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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later
 * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
 */
package org.hibernate.community.dialect;

import java.util.ArrayList;
import java.util.List;

import org.hibernate.dialect.DialectDelegateWrapper;
import org.hibernate.dialect.DmlTargetColumnQualifierSupport;
import org.hibernate.dialect.MySQLSqlAstTranslator;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.internal.util.collections.Stack;
import org.hibernate.query.sqm.ComparisonOperator;
import org.hibernate.sql.ast.Clause;
import org.hibernate.sql.ast.spi.AbstractSqlAstTranslator;
import org.hibernate.sql.ast.tree.MutationStatement;
import org.hibernate.sql.ast.tree.Statement;
import org.hibernate.sql.ast.tree.delete.DeleteStatement;
import org.hibernate.sql.ast.tree.expression.CastTarget;
import org.hibernate.sql.ast.tree.expression.ColumnReference;
import org.hibernate.sql.ast.tree.expression.Expression;
import org.hibernate.sql.ast.tree.expression.Literal;
import org.hibernate.sql.ast.tree.expression.Summarization;
import org.hibernate.sql.ast.tree.from.NamedTableReference;
import org.hibernate.sql.ast.tree.from.QueryPartTableReference;
import org.hibernate.sql.ast.tree.from.ValuesTableReference;
import org.hibernate.sql.ast.tree.insert.ConflictClause;
import org.hibernate.sql.ast.tree.insert.InsertSelectStatement;
import org.hibernate.sql.ast.tree.predicate.BooleanExpressionPredicate;
import org.hibernate.sql.ast.tree.predicate.LikePredicate;
import org.hibernate.sql.ast.tree.select.QueryGroup;
import org.hibernate.sql.ast.tree.select.QueryPart;
import org.hibernate.sql.ast.tree.select.QuerySpec;
import org.hibernate.sql.ast.tree.select.SelectStatement;
import org.hibernate.sql.ast.tree.update.UpdateStatement;
import org.hibernate.sql.exec.internal.JdbcOperationQueryInsertImpl;
import org.hibernate.sql.exec.spi.JdbcOperation;
import org.hibernate.sql.exec.spi.JdbcOperationQueryInsert;

/**
 * A SQL AST translator for MySQL.
 *
 * @author Christian Beikov
 */
public class MySQLLegacySqlAstTranslator extends AbstractSqlAstTranslator {

	public MySQLLegacySqlAstTranslator(SessionFactoryImplementor sessionFactory, Statement statement) {
		super( sessionFactory, statement );
	}

	@Override
	protected void visitInsertSource(InsertSelectStatement statement) {
		if ( statement.getSourceSelectStatement() != null ) {
			if ( statement.getConflictClause() != null ) {
				final List targetColumnReferences = statement.getTargetColumns();
				final List columnNames = new ArrayList<>( targetColumnReferences.size() );
				for ( ColumnReference targetColumnReference : targetColumnReferences ) {
					columnNames.add( targetColumnReference.getColumnExpression() );
				}
				appendSql( "select * from " );
				emulateQueryPartTableReferenceColumnAliasing(
						new QueryPartTableReference(
								new SelectStatement( statement.getSourceSelectStatement() ),
								"excluded",
								columnNames,
								false,
								getSessionFactory()
						)
				);
			}
			else {
				statement.getSourceSelectStatement().accept( this );
			}
		}
		else {
			visitValuesList( statement.getValuesList() );
			if ( statement.getConflictClause() != null && getDialect().getMySQLVersion().isSameOrAfter( 8, 0, 19 ) ) {
				appendSql( " as excluded" );
				char separator = '(';
				for ( ColumnReference targetColumn : statement.getTargetColumns() ) {
					appendSql( separator );
					appendSql( targetColumn.getColumnExpression() );
					separator = ',';
				}
				appendSql( ')' );
			}
		}
	}

	@Override
	public void visitColumnReference(ColumnReference columnReference) {
		final Statement currentStatement;
		if ( getDialect().getMySQLVersion().isBefore( 8, 0, 19 )
				&& "excluded".equals( columnReference.getQualifier() )
				&& ( currentStatement = getStatementStack().getCurrent() ) instanceof InsertSelectStatement
				&& ( (InsertSelectStatement) currentStatement ).getSourceSelectStatement() == null ) {
			// Accessing the excluded row for an insert-values statement in the conflict clause requires the values qualifier
			appendSql( "values(" );
			columnReference.appendReadExpression( this, null );
			append( ')' );
		}
		else {
			super.visitColumnReference( columnReference );
		}
	}

	@Override
	protected void renderDeleteClause(DeleteStatement statement) {
		appendSql( "delete" );
		final Stack clauseStack = getClauseStack();
		try {
			clauseStack.push( Clause.DELETE );
			renderTableReferenceIdentificationVariable( statement.getTargetTable() );
			if ( statement.getFromClause().getRoots().isEmpty() ) {
				appendSql( " from " );
				renderDmlTargetTableExpression( statement.getTargetTable() );
			}
			else {
				visitFromClause( statement.getFromClause() );
			}
		}
		finally {
			clauseStack.pop();
		}
	}

