/*
 * Copyright 2012 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.template.soy.basicfunctions;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.template.soy.data.SoyValue;
import com.google.template.soy.data.restricted.BooleanData;
import com.google.template.soy.data.restricted.NullData;
import com.google.template.soy.data.restricted.UndefinedData;
import com.google.template.soy.exprtree.Operator;
import com.google.template.soy.jssrc.restricted.JsExpr;
import com.google.template.soy.jssrc.restricted.SoyJsCodeUtils;
import com.google.template.soy.jssrc.restricted.SoyJsSrcFunction;
import com.google.template.soy.pysrc.restricted.PyExpr;
import com.google.template.soy.pysrc.restricted.PyExprUtils;
import com.google.template.soy.pysrc.restricted.SoyPySrcFunction;
import com.google.template.soy.shared.restricted.SoyJavaFunction;
import com.google.template.soy.shared.restricted.SoyPureFunction;

import java.util.List;
import java.util.Set;

import javax.inject.Inject;
import javax.inject.Singleton;

/**
 * Soy function that checks whether its argument is a defined nonnull value.
 *
 */
@Singleton
@SoyPureFunction
class IsNonnullFunction implements SoyJavaFunction, SoyJsSrcFunction, SoyPySrcFunction {


  @Inject
  IsNonnullFunction() {}


  @Override public String getName() {
    return "isNonnull";
  }

  @Override public Set<Integer> getValidArgsSizes() {
    return ImmutableSet.of(1);
  }

  @Override public SoyValue computeForJava(List<SoyValue> args) {
    SoyValue arg = args.get(0);
    return BooleanData.forValue(! (arg instanceof UndefinedData || arg instanceof NullData));
  }

  @Override public JsExpr computeForJsSrc(List<JsExpr> args) {
    JsExpr arg = args.get(0);
    JsExpr nullJsExpr = new JsExpr("null", Integer.MAX_VALUE);
    // Note: In JavaScript, "x != null" is equivalent to "x !== undefined && x !== null".
    return SoyJsCodeUtils.genJsExprUsingSoySyntax(
        Operator.NOT_EQUAL, Lists.<JsExpr>newArrayList(arg, nullJsExpr));
  }

  @Override public PyExpr computeForPySrc(List<PyExpr> args) {
    // Note: This check could blow up if the variable was never created at all. However, this should
    // not be possible as a variable not found in the function is assumed to be part of opt_data.
    return PyExprUtils.genPyNotNullCheck(args.get(0));
  }
}