/*
 * Protocol Buffers - Google's data interchange format
 * Copyright 2014 Google Inc.  All rights reserved.
 * https://developers.google.com/protocol-buffers/
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.google.protobuf.jruby;

import com.google.protobuf.DescriptorProtos.FileDescriptorProto;
import com.google.protobuf.Descriptors.Descriptor;
import com.google.protobuf.Descriptors.DescriptorValidationException;
import com.google.protobuf.Descriptors.EnumDescriptor;
import com.google.protobuf.Descriptors.FieldDescriptor;
import com.google.protobuf.Descriptors.FileDescriptor;
import com.google.protobuf.Descriptors.ServiceDescriptor;
import com.google.protobuf.Descriptors.MethodDescriptor;
import com.google.protobuf.ExtensionRegistry;
import com.google.protobuf.InvalidProtocolBufferException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.jruby.*;
import org.jruby.anno.JRubyClass;
import org.jruby.anno.JRubyMethod;
import org.jruby.exceptions.RaiseException;
import org.jruby.runtime.*;
import org.jruby.runtime.builtin.IRubyObject;

@JRubyClass(name = "DescriptorPool")
public class RubyDescriptorPool extends RubyObject {
  public static void createRubyDescriptorPool(Ruby runtime) {
    RubyModule protobuf = runtime.getClassFromPath("Google::Protobuf");
    RubyClass cDescriptorPool =
        protobuf.defineClassUnder(
            "DescriptorPool",
            runtime.getObject(),
            new ObjectAllocator() {
              @Override
              public IRubyObject allocate(Ruby runtime, RubyClass klazz) {
                return new RubyDescriptorPool(runtime, klazz);
              }
            });

    cDescriptorPool.defineAnnotatedMethods(RubyDescriptorPool.class);
    descriptorPool =
        (RubyDescriptorPool)
            cDescriptorPool.newInstance(runtime.getCurrentContext(), Block.NULL_BLOCK);
    cDescriptor = (RubyClass) runtime.getClassFromPath("Google::Protobuf::Descriptor");
    cEnumDescriptor = (RubyClass) runtime.getClassFromPath("Google::Protobuf::EnumDescriptor");
    cFieldDescriptor = (RubyClass) runtime.getClassFromPath("Google::Protobuf::FieldDescriptor");
    cServiceDescriptor =
        (RubyClass) runtime.getClassFromPath("Google::Protobuf::ServiceDescriptor");
    cMethodDescriptor = (RubyClass) runtime.getClassFromPath("Google::Protobuf::MethodDescriptor");
  }

  public RubyDescriptorPool(Ruby runtime, RubyClass klazz) {
    super(runtime, klazz);
    this.fileDescriptors = new ArrayList<>();
    this.symtab = new HashMap<IRubyObject, IRubyObject>();
  }

  @JRubyMethod
  public IRubyObject build(ThreadContext context, Block block) {
    RubyClass cBuilder =
        (RubyClass) context.runtime.getClassFromPath("Google::Protobuf::Internal::Builder");
    RubyBasicObject ctx = (RubyBasicObject) cBuilder.newInstance(context, this, Block.NULL_BLOCK);
    ctx.instance_eval(context, block);
    ctx.callMethod(context, "build"); // Needs to be called to support the deprecated syntax
    return context.nil;
  }

  /*
   * call-seq:
   *     DescriptorPool.lookup(name) => descriptor
   *
   * Finds a Descriptor, EnumDescriptor, FieldDescriptor or ServiceDescriptor by name and returns it,
   * or nil if none exists with the given name.
   *
   * This currently lazy loads the ruby descriptor objects as they are requested.
   * This allows us to leave the heavy lifting to the java library
   */
  @JRubyMethod
  public IRubyObject lookup(ThreadContext context, IRubyObject name) {
    return Helpers.nullToNil(symtab.get(name), context.nil);
  }

  /*
   * call-seq:
   *     DescriptorPool.generated_pool => descriptor_pool
   *
   * Class method that returns the global DescriptorPool. This is a singleton into
   * which generated-code message and enum types are registered. The user may also
   * register types in this pool for convenience so that they do not have to hold
   * a reference to a private pool instance.
   */
  @JRubyMethod(meta = true, name = "generated_pool")
  public static IRubyObject generatedPool(ThreadContext context, IRubyObject recv) {
    return descriptorPool;
  }

