Hard162.java

import java.io.*;
import java.util.LinkedList;
import java.util.List;

public class Hard162 {
	
	public static void main(String[] args) {
		if(args.length < 3) err("<Error: too few arguments>");
		if(args.length > 3) err("<Error: too many arguments>");
		if(!args[0].equals("-d") && !args[0].equals("-c")) err("<Error: unknown operation>");
		File in = new File(args[1]).getAbsoluteFile();
		File out = new File(args[2]).getAbsoluteFile();
		
		out.getParentFile().mkdirs();
		try(FileReader rdr = new FileReader(in); FileWriter wr = new FileWriter(out)) {
			String input = read(rdr);
			String output = args[0].equals("-d") ? decompress(input) : compress(input);
			if(output.startsWith("<")) err(output);
			wr.write(output);
		} catch(IOException e) {
			err("<Error: IO error '" + e.getLocalizedMessage() + "'>");
		}
		
	}
	
	public static String compress(String s) { //Honestly, apostrophes should be allowed too. As should "What?!" and "AAAAAAAAaaaaaaaaaaaaa!!!"
		final int LOWER = 1, UPPER = 2;
		StringBuilder out = new StringBuilder();
		
		int wordType = 0;
		StringBuilder currentWord = new StringBuilder();
		List<String> dict = new LinkedList();
		
		for(int i = 0; i < s.length(); i++) {
			char ch = s.charAt(i);
			if(ch >= 'a' && ch <= 'z') {
				currentWord.append(ch);
				wordType |= LOWER;
			} else if(ch >= 'A' && ch <= 'Z') {
				currentWord.append(ch);
				wordType |= UPPER;
				if((wordType & LOWER) != 0) return "<Error: invalid capitalization>";
			} else if("- .,?!;:\n".indexOf(ch) != -1) {
				if(wordType != 0) {
					String word = currentWord.toString().toLowerCase();
					int index = dict.indexOf(word);
					if(index == -1) {
						index = dict.size();
						dict.add(word);
					}
					out.append(index);
				}
				if(wordType == UPPER) out.append('!');
				if(wordType == (UPPER | LOWER)) out.append('^');
				
				if(ch == ' ' || ch == '-' || ch == '\n') currentWord.setLength(0);
				else if(wordType == 0) return "<error: multiple punctuation in a row>";
				if(ch != '-') out.append(' ');
				if(ch == '\n') out.append("R");
				if(ch != ' ') out.append(ch);
				wordType = 0;
			} else return "<error: invalid character " + ch + ">";
		}
		out.append(" E");
		
		StringBuilder outDict = new StringBuilder();
		outDict.append(dict.size()).append("\n");
		for(String word:dict)
			outDict.append(word).append("\n");
		return outDict.toString() + out.toString().replaceAll("[ ]*\n[ ]*", "\n").trim();
	}
	
	public static String decompress(String s) {
		StringBuilder out = new StringBuilder();
		
		int dictLen = -1;
		List<String> dict = new LinkedList();
		StringBuilder currentWord = new StringBuilder();
		
		int currentNumber = -1;
		char nextChar = 0;
		
		for(int i = 0; i < s.length(); i++) {
			char ch = s.charAt(i);
			if(dict.size() != dictLen) { //Fill dict
				if('0' <= ch && ch <= '9') {
					if(currentNumber == -1) currentNumber = 0;
					currentNumber = currentNumber * 10 + ch - '0';
				} else if(ch == '\n') {
					if(currentNumber != -1) dictLen = currentNumber;
					else dict.add(currentWord.toString());
					currentWord.setLength(0);
					currentNumber = -1;
				} else currentWord.append(ch);
				continue;
			}
			//Decompress
			if('0' <= ch && ch <= '9') {
				if(currentNumber == -1) currentNumber = 0;
				currentNumber = currentNumber * 10 + ch - '0';
			} else if(currentNumber != -1) {
				if(nextChar != 0) out.append(nextChar);
				if(ch == '!') out.append(dict.get(currentNumber).toUpperCase());
				else if(ch == '^') out.append(toFirstUpper(dict.get(currentNumber)));
				else out.append(dict.get(currentNumber));
				currentNumber = -1;
				nextChar = ' ';
			} else if(ch == '-') nextChar = '-';
			else if(".,?!;:".indexOf(ch) != -1) out.append(ch);
			else if(ch == 'R') {
				nextChar = 0;
				out.append('\n');
			} else if(ch == 'E') break;
			else if(ch != ' ' && ch != '\n') return "<Error: unknown character>";
		}
		return out.toString();
	}
	
	// Misc helper functions
	
	private static String read(Reader rdr) throws IOException {
		StringBuilder sb = new StringBuilder();
		int ch;
		while((ch = rdr.read()) != -1)
			sb.append((char)ch);
		return sb.toString();
	}
	
	private static String toFirstUpper(String s) {
		return s.substring(0, 1).toUpperCase() + s.substring(1);
	}
	
	private static void err(String string) {
		System.err.println(string);
		System.exit(1);
	}
}