/**
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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 org.apache.hadoop.hbase.hbtop.terminal.impl;
  
  import static org.apache.hadoop.hbase.hbtop.terminal.impl.EscapeSequences.clearAll;
  import static org.apache.hadoop.hbase.hbtop.terminal.impl.EscapeSequences.cursor;
  import static org.apache.hadoop.hbase.hbtop.terminal.impl.EscapeSequences.moveCursor;
  import static org.apache.hadoop.hbase.hbtop.terminal.impl.EscapeSequences.normal;
  
  import edu.umd.cs.findbugs.annotations.Nullable;
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.OutputStreamWriter;
  import java.io.PrintWriter;
  import java.nio.charset.StandardCharsets;
  import java.util.Queue;
  import java.util.StringTokenizer;
  import java.util.concurrent.ConcurrentLinkedQueue;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.hbtop.terminal.CursorPosition;
  import org.apache.hadoop.hbase.hbtop.terminal.KeyPress;
  import org.apache.hadoop.hbase.hbtop.terminal.Terminal;
  import org.apache.hadoop.hbase.hbtop.terminal.TerminalPrinter;
  import org.apache.hadoop.hbase.hbtop.terminal.TerminalSize;
  
  /**
   * An implementation of the {@link Terminal} interface for normal display mode.
   *
   * This implementation produces output intended for human viewing. In particular, it only displays
   * one screenful of data. The output contains some escape sequences for formatting.
   */
  @InterfaceAudience.Private
  public class TerminalImpl implements Terminal {
  
    private static final Log LOG = LogFactory.getLog(TerminalImpl.class);
  
    private TerminalSize cachedTerminalSize;
  
    private final PrintWriter output;
  
    private final ScreenBuffer screenBuffer;
  
    private final Queue<KeyPress> keyPressQueue;
    private final KeyPressGenerator keyPressGenerator;
  
    public TerminalImpl() {
      this(null);
    }
  
    public TerminalImpl(@Nullable String title) {
      output = new PrintWriter(new OutputStreamWriter(System.out, StandardCharsets.UTF_8));
      sttyRaw();
  
      if (title != null) {
        setTitle(title);
      }
  
      screenBuffer = new ScreenBuffer();
  
      cachedTerminalSize = queryTerminalSize();
      updateTerminalSize(cachedTerminalSize.getColumns(), cachedTerminalSize.getRows());
  
      keyPressQueue = new ConcurrentLinkedQueue<>();
      keyPressGenerator = new KeyPressGenerator(System.in, keyPressQueue);
      keyPressGenerator.start();
  
      Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
        @Override
        public void run() {
          output.printf("%s%s%s%s", moveCursor(0, 0), cursor(true), normal(), clearAll());
          output.flush();
          sttyCooked();
        }
      }));
  
      // Clear the terminal
      output.write(clearAll());
      output.flush();
    }
  
   private void setTitle(String title) {
     output.write(EscapeSequences.setTitle(title));
     output.flush();
   }
 
   private void updateTerminalSize(int columns, int rows) {
     screenBuffer.reallocate(columns, rows);
   }
 
   @Override
   public void clear() {
     screenBuffer.clear();
   }
 
   @Override
   public void refresh() {
     screenBuffer.flush(output);
   }
 
   @Override
   public TerminalSize getSize() {
     return cachedTerminalSize;
   }
 
   @Nullable
   @Override
   public TerminalSize doResizeIfNecessary() {
     TerminalSize currentTerminalSize = queryTerminalSize();
     if (!currentTerminalSize.equals(cachedTerminalSize)) {
       cachedTerminalSize = currentTerminalSize;
       updateTerminalSize(cachedTerminalSize.getColumns(), cachedTerminalSize.getRows());
       return cachedTerminalSize;
     }
     return null;
   }
 
   @Nullable
   @Override
   public KeyPress pollKeyPress() {
     return keyPressQueue.poll();
   }
 
   @Override
   public CursorPosition getCursorPosition() {
     return screenBuffer.getCursorPosition();
   }
 
   @Override
   public void setCursorPosition(int column, int row) {
     screenBuffer.setCursorPosition(column, row);
   }
 
   @Override
   public void hideCursor() {
     screenBuffer.hideCursor();
   }
 
   @Override
   public TerminalPrinter getTerminalPrinter(int startRow) {
     return new TerminalPrinterImpl(screenBuffer, startRow);
   }
 
   @Override
   public void close() {
     keyPressGenerator.stop();
   }
 
   private TerminalSize queryTerminalSize() {
     String sizeString = doStty("size");
 
     int rows = 0;
     int columns = 0;
 
     StringTokenizer tokenizer = new StringTokenizer(sizeString);
     int rc = Integer.parseInt(tokenizer.nextToken());
     if (rc > 0) {
       rows = rc;
     }
 
     rc = Integer.parseInt(tokenizer.nextToken());
     if (rc > 0) {
       columns = rc;
     }
     return new TerminalSize(columns, rows);
   }
 
   private void sttyRaw() {
     doStty("-ignbrk -brkint -parmrk -istrip -inlcr -igncr -icrnl -ixon -opost " +
       "-echo -echonl -icanon -isig -iexten -parenb cs8 min 1");
   }
 
   private void sttyCooked() {
     doStty("sane cooked");
   }
 
   private String doStty(String sttyOptionsString) {
     String [] cmd = {"/bin/sh", "-c", "stty " + sttyOptionsString + " < /dev/tty"};
 
     try {
       Process process = Runtime.getRuntime().exec(cmd);
 
       String ret;
 
       // stdout
       try (BufferedReader stdout = new BufferedReader(new InputStreamReader(
         process.getInputStream(), StandardCharsets.UTF_8))) {
         ret = stdout.readLine();
       }
 
       // stderr
       try (BufferedReader stderr = new BufferedReader(new InputStreamReader(
         process.getErrorStream(), StandardCharsets.UTF_8))) {
         String line = stderr.readLine();
         if ((line != null) && (line.length() > 0)) {
           LOG.error("Error output from stty: " + line);
         }
       }
 
       try {
         process.waitFor();
       } catch (InterruptedException ignored) {
       }
 
       int exitValue = process.exitValue();
       if (exitValue != 0) {
         LOG.error("stty returned error code: " + exitValue);
       }
       return ret;
     } catch (IOException e) {
       throw new RuntimeException(e);
     }
   }
 }