using System;
using System.Globalization;
using System.Text;
using System.Collections.Generic;
using System.IO;
using Newtonsoft.Json.Linq;
using Microsoft.Extensions.Logging;
using Microsoft.EntityFrameworkCore;
using AyaNova.Util;
using AyaNova.Models;


namespace AyaNova.Biz
{

    //This class handles word breaking, processing keywords and searching for results
    public static class Search
    {

        //Initial keyword indexing consists of 
        //WordBreaker - break down into words
        //ProcessKeywords into database

        #region ProcessKeywords into Database

        public static void ProcessNewObjectKeywords(AyContext ct, long localeId, long objectID, AyaType objectType, string name, params string[] text)
        {
            ProcessKeywords(ct, localeId, objectID, objectType, true, name, text);
        }

        public static void ProcessUpdatedObjectKeywords(AyContext ct, long localeId, long objectID, AyaType objectType, string name, params string[] text)
        {
            ProcessKeywords(ct, localeId, objectID, objectType, false, name, text);
        }

        public static void ProcessDeletedObjectKeywords(AyContext ct, long objectID, AyaType objectType)
        {
            //Be careful in future, if you put ToString at the end of each object in the string interpolation
            //npgsql driver will assume it's a string and put quotes around it triggering an error that a string can't be compared to an int
            ct.Database.ExecuteSqlCommand($"delete from asearchkey where objectid={objectID} and objecttype={(int)objectType}");
        }


        /// <summary>
        /// Process the keywords into the dictionary
        /// </summary>    
        private static void ProcessKeywords(AyContext ct, long localeId, long objectID, AyaType objectType, bool newRecord, string name, params string[] text)
        {

            //TODO: Code this, using method idea from v7 code and adding the handling of the new InName flag and Name separately.
            //Note that as initially coded in widget test class the context will be saved by the controller as it is also done with the event log
            //So theoretically I don't save here, but it may turn out that the code requires a save so in that case need to re-do the WidgetController calls to here to 
            //account for the save


            //IF NOT NEW, DELETE ALL EXISTING ENTRIES FOR OBJECT TYPE AND ID
            if (!newRecord)
            {
                ProcessDeletedObjectKeywords(ct, objectID, objectType);
            }

            //BREAK STRING ARRAY INTO KEYWORD LIST            
            List<string> KeyWordList = Break(localeId, text);

            //EARLY EXIT IF NO KEYWORDS OR NAME RECORD TO PROCESS
            if (KeyWordList.Count == 0 && string.IsNullOrWhiteSpace(name))
            {
                return;
            }

            //ITERATE ALL THE KEYWORDS, SEARCH IN THE SEARCHDICTIONARY TABLE AND COLLECT ID'S OF ANY PRE-EXISTING IN DB KEYWORDS

            //ITERATE THROUGH THE KEYWORDS THAT DO *NOT* HAVE MATCHES IN THE SEARCHDICTIONARY AND ADD THEM TO THE SEARCH DICTIONARY, COLLECTING THEIR ID'S

            //CREATE THE SEARCHKEY RECORDS FOR ALL THE KEYWORDS 


        }
        #endregion




        #region Breaker

        //Class to hold relevant locale data for breaking text
        public class LocaleWordBreakingData
        {
            public bool CJKIndex { get; set; }
            public List<string> StopWords { get; set; }
            public LocaleWordBreakingData()
            {
                CJKIndex = false;
                StopWords = new List<string>();
            }
        }

        //Get the current stopwords for the user's locale
        private static LocaleWordBreakingData GetLocaleSearchData(long localeId, AyContext ct = null)
        {
            LocaleWordBreakingData LSD = new LocaleWordBreakingData();
            if (ct == null)
                ct = ServiceProviderProvider.DBContext;
            //Get stopwords
            //Validate locale id, if not right then use default instead 
            var Param = new Api.Controllers.LocaleController.LocaleSubsetParam();
            Param.LocaleId = LocaleBiz.EnsuredLocaleIdStatic(localeId, ct);
            Param.Keys.Add("StopWords1");
            Param.Keys.Add("StopWords2");
            Param.Keys.Add("StopWords3");
            Param.Keys.Add("StopWords4");
            Param.Keys.Add("StopWords5");
            Param.Keys.Add("StopWords6");
            Param.Keys.Add("StopWords7");
            var Stops = LocaleBiz.GetSubsetStatic(Param).Result;

            foreach (KeyValuePair<string, string> kvp in Stops)
            {
                //Each stopwords locale key is a space delimited list of words and in the case of an empty local string (i.e. StopWords7) it's value is a single question mark
                if (kvp.Value != "?")
                {
                    LSD.StopWords.AddRange(kvp.Value.Split(" "));
                }
            }

