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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.List;
import java.util.function.Consumer;

import org.hibernate.LockMode;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.internal.util.collections.Stack;
import org.hibernate.query.IllegalQueryOperationException;
import org.hibernate.query.sqm.ComparisonOperator;
import org.hibernate.sql.ast.Clause;
import org.hibernate.sql.ast.SqlAstNodeRenderingMode;
import org.hibernate.sql.ast.spi.AbstractSqlAstTranslator;
import org.hibernate.sql.ast.spi.SqlSelection;
import org.hibernate.sql.ast.tree.Statement;
import org.hibernate.sql.ast.tree.cte.CteStatement;
import org.hibernate.sql.ast.tree.delete.DeleteStatement;
import org.hibernate.sql.ast.tree.expression.BinaryArithmeticExpression;
import org.hibernate.sql.ast.tree.expression.CaseSearchedExpression;
import org.hibernate.sql.ast.tree.expression.CaseSimpleExpression;
import org.hibernate.sql.ast.tree.expression.Expression;
import org.hibernate.sql.ast.tree.expression.Literal;
import org.hibernate.sql.ast.tree.expression.SqlTuple;
import org.hibernate.sql.ast.tree.expression.Summarization;
import org.hibernate.sql.ast.tree.from.NamedTableReference;
import org.hibernate.sql.ast.tree.from.UnionTableReference;
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.insert.Values;
import org.hibernate.sql.ast.tree.select.QueryPart;
import org.hibernate.sql.ast.tree.select.QuerySpec;
import org.hibernate.sql.ast.tree.update.UpdateStatement;
import org.hibernate.sql.exec.spi.JdbcOperation;

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

	private static final String UNION_ALL = " union all ";

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

	@Override
	protected void visitInsertStatementOnly(InsertSelectStatement statement) {
		if ( statement.getConflictClause() == null || statement.getConflictClause().isDoNothing() ) {
			// Render plain insert statement and possibly run into unique constraint violation
			super.visitInsertStatementOnly( statement );
		}
		else {
			visitInsertStatementEmulateMerge( statement );
			appendSql( ';' );
		}
	}

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

	@Override
	protected void renderFromClauseAfterUpdateSet(UpdateStatement statement) {
		visitFromClause( statement.getFromClause() );
	}

	@Override
	protected void visitConflictClause(ConflictClause conflictClause) {
		if ( conflictClause != null ) {
			if ( conflictClause.isDoUpdate() && conflictClause.getConstraintName() != null ) {
				throw new IllegalQueryOperationException( "Insert conflict 'do update' clause with constraint name is not supported" );
			}
		}
	}

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

	// Sybase does not allow CASE expressions where all result arms contain plain parameters.
	// At least one result arm must provide some type context for inference,
	// so we cast the first result arm if we encounter this condition

	@Override
	protected void visitAnsiCaseSearchedExpression(
			CaseSearchedExpression caseSearchedExpression,
			Consumer resultRenderer) {
		if ( getParameterRenderingMode() == SqlAstNodeRenderingMode.DEFAULT && areAllResultsParameters( caseSearchedExpression ) ) {
			final List whenFragments = caseSearchedExpression.getWhenFragments();
			final Expression firstResult = whenFragments.get( 0 ).getResult();
			super.visitAnsiCaseSearchedExpression(
					caseSearchedExpression,
					e -> {
						if ( e == firstResult ) {
							renderCasted( e );
						}
						else {
							resultRenderer.accept( e );
						}
					}
			);
		}
		else {
			super.visitAnsiCaseSearchedExpression( caseSearchedExpression, resultRenderer );
		}
	}

	@Override
	protected void visitAnsiCaseSimpleExpression(
			CaseSimpleExpression caseSimpleExpression,
			Consumer resultRenderer) {
		if ( getParameterRenderingMode() == SqlAstNodeRenderingMode.DEFAULT && areAllResultsParameters( caseSimpleExpression ) ) {
			final List whenFragments = caseSimpleExpression.getWhenFragments();
			final Expression firstResult = whenFragments.get( 0 ).getResult();
			super.visitAnsiCaseSimpleExpression(
					caseSimpleExpression,
					e -> {
						if ( e == firstResult ) {
							renderCasted( e );
						}
						else {
							resultRenderer.accept( e );
						}
					}
			);
		}
		else {
			super.visitAnsiCaseSimpleExpression( caseSimpleExpression, resultRenderer );
		}
	}

