commons/src/main/java/net/locusworks/common/utils/FileReader.java

package net.locusworks.common.utils;

import static net.locusworks.common.Charsets.UTF_8;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Iterator;
import java.util.NoSuchElementException;

import net.locusworks.common.interfaces.AutoCloseableIterator;

/**
 * Class to read in a file that can be used in the try-with-resource block
 * @author Isaac Parenteau
 * @version 1.0.0
 * @date 02/15/2018
 */
public class FileReader implements AutoCloseableIterator<FileReader.LineInfo>, Iterable<FileReader.LineInfo> {

  private BufferedReader reader;
  private LineInfo info;
  private Integer lineNumber;
  
  /**
   * Constructor
   * @param fileName Name of the file to read
   */
  public FileReader(String fileName) {
    init(fileName);
  }
  
  /**
   * Constructor
   * @param file File to read
   */
  public FileReader(File file) {
    init(file);
  }

  /**
   * Constructor
   * @param reader Buffered reader to read data from
   */
  public FileReader(BufferedReader reader) {
    init(reader);
  }
  
  /**
   * Initialization helper
   * @param fileName Name of the file to load
   * This will look into the resources directory if it cannot
   * find the file directly.
   */
  private void init(String fileName) {
    //check to see if the file exists
    File f = new File(fileName);
    if (f.exists()) {
      init(f); //If it does. load through the file initializer
      return;
    }
    
    //Check to see if the file is in the resources directory
    InputStream is = this.getClass().getResourceAsStream(fileName);
    if (is == null) {
      is = this.getClass().getClassLoader().getResourceAsStream(fileName);
    }
    //If it cant be found, throw a runtime exception
    if (is == null) {
      throw new IllegalArgumentException("Unable to find resource with name of" + fileName);
    }
    
    //Call the buffered reader initializer once the file is found
    init(new BufferedReader(new InputStreamReader(is, UTF_8)));
  }

  /**
   * Initializer helper to load file
   * @param file File to load
   */
  private void init(File file) {
    if (file == null) throw new IllegalArgumentException("File cannot be null");
    if (!file.exists()) throw new IllegalArgumentException("File " + file + " does not exist");
    if (!file.isFile()) throw new IllegalArgumentException("File " + file + " is not a file");
    try {
      init(new BufferedReader(new InputStreamReader(new FileInputStream(file), UTF_8)));
    } catch (Exception ex) {
      throw new RuntimeException(ex);
    }
  }
  
  /**
   * Initializer helper for buffered reader
   * This is ultimately where all initializers end as a buffered reader
   * @param reader buffered reader to load
   */
  private void init(BufferedReader reader) {
    this.reader = reader;
    this.lineNumber = 0;
  }

  @Override
  public boolean hasNext() {
    try {
      String line = this.reader.readLine();
      if (line == null) {
        this.close();
        this.info = null;
        return false;
      }
      this.lineNumber++;
      this.info = new LineInfo(this.lineNumber, line);
      return true;
    } catch (Exception ex) {
      throw new RuntimeException(ex);
    }
  }

  @Override
  public LineInfo next() {
    if (this.info == null) {
      throw new NoSuchElementException("Call to next was initiated but there are no more elements to read");
    }
    return this.info;
  }

  @Override
  public Iterator<LineInfo> iterator() {
    return this;
  }

  @Override
  public void close() {
    if (this.reader != null) {
      try {
        this.reader.close();
      } catch (Exception ex) {
        throw new RuntimeException(ex);
      }
    }
  }

  public static class LineInfo {
    private Integer lineNumber;
    private Integer lineLength;
    private String line;

    /**
     * @param lineNumber the current line number in the file
     * @param line the line information from the file
     */
    public LineInfo(Integer lineNumber, String line) {
      this.lineNumber = lineNumber;
      this.line = line;
      this.lineLength = line.length();
    }

    /**
     * @return the lineNumber
     */
    public Integer getLineNumber() {
      return lineNumber;
    }

    /**
     * @param lineNumber the lineNumber to set
     */
    public void setLineNumber(Integer lineNumber) {
      this.lineNumber = lineNumber;
    }

    /**
     * @return the lineLength
     */
    public Integer getLineLength() {
      return lineLength;
    }

    /**
     * @param lineLength the lineLength to set
     */
    public void setLineLength(Integer lineLength) {
      this.lineLength = lineLength;
    }

    /**
     * @return the line
     */
    public String getLine() {
      return line;
    }

    /**
     * @param line the line to set
     */
    public void setLine(String line) {
      this.line = line;
    }
  }
}