// 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.rules.objc;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Optional;
import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.actions.Artifact;
import com.google.devtools.build.lib.analysis.RuleContext;
import com.google.devtools.build.lib.packages.BuildType;
import com.google.devtools.build.lib.rules.cpp.LibraryToLink;
import javax.annotation.Nullable;
import net.starlark.java.eval.StarlarkValue;

/**
 * Support for rules that compile sources. Provides ways to determine files that should be output,
 * registering Xcode settings and generating the various actions that might be needed for
 * compilation.
 *
 * <p>A subclass should express a particular strategy for compile and link action registration.
 * Subclasses should implement the API without adding new visible methods - rule implementations
 * should be able to use a {@link CompilationSupport} instance to compile and link source without
 * knowing the subclass being used.
 *
 * <p>Methods on this class can be called in any order without impacting the result.
 */
public class CompilationSupport implements StarlarkValue {
  @VisibleForTesting static final String OBJC_MODULE_CACHE_DIR_NAME = "_objc_module_cache";

  @VisibleForTesting
  static final String ABSOLUTE_INCLUDES_PATH_FORMAT =
      "The path '%s' is absolute, but only relative paths are allowed.";

  // Flags for clang 6.1(xcode 6.4)
  @VisibleForTesting
  static final ImmutableList<String> CLANG_GCOV_COVERAGE_FLAGS =
      ImmutableList.of("-fprofile-arcs", "-ftest-coverage");

  @VisibleForTesting
  static final ImmutableList<String> CLANG_LLVM_COVERAGE_FLAGS =
      ImmutableList.of("-fprofile-instr-generate", "-fcoverage-mapping");

  // These are added by Xcode when building, because the simulator is built on OSX
  // frameworks so we aim compile to match the OSX objc runtime.
  @VisibleForTesting
  static final ImmutableList<String> SIMULATOR_COMPILE_FLAGS =
      ImmutableList.of(
          "-fexceptions", "-fasm-blocks", "-fobjc-abi-version=2", "-fobjc-legacy-dispatch");


  @VisibleForTesting
  static final String FILE_IN_SRCS_AND_HDRS_WARNING_FORMAT = "File '%s' is in both srcs and hdrs.";

  @VisibleForTesting
  static final String FILE_IN_SRCS_AND_NON_ARC_SRCS_ERROR_FORMAT =
      "File '%s' is present in both srcs and non_arc_srcs which is forbidden.";

  @VisibleForTesting
  static final String BOTH_MODULE_NAME_AND_MODULE_MAP_SPECIFIED =
      "Specifying both module_name and module_map is invalid, please remove one of them.";

  static final ImmutableList<String> DEFAULT_COMPILER_FLAGS = ImmutableList.of("-DOS_IOS");

  /** Returns information about the given rule's compilation artifacts. */
  // TODO(bazel-team): Remove this information from ObjcCommon and move it internal to this class.
  static CompilationArtifacts compilationArtifacts(RuleContext ruleContext) {
    return compilationArtifacts(ruleContext, new IntermediateArtifacts(ruleContext));
  }

  /**
   * Returns information about the given rule's compilation artifacts. Dependencies specified in the
   * current rule's attributes are obtained via {@code ruleContext}. Output locations are determined
   * using the given {@code intermediateArtifacts} object. The fact that these are distinct objects
   * allows the caller to generate compilation actions pertaining to a configuration separate from
   * the current rule's configuration.
   */
  static CompilationArtifacts compilationArtifacts(
      RuleContext ruleContext, IntermediateArtifacts intermediateArtifacts) {
    return new CompilationArtifacts(ruleContext, intermediateArtifacts);
  }

  private CompilationSupport() {}

  /**
   * Returns the preferred static library for linking, or {@code null} if there is no static
   * library.
   *
   * @param library the input library.
   */
  @Nullable
  public static Artifact getStaticLibraryForLinking(LibraryToLink library) {
    if (library.getStaticLibrary() != null) {
      return library.getStaticLibrary();
    } else if (library.getPicStaticLibrary() != null) {
      return library.getPicStaticLibrary();
    } else {
      return null;
    }
  }

  /**
   * Returns the preferred variant of the library for linking.
   *
   * @param library the input library.
   */
  public static Artifact getLibraryForLinking(LibraryToLink library) {
    if (library.getStaticLibrary() != null) {
      return library.getStaticLibrary();
    } else if (library.getPicStaticLibrary() != null) {
      return library.getPicStaticLibrary();
    } else if (library.getInterfaceLibrary() != null) {
      return library.getInterfaceLibrary();
    } else {
      return library.getDynamicLibrary();
    }
  }

  public static Optional<Artifact> getCustomModuleMap(RuleContext ruleContext) {
    if (ruleContext.attributes().has("module_map", BuildType.LABEL)) {
      return Optional.fromNullable(ruleContext.getPrerequisiteArtifact("module_map"));
    }
    return Optional.absent();
  }
}