// Copyright 2014 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.syntax;

import static com.google.devtools.build.lib.syntax.compiler.ByteCodeUtils.append;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.devtools.build.lib.syntax.compiler.ByteCodeMethodCalls;
import com.google.devtools.build.lib.syntax.compiler.ByteCodeUtils;
import com.google.devtools.build.lib.syntax.compiler.DebugInfo;
import com.google.devtools.build.lib.syntax.compiler.VariableScope;

import net.bytebuddy.implementation.bytecode.ByteCodeAppender;
import net.bytebuddy.implementation.bytecode.Duplication;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * Syntax node for dictionary literals.
 */
public class DictionaryLiteral extends Expression {

  static final class DictionaryEntryLiteral extends ASTNode {

    private final Expression key;
    private final Expression value;

    public DictionaryEntryLiteral(Expression key, Expression value) {
      this.key = key;
      this.value = value;
    }

    Expression getKey() {
      return key;
    }

    Expression getValue() {
      return value;
    }

    @Override
    public String toString() {
      StringBuilder sb = new StringBuilder();
      sb.append(key);
      sb.append(": ");
      sb.append(value);
      return sb.toString();
    }

    @Override
    public void accept(SyntaxTreeVisitor visitor) {
      visitor.visit(this);
    }
  }

  private final ImmutableList<DictionaryEntryLiteral> entries;

  public DictionaryLiteral(List<DictionaryEntryLiteral> exprs) {
    this.entries = ImmutableList.copyOf(exprs);
  }

  /** A new literal for an empty dictionary, onto which a new location can be specified */
  public static DictionaryLiteral emptyDict() {
    return new DictionaryLiteral(ImmutableList.<DictionaryEntryLiteral>of());
  }

  @Override
  Object doEval(Environment env) throws EvalException, InterruptedException {
    // We need LinkedHashMap to maintain the order during iteration (e.g. for loops)
    Map<Object, Object> map = new LinkedHashMap<>();
    for (DictionaryEntryLiteral entry : entries) {
      if (entry == null) {
        throw new EvalException(getLocation(), "null expression in " + this);
      }
      Object key = entry.key.eval(env);
      EvalUtils.checkValidDictKey(key);
      Object val = entry.value.eval(env);
      map.put(key, val);
    }
    return ImmutableMap.copyOf(map);
  }

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("{");
    String sep = "";
    for (DictionaryEntryLiteral e : entries) {
      sb.append(sep);
      sb.append(e);
      sep = ", ";
    }
    sb.append("}");
    return sb.toString();
  }

  @Override
  public void accept(SyntaxTreeVisitor visitor) {
    visitor.visit(this);
  }

  public ImmutableList<DictionaryEntryLiteral> getEntries() {
    return entries;
  }

  @Override
  void validate(ValidationEnvironment env) throws EvalException {
    for (DictionaryEntryLiteral entry : entries) {
      entry.key.validate(env);
      entry.value.validate(env);
    }
  }

  @Override
  ByteCodeAppender compile(VariableScope scope, DebugInfo debugInfo) throws EvalException {
    List<ByteCodeAppender> code = new ArrayList<>();
    append(code, ByteCodeMethodCalls.BCImmutableMap.builder);

    for (DictionaryEntryLiteral entry : entries) {
      code.add(entry.key.compile(scope, debugInfo));
      append(code, Duplication.SINGLE, EvalUtils.checkValidDictKey);
      code.add(entry.value.compile(scope, debugInfo));
      // add it to the builder which is already on the stack and returns itself
      append(code, ByteCodeMethodCalls.BCImmutableMap.Builder.put);
    }
    append(code, ByteCodeMethodCalls.BCImmutableMap.Builder.build);
    return ByteCodeUtils.compoundAppender(code);
  }
}