using System.IO;
using System.Text.RegularExpressions;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using Umbraco.Core.IO;
using Umbraco.Core.Manifest;

namespace Umbraco.Web.UI.JavaScript
{
    /// <summary>
    /// Reads from all defined manifests and ensures that any of their initialization is output with the
    /// main Umbraco initialization output.
    /// </summary>
    internal class JsInitialization
    {        
        private readonly ManifestParser _parser;

        public JsInitialization(ManifestParser parser)
        {
            _parser = parser;
        }

        //used to strip comments
        internal static readonly Regex Comments = new Regex("(/\\*.*\\*/)", RegexOptions.Compiled);
        //used for dealing with js functions inside of json (which is not a supported json syntax)
        private const string PrefixJavaScriptObject = "@@@@";
        private static readonly Regex JsFunctionParser = new Regex(string.Format("(\"{0}(.*?)\")+", PrefixJavaScriptObject),
                                                                    RegexOptions.Multiline
                                                                    | RegexOptions.CultureInvariant
                                                                    | RegexOptions.Compiled);
        //used to replace the tokens in the js main
        private static readonly Regex Token = new Regex("(\"##\\w+?##\")", RegexOptions.Compiled);

        /// <summary>
        /// Processes all found manifest files and outputs the main.js file containing all plugin manifests
        /// </summary>
        public string GetJavascriptInitialization(JArray umbracoInit)
        {
            foreach (var m in _parser.GetManifests())
            {
                ManifestParser.MergeJArrays(umbracoInit, m.JavaScriptInitialize);
            }

            return ParseMain(
                umbracoInit.ToString(),
                IOHelper.ResolveUrl(SystemDirectories.Umbraco));
        }

        /// <summary>
        /// Returns the default config as a JArray
        /// </summary>
        /// <returns></returns>
        internal static JArray GetDefaultInitialization()
        {
            var init = Resources.JsInitialize;
            var jArr = JsonConvert.DeserializeObject<JArray>(init);
            return jArr;
        }

        /// <summary>
        /// Parses the JsResources.Main and replaces the replacement tokens accordingly.
        /// </summary>
        /// <param name="replacements"></param>
        /// <returns></returns>
        internal static string ParseMain(params string[] replacements)
        {
            var count = 0;

            return Token.Replace(Resources.Main, match =>
            {
                var replaced = replacements[count];

                //we need to cater for the special syntax when we have js function() objects contained in the json
                var jsFunctionParsed = JsFunctionParser.Replace(replaced, "$2");

                count++;

                return jsFunctionParsed;
            });
        }

    }
}