            LSD.CJKIndex = LocaleBiz.GetCJKIndex(localeId, ct).Result;
            return LSD;
        }

        public enum TokenTypes
        { Nothing, Separator, CJK, Latin };

        /// <summary>
        /// Take an array of strings and 
        /// return a single string
        /// containing unique only, lowercase comma delimited 
        /// keywords suitable for passing to a 
        /// stored procedure or other function
        /// 
        /// Use Locale setting CJKIndex=true to handle Chinese, Japanese, Korean etc
        /// (languages with no easily identifiable word boundaries as in english)
        /// </summary>
        /// 
        /// <param name="localeId"></param>
        /// <param name="text">An array of 0 to * strings of text</param>
        /// <returns>List of strings</returns>
        internal static List<string> Break(long localeId, params string[] text)
        {
            List<string> KeyWordList = new List<string>(BreakCore(localeId, false, text).Split(','));
            return KeyWordList;
        }

        /// <summary>
        /// Used to Process users search phrase and preserve wild
        /// cards entered
        /// </summary>
        /// <param name="localeId"></param>
        /// <param name="text"></param>
        /// <returns></returns>
        internal static string BreakSearchPhrase(long localeId, params string[] text)
        {
            return BreakCore(localeId, true, text);
        }

        /// <summary>
        /// Stop words list reset upon login or editing of localized text
        /// used for eliminating noise words from search dictionary
        /// </summary>
        public static System.Collections.Generic.List<string> StopList = null;

        internal static string BreakCore(long localeId, bool KeepWildCards, params string[] text)
        {
            //Get stopwords and CJKIndex flag value
            LocaleWordBreakingData LSD = GetLocaleSearchData(localeId);
            int MAXWORDLENGTH = 255;
            StringBuilder sbResults = new StringBuilder();
            //List to temporarily hold parsed words
            //used to easily ensure unique words only
            List<string> tempParsedWords = new List<string>();

            StringBuilder sb = new StringBuilder();
            StringBuilder sbWord = new StringBuilder();
            // System.IO.StringWriter sr = new System.IO.StringWriter(sb);
            // System.Xml.XmlTextWriter w = new System.Xml.XmlTextWriter(sr);

            // w.Formatting = System.Xml.Formatting.Indented;
            // w.WriteStartElement("Items");


            //Loop through each of the passed in strings
            foreach (string s in text)
            {
                if (s == null || s == "") continue;
                //get all the characters in a unicode compliant manner...
                TextElementEnumerator t = StringInfo.GetTextElementEnumerator(s);
                //start at the top
                t.Reset();

                TokenTypes LastToken = TokenTypes.Nothing;

                //Used by CJK
                bool BasicLatinBlock = true;

                //Process each "character" (text element,glyph whatever) in the 
                //current string
                while (t.MoveNext())
                {
                    //get it as a character
                    char c = t.GetTextElement()[0];

                    if (!LSD.CJKIndex)
                    {
                        #region regular tokenizer

                        //Is it a token we want to include?
                        //Or a wildcard character
                        if (char.IsLetterOrDigit(c) || (KeepWildCards && c == '%'))
                        {
                            #region Include token
                            //All latin text is converted to lower case
                            c = char.ToLower(c);

                            //Do we already have a word?
                            if (sbWord.Length > 0)
                            {
                                //Maybe we need to flush this word into the word list
                                //if we're over the word length limit 
                                if (sbWord.Length >= MAXWORDLENGTH)
                                {
                                    //flush away...
                                    if (!tempParsedWords.Contains(sbWord.ToString()))
                                    {
                                        tempParsedWords.Add(sbWord.ToString());
                                    }
                                    sbWord.Length = 0;
                                    sbWord.Append(c);
                                    LastToken = TokenTypes.Latin;
                                    continue;

                                }
                            }

                            //append character and go on to next one
                            sbWord.Append(c);
                            LastToken = TokenTypes.Latin;
                            continue;
                            #endregion
                        }
                        else
                        {
                            #region Word Boundary token
                            LastToken = TokenTypes.Separator;
                            if (sbWord.Length > 0)
                            {
                                //flush away...
                                if (!tempParsedWords.Contains(sbWord.ToString()))
                                {
                                    tempParsedWords.Add(sbWord.ToString());
                                }
                                sbWord.Length = 0;
                                continue;
                            }

                            #endregion
                        }
                        #endregion
                    }
                    else
                    {
                        #region CJK Tokenizer

                        //Is it a basic latin charater? (ascii basically)
                        //see: http://www.unicode.org/charts/index.html
                        //and here for a funky online viewer:
                        //http://www.fileformat.info/info/unicode/block/index.htm
                        //we need to know this so that regular english text
                        //within cjk text gets properly indexed as whole words
                        BasicLatinBlock = false;
                        if ((int)c < 256) BasicLatinBlock = true;

