using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using Microsoft.Data.Sqlite;
using Microsoft.Extensions.Configuration;
using Microsoft.VisualBasic;
using NLog;

namespace ChaosBot.Database
{
    public static class Controller
    {
        static SqliteConnection _conn = new SqliteConnection($"Data Source={System.IO.Directory.GetCurrentDirectory()}/{Program.Cfg.GetValue<string>("Bot:Database")}");
        private static Logger _logger = Program._logger;
        
        public static DataTable RawQuery(string query)
        {
            DataTable dt = new DataTable();
            
            try
            {
                using (_conn)
                {
                    _conn.Open();

                    SqliteCommand cmd = _conn.CreateCommand();
                    cmd.CommandText = query;
                    SqliteDataReader executeReader = cmd.ExecuteReader(CommandBehavior.SingleResult);
                    
                    dt.Load(executeReader);
                    
                    _conn.Close();
                }
            }
            catch (Exception ex)
            {
                _logger.Fatal($"Controllers.DBWork.RawQuery: Exception [{ex}] thrown, <[{ex.Message}]>.");
            }
            
            return dt;
        }
        
        public static void InsertQuery(string table, Dictionary<string, object> parameters)
        {
            try
            {
                using (_conn)
                {
                    _conn.Open();

                    SqliteCommand cmd = _conn.CreateCommand();
                    StringBuilder commandText = new StringBuilder();
                    commandText.Append("INSERT INTO ");
                    commandText.Append(table);
                    commandText.Append(" (");
                    
                    foreach (string key in parameters.Keys)
                    {
                        commandText.Append($"{key}, ");
                    }
                    
                    commandText.Remove(commandText.Length - 2, 2);
                    commandText.Append(") VALUES (");
                    
                    foreach (string key in parameters.Keys)
                    {
                        commandText.Append($"@{key},");
                    }
                    
                    commandText.Remove(commandText.Length - 1, 1);
                    commandText.Append(")");
                    
                    cmd.CommandText = commandText.ToString();
                    
                    foreach (string key in parameters.Keys)
                    {
                        cmd.Parameters.AddWithValue($"@{key}", parameters.GetValueOrDefault(key));
                    }
                    
                    cmd.Prepare();
                    cmd.ExecuteNonQuery();

                    _conn.Close();
                }
            }
            catch (Exception ex)
            {
                _logger.Fatal($"Controllers.DBWork.RawQuery: Exception [{ex}] thrown, <[{ex.Message}]>.");
            }
        }

        public static int TransactionQuery(List<SqliteCommand> cmds)
        {
            SqliteCommand command = _conn.CreateCommand();
            SqliteTransaction transaction;

            _conn.Open();
            
            // Start a local transaction.
            transaction = _conn.BeginTransaction();

            // Must assign both transaction object and connection
            // to Command object for a pending local transaction
            command.Connection = _conn;
            command.Transaction = transaction;

            try
            {
                foreach (var cmd in cmds)
                {
                    command.CommandText = cmd.CommandText;
                    command.ExecuteNonQuery();
                }
 
                // Attempt to commit the transaction.
                transaction.Commit();
                _logger.Info($"{cmds.Count} record(s) are written to database.");
            }
            catch (Exception ex)
            {
                _logger.Warn("Commit Exception Type: {0}", ex.GetType());
                _logger.Warn("  Message: {0}", ex.Message);

                // Attempt to roll back the transaction.
                try
                {
                    transaction.Rollback();
                }
                catch (Exception ex2)
                {
                    // This catch block will handle any errors that may have occurred
                    // on the server that would cause the rollback to fail, such as
                    // a closed connection.
                    _logger.Warn("Rollback Exception Type: {0}", ex2.GetType());
                    _logger.Warn("  Message: {0}", ex2.Message);
                }

                return 0;
            }

            _conn.Close();
            return cmds.Count;
        }
        
        public static DataTable SelectQuery(string table, string selectColumns = "*", Dictionary<string, object> filterColumns = null, string orderByKey = null)
        {
            DataTable dt = new DataTable();
        
            try
            {
                using (_conn)
                {
                    _conn.Open();
                    SqliteCommand cmd = _conn.CreateCommand();

                    string filter = null;
                    if (filterColumns != null)
                    {
                        List<string> filterList = new List<string>();
                        foreach (string key in filterColumns.Keys)
                        {
                            filterList.Add($"{key} = @{key}");
                        }

                        filter = $"WHERE {Strings.Join(filterList.ToArray(), " AND ")}";

                        foreach (string key in filterColumns.Keys)
                        {
                            cmd.Parameters.AddWithValue($@"{key}", filterColumns.GetValueOrDefault(key));
                        }
                    }

                    string order = null;
                    if (orderByKey != null)
                    {
                        order = $"ORDER BY {orderByKey}";
                    }
                    
                    string query = $"SELECT {selectColumns} FROM {table} {filter} {order}";

                    cmd.CommandText = query;
                    cmd.Prepare();
                    SqliteDataReader executeReader = cmd.ExecuteReader();
                
                    dt.Load(executeReader);
                
                    _conn.Close();
                }
            }
            catch (Exception ex)
            {
                _logger.Fatal($"Controllers.DBWork.RawQuery: Exception [{ex}] thrown, <[{ex.Message}]>.");
            }
        
            return dt;
        }
    }
}