package org.limewire.util;

import java.util.NoSuchElementException;

/**
 * Provides a string tokenizer that respects quotes. If a separator is followed
 * by a quote the next token will extend to the next quote even if there are
 * separators in between. Quote characters will not be returned.
 * <p>
 * Based on code from the XNap-Commons (http;//xnap-commons.sf.net)
 */
public class QuotedStringTokenizer {

    public static final char QUOTE_CHAR = '"';

    private final boolean returnSeparators;

    private final String text;

    private final int maxIndex;

    private String separators;

    private int index;

    /**
     * Constructs a <code>QuotedStringTokenizer</code>.
     * 
     * @see java.util.StringTokenizer
     */
    public QuotedStringTokenizer(String text, String separators, boolean returnSeparators) {
        this.text = text;
        this.maxIndex = text.length() - 1;
        this.separators = separators;
        this.returnSeparators = returnSeparators;
    }

    /**
     * Constructs a <code>QuotedStringTokenizer</code>.
     * 
     * @see java.util.StringTokenizer
     */
    public QuotedStringTokenizer(String text, String separators) {
        this(text, separators, false);
    }

    /**
     * Constructs a <code>QuotedStringTokenizer</code>.
     * 
     * @see java.util.StringTokenizer
     */
    public QuotedStringTokenizer(String text) {
        this(text, " ", false);
    }

    public int countTokens() {
        int count = 0;
        int i = index;
        Token token;
        while ((token = nextToken(i)) != null) {
            count++;
            i = token.nextIndex;
        }
        return count;
    }

    public boolean hasMoreTokens() {
        return nextToken(index) != null;
    }

    public String nextToken(String separators) {
        this.separators = separators;
        return nextToken();
    }

    public String nextToken() {
        Token token = nextToken(index);
        if (token != null) {
            index = token.nextIndex;
            return token.text;
        }
        throw new NoSuchElementException();
    }

    protected Token nextToken(int index) {
        if (index > maxIndex) {
            return null;
        }

        if (returnSeparators && separators.indexOf(text.charAt(index)) != -1) {
            return new Token(text.substring(index, index + 1), index + 1);
        }

        // lets get started
        int i = index;
        boolean inQuotes = false;
        StringBuilder token = new StringBuilder();

        // eat separators
        while (i <= maxIndex && separators.indexOf(text.charAt(i)) != -1) {
            i++;
        }

        if (i > maxIndex) {
            return null;
        }

        while (i <= maxIndex) {
            char c = text.charAt(i);
            if (separators.indexOf(c) != -1) {
                if (inQuotes) {
                    token.append(c);
                } else {
                    return new Token(token.toString(), i);
                }
            } else if (c == QUOTE_CHAR) {
                // TODO add support for escaping of quote characters
                inQuotes = !inQuotes;
            } else {
                token.append(c);
            }
            i++;
        }

        return new Token(token.toString(), i);
    }

    private static class Token {

        Token(String text, int nextIndex) {
            this.text = text;
            this.nextIndex = nextIndex;
        }

        String text;

        int nextIndex;
    }

}