/*
 * Copyright (C) 2018 The Android Open Source Project
 *
 * 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.android.incallui.rtt.impl;

import android.os.Parcel;
import android.os.Parcelable;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import com.android.incallui.rtt.protocol.Constants;
import com.google.common.base.Splitter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/** Message class that holds one RTT chat content. */
final class RttChatMessage implements Parcelable {

  private static final Splitter SPLITTER = Splitter.on(Constants.BUBBLE_BREAKER);

  boolean isRemote;
  public boolean hasAvatar;
  private final StringBuilder content = new StringBuilder();
  private boolean isFinished;

  public boolean isFinished() {
    return isFinished;
  }

  public void finish() {
    isFinished = true;
  }

  public void append(String text) {
    for (int i = 0; i < text.length(); i++) {
      char c = text.charAt(i);
      if (c != '\b') {
        content.append(c);
      } else if (content.length() > 0) {
        content.deleteCharAt(content.length() - 1);
      }
    }
  }

  public String getContent() {
    return content.toString();
  }

  /**
   * Computes delta change of two string.
   *
   * <p>e.g. "hello world" -> "hello" : "\b\b\b\b\b\b"
   *
   * <p>"hello world" -> "hello mom!" : "\b\b\b\b\bmom!"
   *
   * <p>"hello world" -> "hello d" : "\b\b\b\b\bd"
   *
   * <p>"hello world" -> "hello new world" : "\b\b\b\b\bnew world"
   */
  static String computeChangedString(String oldMessage, String newMesssage) {
    StringBuilder modify = new StringBuilder();
    int indexChangeStart = 0;
    while (indexChangeStart < oldMessage.length()
        && indexChangeStart < newMesssage.length()
        && oldMessage.charAt(indexChangeStart) == newMesssage.charAt(indexChangeStart)) {
      indexChangeStart++;
    }
    for (int i = indexChangeStart; i < oldMessage.length(); i++) {
      modify.append('\b');
    }
    for (int i = indexChangeStart; i < newMesssage.length(); i++) {
      modify.append(newMesssage.charAt(i));
    }
    return modify.toString();
  }

  /** Convert remote input text into an array of {@code RttChatMessage}. */
  static List<RttChatMessage> getRemoteRttChatMessage(
      @Nullable RttChatMessage currentMessage, @NonNull String text) {
    Iterator<String> splitText = SPLITTER.split(text).iterator();
    List<RttChatMessage> messageList = new ArrayList<>();

    String firstMessageContent = splitText.next();
    RttChatMessage firstMessage = currentMessage;
    if (firstMessage == null) {
      firstMessage = new RttChatMessage();
      firstMessage.isRemote = true;
    }
    firstMessage.append(firstMessageContent);
    if (splitText.hasNext() || text.endsWith(Constants.BUBBLE_BREAKER)) {
      firstMessage.finish();
    }
    messageList.add(firstMessage);

    while (splitText.hasNext()) {
      String singleMessageContent = splitText.next();
      if (singleMessageContent.isEmpty()) {
        continue;
      }
      RttChatMessage message = new RttChatMessage();
      message.append(singleMessageContent);
      message.isRemote = true;
      if (splitText.hasNext()) {
        message.finish();
      }
      messageList.add(message);
    }

    return messageList;
  }

  @Override
  public int describeContents() {
    return 0;
  }

  @Override
  public void writeToParcel(Parcel dest, int flags) {
    dest.writeString(getContent());
    boolean[] values = new boolean[2];
    values[0] = isRemote;
    values[1] = isFinished;
    dest.writeBooleanArray(values);
  }

  public static final Parcelable.Creator<RttChatMessage> CREATOR =
      new Parcelable.Creator<RttChatMessage>() {
        @Override
        public RttChatMessage createFromParcel(Parcel in) {
          return new RttChatMessage(in);
        }

        @Override
        public RttChatMessage[] newArray(int size) {
          return new RttChatMessage[size];
        }
      };

  private RttChatMessage(Parcel in) {
    content.append(in.readString());
    boolean[] values = new boolean[2];
    in.readBooleanArray(values);
    isRemote = values[0];
    isFinished = values[1];
  }

  RttChatMessage() {}
}