	@Override
	protected void renderUpdateClause(UpdateStatement updateStatement) {
		if ( updateStatement.getFromClause().getRoots().isEmpty() ) {
			super.renderUpdateClause( updateStatement );
		}
		else {
			appendSql( "update " );
			renderFromClauseSpaces( updateStatement.getFromClause() );
		}
	}

	@Override
	protected void renderDmlTargetTableExpression(NamedTableReference tableReference) {
		super.renderDmlTargetTableExpression( tableReference );
		if ( getClauseStack().getCurrent() != Clause.INSERT ) {
			renderTableReferenceIdentificationVariable( tableReference );
		}
	}

	@Override
	protected boolean supportsJoinsInDelete() {
		return true;
	}

	@Override
	protected JdbcOperationQueryInsert translateInsert(InsertSelectStatement sqlAst) {
		visitInsertStatement( sqlAst );

		return new JdbcOperationQueryInsertImpl(
				getSql(),
				getParameterBinders(),
				getAffectedTableNames(),
				getUniqueConstraintNameThatMayFail(sqlAst)
		);
	}

	@Override
	protected void visitConflictClause(ConflictClause conflictClause) {
		visitOnDuplicateKeyConflictClause( conflictClause );
	}

	@Override
	protected String determineColumnReferenceQualifier(ColumnReference columnReference) {
		final DmlTargetColumnQualifierSupport qualifierSupport = getDialect().getDmlTargetColumnQualifierSupport();
		final MutationStatement currentDmlStatement;
		final String dmlAlias;
		// Since MySQL does not support aliasing the insert target table,
		// we must detect column reference that are used in the conflict clause
		// and use the table expression as qualifier instead
		if ( getClauseStack().getCurrent() != Clause.SET
				|| !( ( currentDmlStatement = getCurrentDmlStatement() ) instanceof InsertSelectStatement )
				|| ( dmlAlias = currentDmlStatement.getTargetTable().getIdentificationVariable() ) == null
				|| !dmlAlias.equals( columnReference.getQualifier() ) ) {
			return columnReference.getQualifier();
		}
		// Qualify the column reference with the table expression also when in subqueries
		else if ( qualifierSupport != DmlTargetColumnQualifierSupport.NONE || !getQueryPartStack().isEmpty() ) {
			return getCurrentDmlStatement().getTargetTable().getTableExpression();
		}
		else {
			return null;
		}
	}

	@Override
	protected void renderExpressionAsClauseItem(Expression expression) {
		expression.accept( this );
	}

	@Override
	protected void visitRecursivePath(Expression recursivePath, int sizeEstimate) {
		// MySQL determines the type and size of a column in a recursive CTE based on the expression of the non-recursive part
		// Due to that, we have to cast the path in the non-recursive path to a varchar of appropriate size to avoid data truncation errors
		if ( sizeEstimate == -1 ) {
			super.visitRecursivePath( recursivePath, sizeEstimate );
		}
		else {
			appendSql( "cast(" );
			recursivePath.accept( this );
			appendSql( " as char(" );
			appendSql( sizeEstimate );
			appendSql( "))" );
		}
	}

	@Override
	public void visitBooleanExpressionPredicate(BooleanExpressionPredicate booleanExpressionPredicate) {
		final boolean isNegated = booleanExpressionPredicate.isNegated();
		if ( isNegated ) {
			appendSql( "not(" );
		}
		booleanExpressionPredicate.getExpression().accept( this );
		if ( isNegated ) {
			appendSql( CLOSE_PARENTHESIS );
		}
	}

	@Override
	protected String getForShare(int timeoutMillis) {
		return getDialect().getVersion().isSameOrAfter( 8 ) ? " for share" : " lock in share mode";
	}

	protected boolean shouldEmulateFetchClause(QueryPart queryPart) {
		// Check if current query part is already row numbering to avoid infinite recursion
		return useOffsetFetchClause( queryPart ) && getQueryPartForRowNumbering() != queryPart
				&& getDialect().supportsWindowFunctions() && !isRowsOnlyFetchClauseType( queryPart );
	}

	@Override
	public void visitQueryGroup(QueryGroup queryGroup) {
		if ( shouldEmulateFetchClause( queryGroup ) ) {
			emulateFetchOffsetWithWindowFunctions( queryGroup, true );
		}
		else {
			super.visitQueryGroup( queryGroup );
		}
	}

	@Override
	public void visitQuerySpec(QuerySpec querySpec) {
		if ( shouldEmulateFetchClause( querySpec ) ) {
			emulateFetchOffsetWithWindowFunctions( querySpec, true );
		}
		else {
			super.visitQuerySpec( querySpec );
		}
	}

	@Override
	public void visitValuesTableReference(ValuesTableReference tableReference) {
		emulateValuesTableReferenceColumnAliasing( tableReference );
	}

