using System;
using System.Collections.Generic;

namespace MahTweets.Extensions.Twitter.Mango
{
    internal static class TwitterHelper
    {
        public const string RetweetPrefix = "RT @";
        public const string MentionPrefix = "@";
        public const string DirectmessagePrefix = "d ";
        public const int TweetLength = 140;

        public const string TimelineSetting = "TimelineFrequency";
        public const string DirectmsgSetting = "DirectMessageFrequency";
        public const string MentionSetting = "MentionFrequency";
        public const string RetweetSetting = "RetweetFrequency";
        public const string ListsSetting = "ListsFrequency";
        public const string TweetsPerCallSetting = "TweetsPerCall";
        public const string GeotagSetting = "GeoTag";
        public const string UserstreamSetting = "UserStream";

        public static IList<string> SplitIntoMessages(string text)
        {
            var outputTweets = new List<string>();

            // don't need to split, return single item in list
            if (text.Length <= TweetLength)
            {
                outputTweets.Add(text.Trim());
                return outputTweets;
            }

            // if we have a Twitter-specific message, extract it so that 
            // we can add it to multiple messages
            string contents;
            var prefix = GetTweetPrefix(text, out contents);

            var array = contents.Split(new[] {' '});
            var maximumLength = TweetLength - 2 - prefix.Length;

            var str = string.Empty;

            foreach (var t in array)
            {
                if ((str.Length + 1 + t.Length) <= maximumLength)
                {
                    str = string.Concat(str, " ", t);
                }
                else
                {
                    outputTweets.Add(prefix + str.Trim());
                    str = t;
                }
            }

            // add final tweet
            outputTweets.Add(prefix + str.Trim());
            return outputTweets;
        }

        public static string GetTweetPrefix(string text, out string contents)
        {
            var prefix = string.Empty;
            if (text.StartsWith(MentionPrefix, StringComparison.InvariantCultureIgnoreCase))
            {
                // check each word and remove multiple '@'s if they're found
                var allWords = text.Split(new[] {' '});

                var mentionNames = new List<string>();

                foreach (var t in allWords)
                {
                    if (t.StartsWith("@") && t.Length > 1)
                        mentionNames.Add(t);
                    else
                        break;
                }

                // we have a mention 
                //prefix = text.Substring(0, text.IndexOf(" ", TwitterHelper.MENTION_PREFIX.Length + 1));
                prefix = string.Join(" ", mentionNames.ToArray());
            }
            else if (text.StartsWith(DirectmessagePrefix, StringComparison.InvariantCultureIgnoreCase))
            {
                // we have a DM - get the prefix and the name
                prefix = text.Substring(0, text.IndexOf(" ", DirectmessagePrefix.Length + 1));
            }
            else if (text.StartsWith(RetweetPrefix, StringComparison.InvariantCultureIgnoreCase))
            {
                // we have a RT - get the prefix and the name
                prefix = text.Substring(0, text.IndexOf(" ", RetweetPrefix.Length + 1));
            }

            if (prefix != string.Empty)
            {
                prefix = string.Concat(prefix, " ");
                contents = text.Replace(prefix, string.Empty);
            }
            else
            {
                contents = text;
            }

            return prefix;
        }
    }
}