/*
 * Copyright 2017-present Facebook, Inc.
 *
 * 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.facebook.buck.android.resources;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSortedSet;
import com.google.common.collect.Maps;
import java.io.PrintStream;
import java.nio.ByteBuffer;
import java.util.Comparator;
import java.util.Map;
import java.util.stream.IntStream;

/**
 * A ResourceTable is the top-level representation of resources.arsc. It consists of a header:
 * ResTable_header u32 chunk_type u32 header_size u32 chunk_size u32 package_count
 *
 * <p>The header is followed by a StringPool and then package_count packages.
 *
 * <p>In practice, aapt always generates .arsc files with package_count == 1.
 */
public class ResourceTable extends ResChunk {
  public static final int HEADER_SIZE = 12;

  private final StringPool strings;
  private final ResTablePackage resPackage;

  public ResourceTable(StringPool strings, ResTablePackage resPackage) {
    super(
        CHUNK_RESOURCE_TABLE,
        HEADER_SIZE,
        HEADER_SIZE + strings.getChunkSize() + resPackage.getChunkSize());
    this.strings = strings;
    this.resPackage = resPackage;
  }

  public static ResourceTable get(ByteBuffer buf) {
    int type = buf.getShort();
    int headerSize = buf.getShort();
    int chunkSize = buf.getInt();
    int packageCount = buf.getInt();

    Preconditions.checkState(type == CHUNK_RESOURCE_TABLE);
    Preconditions.checkState(headerSize == HEADER_SIZE);
    Preconditions.checkState(packageCount == 1);

    StringPool strings = StringPool.get(slice(buf, buf.position()));
    ResTablePackage resPackage =
        ResTablePackage.get(slice(buf, HEADER_SIZE + strings.getChunkSize()));

    Preconditions.checkState(
        chunkSize == HEADER_SIZE + strings.getChunkSize() + resPackage.getChunkSize());

    return new ResourceTable(strings, resPackage);
  }

  @Override
  public void put(ByteBuffer buf) {
    putChunkHeader(buf);
    buf.putInt(1); // packageCount
    Preconditions.checkState(buf.position() == HEADER_SIZE);
    strings.put(buf);
    Preconditions.checkState(buf.position() == HEADER_SIZE + strings.getChunkSize());
    resPackage.put(buf);
  }

  public void reassignIds(ReferenceMapper refMapping) {
    resPackage.reassignIds(refMapping);
  }

  public static ResourceTable slice(ResourceTable table, Map<Integer, Integer> countsToExtract) {
    ResTablePackage newPackage = ResTablePackage.slice(table.resPackage, countsToExtract);

    StringPool strings = table.strings;
    // Figure out what strings are used by the retained references.
    ImmutableSortedSet.Builder<Integer> stringRefs =
        ImmutableSortedSet.orderedBy(
            Comparator.comparing(strings::getString).thenComparingInt(i -> i));
    newPackage.visitStringReferences(stringRefs::add);
    ImmutableList<Integer> stringsToExtract = stringRefs.build().asList();
    ImmutableMap<Integer, Integer> stringMapping =
        Maps.uniqueIndex(
            IntStream.range(0, stringsToExtract.size())::iterator, stringsToExtract::get);

    // Extract a StringPool that contains just the strings used by the new package.
    // This drops styles.
    StringPool newStrings =
        StringPool.create(stringsToExtract.stream().map(strings::getString)::iterator);

    // Adjust the string references.
    newPackage.transformStringReferences(stringMapping::get);

    return new ResourceTable(newStrings, newPackage);
  }

  public void dump(PrintStream out) {
    out.format("Package Groups (1)\n");
    resPackage.dump(strings, out);
  }

  public StringPool getStrings() {
    return strings;
  }

  public ResTablePackage getPackage() {
    return resPackage;
  }

  public void dumpStrings(PrintStream out) {
    strings.dump(out);
  }
}