using System;
using System.Collections.Generic;
using Sarand.Net.Standard.Base.Core;
using Sarand.Net.Standard.Base.Utils;

namespace Sarand.Net.Standard.Base.Dbas
{
	//==========================================================================
	//[Serializable()]
	public enum DbColumnDataType
	{
		// Ref. https://msdn.microsoft.com/en-us/library/yy6y35y8%28v=vs.110%29.aspx
		Unknown = -1,
		VarChar,    // SQL_C_CHAR,
		Bit,        // SQL_C_BIT,
		TinyInt,    // SQL_C_TINYINT,
		SmallInt,   // SQL_C_SHORT,
		Int,        // SQL_C_SLONG,
		BigInt,     // SQL_C_SBIGINT,
		Single,     // SQL_C_REAL,
		Double,     // SQL_C_DOUBLE,
		Decimal,    // SQL_DECIMAL?,
		DateTime,   // SQL_C_TYPE_TIMESTAMP
		Binary,
	};
	//[Serializable()]
	public enum DbColumnNullable
	{
		NoNulls = 0,  // SQL_NO_NULLS,
		Nullable = 1,  // SQL_NULLABLE,
		Unknown = 2,  // SQL_NULLABLE_UNKNOWN,  // Not known whether or not a data type supports null values.
	};
	//==========================================================================
	//[Serializable()]
	public class DbDfnColumn
	{
		//-------------------------------------------------------------------
		// Data members.
		//-------------------------------------------------------------------
		// Construction.
		public DbDfnColumn() { }
		public DbDfnColumn(String schema, String table, short pos, String name)
		{
			Schema = schema;
			Table = table;
			Pos = pos;
			Name = name;
		}
		//-------------------------------------------------------------------
		// Attributes.
		public String Schema { get; set; } = String.Empty;
		public String Table { get; set; } = String.Empty;
		public short Pos { get; set; } = 0;
		public String Name { get; set; } = String.Empty;
		public DbColumnDataType DataType { get; set; } = DbColumnDataType.Unknown;
		public String DataTypeName { get; set; } = String.Empty;
		public short DataTypeNative { get; set; } = 0;
		public String DataTypeNameNative { get; set; } = String.Empty;
		public bool IsIdentity { get; set; } = false;
		public long Size { get; set; } = 0;
		public long BufferLen { get; set; } = 0;
		public short DecimalDigits { get; set; } = 0;
		public DbColumnNullable Nullable { get; set; } = DbColumnNullable.Unknown;
		public bool IsNullable { get; set; } = false;
		public String Remarks { get; set; } = String.Empty;
		//-------------------------------------------------------------------
		// Format.
		public String GetFormat()
		{
			String dataType = StringUtil.OnEmpty(DataTypeNameNative, DataTypeName);
			String format = dataType;
			if (dataType.ContainsCI("char") || dataType.ContainsCI("bin"))
			{
				if (Size > 0) format += "(" + Size + ")";
				else format += "(max)";
			}
			return format;
		}
		//-------------------------------------------------------------------
		// Variable type and default - used in variable declaration.

		/// <summary>
		/// Column data type name as used in property names.
		/// <para>- Binary represented as 'ByteArray'.</para>
		/// <para>- Other data types represented by their variable type.</para>
		/// </summary>
		public String GetVariableTypeName()
		{
			switch (DataType)
			{
				case DbColumnDataType.Binary:
					return "ByteArray";
			}
			return GetVariableType();
		}

