script", "<!--<script");
                    html = html.Replace("</script>", "</script>-->");
                }

                if (isMainIndexPage)
                {
                    html = html.Replace("</body>", GetCommonJavascript(mode, appVersion) + "</body>");
                }

                var bytes = Encoding.UTF8.GetBytes(html);

                return new MemoryStream(bytes);
            }
        }

        /// <summary>
        /// Gets the meta tags.
        /// </summary>
        /// <returns>System.String.</returns>
        private string GetMetaTags(string mode)
        {
            var sb = new StringBuilder();

            if (string.Equals(mode, "cordova", StringComparison.OrdinalIgnoreCase) ||
                string.Equals(mode, "android", StringComparison.OrdinalIgnoreCase))
            {
                sb.Append("<meta http-equiv=\"Content-Security-Policy\" content=\"default-src * 'self' 'unsafe-inline' 'unsafe-eval' data: gap: file: filesystem: ws: wss:;\">");
            }

            return sb.ToString();
        }

        /// <summary>
        /// Gets the common javascript.
        /// </summary>
        /// <param name="mode">The mode.</param>
        /// <param name="version">The version.</param>
        /// <returns>System.String.</returns>
        private string GetCommonJavascript(string mode, string version)
        {
            var builder = new StringBuilder();

            builder.Append("<script>");
            if (!string.IsNullOrWhiteSpace(mode))
            {
                builder.AppendFormat("window.appMode='{0}';", mode);
            }

            else
            {
                builder.AppendFormat("window.dashboardVersion='{0}';", version);
            }

            builder.Append("</script>");

            var versionString = string.IsNullOrWhiteSpace(mode) ? "?v=" + version : string.Empty;

            var files = new List<string>();

            files.Add("scripts/apploader.js" + versionString);

            if (string.Equals(mode, "cordova", StringComparison.OrdinalIgnoreCase))
            {
                files.Insert(0, "cordova.js");
            }

            var tags = files.Select(s => string.Format("<script src=\"{0}\" defer></script>", s)).ToArray();

            builder.Append(string.Join(string.Empty, tags));

            return builder.ToString();
        }

        /// <summary>
        /// Gets the raw resource stream.
        /// </summary>
        private Stream GetRawResourceStream(string virtualPath)
        {
            return _resourceFileManager.GetResourceFileStream(_basePath, virtualPath);
        }

    }
}
