using System;
using System.Collections.Generic;

namespace MahTweets.Extensions.Twitter
{
    internal static class TwitterHelper
    {
        public const string RETWEET_PREFIX = "RT @";
        public const string MENTION_PREFIX = "@";
        public const string DIRECTMESSAGE_PREFIX = "d ";
        public const int TWEET_LENGTH = 140;

        public const string TIMELINE_SETTING = "TimelineFrequency";
        public const string DIRECTMSG_SETTING = "DirectMessageFrequency";
        public const string MENTION_SETTING = "MentionFrequency";
        public const string RETWEET_SETTING = "RetweetFrequency";
        public const string LISTS_SETTING = "ListsFrequency";
        public const string TWEETSPERCALL_SETTING = "TweetsPerCall";
        public const string GEOTAG_SETTING = "GeoTag";
        public const string USERSTREAM_SETTING = "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 <= TWEET_LENGTH)
            {
                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;
            string prefix = GetTweetPrefix(text, out contents);

            string[] array = contents.Split(new[] {' '});
            int maximumLength = TWEET_LENGTH - 2 - prefix.Length;

            string str = string.Empty;

            for (int i = 0; i < array.Length; i++)
            {
                if ((str.Length + 1 + array[i].Length) <= maximumLength)
                {
                    str = string.Concat(str, " ", array[i]);
                }
                else
                {
                    outputTweets.Add(prefix + str.Trim());
                    str = array[i];
                }
            }

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

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

                var mentionNames = new List<string>();

                for (int i = 0; i < allWords.Length; i++)
                {
                    if (allWords[i].StartsWith("@") && allWords[i].Length > 1)
                        mentionNames.Add(allWords[i]);
                    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(DIRECTMESSAGE_PREFIX, StringComparison.InvariantCultureIgnoreCase))
            {
                // we have a DM - get the prefix and the name
                prefix = text.Substring(0, text.IndexOf(" ", DIRECTMESSAGE_PREFIX.Length + 1));
            }
            else if (text.StartsWith(RETWEET_PREFIX, StringComparison.InvariantCultureIgnoreCase))
            {
                // we have a RT - get the prefix and the name
                prefix = text.Substring(0, text.IndexOf(" ", RETWEET_PREFIX.Length + 1));
            }

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

            return prefix;
        }
    }
}