using System;
using System.Collections.Generic;
using System.Data;

namespace TShockAPI.DB
{
    public static class DbExt
    {

        /// <summary>
        /// Executes a query on a database.
        /// </summary>
        /// <param name="olddb">Database to query</param>
        /// <param name="query">Query string with parameters as @0, @1, etc.</param>
        /// <param name="args">Parameters to be put in the query</param>
        /// <returns>Rows affected by query</returns>
        public static int Query(this IDbConnection olddb, string query, params object[] args)
        {
            using (var db = olddb.CloneEx())
            {
                db.Open();
                using (var com = db.CreateCommand())
                {
                    com.CommandText = query;
                    for (int i = 0; i < args.Length; i++)
                        com.AddParameter("@" + i, args[i]);

                    return com.ExecuteNonQuery();
                }
            }
        }
        /// <summary>
        /// Executes a query on a database.
        /// </summary>
        /// <param name="olddb">Database to query</param>
        /// <param name="query">Query string with parameters as @0, @1, etc.</param>
        /// <param name="args">Parameters to be put in the query</param>
        /// <returns>Query result as IDataReader</returns>
        public static QueryResult QueryReader(this IDbConnection olddb, string query, params object[] args)
        {
            var db = olddb.CloneEx();
            db.Open();
            using (var com = db.CreateCommand())
            {
                com.CommandText = query;
                for (int i = 0; i < args.Length; i++)
                    com.AddParameter("@" + i, args[i]);

                return new QueryResult(db, com.ExecuteReader());
            }
        }

        public static IDbDataParameter AddParameter(this IDbCommand command, string name, object data)
        {
            var parm = command.CreateParameter();
            parm.ParameterName = name;
            parm.Value = data;
            command.Parameters.Add(parm);
            return parm;
        }

        public static IDbConnection CloneEx(this IDbConnection conn)
        {
            var clone = (IDbConnection)Activator.CreateInstance(conn.GetType());
            clone.ConnectionString = conn.ConnectionString;
            return clone;
        }

        public static SqlType GetSqlType(this IDbConnection conn)
        {
            var name = conn.GetType().Name;
            if (name == "SqliteConnection")
                return SqlType.Sqlite;
            if (name == "MySqlConnection")
                return SqlType.Mysql;
            return SqlType.Unknown;
        }

        static readonly Dictionary<Type, Func<IDataReader, int, object>> ReadFuncs = new Dictionary<Type, Func<IDataReader, int, object>>()
        {
            {typeof(bool), (s, i) => s.GetBoolean(i)},
            {typeof(byte), (s, i) => s.GetByte(i)},
            {typeof(Int16), (s, i) => s.GetInt16(i)},
            {typeof(Int32), (s, i) => s.GetInt32(i)},
            {typeof(Int64), (s, i) => s.GetInt64(i)},
            {typeof(string), (s, i) => s.GetString(i)},
            {typeof(decimal), (s, i) => s.GetDecimal(i)},
            {typeof(float), (s, i) => s.GetFloat(i)},
            {typeof(double), (s, i) => s.GetDouble(i)},
            {typeof(object), (s, i) => s.GetValue(i)},
        };

        public static T Get<T>(this IDataReader reader, string column)
        {
            return reader.Get<T>(reader.GetOrdinal(column));
        }

        public static T Get<T>(this IDataReader reader, int column)
        {
            if (reader.IsDBNull(column))
                return default(T);

            if (ReadFuncs.ContainsKey(typeof(T)))
                return (T)ReadFuncs[typeof(T)](reader, column);

            throw new NotImplementedException();
        }
    }

    public enum SqlType
    {
        Unknown,
        Sqlite,
        Mysql
    }

    public class QueryResult : IDisposable
    {
        public IDbConnection Connection { get; protected set; }
        public IDataReader Reader { get; protected set; }

        public QueryResult(IDbConnection conn, IDataReader reader)
        {
            Connection = conn;
            Reader = reader;
        }

        public void Dispose()
        {
            Reader.Dispose();
            Connection.Dispose();
        }

        public bool Read()
        {
            return Reader.Read();
        }
        public T Get<T>(string column)
        {
            return Reader.Get<T>(Reader.GetOrdinal(column));
        }
    }

}