  @JRubyMethod(required = 1)
  public IRubyObject add_serialized_file(ThreadContext context, IRubyObject data) {
    byte[] bin = data.convertToString().getBytes();
    try {
      FileDescriptorProto.Builder builder =
          FileDescriptorProto.newBuilder().mergeFrom(bin, registry);
      registerFileDescriptor(context, builder);
    } catch (InvalidProtocolBufferException e) {
      throw RaiseException.from(
          context.runtime,
          (RubyClass) context.runtime.getClassFromPath("Google::Protobuf::ParseError"),
          e.getMessage());
    }
    return context.nil;
  }

  protected void registerFileDescriptor(
      ThreadContext context, FileDescriptorProto.Builder builder) {
    final FileDescriptor fd;
    try {
      fd = FileDescriptor.buildFrom(builder.build(), existingFileDescriptors());
    } catch (DescriptorValidationException e) {
      throw context.runtime.newRuntimeError(e.getMessage());
    }

    String packageName = fd.getPackage();
    if (!packageName.isEmpty()) {
      packageName = packageName + ".";
    }

    // Need to make sure enums are registered first in case anything references them
    for (EnumDescriptor ed : fd.getEnumTypes()) registerEnumDescriptor(context, ed, packageName);
    for (Descriptor message : fd.getMessageTypes())
      registerDescriptor(context, message, packageName);
    for (FieldDescriptor fieldDescriptor : fd.getExtensions())
      registerExtension(context, fieldDescriptor, packageName);
    for (ServiceDescriptor serviceDescriptor : fd.getServices())
      registerService(context, serviceDescriptor, packageName);

    // Mark this as a loaded file
    fileDescriptors.add(fd);
  }

  private void registerDescriptor(ThreadContext context, Descriptor descriptor, String parentPath) {
    String fullName = parentPath + descriptor.getName();
    String fullPath = fullName + ".";
    RubyString name = context.runtime.newString(fullName);

    RubyDescriptor des = (RubyDescriptor) cDescriptor.newInstance(context, Block.NULL_BLOCK);
    des.setName(name);
    des.setDescriptor(context, descriptor, this);
    symtab.put(name, des);

    // Need to make sure enums are registered first in case anything references them
    for (EnumDescriptor ed : descriptor.getEnumTypes())
      registerEnumDescriptor(context, ed, fullPath);
    for (Descriptor message : descriptor.getNestedTypes())
      registerDescriptor(context, message, fullPath);
    for (FieldDescriptor fieldDescriptor : descriptor.getExtensions())
      registerExtension(context, fieldDescriptor, fullPath);
  }

  private void registerExtension(
      ThreadContext context, FieldDescriptor descriptor, String parentPath) {
    if (descriptor.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
      registry.add(descriptor, descriptor.toProto());
    } else {
      registry.add(descriptor);
    }
    RubyString name = context.runtime.newString(parentPath + descriptor.getName());
    RubyFieldDescriptor des =
        (RubyFieldDescriptor) cFieldDescriptor.newInstance(context, Block.NULL_BLOCK);
    des.setName(name);
    des.setDescriptor(context, descriptor, this);
    // For MessageSet extensions, there is the possibility of a name conflict. Prefer the Message.
    symtab.putIfAbsent(name, des);
  }

  private void registerEnumDescriptor(
      ThreadContext context, EnumDescriptor descriptor, String parentPath) {
    RubyString name = context.runtime.newString(parentPath + descriptor.getName());
    RubyEnumDescriptor des =
        (RubyEnumDescriptor) cEnumDescriptor.newInstance(context, Block.NULL_BLOCK);
    des.setName(name);
    des.setDescriptor(context, descriptor);
    symtab.put(name, des);
  }

  private void registerService(
      ThreadContext context, ServiceDescriptor descriptor, String parentPath) {
    String fullName = parentPath + descriptor.getName();
    RubyString name = context.runtime.newString(fullName);
    RubyServiceDescriptor des =
        (RubyServiceDescriptor) cServiceDescriptor.newInstance(context, Block.NULL_BLOCK);
    des.setName(name);
    // n.b. this will also construct the descriptors for the service's methods.
    des.setDescriptor(context, descriptor, this);
    symtab.putIfAbsent(name, des);
  }

  private FileDescriptor[] existingFileDescriptors() {
    return fileDescriptors.toArray(new FileDescriptor[fileDescriptors.size()]);
  }

  private static RubyClass cDescriptor;
  private static RubyClass cEnumDescriptor;
  private static RubyClass cFieldDescriptor;
  private static RubyClass cServiceDescriptor;
  private static RubyClass cMethodDescriptor;
  private static RubyDescriptorPool descriptorPool;

  private List<FileDescriptor> fileDescriptors;
  private Map<IRubyObject, IRubyObject> symtab;
  protected static final ExtensionRegistry registry = ExtensionRegistry.newInstance();
}
