using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
using System.Text.RegularExpressions;
using CefSharp;
using TweetDuck.Utils;
using TweetLib.Core.Utils;

namespace TweetDuck.Browser.Handling{
    class ResourceRequestHandlerBase : ResourceRequestHandler{
        private static readonly Regex TweetDeckResourceUrl = new Regex(@"/dist/(.*?)\.(.*?)\.(css|js)$");
        private static readonly SortedList<string, string> TweetDeckHashes = new SortedList<string, string>(4);

        public static void LoadResourceRewriteRules(string rules){
            if (string.IsNullOrEmpty(rules)){
                return;
            }

            TweetDeckHashes.Clear();

            foreach(string rule in rules.Replace(" ", "").ToLower().Split(',')){
                var (key, hash) = StringUtils.SplitInTwo(rule, '=') ?? throw new ArgumentException("A rule must have one '=' character: " + rule);

                if (hash.All(chr => char.IsDigit(chr) || (chr >= 'a' && chr <= 'f'))){
                    TweetDeckHashes.Add(key, hash);
                }
                else{
                    throw new ArgumentException("Invalid hash characters: " + rule);
                }
            }
        }

        protected override CefReturnValue OnBeforeResourceLoad(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IRequestCallback callback){
            if (request.ResourceType == ResourceType.CspReport){
                callback.Dispose();
                return CefReturnValue.Cancel;
            }

            if (BrowserUtils.HasDevTools){
                NameValueCollection headers = request.Headers;
                headers.Remove("x-devtools-emulate-network-conditions-client-id");
                request.Headers = headers;
            }

            return base.OnBeforeResourceLoad(browserControl, browser, frame, request, callback);
        }

        protected override bool OnResourceResponse(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IResponse response){
            if ((request.ResourceType == ResourceType.Script || request.ResourceType == ResourceType.Stylesheet) && TweetDeckHashes.Count > 0){
                string url = request.Url;
                Match match = TweetDeckResourceUrl.Match(url);

                if (match.Success && TweetDeckHashes.TryGetValue($"{match.Groups[1]}.{match.Groups[3]}", out string hash)){
                    if (match.Groups[2].Value == hash){
                        Program.Reporter.LogVerbose("[RequestHandlerBase] Accepting " + url);
                    }
                    else{
                        Program.Reporter.LogVerbose("[RequestHandlerBase] Replacing " + url + " hash with " + hash);
                        request.Url = TweetDeckResourceUrl.Replace(url, $"/dist/$1.{hash}.$3");
                        return true;
                    }
                }
            }

            return base.OnResourceResponse(browserControl, browser, frame, request, response);
        }
    }
}