// Copyright (c) 2023-present schick Informatik
// Description: Container class for self-learning, volatile information that
// is added by parsing Excel sheets. Here common wrong/misspelled data fields
// are mapped to valid ones.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data.SqlClient;
using System.Threading.Tasks;

namespace bsmd.database
{
    public class ValueMapping : DatabaseEntityAsync, INotifyPropertyChanged
    {

        #region Construction
        public ValueMapping()
        {
            this.tablename = "[dbo].[ValueMapping]";
        }

        #endregion

        #region enums

        public enum MappingType
        {
            COUNTRY,
            GENDER,
            DOCUMENT_TYPE,
            LOCODE
        }

        #endregion

        #region Fields

        private static Dictionary<MappingType, Dictionary<string, ValueMapping>> _dicts;
        private static Dictionary<MappingType, List<string>> _invalidKeys;

        private string _key, _value, _valueText;

        #endregion

        #region Properties

        public event PropertyChangedEventHandler PropertyChanged;

        public static Dictionary<MappingType, Dictionary<string, ValueMapping>> Dicts
        {
            get
            {
                if (_dicts == null)
                {
                    _dicts = new Dictionary<MappingType, Dictionary<string, ValueMapping>>();
                    foreach (MappingType type in Enum.GetValues(typeof(MappingType)))
                        _dicts[type] = new Dictionary<string, ValueMapping>();
                }
                return _dicts;
            }
        }

        public static Dictionary<MappingType, List<string>> InvalidKeys
        {
            get
            {
                if (_invalidKeys == null)
                {
                    _invalidKeys = new Dictionary<MappingType, List<string>>();
                    // get the keys initialized that cannot be assigned
                    foreach (MappingType type in Enum.GetValues(typeof(MappingType)))
                        _invalidKeys[type] = new List<string>();                    
                }
                return _invalidKeys;
            }
        }

        public MappingType EntryType { get; private set; }

        public string Key
        {
            get { return _key; }
            set
            {
                if (!value.Equals(_key)) this.IsDirty = true;
                this._key = value;
                this.OnPropertyChanged("Key");
            }
        }

        public string Value
        {
            get { return _value; }
            set
            {
                if (!value.Equals(_value)) this.IsDirty = true;
                _value = value;
                OnPropertyChanged("Value");
            }
        }

        public string ValueText
        {
            get { return _valueText; }
            set
            {
                this._valueText = value; 
                this.OnPropertyChanged("ValueText");
            }
        }

        public DateTime? Created { get; private set; }

        public DateTime? Changed { get; private set; }

        #endregion

        #region public funcs

        /// <summary>
        /// creates and saves a new entry and adds it to the internal dictionaries
        /// </summary>        
        /// <returns>true if entry was actually created, false if already present</returns>
        public static async Task<bool> Create(MappingType type, string key, string value)
        {
            if (!Dicts[type].ContainsKey(key))
            {
                ValueMapping vm = new ValueMapping()
                {
                    EntryType = type,
                    Key = key,
                    Value = value
                };

                if (value.Equals("*"))
                    InvalidKeys[type].Add(key);
                else 
                    Dicts[type][key] = vm;
                return await DBManagerAsync.SaveAsync(vm) == 1;
            }
            return false;
        }

        /// <summary>
        /// Create through manual editing in global scope
        /// </summary>        
        public static ValueMapping Create(MappingType type)
        {
            ValueMapping vm = new ValueMapping()
            {
                EntryType = type
            };
            return vm;
        }

        /// <summary>
        /// deletes an entry and removes it from the database
        /// </summary>        
        /// <returns>true if successful, false if value was not found</returns>
        public static async Task<bool> Delete(MappingType type, string key)
        {
            if (!Dicts.ContainsKey(type)) return false;
            if (!Dicts[type].ContainsKey(key)) return false;
            ValueMapping vm = Dicts[type][key];
            Dicts[type].Remove(key);
            return await DBManagerAsync.DeleteAsync(vm) == 1;
        }

        /// <summary>
        /// updates an existing value and saves it
        /// </summary>        
        /// <returns>true if successful</returns>
        public async Task<bool> Update(string newValue)
        {
            this.Value = newValue;
            return await DBManagerAsync.SaveAsync(this) == 1;
        }

        /// <summary>
        /// (re-)loads all value mapping dictionaries
        /// </summary>
        public static async void LoadDicts()
        {
            foreach(MappingType type in Enum.GetValues(typeof(MappingType)))
            {
                Dicts[type].Clear();
                List<ValueMapping> mappings = await DBManagerAsync.LoadValuesForType(type);
                foreach (ValueMapping mapping in mappings)
                {
                    if (mapping.Value.Equals("*"))
                        InvalidKeys[type].Add(mapping.Key);
                    else
                        Dicts[type][mapping.Key] = mapping;
                }
            }
        }

        #endregion

        #region DatabaseEntity implementation

        public override void PrepareSave(System.Data.IDbCommand cmd)
        {
            SqlCommand scmd = cmd as SqlCommand;

            scmd.Parameters.AddWithValue("@TYPE", this.EntryType);
            scmd.Parameters.AddWithNullableValue("@KEY", this.Key);
            scmd.Parameters.AddWithNullableValue("@VALUE", this.Value);

            if(this.IsNew)
            {
                this.CreateId();
                scmd.Parameters.AddWithValue("@ID", this.Id);
                scmd.CommandText = $"INSERT INTO {Tablename} (Id, EntryType, MappingKey, MappingValue) VALUES (@ID, @TYPE, @KEY, @VALUE)";
            }
            else
            {
                scmd.Parameters.AddWithValue("@ID", this.Id);
                scmd.CommandText = $"UPDATE {Tablename} SET EntryType = @TYPE, MappingKey = @KEY, MappingValue = @VALUE WHERE Id = @ID";
            }
        }

        public override void PrepareLoadCommand(System.Data.IDbCommand cmd, Message.LoadFilter filter, params object[] criteria)
        {
            string query = $"SELECT Id, EntryType, MappingKey, MappingValue, Created, Changed FROM {Tablename}";
            switch (filter)
            {
                case Message.LoadFilter.BY_TYPE:
                    query += " WHERE EntryType = @TYPE";
                    ((SqlCommand)cmd).Parameters.AddWithValue("@TYPE", criteria[0]);
                    break;
                default:
                    break;
            }
            query += " ORDER BY MappingKey";
            cmd.CommandText = query;
        }

        protected override DatabaseEntityAsync ReadRowFromReader(System.Data.IDataReader reader)
        {
            ValueMapping vm = null;
            if (reader != null)
            {
                vm = new ValueMapping();

                vm.id = reader.GetGuid(0);

                if (!reader.IsDBNull(1)) vm.EntryType = (ValueMapping.MappingType)reader.GetByte(1);
                if (!reader.IsDBNull(2)) vm._key = reader.GetString(2);
                if (!reader.IsDBNull(3)) vm._value = reader.GetString(3);
                if (!reader.IsDBNull(4)) vm.Created = reader.GetDateTime(4);
                if (!reader.IsDBNull(5)) vm.Changed = reader.GetDateTime(5);

            }
            return vm;
        }

        #endregion

        #region protected methods

        protected void OnPropertyChanged(string name = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
        }

        #endregion

    }
}