using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using DTS.Common.Storage;
using DTS.Common.Utilities.Logging;
// ReSharper disable InconsistentNaming

// ReSharper disable once CheckNamespace
namespace DTS.Slice.Users
{
    public class Tags
    {
        
        /// <summary>
        /// represents a single tag, which is composed of an ID and a string of text
        /// we don't currently let you obsolete, delete, or edit tags, just add
        /// </summary>
        public class Tag: ICloneable
        {
            public Tag(string tagText, int tagId)
            {
                ID = tagId;
                Text = tagText;
                IsObsolete = false;
            }
            public const int INVALID_ID = -1;
            public int ID { get; set; }
            public string Text { get; set; }
            public bool IsObsolete { get; set; }
            public Tag(Tag copy)
            {
                ID = copy.ID;
                Text = copy.Text;
                IsObsolete = copy.IsObsolete;
            }

            public Tag(IDataRecord reader)
            {
                try
                {
                    ID = Convert.ToInt32(reader[DbOperations.Tags.TagFields.TagId.ToString()]);
                    IsObsolete = Convert.ToBoolean(reader[DbOperations.Tags.TagFields.Obsolete.ToString()]);
                    Text = Convert.ToString(reader[DbOperations.Tags.TagFields.TagText.ToString()]);
                }
                catch (Exception ex)
                {
                    APILogger.Log(ex);
                }
            }

            public Tag(DataRow dr)
            {
                try
                {
                    IsObsolete = Convert.ToBoolean(dr[DbOperations.Tags.TagFields.Obsolete.ToString()]);
                    ID = Convert.ToInt32(dr[DbOperations.Tags.TagFields.TagId.ToString()]);
                    Text = Convert.ToString(dr[DbOperations.Tags.TagFields.TagText.ToString()]);
                }
                catch (Exception ex) { APILogger.Log(ex); }
            }
            public object Clone()
            {
                return new Tag(this);
            }
        }
        private static Tags _tagsInstance;
        public static Tags TagsInstance
        {
            get
            {
                if (null == _tagsInstance) { _tagsInstance = new Tags(); }
                return _tagsInstance;
            }
        }
        private static readonly object LOCK_OBJECT = new object();
        public Tags()
        {
            _tagsLookup = new Dictionary<string, Tag>();
            UpdateList();
        }
        /// <summary>
        /// holds a cached collection of tags.  This collection however is currently only populated on startup
        /// and not updated except explicitly when a user adds a tag
        /// </summary>
        // ReSharper disable once RedundantDefaultMemberInitializer
        private readonly Dictionary<string, Tag> _tagsLookup = null;
        
        /// <summary>
        /// Adds a tag if not present in memory cache to db
        /// </summary>
        /// <param name="tagText"></param>
        /// <returns></returns>
        public static bool AddTag(string tagText)
        {
            if (string.IsNullOrEmpty(tagText)) { return false; }

            // is it already in the dictionary?
            if (TagsInstance.ContainsTag(tagText)) return false;
            TagsInstance.Commit(new Tag(tagText, Tag.INVALID_ID));
            return true;
        }
        /// <summary>
        /// Changes the ID of a tag during database migration
        /// </summary>
        /// <param name="tagText"></param>
        /// <returns></returns>
        public static bool MigrateTag(string tagText)
        {
            if (string.IsNullOrEmpty(tagText)) { return false; }

            TagsInstance.Commit(new Tag(tagText, Tag.INVALID_ID));
            return true;
        }
        /// <summary>
        /// commits a tag to db if doesn't already exist in db
        /// </summary>
        /// <param name="tag"></param>
        private void Commit(Tag tag)
        {
            try
            {
                if (-1 == GetIDFromTagText(tag.Text))
                {
                    Insert(tag);
                }
                else { UpdateAll(tag); }

                lock (LOCK_OBJECT)
                {
                    _tagsLookup[tag.Text] = tag;
                }
            }
            catch (Exception ex)
            {
                APILogger.Log(ex);
            }
        }
        private void UpdateAll(Tag tag)
        {
            //nothing to do currently?  (we don't let you rename or edit, or obsolete, or delete ...)
            tag.ID = GetTagIdFromText(tag.Text);
        }
        /// <summary>
        /// inserts a tag into the db
        /// </summary>
        /// <param name="tag"></param>
        private void Insert(Tag tag)
        {
            using (var cmd = DbOperations.GetSQLCommand(true))
            {
                try
                {
                    cmd.CommandType = CommandType.StoredProcedure;
                    cmd.CommandText = DbOperationsEnum.StoredProcedure.sp_TagsInsert.ToString();

                    #region params

                    cmd.Parameters.Add(new SqlParameter("@TagText", SqlDbType.NVarChar, 255) {Value = tag.Text});
                    cmd.Parameters.Add(new SqlParameter("@Obsolete", SqlDbType.Bit) {Value = tag.IsObsolete});
                    var newIdParam = new SqlParameter("@new_id", SqlDbType.Int) {Direction = ParameterDirection.Output};
                    cmd.Parameters.Add(newIdParam);
                    var errorNumberParam =
                        new SqlParameter("@errorNumber", SqlDbType.Int) {Direction = ParameterDirection.Output};
                    cmd.Parameters.Add(errorNumberParam);
                    var errorMessageParam =
                        new SqlParameter("@errorMessage", SqlDbType.NVarChar, 250)
                        {
                            Direction = ParameterDirection.Output
                        };
                    cmd.Parameters.Add(errorMessageParam);

