// ---------------------------------

// SmarterSql (c) Johan Sassner 2008

// ---------------------------------

using System.Collections.Generic;

using Sassner.SmarterSql.Objects;

using Sassner.SmarterSql.Parsing.Predicates;

using Sassner.SmarterSql.Parsing.SelectItems;

using Sassner.SmarterSql.ParsingUtils;

using Sassner.SmarterSql.Tree;

using Sassner.SmarterSql.Utils;



namespace Sassner.SmarterSql.Parsing.Keywords {

	public class KeywordDerivedTable {

		#region Derived tables parsing functions



		/// <summary>

		/// Parse a derived table

		/// </summary>

		/// <param name="parser"></param>

		/// <param name="currentStartSpan"></param>

		/// <param name="lstTokens"></param>

		/// <param name="i"></param>

		/// <param name="lstSysObjects"></param>

		/// <param name="startIndex"></param>

		/// <param name="sysObjectId"></param>

		/// <param name="addedSysObject"></param>

		/// <param name="addedTableSource"></param>

		/// <param name="startToken"></param>

		public static bool ParseDerivedTable(Parser parser, StatementSpans currentStartSpan, List<TokenInfo> lstTokens, ref int i,

				List<SysObject> lstSysObjects, int startIndex, ref int sysObjectId, out SysObject addedSysObject, out TableSource addedTableSource,

				TokenInfo startToken) {

			TokenInfo nextToken = InStatement.GetNextNonCommentToken(lstTokens, ref i);

			if (null == nextToken || nextToken.Kind != TokenKind.LeftParenthesis) {

				addedSysObject = null;

				addedTableSource = null;

				return false;

			}



			int offset = nextToken.MatchingParenToken;

			nextToken = InStatement.GetNextNonCommentToken(lstTokens, offset);

			if (null != nextToken && nextToken.Kind == TokenKind.RightParenthesis && offset + 1 < lstTokens.Count) {

				int startSubSelect = InStatement.GetNextNonCommentToken(lstTokens, i + 1, i + 1);

				int endSubSelect = offset - 1;

				if (startSubSelect > endSubSelect) {

					addedSysObject = null;

					addedTableSource = null;

					return false;

				}



				// Parse sub select

				parser.ParseTokenRange(currentStartSpan, startSubSelect, endSubSelect, lstSysObjects);



				StatementSpans ss = parser.SegmentUtils.GetStatementSpan(startSubSelect);

				List<SysObjectColumn> lstSysObjectColumn = new List<SysObjectColumn>();

				if (null != ss && null != ss.SelectItems) {

					// Set the new sysobject for the columns

					foreach (SelectItem selectItem in ss.SelectItems) {

						foreach (SysObjectColumn sysObjectColumn in selectItem.SysObjectColumns) {

							if (null != sysObjectColumn) {

								lstSysObjectColumn.Add(sysObjectColumn);

							}

						}

					}

				}



				int statementStartIndex = i;

				int statementEndIndex = offset;

				int tableStartIndex = startSubSelect;

				int realEndIndex;

				if (GetAliasAndSearchCondition(parser, statementStartIndex, tableStartIndex, statementEndIndex, out realEndIndex, lstTokens, lstSysObjects,

						startSubSelect, currentStartSpan, startToken, Common.enSqlTypes.DerivedTable, ref sysObjectId, out addedSysObject,

						out addedTableSource, startIndex, lstSysObjectColumn)) {

					i = realEndIndex;

					return true;

				}

			}

			addedSysObject = null;

			addedTableSource = null;

			return false;

		}



		public static bool GetAliasAndSearchCondition(Parser parser, int startStatementIndex, int startTableIndex, int endStatementIndex, out int realEndIndex,

					List<TokenInfo> lstTokens, List<SysObject> lstSysObjects, int statementStartIndex, StatementSpans currentStartSpan,

