// Copyright 2018 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.analysis.config;

import com.google.auto.value.AutoValue;
import com.google.auto.value.extension.memoized.Memoized;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableList.Builder;
import com.google.devtools.common.options.Converters.RegexPatternConverter;
import com.google.devtools.common.options.OptionsParsingException;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Represents a list of regexes over mnemonics and changes to add or remove keys, parsed from a
 * {@code --modify_execution_info} option.
 */
@AutoValue
public abstract class ExecutionInfoModifier {

  private static final Pattern MODIFIER_PATTERN =
      Pattern.compile("^(?<pattern>.+)=(?<sign>[+-])(?<key>.+)$");

  private static final ExecutionInfoModifier EMPTY = create("", ImmutableList.of());

  abstract String option();
  abstract ImmutableList<Expression> expressions();

  @AutoValue
  abstract static class Expression {
    // Patterns do not have a useful equals(), so compare by the regex and memoize the derived
    // Pattern.
    @Memoized
    Pattern pattern() {
      return Pattern.compile(regex());
    }

    abstract String regex();

    abstract boolean remove();

    abstract String key();
  }

  /** Constructs an instance of ExecutionInfoModifier by parsing an option string. */
  public static class Converter
      implements com.google.devtools.common.options.Converter<ExecutionInfoModifier> {
    @Override
    public ExecutionInfoModifier convert(String input) throws OptionsParsingException {
      if (Strings.isNullOrEmpty(input)) {
        return EMPTY;
      }

      ImmutableList.Builder<Expression> expressionBuilder = ImmutableList.builder();
      for (String spec : Splitter.on(",").split(input)) {
        Matcher specMatcher = MODIFIER_PATTERN.matcher(spec);
        if (!specMatcher.matches()) {
          throw new OptionsParsingException(
              String.format("malformed expression '%s'", spec), input);
        }
        expressionBuilder.add(
            new AutoValue_ExecutionInfoModifier_Expression(
                // Convert to get a useful exception if it's not a valid pattern, but use the regex
                // (see comment in Expression)
                new RegexPatternConverter().convert(specMatcher.group("pattern")).pattern(),
                specMatcher.group("sign").equals("-"),
                specMatcher.group("key")));
      }
      return ExecutionInfoModifier.create(input, expressionBuilder.build());
    }

    @Override
    public String getTypeDescription() {
      return "regex=[+-]key,regex=[+-]key,...";
    }
  }

  private static ExecutionInfoModifier create(String input, ImmutableList<Expression> expressions) {
    return new AutoValue_ExecutionInfoModifier(input, expressions);
  }

  /**
   * Determines whether the given {@code mnemonic} (e.g. "CppCompile") matches any of the patterns.
   */
  public boolean matches(String mnemonic) {
    return expressions().stream().anyMatch(expr -> expr.pattern().matcher(mnemonic).matches());
  }

  /** Modifies the given map of {@code executionInfo} to add or remove the keys for this option. */
  void apply(String mnemonic, Map<String, String> executionInfo) {
    for (Expression expr : expressions()) {
      if (expr.pattern().matcher(mnemonic).matches()) {
        if (expr.remove()) {
          executionInfo.remove(expr.key());
        } else {
          executionInfo.put(expr.key(), "");
        }
      }
    }
  }
}