import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;

/**
 * @author gtowell 
 * Written: Jan 29, 2020
 * 
 *         A small class that counts the number of uses of each word in a file.
 *         This class illustrates the use of inner classes, ArrayList, readme,
 *         and StringBuffer
 */
public class WordCounter {
	/**
	 * Inner class to hold together the word and its count.
	 */
	private class WW {
		/** The word */
		public final String word;
		/** The number of times the word is used in the document */
		public int count;

		/**
		 * Constructor initializing both word and count
		 * 
		 * @param word  the word
		 * @param count the count. This is almost always zero
		 */
		public WW(String word, int count) {
			this.word = word;
			this.count = count;
		}

		/**
		 * Simple string representation of the inner class.
		 */
		public String toString() {
			return word + ":" + count;
		}
	}

	/** An arrayList holding all of the Word and Count objects */
	private ArrayList<WW> counts = new ArrayList<>();

	public static void main(String[] args) {
		WordCounter wc = new WordCounter();
		wc.countFile("ham.txt");
		System.out.println(wc);
	}

	/**
	 * Does most of the heavy lifting. Reads a file and fills in the counts
	 * arraylist appropriately
	 * 
	 * @param filename the name of the file to be read.
	 */
	void countFile(String filename) {
		try (BufferedReader br = new BufferedReader(new FileReader(filename));) {
			String line;
			while (null != (line = br.readLine())) { // read line and test if there is a line to read
				String[] ss = line.split("\\s+"); // split the line by spaces
				for (String token : ss) {
					// take the token i.e. word, lower case it, then get rid of punctuation
					token = token.toLowerCase().replace(".", "").replace(",", "").replace("?", "").replace("!", "");
					if (token.length() > 0) {
						WW wordS = findWord(token);
						if (wordS == null) { // if have not already seen the word, add it to the arraylist
							wordS = new WW(token, 0);
							counts.add(wordS);
						}
						wordS.count++; // increment the number of times the word has been seen
					}
				}
			}
		} catch (FileNotFoundException e) {
			System.err.println("Error in opening the file:" + filename);
			System.exit(1);
		} catch (IOException ioe) {
			System.err.println("Error reading file " + ioe);
			System.exit(1);
		}
	}

	/**
	 * Find a word in the list of seen words
	 * 
	 * @param w the word to be found
	 * @return the WW object containing the word. Or null if the word has not been
	 *         seen
	 */
	private WW findWord(String w) {
		for (WW aWord : counts) {
			if (aWord.word.equals(w))
				return aWord;
		}
		return null;
	}

	public String toString() {
		// StringBuffer is a modifiable string. If you are changing a string a lot, it
		// is much more efficient.
		StringBuffer sb = new StringBuffer();
		for (WW aWord : counts) {
			sb.append(aWord);
			sb.append("\n");
		}
		sb.append("Distinct words: " + counts.size());
		return sb.toString();
	}
}