                        if (BasicLatinBlock)
                        {
                            //Is it a token we want to include?
                            if (char.IsLetterOrDigit(c) || (KeepWildCards && c == '%'))
                            {
                                #region Latin Include token
                                //All latin text is converted to lower case
                                c = char.ToLower(c);

                                //Do we already have a word?
                                if (sbWord.Length > 0)
                                {
                                    //Maybe we need to flush this word into the word list
                                    //if we're over the word length limit or we are going from 
                                    //CJK to latin
                                    if (LastToken == TokenTypes.CJK || sbWord.Length >= MAXWORDLENGTH)
                                    {
                                        //flush away...
                                        if (!tempParsedWords.Contains(sbWord.ToString()))
                                        {
                                            tempParsedWords.Add(sbWord.ToString());
                                        }
                                        sbWord.Length = 0;
                                        sbWord.Append(c);
                                        LastToken = TokenTypes.Latin;
                                        continue;

                                    }
                                }

                                //append character and go on to next one
                                sbWord.Append(c);
                                LastToken = TokenTypes.Latin;
                                continue;
                                #endregion
                            }
                            else
                            {
                                #region Latin Word Boundary token
                                LastToken = TokenTypes.Separator;
                                if (sbWord.Length > 0)
                                {
                                    //flush away...
                                    if (!tempParsedWords.Contains(sbWord.ToString()))
                                    {
                                        tempParsedWords.Add(sbWord.ToString());
                                    }
                                    sbWord.Length = 0;

                                    continue;

                                }

                                #endregion
                            }

                        }
                        else//CJK character
                        {
                            if (char.IsLetter(c) || (KeepWildCards && c == '%'))
                            {
                                #region CJK Include token
                                //Do we already have a word?
                                if (sbWord.Length > 0)
                                {
                                    //Maybe we need to flush this word into the word list
                                    //if we're over the word length limit or we are going from 
                                    //latin TO CJK 
                                    if (LastToken == TokenTypes.Latin || sbWord.Length >= MAXWORDLENGTH)
                                    {
                                        //flush away...
                                        if (!tempParsedWords.Contains(sbWord.ToString()))
                                        {
                                            tempParsedWords.Add(sbWord.ToString());
                                        }
                                        sbWord.Length = 0;
                                        sbWord.Append(c);
                                        LastToken = TokenTypes.CJK;
                                        continue;

                                    }

                                    if (LastToken == TokenTypes.CJK)
                                    {
                                        //we're here because there is more than zero characters already stored
                                        //and the last was CJK so we need append current character
                                        //and flush the resultant 2 character n-gram 
                                        sbWord.Append(c);
                                        System.Diagnostics.Debug.Assert(sbWord.Length == 2);
                                        //flush away...
                                        if (!tempParsedWords.Contains(sbWord.ToString()))
                                        {
                                            tempParsedWords.Add(sbWord.ToString());
                                        }
                                        sbWord.Length = 0;
                                        sbWord.Append(c);
                                        LastToken = TokenTypes.CJK;
                                        continue;

                                    }
                                }

                                //append character and go on to next one
                                sbWord.Append(c);
                                LastToken = TokenTypes.CJK;
                                continue;
                                #endregion


                            }
                            else
                            {
                                #region CJK Word Boundary token
                                LastToken = TokenTypes.Separator;
                                if (sbWord.Length > 0)
                                {
                                    //flush away...
                                    if (!tempParsedWords.Contains(sbWord.ToString()))
                                    {
                                        tempParsedWords.Add(sbWord.ToString());
                                    }
                                    sbWord.Length = 0;
                                    continue;
                                }

                                #endregion
                            }

                        }

                        #endregion
                    }
                }

                //Flush out the last word
                if (sbWord.Length > 0)
                {
                    //flush away...
                    if (!tempParsedWords.Contains(sbWord.ToString()))
                    {
                        tempParsedWords.Add(sbWord.ToString());
                    }
                    sbWord.Length = 0;
                }
            }


            //bail early if there is nothing indexed
            if (tempParsedWords.Count == 0) return "";


            //Make a return string array
            //from the word list
            foreach (string s in tempParsedWords)
            {
                //Add only non stopwords
                if (!StopList.Contains(s))
                {
                    sbResults.Append(s);
                    sbResults.Append(",");
                }
            }

            //sometimes all the results are stop words so you end up 
            //here with nothing in sbResults. 
            return sbResults.ToString().TrimEnd(',');

        }

        #endregion





    }//eoc

}//eons