// Copyright 2017 The Bazel Authors. All rights reserved.
//
// 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.devtools.build.lib.rules.platform;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
import com.google.devtools.build.lib.analysis.platform.ConstraintValueInfo;
import com.google.devtools.build.lib.analysis.platform.ToolchainInfo;
import com.google.devtools.build.lib.events.Location;
import com.google.devtools.build.lib.packages.SkylarkClassObjectConstructor;
import com.google.devtools.build.lib.packages.ToolchainConstructor;
import com.google.devtools.build.lib.syntax.Environment;
import com.google.devtools.build.lib.syntax.EvalException;
import com.google.devtools.build.lib.syntax.FuncallExpression;
import com.google.devtools.build.lib.syntax.SkylarkDict;
import com.google.devtools.build.lib.syntax.SkylarkList;
import java.util.Map;
import java.util.Set;
import javax.annotation.Nullable;

/** Skylark value that can be used to create toolchains. */
public class SkylarkToolchainConstructor extends SkylarkClassObjectConstructor
    implements ToolchainConstructor {

  private static final String EXEC_COMPATIBLE_WITH = "exec_compatible_with";
  private static final String TARGET_COMPATIBLE_WITH = "target_compatible_with";

  public SkylarkToolchainConstructor(Location location) {
    super(
        "<no name>", // name is set on export.
        location);
  }

  @Override
  @Nullable
  protected Object call(Object[] args, @Nullable FuncallExpression ast, @Nullable Environment env)
      throws EvalException, InterruptedException {

    // Decode arguments.
    @SuppressWarnings("unchecked")
    SkylarkDict<String, Object> receivedArguments = (SkylarkDict<String, Object>) args[0];
    @SuppressWarnings("unchecked")
    Iterable<ConstraintValueInfo> execConstraints =
        ConstraintValue.constraintValues(
            (SkylarkList<TransitiveInfoCollection>) receivedArguments.get(EXEC_COMPATIBLE_WITH));
    @SuppressWarnings("unchecked")
    Iterable<ConstraintValueInfo> targetConstraints =
        ConstraintValue.constraintValues(
            (SkylarkList<TransitiveInfoCollection>) receivedArguments.get(TARGET_COMPATIBLE_WITH));
    Map<String, Object> toolchainData =
        collectData(
            receivedArguments, ImmutableSet.of(EXEC_COMPATIBLE_WITH, TARGET_COMPATIBLE_WITH));
    Location loc = ast != null ? ast.getLocation() : Location.BUILTIN;

    return new ToolchainInfo(getKey(), execConstraints, targetConstraints, toolchainData, loc);
  }

  private Map<String, Object> collectData(
      SkylarkDict<String, Object> receivedArguments, Set<String> ignoredKeys) {

    ImmutableMap.Builder<String, Object> builder = new ImmutableMap.Builder<>();
    for (Map.Entry<String, Object> entry : receivedArguments.entrySet()) {
      String key = entry.getKey();
      Object value = entry.getValue();
      if (!ignoredKeys.contains(key)) {
        builder.put(key, value);
      }
    }

    return builder.build();
  }
}