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package com.blazebit.persistence.impl.dialect;

import java.util.List;
import java.util.Map;

import com.blazebit.persistence.spi.DbmsModificationState;
import com.blazebit.persistence.spi.DbmsStatementType;
import com.blazebit.persistence.spi.ValuesStrategy;

public class H2DbmsDialect extends DefaultDbmsDialect {
    
    @Override
    public boolean supportsReturningAllGeneratedKeys() {
        return false;
    }
    
	@Override
	public boolean supportsWithClause() {
		return true;
	}

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

	@Override
	public String getWithClause(boolean recursive) {
		return "with recursive";
	}

    @Override
    public Map appendExtendedSql(StringBuilder sqlSb, DbmsStatementType statementType, boolean isSubquery, boolean isEmbedded, StringBuilder withClause, String limit, String offset, String[] returningColumns, Map includedModificationStates) {
        if (isSubquery) {
            sqlSb.insert(0, '(');
        }
        
        if (isSubquery && returningColumns != null) {
            throw new IllegalArgumentException("Returning columns in a subquery is not possible for this dbms!");
        }
        
        // NOTE: this only works for insert and select statements, but H2 does not support CTEs in modification queries anyway so it's ok
        if (withClause != null) {
            sqlSb.insert(indexOfIgnoreCase(sqlSb, "select"), withClause);
        }
        if (limit != null) {
            appendLimit(sqlSb, isSubquery, limit, offset);
        }
        
        if (isSubquery) {
            sqlSb.append(')');
        }
        
        return null;
    }
    
    @Override
    protected void appendSetOperands(StringBuilder sqlSb, String operator, boolean isSubquery, List operands, boolean hasOuterClause) {
        if (!hasOuterClause) {
            super.appendSetOperands(sqlSb, operator, isSubquery, operands, hasOuterClause);
        } else {
            sqlSb.append("select * from (");
            super.appendSetOperands(sqlSb, operator, isSubquery, operands, hasOuterClause);
            sqlSb.append(')');
        }
    }

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

    @Override
    public ValuesStrategy getValuesStrategy() {
        return ValuesStrategy.SELECT_VALUES;
    }
}