                    #endregion params

                    cmd.ExecuteNonQuery();
                    if (int.Parse(errorNumberParam.Value.ToString()) != 0)
                    {
                        //errorMessageParam.Value
                    }


                    tag.ID = int.Parse(newIdParam.Value.ToString());
                }
                finally
                {
                    cmd.Connection.Dispose();
                }
            }
        }
        /// <summary>
        /// retrieves a string text associated with an ID FROM CACHED copies
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        private string GetTagTextFromId(int id)
        {
            lock (LOCK_OBJECT)
            {
                if (_tagsLookup == null) return null;
                var e = _tagsLookup.GetEnumerator();
                while (e.MoveNext())
                {
                    if (e.Current.Value.ID != id) continue;
                    var returnText = e.Current.Value.Text;
                    e.Dispose();
                    return returnText;
                }
            }
            return null;
        }
        /// <summary>
        /// Gets an ID for a given tag text FROM DB
        /// returns InvalidID if not found
        /// </summary>
        /// <param name="text"></param>
        /// <returns></returns>
        private int GetTagIdFromText(string text)
        {
            using (var cmd = DbOperations.GetSQLCommand(true))
            {
                try
                {
                    cmd.CommandType = CommandType.StoredProcedure;
                    cmd.CommandText = DbOperationsEnum.StoredProcedure.sp_TagsGetId.ToString();

                    #region params

                    cmd.Parameters.Add(new SqlParameter("@TagText", SqlDbType.NVarChar, 255) {Value = text});
                    var tagIdParam = new SqlParameter("@TagId", SqlDbType.Int) {Direction = ParameterDirection.Output};
                    cmd.Parameters.Add(tagIdParam);

                    #endregion params

                    cmd.ExecuteNonQuery();

                    if (DBNull.Value.Equals(tagIdParam.Value))
                    {
                        return Tag.INVALID_ID;
                    }
                    var tagIdtemp = int.Parse(tagIdParam.Value.ToString());
                    return tagIdtemp == 0 ? Tag.INVALID_ID : tagIdtemp;
                }
                finally
                {
                    cmd.Connection.Dispose();
                }
            }
            
        }

        /// <summary>
        /// returns true if a given tag text is contained in cached in memory tags
        /// </summary>
        /// <param name="text"></param>
        /// <returns></returns>
        public bool ContainsTag(string text)
        {
            lock (LOCK_OBJECT)
            {
                return _tagsLookup.ContainsKey(text);
            }
        }
        /// <summary>
        /// adds multiple tags at once
        /// note that tags will have their start trimmed before commiting
        /// </summary>
        /// <param name="tagText"></param>
        /// <returns></returns>
        public static bool[] AddRange(string[] tagText)
        {
            List<bool> rv = new List<bool>();
            if (null == tagText || 0 == tagText.Length) { return null; }
            foreach (string s in tagText)
            {
                var tag = s.TrimStart();
                rv.Add(AddTag(tag));
            }
            return rv.ToArray();
        }
        /// <summary>
        /// gets an ID for a given tag text FROM DB
        /// </summary>
        /// <param name="tagText"></param>
        /// <returns></returns>
        public static int GetIDFromTagText(string tagText)
        {
            return TagsInstance.GetTagIdFromText(tagText);
        }
        /// <summary>
        /// gets an array of ids given an array of tag texts
        /// </summary>
        /// <param name="tagText"></param>
        /// <returns></returns>
        public static int[] GetIDsFromTagText(string[] tagText)
        {
            if (null == tagText || 0 == tagText.Length) { return null; }

            return tagText.Select(s => s.TrimStart()).Select(text => GetIDFromTagText(text)).Where(id => id != Tag.INVALID_ID).ToArray();
        }
        /// <summary>
        /// returns a string for a given id from memory cache
        /// returns null if it doesn't exist or is an invalid id
        /// </summary>
        /// <param name="tagID"></param>
        /// <returns></returns>
        public static string GetTagTextFromID(int tagID)
        {
            if (0 > tagID || tagID == Tag.INVALID_ID)
            {
                // Not a valid ID
                return null;
            }
            return TagsInstance.GetTagTextFromId(tagID);
        }

        /// <summary>
        /// returns an array of tag text given an array of tag ids.
        /// skips invalid tags or tag text
        /// </summary>
        /// <param name="tagId"></param>
        /// <returns></returns>
        public static string[] GetTagTextFromIDs(int[] tagId)
        {
            if (null == tagId || 0 == tagId.Length) { return new string [0]; }

            return tagId.Where(i => i != Tag.INVALID_ID).Select(i => GetTagTextFromID(i)).Where(tag => !string.IsNullOrWhiteSpace(tag)).ToArray();
        }

        /// <summary>
        /// retrieves all tags and updates the cached dictionary of tags
        /// </summary>
        public void UpdateList()
        {
            lock (LOCK_OBJECT)
            {
                _tagsLookup.Clear();
                using (var cmd = DbOperations.GetSQLCommand(true))
                {
                    try
                    {
                        cmd.CommandType = CommandType.StoredProcedure;
                        cmd.CommandText = DbOperationsEnum.StoredProcedure.sp_TagsGet.ToString();
                        cmd.Parameters.Add(new SqlParameter("@TagId", SqlDbType.Int) {Value = null});

                        var reader = cmd.ExecuteReader();
                        while (reader.Read())
                        {

                            var t = new Tag(reader);
                            if (t.ID == 0) continue;
                            _tagsLookup[t.Text] = t;
                        }
                        reader.Close();
                    }
                    finally
                    {
                        cmd.Connection.Dispose();
                    }
                }
            }
        }
    }
}