	@Override
	public void visitQueryPartTableReference(QueryPartTableReference tableReference) {
		if ( getDialect().getVersion().isSameOrAfter( 8 ) ) {
			super.visitQueryPartTableReference( tableReference );
		}
		else {
			emulateQueryPartTableReferenceColumnAliasing( tableReference );
		}
	}

	@Override
	public void visitOffsetFetchClause(QueryPart queryPart) {
		if ( !isRowNumberingCurrentQueryPart() ) {
			renderCombinedLimitClause( queryPart );
		}
	}

	@Override
	protected void renderComparison(Expression lhs, ComparisonOperator operator, Expression rhs) {
		renderComparisonDistinctOperator( lhs, operator, rhs );
	}

	@Override
	protected void renderPartitionItem(Expression expression) {
		if ( expression instanceof Literal ) {
			appendSql( "'0'" );
		}
		else if ( expression instanceof Summarization ) {
			Summarization summarization = (Summarization) expression;
			renderCommaSeparated( summarization.getGroupings() );
			appendSql( " with " );
			appendSql( summarization.getKind().sqlText() );
		}
		else {
			expression.accept( this );
		}
	}

	@Override
	public void visitLikePredicate(LikePredicate likePredicate) {
		// Custom implementation because MySQL uses backslash as the default escape character
		if ( getDialect().getVersion().isSameOrAfter( 8, 0, 24 ) ) {
			// From version 8.0.24 we can override this by specifying an empty escape character
			// See https://dev.mysql.com/doc/refman/8.0/en/string-comparison-functions.html#operator_like
			super.visitLikePredicate( likePredicate );
			if ( !getDialect().isNoBackslashEscapesEnabled() && likePredicate.getEscapeCharacter() == null ) {
				appendSql( " escape ''" );
			}
		}
		else {
			if ( likePredicate.isCaseSensitive() ) {
				likePredicate.getMatchExpression().accept( this );
				if ( likePredicate.isNegated() ) {
					appendSql( " not" );
				}
				appendSql( " like " );
				renderBackslashEscapedLikePattern(
						likePredicate.getPattern(),
						likePredicate.getEscapeCharacter(),
						getDialect().isNoBackslashEscapesEnabled()
				);
			}
			else {
				appendSql( getDialect().getLowercaseFunction() );
				appendSql( OPEN_PARENTHESIS );
				likePredicate.getMatchExpression().accept( this );
				appendSql( CLOSE_PARENTHESIS );
				if ( likePredicate.isNegated() ) {
					appendSql( " not" );
				}
				appendSql( " like " );
				appendSql( getDialect().getLowercaseFunction() );
				appendSql( OPEN_PARENTHESIS );
				renderBackslashEscapedLikePattern(
						likePredicate.getPattern(),
						likePredicate.getEscapeCharacter(),
						getDialect().isNoBackslashEscapesEnabled()
				);
				appendSql( CLOSE_PARENTHESIS );
			}
			if ( likePredicate.getEscapeCharacter() != null ) {
				appendSql( " escape " );
				likePredicate.getEscapeCharacter().accept( this );
			}
		}
	}

	@Override
	public boolean supportsRowValueConstructorSyntaxInSet() {
		return false;
	}

	@Override
	public boolean supportsRowValueConstructorSyntaxInInList() {
		return getDialect().getVersion().isSameOrAfter( 5, 7 );
	}

	@Override
	protected boolean supportsRowValueConstructorSyntaxInQuantifiedPredicates() {
		return false;
	}

	@Override
	protected boolean supportsIntersect() {
		return false;
	}

	@Override
	protected boolean supportsDistinctFromPredicate() {
		// It supports a proprietary operator
		return true;
	}

	@Override
	protected boolean supportsSimpleQueryGrouping() {
		return getDialect().getVersion().isSameOrAfter( 8 );
	}

	@Override
	protected boolean supportsNestedSubqueryCorrelation() {
		return false;
	}

	@Override
	protected boolean supportsWithClause() {
		return getDialect().getVersion().isSameOrAfter( 8 );
	}

	@Override
	protected String getDual() {
		return "dual";
	}

	@Override
	protected String getFromDualForSelectOnly() {
		return getDialect().getVersion().isSameOrAfter( 8 ) ? "" : ( " from " + getDual() );
	}

	@Override
	public MySQLLegacyDialect getDialect() {
		return (MySQLLegacyDialect) DialectDelegateWrapper.extractRealDialect( super.getDialect() );
	}

	@Override
	public void visitCastTarget(CastTarget castTarget) {
		String sqlType = MySQLSqlAstTranslator.getSqlType( castTarget, getSessionFactory() );
		if ( sqlType != null ) {
			appendSql( sqlType );
		}
		else {
			super.visitCastTarget( castTarget );
		}
	}

	@Override
	protected void renderStringContainsExactlyPredicate(Expression haystack, Expression needle) {
		// MySQL can't cope with NUL characters in the position function, so we use a like predicate instead
		haystack.accept( this );
		appendSql( " like concat('%',replace(replace(replace(" );
		needle.accept( this );
		appendSql( ",'~','~~'),'?','~?'),'%','~%'),'%') escape '~'" );
	}
}