					TokenInfo startToken, Common.enSqlTypes sqlType, ref int sysObjectId, out SysObject addedSysObject,

					out TableSource addedTableSource, int startIndex, List<SysObjectColumn> lstSysObjectColumn) {

			TokenInfo nextToken;

			string Table = string.Empty;

			string Alias;

			int endTableIndex = endStatementIndex + 1;

			if (parser.ExtractTableAlias(endTableIndex, ref endTableIndex, out Alias)) {

				Table = Alias;

			}



			realEndIndex = endTableIndex;

			List<string> lstNewColumNames = null;

			if (sqlType == Common.enSqlTypes.DerivedTable) {

				lstNewColumNames = GetDerivedTableNewColumnNames(lstTokens, ref realEndIndex);

			}

			int startSearchCondition = realEndIndex;

			List<Predicate> predicates;



			if (startToken.Kind == TokenKind.KeywordJoin) {

				realEndIndex = KeywordSearchCondition.FindLengthOfSearchCondition(parser, lstTokens, startSearchCondition);

				while (startSearchCondition < realEndIndex) {

					nextToken = InStatement.GetNextNonCommentToken(lstTokens, startSearchCondition);

					if (null == nextToken) {

						addedSysObject = null;

						addedTableSource = null;

						realEndIndex = 0;

						return false;

					}

					if (nextToken.Kind == TokenKind.KeywordOn) {

						startSearchCondition++;

						break;

					}

					startSearchCondition++;

				}

			}



			// Create a SysObject object

			addedSysObject = SysObject.CreateTemporarySysObject(Table, sqlType, ref sysObjectId);

			lstSysObjects.Add(addedSysObject);

			foreach (SysObjectColumn sysObjectColumn in lstSysObjectColumn) {

				sysObjectColumn.ParentSysObject = addedSysObject;

				addedSysObject.AddColumn(sysObjectColumn);

			}

			// If we have matching new column names, set them

			if (null != lstNewColumNames && lstNewColumNames.Count == addedSysObject.Columns.Count) {

				for (int j = 0; j < addedSysObject.Columns.Count; j++) {

					addedSysObject.Columns[j].ColumnName = lstNewColumNames[j];

				}

			}



			// Create the table source

			StatementSpans ss = parser.SegmentUtils.GetStatementSpan(startTableIndex);

			Table table = new Table("", "", "", Table, Alias, addedSysObject, ss, startTableIndex, endTableIndex, true);

			addedTableSource = new TableSource(lstTokens[startTableIndex].Token, table, startIndex, realEndIndex);

			parser.TableSources.Add(addedTableSource);

			if (null != currentStartSpan) {

				currentStartSpan.AddTableSource(addedTableSource);

			}



			// Find the search conditions and parse them

			KeywordSearchCondition.ParseSearchCondition(parser, lstTokens, startSearchCondition, realEndIndex, lstSysObjects, out predicates);

			return true;

		}



		/// <summary>

		/// Get new column aliases for a derived table

		/// </summary>

		/// <param name="lstTokens"></param>

		/// <param name="i"></param>

		/// <returns></returns>

		private static List<string> GetDerivedTableNewColumnNames(List<TokenInfo> lstTokens, ref int i) {

			TokenInfo token;

			if (!InStatement.GetIfAllNextValidToken(lstTokens, ref i, out token, TokenKind.LeftParenthesis)) {

				return null;

			}

			if (-1 == token.MatchingParenToken || i > token.MatchingParenToken) {

				return null;

			}



			int matchingParenIndex = token.MatchingParenToken;

			List<string> lstNewColumNames = new List<string>();

			i++;

			while (i < matchingParenIndex) {

				token = InStatement.GetNextNonCommentToken(lstTokens, ref i);

				if (null != token) {

					if (token.Type == TokenType.Identifier) {

						lstNewColumNames.Add(token.Token.UnqoutedImage);

						token.TokenContextType = TokenContextType.NewColumnAlias;

					}

				} else {

					break;

				}

				i++;

			}

			return lstNewColumNames;

		}



		#endregion

	}

}