/*
 * 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.uima.ducc.agent.metrics.collectors;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

import org.apache.uima.ducc.common.agent.metrics.memory.NodeMemory;
import org.apache.uima.ducc.common.node.metrics.NodeMemoryInfo;
import org.apache.uima.ducc.common.utils.Utils;

public class NodeMemInfoCollector implements CallableMemoryCollector {
  private long fakeMemorySize = -1;

  private String[] targetFields;

  private int uidMax = 500; // default. Used to sum up memory of processes owned by uids < uidMax

  public NodeMemInfoCollector(String[] targetFields) {
    this.targetFields = targetFields;
    String tmp;

    if ((tmp = System.getProperty("ducc.agent.node.metrics.fake.memory.size")) != null) {
      try {
        fakeMemorySize = Long.parseLong(tmp);
      } catch (NumberFormatException e) {
        e.printStackTrace();
      }
    }

    uidMax = Utils.getMaxSystemUserId();
  }

  public NodeMemory call() throws Exception {

    BufferedReader fileReader = new BufferedReader(new FileReader("/proc/meminfo"));
    // the order of fields corresponds to the field label position
    long memInfoValues[] = new long[targetFields.length];
    try {
      String line;
      // Read each line from meminfo file
      while ((line = fileReader.readLine()) != null) {
        // parse line and remove spaces
        String[] parts = line.trim().split("\\s+");

        // ignore lines that contain fields we dont need. The
        // targetFields array
        // contains labels of fields we are interested in. For each line
        // read
        // from file try to find a match.
        for (int i = 0; i < targetFields.length; i++) {
          if (parts[0].equals(targetFields[i])) {
            // got a field we need
            try {
              memInfoValues[i] = Long.parseLong(parts[1]);
            } catch (NumberFormatException e) {
              throw e;
            }
            break; // get the next field
          }
        }
      }
    } catch (Exception e) {
      e.printStackTrace();
      throw e;
    } finally {
      fileReader.close();
    }
    long memUsed = 0;
    // if running ducc in simulation mode skip memory adjustment. Report free memory =
    // fakeMemorySize
    if (fakeMemorySize == -1) {
      // sum up memory of all processes owned by UIDs < gidMax
      memUsed = collectRSSFromPSCommand();
      // System.out.println("Total:"+memInfoValues[0] + " Available:"+memInfoValues[1] +"
      // Calculated:"+(memInfoValues[0] - memUsed)+" Priviledged Memory:"+memUsed);
    }

    memInfoValues[1] = memInfoValues[0] - memUsed;
    return new NodeMemoryInfo(memInfoValues, fakeMemorySize);
  }

  private long collectRSSFromPSCommand() throws Exception {
    InputStream stream = null;
    BufferedReader reader = null;

    ProcessBuilder pb;
    if (Utils.isMac()) {
      pb = new ProcessBuilder("ps", "-Ao", "user=,pid=,uid=,rss=");
    } else {
      pb = new ProcessBuilder("ps", "-Ao", "user:32,pid,uid,rss", "--no-heading");
    }
    pb.redirectErrorStream(true);
    Process proc = pb.start();
    // spawn ps command and scrape the output
    stream = proc.getInputStream();
    reader = new BufferedReader(new InputStreamReader(stream));
    String line;
    String regex = "\\s+";
    long memoryUsed = 0;
    // read the next line from ps output
    while ((line = reader.readLine()) != null) {
      String tokens[] = line.split(regex);
      if (tokens.length > 0) {
        try {
          int uid = Integer.valueOf(tokens[2]);
          if (uid < uidMax) {
            memoryUsed += Long.valueOf(tokens[3]);
          }
        } catch (NumberFormatException nfe) {

        }
      }
    }
    stream.close();
    return memoryUsed;
  }

  public static void main(String[] args) {
    String[] meminfoTargetFields = new String[] { "MemTotal:", "MemFree:", "SwapTotal:",
        "SwapFree:" };

    try {
      NodeMemInfoCollector nmi = new NodeMemInfoCollector(meminfoTargetFields);
      ExecutorService pool = Executors.newFixedThreadPool(1);
      while (true) {
        Future<NodeMemory> nmiFuture = pool.submit(nmi);
        NodeMemory memInfo = nmiFuture.get();
        System.out.println("... Meminfo Data -" + " Memory Total:" + memInfo.getMemTotal()
                + " Memory Free:" + memInfo.getMemFree() + " Swap Total:" + memInfo.getSwapTotal()
                + " Swap Free:" + memInfo.getSwapFree());
        synchronized (nmi) {
          nmi.wait(4000);
        }
      }

    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}