content: /*
   * Copyright 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.server.display.utils;
  
  
  import java.lang.StringBuilder;
  import java.lang.System;
  
  import android.util.Slog;
  
  /**
   * A utility to log multiple points and curves in a structured way so they can be easily consumed
   * by external tooling
   *
   * To start a plot, call {@link Plog.start} with the plot's title; to add a point to it, call
   * {@link Plog.logPoint} with the point name (that will appear in the legend) and coordinates; and
   * to log a curve, call {@link Plog.logCurve} with its name and points.
   */
  public abstract class Plog {
      // A unique identifier used to group points and curves that belong on the same plot.
      private long mId;
  
      /**
       * Returns a Plog instance that emits messages to the system log.
       *
       * @param tag The tag of the emitted messages in the system log.
       * @return A plog instance that emits messages to the system log.
       */
      public static Plog createSystemPlog(String tag) {
          return new SystemPlog(tag);
      }
  
      /**
       * Start a new plot.
       *
       * @param title The plot title.
       * @return The Plog instance (for chaining).
       */
      public Plog start(String title) {
          mId = System.currentTimeMillis();
          write(formatTitle(title));
          return this;
      }
  
      /**
       * Adds a point to the current plot.
       *
       * @param name The point name (that will appear in the legend).
       * @param x The point x coordinate.
       * @param y The point y coordinate.
       * @return The Plog instance (for chaining).
       */
      public Plog logPoint(String name, float x, float y) {
          write(formatPoint(name, x, y));
          return this;
      }
  
      /**
       * Adds a curve to the current plot.
       *
       * @param name The curve name (that will appear in the legend).
       * @param xs The curve x coordinates.
       * @param ys The curve y coordinates.
       * @return The Plog instance (for chaining).
       */
      public Plog logCurve(String name, float[] xs, float[] ys) {
          write(formatCurve(name, xs, ys));
          return this;
      }
  
      private String formatTitle(String title) {
          return "title: " + title;
      }
  
      private String formatPoint(String name, float x, float y) {
          return "point: " + name + ": (" + x + "," + y + ")";
      }
  
      private String formatCurve(String name, float[] xs, float[] ys) {
          StringBuilder sb = new StringBuilder();
          sb.append("curve: " + name + ": [");
          int n = xs.length <= ys.length ? xs.length : ys.length;
          for (int i = 0; i < n; i++) {
              sb.append("(" + xs[i] + "," + ys[i] + "),");
          }
          sb.append("]");
          return sb.toString();
      }
  
      private void write(String message) {
          emit("[PLOG " + mId + "] " + message);
      }
  
      /**
       * Emits a message (depending on the concrete Plog implementation).
       *
       * @param message The message.
       */
      protected abstract void emit(String message);
  
      /**
       * A Plog that emits messages to the system log.
       */
      public static class SystemPlog extends Plog {
          // The tag of the emitted messages in the system log.
          private final String mTag;
  
          /**
           * Returns a Plog instance that emits messages to the system log.
           *
           * @param tag The tag of the emitted messages in the system log.
           * @return A Plog instance that emits messages to the system log.
           */
          public SystemPlog(String tag) {
              mTag = tag;
          }
  
          /**
           * Emits a message to the system log.
           *
           * @param message The message.
           */
          protected void emit(String message) {
              Slog.d(mTag, message);
          }
      }
  }
  