using Knoks.Framework.Extentions;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;

namespace Knoks.Framework.DataAccess
{
    public static class DbMetaData
    {
        private const string storedProcedureParamsQuery =
            @"SELECT SPECIFIC_NAME,PARAMETER_MODE,PARAMETER_NAME,DATA_TYPE,CHARACTER_MAXIMUM_LENGTH 
            FROM INFORMATION_SCHEMA.PARAMETERS P
            INNER JOIN sys.objects AS SO 
            ON object_name(SO.OBJECT_ID)  = P.SPECIFIC_NAME
            WHERE SO.type = 'P'
            ORDER BY SPECIFIC_NAME ASC,ORDINAL_POSITION ASC";

        public static Dictionary<string, List<ParamMetaData>> LoadParamMetaDataSet(string connectionString)
        {
            using (var conn = new SqlConnection(connectionString))
            using (var cmd = new SqlCommand(storedProcedureParamsQuery, conn))
            {
                conn.Open();
                using (var reader = cmd.ExecuteReader())
                {
                    var procParams = new List<ParamMetaData>();
                    var procName = string.Empty;
                    var resultParams = new Dictionary<string, List<ParamMetaData>>(StringComparer.OrdinalIgnoreCase);

                    while (reader.Read())
                    {
                        var param = ParamMetaData.LoadFromReader(reader);

                        if (param.ProcName != procName)
                        {
                            if (procName != string.Empty)
                            {
                                resultParams.Add(procName, procParams);
                                procParams = new List<ParamMetaData>();
                            }

                            procName = param.ProcName;
                        }

                        procParams.Add(param);
                    }

                    resultParams.Add(procName, procParams);

                    return resultParams;
                }
            }
        }
    }

    public class ParamMetaData
    {
        public string ProcName { get; private set; }
        public string ParamName { get; private set; }
        public ParameterDirection Direction { get; private set; }
        public SqlDbType DataType { get; private set; }
        public int? Size { get; private set; }

        public SqlParameter GetSqlParameter(object value)
        {
            return new SqlParameter(ParamName, DataType)
            {
                Value = value ?? DBNull.Value,
                Size = Size ?? 0,
                Direction = Direction
            };
        }

        public static ParamMetaData LoadFromReader(IDataReader reader)
        {
            return new ParamMetaData
            {
                ProcName = reader["SPECIFIC_NAME"].ToString(),
                ParamName = reader["PARAMETER_NAME"].ToString(),
                Direction = ConvertToDirection(reader["PARAMETER_MODE"].ToString()),
                DataType = ConvertToDataType(reader["DATA_TYPE"].ToString()),
                Size = Helper.GetNullableInt32(reader["CHARACTER_MAXIMUM_LENGTH"])
            };
        }

        private static SqlDbType ConvertToDataType(string dataTypeStr)
        {
            if (dataTypeStr == "table type") return SqlDbType.Structured;

            return dataTypeStr.ToEnum<SqlDbType>();
        }

        private static ParameterDirection ConvertToDirection(string value)
        {
            switch (value)
            {
                case "IN": return ParameterDirection.Input;
                case "OUT": return ParameterDirection.Output;
                case "INOUT": return ParameterDirection.InputOutput;
                case "ReturnValue": return ParameterDirection.ReturnValue;
                default: throw new InvalidCastException($"Cast error. String value '{ value ?? "[null]" }' to { typeof(ParameterDirection) } type");
            }
        }
    }
}