// Copyright 2015 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.packages;

import com.google.common.base.Preconditions;
import com.google.common.base.Strings;
import com.google.common.base.Verify;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
import com.google.devtools.build.lib.cmdline.RepositoryName;
import com.google.devtools.build.lib.cmdline.TargetParsingException;
import com.google.devtools.build.lib.cmdline.TargetPattern;
import com.google.devtools.build.lib.events.StoredEventHandler;
import com.google.devtools.build.lib.packages.RuleFactory.BuildLangTypedAttributeValuesMap;
import java.util.Map;
import java.util.stream.Collectors;
import net.starlark.java.eval.Dict;
import net.starlark.java.eval.EvalException;
import net.starlark.java.eval.StarlarkSemantics;
import net.starlark.java.eval.StarlarkThread;

/** A helper for the {@link WorkspaceFactory} to create repository rules */
public class WorkspaceFactoryHelper {

  public static Rule createAndAddRepositoryRule(
      Package.Builder pkg,
      RuleClass ruleClass,
      RuleClass bindRuleClass,
      Map<String, Object> kwargs,
      StarlarkSemantics semantics,
      ImmutableList<StarlarkThread.CallStackEntry> callstack)
      throws RuleFactory.InvalidRuleException, Package.NameConflictException, LabelSyntaxException,
          InterruptedException {
    StoredEventHandler eventHandler = new StoredEventHandler();
    BuildLangTypedAttributeValuesMap attributeValues = new BuildLangTypedAttributeValuesMap(kwargs);
    Rule rule =
        RuleFactory.createRule(pkg, ruleClass, attributeValues, eventHandler, semantics, callstack);
    pkg.addEvents(eventHandler.getEvents());
    pkg.addPosts(eventHandler.getPosts());
    overwriteRule(pkg, rule);
    for (Map.Entry<String, Label> entry :
        ruleClass.getExternalBindingsFunction().apply(rule).entrySet()) {
      Label nameLabel = Label.parseAbsolute("//external:" + entry.getKey(), ImmutableMap.of());
      addBindRule(pkg, bindRuleClass, nameLabel, entry.getValue(), semantics, callstack);
    }
    // NOTE(wyv): What is this madness?? This is the only instance where a repository rule can
    // register toolchains upon being instantiated. We should look into converting
    // android_{s,n}dk_repository into module extensions.
    ImmutableList.Builder<TargetPattern> toolchains = new ImmutableList.Builder<>();
    for (String pattern : ruleClass.getToolchainsToRegisterFunction().apply(rule)) {
      try {
        toolchains.add(TargetPattern.defaultParser().parse(pattern));
      } catch (TargetParsingException e) {
        throw new LabelSyntaxException(e.getMessage());
      }
    }
    pkg.addRegisteredToolchains(toolchains.build());
    return rule;
  }

  /**
   * Updates the map of attributes specified by the user to match the set of attributes decared in
   * the rule definition.
   */
  public static Map<String, Object> getFinalKwargs(Map<String, Object> kwargs) {
    // 'repo_mapping' is not an explicit attribute of any rule and so it would
    // result in a rule error if propagated to the rule factory.
    return kwargs.entrySet().stream()
        .filter(x -> !x.getKey().equals("repo_mapping"))
        .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
  }

  /**
   * Adds an entry in the repo map for {@code externalRepoName} from the main repo name to
   * {@code @}.
   *
   * <p>This is so that labels that refer to the main workspace name (either from the main workspace
   * or from an external repository) in different forms all resolve to the same label.
   *
   * <p>For example, consider a main workspace with the name {@code foo}. The labels
   * {@code @foo//:bar} and {@code //:bar} from the main workspace should resolve to the same thing.
   * Additionally, the labels {@code @foo//:bar} and {@code @//:bar} from an external repository
   * should also evaluate to the same thing.
   */
  public static void addMainRepoEntry(
      Package.Builder builder, String externalRepoName, StarlarkSemantics semantics)
      throws LabelSyntaxException {
    if (!Strings.isNullOrEmpty(builder.getPackageWorkspaceName())) {
      // Create repository names with validation, LabelSyntaxException is thrown is the name
      // is not valid.
      builder.addRepositoryMappingEntry(
          RepositoryName.create("@" + externalRepoName),
          RepositoryName.create("@" + builder.getPackageWorkspaceName()),
          RepositoryName.MAIN);
    }
  }

  /**
   * Processes {@code repo_mapping} attribute and populates the package builder with the mappings.
   *
   * @throws EvalException if {@code repo_mapping} is present in kwargs but is not a
   *     string-to-string dict.
   */
  public static void addRepoMappings(
      Package.Builder builder, Map<String, Object> kwargs, String externalRepoName)
      throws EvalException, LabelSyntaxException {
    Object repoMapping = kwargs.get("repo_mapping");
    if (repoMapping != null) {
      for (Map.Entry<String, String> e :
          Dict.cast(repoMapping, String.class, String.class, "repo_mapping").entrySet()) {
        // Create repository names with validation; may throw LabelSyntaxException.
        builder.addRepositoryMappingEntry(
            RepositoryName.create("@" + externalRepoName),
            RepositoryName.create(e.getKey()),
            RepositoryName.create(e.getValue()));
      }
    }
  }

  static void addBindRule(
      Package.Builder pkg,
      RuleClass bindRuleClass,
      Label virtual,
      Label actual,
      StarlarkSemantics semantics,
      ImmutableList<StarlarkThread.CallStackEntry> callstack)
      throws RuleFactory.InvalidRuleException, Package.NameConflictException, InterruptedException {

    Map<String, Object> attributes = Maps.newHashMap();
    // Bound rules don't have a name field, but this works because we don't want more than one
    // with the same virtual name.
    attributes.put("name", virtual.getName());
    if (actual != null) {
      attributes.put("actual", actual);
    }
    StoredEventHandler handler = new StoredEventHandler();
    BuildLangTypedAttributeValuesMap attributeValues =
        new BuildLangTypedAttributeValuesMap(attributes);
    Rule rule =
        RuleFactory.createRule(pkg, bindRuleClass, attributeValues, handler, semantics, callstack);
    overwriteRule(pkg, rule);
    rule.setVisibility(ConstantRuleVisibility.PUBLIC);
  }

  private static void overwriteRule(Package.Builder pkg, Rule rule)
      throws Package.NameConflictException {
    Preconditions.checkArgument(rule.getOutputFiles().isEmpty());
    Target old = pkg.getTarget(rule.getName());
    if (old != null) {
      if (old instanceof Rule) {
        Verify.verify(((Rule) old).getOutputFiles().isEmpty());
      }
      pkg.replaceTarget(rule);
    } else {
      pkg.addRule(rule);
    }
  }
}