/*
 * 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.base.Preconditions;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Maps;
import com.google.template.soy.data.SoyDict;
import com.google.template.soy.data.SoyMap;
import com.google.template.soy.data.SoyValue;
import com.google.template.soy.data.SoyValueProvider;
import com.google.template.soy.data.internal.DictImpl;
import com.google.template.soy.jssrc.restricted.JsExpr;
import com.google.template.soy.jssrc.restricted.SoyJsSrcFunction;
import com.google.template.soy.pysrc.restricted.PyExpr;
import com.google.template.soy.pysrc.restricted.PyFunctionExprBuilder;
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.Map;
import java.util.Set;

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

/**
 * Soy function that creates a new map equivalent to augmenting an existing map with additional
 * mappings.
 *
 */
@Singleton
@SoyPureFunction
public final class AugmentMapFunction
    implements SoyJavaFunction, SoyJsSrcFunction, SoyPySrcFunction {

  @Inject AugmentMapFunction() {}


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

  @Override public Set<Integer> getValidArgsSizes() {
    return ImmutableSet.of(2);
  }

  @SuppressWarnings("ConstantConditions")  // IntelliJ
  @Override public SoyValue computeForJava(List<SoyValue> args) {
    SoyValue arg0 = args.get(0);
    SoyValue arg1 = args.get(1);

    Preconditions.checkArgument(arg0 instanceof SoyMap,
        "First argument to augmentMap() function is not SoyMap.");
    Preconditions.checkArgument(arg1 instanceof SoyMap,
        "Second argument to augmentMap() function is not SoyMap.");

    // TODO: Support map with nonstring key.
    Preconditions.checkArgument(arg0 instanceof SoyDict,
        "First argument to augmentMap() function is not SoyDict. Currently, augmentMap() doesn't" +
            " support maps that are not dicts (it is a todo).");
    Preconditions.checkArgument(arg1 instanceof SoyDict,
        "Second argument to augmentMap() function is not SoyDict. Currently, augmentMap() doesn't" +
            " support maps that are not dicts (it is a todo).");
    return augmentMap((SoyDict) arg0, (SoyDict) arg1);
  }

  /**
   * Combine the two maps.
   */
  public static SoyDict augmentMap(SoyDict first, SoyDict second) {
    Map<String, SoyValueProvider> map =
        Maps.newHashMapWithExpectedSize(first.getItemCnt() + second.getItemCnt());
    map.putAll(first.asJavaStringMap());
    map.putAll(second.asJavaStringMap());
    return DictImpl.forProviderMap(map);
  }

  @Override public JsExpr computeForJsSrc(List<JsExpr> args) {
    JsExpr arg0 = args.get(0);
    JsExpr arg1 = args.get(1);

    String exprText = "soy.$$augmentMap(" + arg0.getText() + ", " + arg1.getText() + ")";
    return new JsExpr(exprText, Integer.MAX_VALUE);
  }

  @Override public PyExpr computeForPySrc(List<PyExpr> args) {
    PyFunctionExprBuilder fnBuilder = new PyFunctionExprBuilder("dict");
    fnBuilder.addArg(args.get(0)).setUnpackedKwargs(args.get(1));
    return fnBuilder.asPyExpr();
  }
}