package lambda2sql;

import static com.trigersoft.jaque.expression.ExpressionType.Equal;

import static com.trigersoft.jaque.expression.ExpressionType.LogicalAnd;

import static com.trigersoft.jaque.expression.ExpressionType.LogicalOr;

import com.trigersoft.jaque.expression.*;

public class ToSqlVisitor implements ExpressionVisitor<StringBuilder> {

private StringBuilder sb = new StringBuilder();

private Expression body;

@Override

public StringBuilder visit(BinaryExpression e) {

boolean quote = e != body && e.getExpressionType() == LogicalOr;

if( quote ) sb.append('(');

e.getFirst().accept(this);

sb.append(' ').append(toSqlOp(e.getExpressionType())).append(' ');

e.getSecond().accept(this);

if( quote ) sb.append(')');

return sb;

}

public static String toSqlOp(int expressionType) {

switch(expressionType) {

case Equal: return "=";

case LogicalAnd: return "AND";

case LogicalOr: return "OR";

}

return ExpressionType.toString(expressionType);

}

@Override

public StringBuilder visit(ConstantExpression e) {

if (e.getValue() instanceof String) {

return sb.append("'").append(e.getValue().toString()).append("'");

}

return sb.append(e.getValue().toString());

}

@Override

public StringBuilder visit(InvocationExpression e) {

return e.getTarget().accept(this);

}

@Override

public StringBuilder visit(LambdaExpression<?> e) {

this.body = e.getBody();

return body.accept(this);

}

@Override

public StringBuilder visit(MemberExpression e) {

String name = e.getMember().getName();

name = name.replaceAll("^(get)", "");

name = name.substring(0, 1).toLowerCase() + name.substring(1);

return sb.append(name);

}

@Override

public StringBuilder visit(ParameterExpression e) {

return sb;

}

@Override

public StringBuilder visit(UnaryExpression e) {

sb.append(ExpressionType.toString(e.getExpressionType()));

return e.getFirst().accept(this);

}

}