// Copyright 2016 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.bazel.repository.skylark;

import static com.google.devtools.build.lib.packages.Attribute.attr;
import static com.google.devtools.build.lib.packages.Type.BOOLEAN;
import static com.google.devtools.build.lib.packages.Type.STRING;
import static com.google.devtools.build.lib.packages.Type.STRING_LIST;

import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.analysis.BaseRuleClasses;
import com.google.devtools.build.lib.analysis.skylark.StarlarkAttrModule.Descriptor;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
import com.google.devtools.build.lib.packages.AttributeValueSource;
import com.google.devtools.build.lib.packages.BazelStarlarkContext;
import com.google.devtools.build.lib.packages.Package;
import com.google.devtools.build.lib.packages.Package.NameConflictException;
import com.google.devtools.build.lib.packages.PackageFactory;
import com.google.devtools.build.lib.packages.PackageFactory.PackageContext;
import com.google.devtools.build.lib.packages.Rule;
import com.google.devtools.build.lib.packages.RuleClass;
import com.google.devtools.build.lib.packages.RuleClass.Builder.RuleClassType;
import com.google.devtools.build.lib.packages.RuleFactory.InvalidRuleException;
import com.google.devtools.build.lib.packages.SkylarkExportable;
import com.google.devtools.build.lib.packages.WorkspaceFactoryHelper;
import com.google.devtools.build.lib.skylarkbuildapi.repository.RepositoryModuleApi;
import com.google.devtools.build.lib.syntax.Dict;
import com.google.devtools.build.lib.syntax.EvalException;
import com.google.devtools.build.lib.syntax.Module;
import com.google.devtools.build.lib.syntax.Printer;
import com.google.devtools.build.lib.syntax.Sequence;
import com.google.devtools.build.lib.syntax.Starlark;
import com.google.devtools.build.lib.syntax.StarlarkCallable;
import com.google.devtools.build.lib.syntax.StarlarkThread;
import com.google.devtools.build.lib.syntax.Tuple;
import java.util.Map;

/**
 * The Starlark module containing the definition of {@code repository_rule} function to define a
 * Starlark remote repository.
 */
public class SkylarkRepositoryModule implements RepositoryModuleApi {

  @Override
  public StarlarkCallable repositoryRule(
      StarlarkCallable implementation,
      Object attrs,
      Boolean local,
      Sequence<?> environ, // <String> expected
      Boolean configure,
      Boolean remotable,
      String doc,
      StarlarkThread thread)
      throws EvalException {
    BazelStarlarkContext context = BazelStarlarkContext.from(thread);
    context.checkLoadingOrWorkspacePhase("repository_rule");
    // We'll set the name later, pass the empty string for now.
    RuleClass.Builder builder = new RuleClass.Builder("", RuleClassType.WORKSPACE, true);

    ImmutableList<StarlarkThread.CallStackEntry> callstack = thread.getCallStack();
    builder.setCallStack(
        callstack.subList(0, callstack.size() - 1)); // pop 'repository_rule' itself

    builder.addAttribute(attr("$local", BOOLEAN).defaultValue(local).build());
    builder.addAttribute(attr("$configure", BOOLEAN).defaultValue(configure).build());
    if (thread.getSemantics().experimentalRepoRemoteExec()) {
      builder.addAttribute(attr("$remotable", BOOLEAN).defaultValue(remotable).build());
      BaseRuleClasses.execPropertiesAttribute(builder);
    }
    builder.addAttribute(attr("$environ", STRING_LIST).defaultValue(environ).build());
    BaseRuleClasses.nameAttribute(builder);
    BaseRuleClasses.commonCoreAndSkylarkAttributes(builder);
    builder.add(attr("expect_failure", STRING));
    if (attrs != Starlark.NONE) {
      for (Map.Entry<String, Descriptor> attr :
          Dict.cast(attrs, String.class, Descriptor.class, "attrs").entrySet()) {
        Descriptor attrDescriptor = attr.getValue();
        AttributeValueSource source = attrDescriptor.getValueSource();
        String attrName = source.convertToNativeName(attr.getKey());
        if (builder.contains(attrName)) {
          throw Starlark.errorf(
              "There is already a built-in attribute '%s' which cannot be overridden", attrName);
        }
        builder.addAttribute(attrDescriptor.build(attrName));
      }
    }
    builder.setConfiguredTargetFunction(implementation);
    builder.setRuleDefinitionEnvironmentLabelAndDigest(
        (Label) Module.ofInnermostEnclosingStarlarkFunction(thread).getLabel(),
        context.getTransitiveDigest());
    builder.setWorkspaceOnly();
    return new RepositoryRuleFunction(builder, implementation);
  }

