/*
 * 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 opennlp.model;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.StringTokenizer;
import java.util.zip.GZIPInputStream;


public abstract class AbstractModelReader {

  /**
   * The number of predicates contained in the model.
   */
  protected int NUM_PREDS;
  protected DataReader dataReader;
  
  public AbstractModelReader(File f) throws IOException { 
    String filename = f.getName();
    InputStream input;
    // handle the zipped/not zipped distinction
    if (filename.endsWith(".gz")) {
      input = new GZIPInputStream(new FileInputStream(f));
      filename = filename.substring(0,filename.length()-3);
    }
    else {
      input = new FileInputStream(f);
    }

    // handle the different formats
    if (filename.endsWith(".bin")) {
      this.dataReader = new BinaryFileDataReader(input);
    }
    else {  // filename ends with ".txt"
      this.dataReader = new PlainTextFileDataReader(input);
    }
  }

  public AbstractModelReader(DataReader dataReader) {
    super();
    this.dataReader = dataReader;
  }
  
  /**
   * Implement as needed for the format the model is stored in.
   */
  public int readInt() throws java.io.IOException {
    return dataReader.readInt();
  }

  /**
   * Implement as needed for the format the model is stored in.
   */
  public double readDouble() throws java.io.IOException {
    return dataReader.readDouble();
  }

  /**
   * Implement as needed for the format the model is stored in.
   */
  public String readUTF() throws java.io.IOException {
    return dataReader.readUTF();
  }
      
  public AbstractModel getModel() throws IOException {
    checkModelType();
    return constructModel();
  }

  public abstract void checkModelType() throws java.io.IOException;
  
  public abstract AbstractModel constructModel() throws java.io.IOException;

  protected String[] getOutcomes() throws java.io.IOException {
      int numOutcomes = readInt();
      String[] outcomeLabels = new String[numOutcomes];
      for (int i=0; i<numOutcomes; i++) outcomeLabels[i] = readUTF();
      return outcomeLabels;
  }

  protected int[][] getOutcomePatterns() throws java.io.IOException {
      int numOCTypes = readInt();
      int[][] outcomePatterns = new int[numOCTypes][];
      for (int i=0; i<numOCTypes; i++) {
          StringTokenizer tok = new StringTokenizer(readUTF(), " ");
          int[] infoInts = new int[tok.countTokens()];
          for (int j = 0; tok.hasMoreTokens(); j++) {
              infoInts[j] = Integer.parseInt(tok.nextToken());
          }
          outcomePatterns[i] = infoInts;
      }
      return outcomePatterns;
  }

  protected String[] getPredicates() throws java.io.IOException {
      NUM_PREDS = readInt();
      String[] predLabels = new String[NUM_PREDS];
      for (int i=0; i<NUM_PREDS; i++)
          predLabels[i] = readUTF();
      return predLabels;
  }

  /**
   * Reads the parameters from a file and populates an array of context objects.
   * @param outcomePatterns The outcomes patterns for the model.  The first index refers to which 
   * outcome pattern (a set of outcomes that occurs with a context) is being specified.  The
   * second index specifies the number of contexts which use this pattern at index 0, and the
   * index of each outcomes which make up this pattern in indicies 1-n.  
   * @return An array of context objects.
   * @throws java.io.IOException when the model file does not match the outcome patterns or can not be read.
   */
  protected Context[] getParameters(int[][] outcomePatterns) throws java.io.IOException {
    Context[] params = new Context[NUM_PREDS];
    int pid=0;
    for (int i=0; i<outcomePatterns.length; i++) {
      //construct outcome pattern
      int[] outcomePattern = new int[outcomePatterns[i].length-1];
      for (int k=1; k<outcomePatterns[i].length; k++) {
        outcomePattern[k-1] = outcomePatterns[i][k];
      }
      //System.err.println("outcomePattern "+i+" of "+outcomePatterns.length+" with "+outcomePatterns[i].length+" outcomes ");
      //populate parameters for each context which uses this outcome pattern. 
      for (int j=0; j<outcomePatterns[i][0]; j++) {
        double[] contextParameters = new double[outcomePatterns[i].length-1];
        for (int k=1; k<outcomePatterns[i].length; k++) {
          contextParameters[k-1] = readDouble();
        }
        params[pid] = new Context(outcomePattern,contextParameters);
        pid++;
      }
    }
    return params;
  }

}
