/**
 * This adds a "toTitleCase" method to all String objects to convert all
 * words to Title Caps.  It attempts to be clever about *un*capitalizing
 * small words like a/an/the in the input.
 *
 * The list of "small words" which are not capped comes from
 * the New York Times Manual of Style, plus "vs" and "v".
 *
 * Original Perl version by:
 *   John Gruber
 *   http://daringfireball.net/
 *   10 May 2008
 *
 * Adapted to JavaScript by:
 *   Marshall Elfstrand
 *   http://vengefulcow.com/
 *   21 May 2008
 *
 * License: http://www.opensource.org/licenses/mit-license.php
 */

/**
 * Module for title case constants/methods.
 */
var TitleCase = {};


// --------------------------------------------------------------------------
// Lists of specially handled words
// --------------------------------------------------------------------------

/**
 * Words that should not be capitalized in the middle of a title.
 */
TitleCase.SMALL_WORDS = [
    "a", "an", "and", "as", "at", "but", "by", "en", "for", "if", "in",
    "of", "on", "or", "the", "to", "v[.]?", "via", "vs[.]?"
];

/**
 * Words that should always appear in uppercase.
 */
TitleCase.UPPERCASE_WORDS = [ "AT&T", "Q&A" ];


// --------------------------------------------------------------------------
// Pre-defined regular expressions
// --------------------------------------------------------------------------

/**
 * Small word list in regular expression format.
 */
TitleCase.SMALL_RE = TitleCase.SMALL_WORDS.join("|");

/**
 * Regular expression to use for splitting tokens in the input.
 */
TitleCase.SPLIT_PATTERN = /([:.;?!][ ]|(?:[ ]|^)["“])/;

/**
 * Regular expression to use for matching words to be capitalized.
 */
TitleCase.BASE_PATTERN = /\b([A-Za-z][a-z.'’]*)\b/g;

/**
 * Regular expression to use for matching words with inline dots.
 */
TitleCase.INLINE_DOT_PATTERN = /[A-Za-z][.][A-Za-z]/;

/**
 * Regular expression to use for matching small words.
 */
TitleCase.SMALL_WORD_PATTERN =
    new RegExp('\\b(' + TitleCase.SMALL_RE + ')\\b', 'ig');

/**
 * Regular expression to use for matching small words at the beginning
 * of the title.
 */
TitleCase.SMALL_WORD_FIRST_PATTERN =
    new RegExp('^(\\W*)(' + TitleCase.SMALL_RE + ')\\b', 'ig');

/**
 * Regular expression to use for matching small words at the end
 * of the title.
 */
TitleCase.SMALL_WORD_LAST_PATTERN =
    new RegExp('\\b(' + TitleCase.SMALL_RE + ')(\\W*)$', 'ig');
    
/**
 * Regular expression to use for matching "v." and "vs."
 */
TitleCase.VS_PATTERN = / V(s?)\. /g;

/**
 * Regular expression to use for matching apostrophe-S.
 */
TitleCase.POSSESSIVE_PATTERN = /(['’])S\b/g;

/**
 * Regular expression to use for matching uppercase words.
 */
TitleCase.UPPERCASE_PATTERN =
    new RegExp('\\b(' + TitleCase.UPPERCASE_WORDS.join("|") + ')\\b', 'ig');


// --------------------------------------------------------------------------
// Helper methods
// --------------------------------------------------------------------------

/**
 * Capitalizes the first letter in the given string.
 */
TitleCase.capitalize = function(w) {
    return w.substr(0, 1).toUpperCase() + w.substr(1).toLowerCase();
}

/**
 * Capitalizes the first letter in the given string, unless the
 * string contains a dot in the middle of it.  This is used as
 * a replacement function in the "toTitleCase" method.
 */
TitleCase.capitalizeUnlessInlineDot = function(w) {
    if (TitleCase.INLINE_DOT_PATTERN.test(w)) return w;
    else return TitleCase.capitalize(w);
}

/**
 * Capitalizes the given word, honoring any leading punctuation.
 * This is used as a replacement function in the "toTitleCase" method.
 */
TitleCase.capitalizeFirstWord = function(match, leadingPunctuation, smallWord) {
    return leadingPunctuation + TitleCase.capitalize(smallWord);
}

/**
 * Capitalizes the given word, honoring any trailing punctuation.
 * This is used as a replacement function in the "toTitleCase" method.
 */
TitleCase.capitalizeLastWord = function(match, smallWord, trailingPunctuation) {
    return TitleCase.capitalize(smallWord) + trailingPunctuation;
}

/**
 * Calls "toLowerCase" on the given string.
 * This is used as a replacement function in the "toTitleCase" method.
 */
TitleCase.toLowerCase = function(w) {
    return w.toLowerCase();
}

/**
 * Calls "toUpperCase" on the given string.
 * This is used as a replacement function in the "toTitleCase" method.
 */
TitleCase.toUpperCase = function(w) {
    return w.toUpperCase();
}


// --------------------------------------------------------------------------
// Main title case method
// --------------------------------------------------------------------------

/**
 * Converts the words in the input string to Title Caps.
 */
TitleCase.toTitleCase = function(input) {
    var result = "";

    var tokens = input.split(TitleCase.SPLIT_PATTERN);
    for (var i = 0; i < tokens.length; i++) {
        var s = tokens[i];

        // Capitalize all words except those with inline dots.
        s = s.replace(TitleCase.BASE_PATTERN,
                      TitleCase.capitalizeUnlessInlineDot);
        
        // Lowercase our list of small words.
        s = s.replace(TitleCase.SMALL_WORD_PATTERN,
                      TitleCase.toLowerCase);
        
        // If the first word in the title is a small word, capitalize it.
        s = s.replace(TitleCase.SMALL_WORD_FIRST_PATTERN,
                      TitleCase.capitalizeFirstWord);
                      
        // If the last word in the title is a small word, capitalize it.
        s = s.replace(TitleCase.SMALL_WORD_LAST_PATTERN,
                      TitleCase.capitalizeLastWord);
        
        result += s;
    }
    
    // Handle special cases.
    result = result.replace(TitleCase.VS_PATTERN, ' v$1. ');
    result = result.replace(TitleCase.POSSESSIVE_PATTERN, '$1s');
    result = result.replace(TitleCase.UPPERCASE_PATTERN,
                            TitleCase.toUpperCase);
                            
    return result;
}


// Add the title case method to all String objects.
String.prototype.toTitleCase = function() {
    return TitleCase.toTitleCase(this);
}