  // RepositoryRuleFunction is the result of repository_rule(...).
  // It is a callable value; calling it yields a Rule instance.
  private static final class RepositoryRuleFunction implements StarlarkCallable, SkylarkExportable {
    private final RuleClass.Builder builder;
    private final StarlarkCallable implementation;
    private Label extensionLabel;
    private String exportedName;

    private RepositoryRuleFunction(RuleClass.Builder builder, StarlarkCallable implementation) {
      this.builder = builder;
      this.implementation = implementation;
    }

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

    @Override
    public boolean isImmutable() {
      return true;
    }

    @Override
    public void export(Label extensionLabel, String exportedName) {
      this.extensionLabel = extensionLabel;
      this.exportedName = exportedName;
    }

    @Override
    public boolean isExported() {
      return extensionLabel != null;
    }

    @Override
    public void repr(Printer printer) {
      if (exportedName == null) {
        printer.append("<anonymous starlark repository rule>");
      } else {
        printer.append("<starlark repository rule " + extensionLabel + "%" + exportedName + ">");
      }
    }

    @Override
    public Object call(StarlarkThread thread, Tuple<Object> args, Dict<String, Object> kwargs)
        throws EvalException, InterruptedException {
      if (!args.isEmpty()) {
        throw new EvalException(null, "unexpected positional arguments");
      }
      String ruleClassName;
      // If the function ever got exported (the common case), we take the name
      // it was exported to. Only in the not intended case of calling an unexported
      // repository function through an exported macro, we fall back, for lack of
      // alternatives, to the name in the local context.
      // TODO(b/111199163): we probably should disallow the use of non-exported
      // repository rules anyway.
      if (isExported()) {
        ruleClassName = exportedName;
      } else {
        // repository_rules should be subject to the same "exported" requirement
        // as package rules, but sadly we forgot to add the necessary check and
        // now many projects create and instantiate repository_rules without an
        // intervening export; see b/111199163. An incompatible flag is required.
        if (false) {
          throw new EvalException(null, "attempt to instantiate a non-exported repository rule");
        }

        // The historical workaround was a fragile hack to introspect on the call
        // expression syntax, f() or x.f(), to find the name f, but we no longer
        // have access to the call expression, so now we just create an ugly
        // name from the function. See github.com/bazelbuild/bazel/issues/10441
        ruleClassName = "unexported_" + implementation.getName();
      }
      try {
        RuleClass ruleClass = builder.build(ruleClassName, ruleClassName);
        PackageContext context = PackageFactory.getContext(thread);
        Package.Builder packageBuilder = context.getBuilder();

        // TODO(adonovan): is this cast safe? Check.
        String name = (String) kwargs.get("name");
        WorkspaceFactoryHelper.addMainRepoEntry(packageBuilder, name, thread.getSemantics());
        WorkspaceFactoryHelper.addRepoMappings(packageBuilder, kwargs, name);
        Rule rule =
            WorkspaceFactoryHelper.createAndAddRepositoryRule(
                context.getBuilder(),
                ruleClass,
                /*bindRuleClass=*/ null,
                WorkspaceFactoryHelper.getFinalKwargs(kwargs),
                thread.getSemantics(),
                thread.getCallStack());
        return rule;
      } catch (InvalidRuleException | NameConflictException | LabelSyntaxException e) {
        throw Starlark.errorf("%s", e.getMessage());
      }
    }
  }

  @Override
  public void failWithIncompatibleUseCcConfigureFromRulesCc(StarlarkThread thread)
      throws EvalException {
    if (thread.getSemantics().incompatibleUseCcConfigureFromRulesCc()) {
      throw Starlark.errorf(
          "Incompatible flag "
              + "--incompatible_use_cc_configure_from_rules_cc has been flipped. Please use "
              + "cc_configure and related logic from https://github.com/bazelbuild/rules_cc. "
              + "See https://github.com/bazelbuild/bazel/issues/10134 for details and migration "
              + "instructions.");
    }
  }
}