		/// <summary>
		/// Column data type name as used in variable declarations.
		/// <para>- VarChar represented as 'String'.</para>
		/// <para>- Bit represented as 'Boolean'.</para>
		/// <para>- TinyInt/SmallInt/BigInt represented as 'Int16/32/64'.</para>
		/// <para>- Single/Double/Decimal/DateTime represented 'as-is'.</para>
		/// <para>- Binary represented as 'Byte[]'.</para>
		/// </summary>
		public String GetVariableType()
		{
			switch (DataType)
			{
				case DbColumnDataType.VarChar:
					return "String";
				case DbColumnDataType.Bit:
					return "Boolean";
				case DbColumnDataType.TinyInt:
					return "Byte";
				case DbColumnDataType.SmallInt:
					return "Int16";
				case DbColumnDataType.Int:
					return "Int32";
				case DbColumnDataType.BigInt:
					return "Int64";
				case DbColumnDataType.Single:
					return "Single";
				case DbColumnDataType.Double:
					return "Double";
				case DbColumnDataType.Decimal:
					return "Decimal";
				case DbColumnDataType.DateTime:
					return "DateTime";
				case DbColumnDataType.Binary:
					return "Byte[]";
			}
			return String.Empty;
		}

		/// <summary>
		/// Default value to be used in column value declarations.
		/// </summary>
		public String GetVariableDefault()
		{
			switch (DataType)
			{
				case DbColumnDataType.VarChar:
					return "String.Empty";
				case DbColumnDataType.Bit:
					return "false";
				case DbColumnDataType.TinyInt:
					return "0";
				case DbColumnDataType.SmallInt:
					return "0";
				case DbColumnDataType.Int:
					return "0";
				case DbColumnDataType.BigInt:
					return "0";
				case DbColumnDataType.Single:
					return "0.0f";
				case DbColumnDataType.Double:
					return "0.0";
				case DbColumnDataType.Decimal:
					return "0.0m";
				case DbColumnDataType.DateTime:
					return "DateTime.MinValue";
				case DbColumnDataType.Binary:
					return "null";
			}
			return String.Empty;
		}
		/// <summary>
		/// Method suffix to use for 'GetValue' calls.
		/// <para>- Binary represented as 'ByteArray'.</para>
		/// <para>- Other data types represented by their variable type.</para>
		/// </summary>
		public String GetGetFieldSuffix()
		{
			switch (DataType)
			{
				case DbColumnDataType.VarChar:
				case DbColumnDataType.Bit:
				case DbColumnDataType.TinyInt:
				case DbColumnDataType.SmallInt:
				case DbColumnDataType.Int:
				case DbColumnDataType.BigInt:
				case DbColumnDataType.Single:
				case DbColumnDataType.Double:
				case DbColumnDataType.Decimal:
				case DbColumnDataType.DateTime:
					return GetVariableType();
				case DbColumnDataType.Binary:
					return "ByteArray";
			}
			return String.Empty;
		}
		//-------------------------------------------------------------------
	}
	//==========================================================================
	// Column list extensions.
	public static class DbDfnColumnList
	{
		// List of column names.
		public static List<String> GetNames(this List<DbDfnColumn> columns)
		{
			List<String> names = new List<String>();
			foreach (var column in columns)
			{
				names.Add(column.Name);
			}
			return names;
		}
		// Identity column.
		public static String GetIdentityColumnName(this List<DbDfnColumn> columns)
		{
			List<String> names = new List<String>();
			foreach (var column in columns)
			{
				if (column.IsIdentity)
					return column.Name;
			}
			return String.Empty;
		}
		public static String GetIdentityColumnVariableTypeName(this List<DbDfnColumn> columns)
		{
			List<String> names = new List<String>();
			foreach (var column in columns)
			{
				if (column.IsIdentity)
					return column.GetVariableTypeName();
			}
			return String.Empty;
		}

		// Locate the column in the list:
		public static DbDfnColumn GetColumnByPos(this List<DbDfnColumn> columns, short pos)
		{
			foreach (var column in columns)
			{
				if (column.Pos == pos)
					return column;
			}
			return null;
		}
		public static DbDfnColumn GetColumnByName(this List<DbDfnColumn> columns, String name)
		{
			foreach (var column in columns)
			{
				if (column.Name.EqualsCI(name))
					return column;
			}
			return null;
		}
	}
	//==========================================================================
}