	@Override
	protected boolean renderNamedTableReference(NamedTableReference tableReference, LockMode lockMode) {
		final String tableExpression = tableReference.getTableExpression();
		if ( tableReference instanceof UnionTableReference && lockMode != LockMode.NONE && tableExpression.charAt( 0 ) == '(' ) {
			// SQL Server requires to push down the lock hint to the actual table names
			int searchIndex = 0;
			int unionIndex;
			while ( ( unionIndex = tableExpression.indexOf( UNION_ALL, searchIndex ) ) != -1 ) {
				append( tableExpression, searchIndex, unionIndex );
				renderLockHint( lockMode );
				appendSql( UNION_ALL );
				searchIndex = unionIndex + UNION_ALL.length();
			}
			append( tableExpression, searchIndex, tableExpression.length() - 1 );
			renderLockHint( lockMode );
			appendSql( " )" );

			registerAffectedTable( tableReference );
			renderTableReferenceIdentificationVariable( tableReference );
		}
		else {
			super.renderNamedTableReference( tableReference, lockMode );
			renderLockHint( lockMode );
		}
		// Just always return true because SQL Server doesn't support the FOR UPDATE clause
		return true;
	}

	private void renderLockHint(LockMode lockMode) {
		if ( LockMode.READ.lessThan( lockMode ) ) {
			appendSql( " holdlock" );
		}
	}

	@Override
	protected LockStrategy determineLockingStrategy(
			QuerySpec querySpec,
			ForUpdateClause forUpdateClause,
			Boolean followOnLocking) {
		// No need for follow on locking
		return LockStrategy.CLAUSE;
	}

	@Override
	protected void renderForUpdateClause(QuerySpec querySpec, ForUpdateClause forUpdateClause) {
		// Sybase does not support the FOR UPDATE clause
	}

	@Override
	protected void visitValuesList(List valuesList) {
		visitValuesListEmulateSelectUnion( valuesList );
	}

	@Override
	public void visitValuesTableReference(ValuesTableReference tableReference) {
		append( '(' );
		visitValuesListEmulateSelectUnion( tableReference.getValuesList() );
		append( ')' );
		renderDerivedTableReference( tableReference );
	}

	@Override
	public void visitOffsetFetchClause(QueryPart queryPart) {
		assertRowsOnlyFetchClauseType( queryPart );
		if ( !queryPart.isRoot() && queryPart.getOffsetClauseExpression() != null ) {
			throw new IllegalArgumentException( "Can't emulate offset clause in subquery" );
		}
	}

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

	@Override
	protected void renderSelectTupleComparison(
			List lhsExpressions,
			SqlTuple tuple,
			ComparisonOperator operator) {
		emulateSelectTupleComparison( lhsExpressions, tuple.getExpressions(), operator, true );
	}

	@Override
	protected void renderPartitionItem(Expression expression) {
		if ( expression instanceof Literal ) {
			// Note that this depends on the SqmToSqlAstConverter to add a dummy table group
			appendSql( "dummy_.x" );
		}
		else if ( expression instanceof Summarization ) {
			// This could theoretically be emulated by rendering all grouping variations of the query and
			// connect them via union all but that's probably pretty inefficient and would have to happen
			// on the query spec level
			throw new UnsupportedOperationException( "Summarization is not supported by DBMS" );
		}
		else {
			expression.accept( this );
		}
	}

	@Override
	public void visitBinaryArithmeticExpression(BinaryArithmeticExpression arithmeticExpression) {
		appendSql( OPEN_PARENTHESIS );
		visitArithmeticOperand( arithmeticExpression.getLeftHandOperand() );
		appendSql( arithmeticExpression.getOperator().getOperatorSqlTextString() );
		visitArithmeticOperand( arithmeticExpression.getRightHandOperand() );
		appendSql( CLOSE_PARENTHESIS );
	}

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

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

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

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

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