/**
 * replace all :emoji: codes with corresponding image
 * @param {string} inputString
 * @return {string}
**/
function formatEmojis(inputString) {
    return inputString.replace(/:([^ \t:]+):/g, function(returnFailed, emoji) {
        var emojiDom = makeEmojiDom(emoji);
        if (emojiDom) {
            var domParent = document.createElement("span");
            domParent.className = returnFailed === inputString ? R.klass.emoji.medium : R.klass.emoji.small;
            domParent.appendChild(emojiDom);
            return domParent.outerHTML;
        }
        return returnFailed;
    });
}

/**
 * @param {string} fullText
 * @return {string}
**/
function formatText(fullText) {
    if (!fullText || fullText == "")
        return "";
    var msgContents = fullText.split(/\r?\n/g);

    for (var msgContentIndex=0, nbMsgContents = msgContents.length; msgContentIndex < nbMsgContents; msgContentIndex++) {
        var msgContent = msgContents[msgContentIndex].trim()
            ,_msgContent = ""
            ,currentMods = {}
            ,quote = false
            ,i =0

        msgContent = msgContent.replace(new RegExp('<([@#]?)([^>]*)>', 'g'),
            function(matched, type, entity) {
                var sub = entity.split('|');

                if (type === '@') {
                    if (!sub[1]) {
                        var user = SLACK.context.users[sub[0]];
                        sub[1] = user ? ('@' +user.name) : locale.unknownMember;
                    } else if ('@' !== sub[1][0]) {
                        sub[1] = '@' +sub[1];
                    }
                    sub[0] = '#' +sub[0];
                    sub[2] = R.klass.msg.link +' ' +R.klass.msg.linkuser;
                } else if (type === '#') {
                    if (!sub[1]) {
                        var chan = SLACK.context.channels[sub[0]];
                        sub[1] = chan ? ('#' +chan.name) : locale.unknownChannel;
                    } else if ('#' !== sub[1][0]) {
                        sub[1] = '#' +sub[1];
                    }
                    sub[0] = '#' +sub[0];
                    sub[2] = R.klass.msg.link +' ' +R.klass.msg.linkchan;
                } else if (sub[0].indexOf("://") !== -1) {
                    if (!sub[1])
                        sub[1] = sub[0];
                    sub[2] = R.klass.msg.link;
                } else {
                    return matched;
                }
                return '<a href="' +sub[0] +'" class="' +sub[2] +'"' +(!type ? ' target="_blank"' : '') +'>' +sub[1] +'</a>';
            });
        msgContent = formatEmojis(msgContent);
        var msgLength = msgContent.length;
        var isAlphadec = function(c) {
            return ((c >= 'A' && c <= 'Z') ||
                (c >= 'a' && c <= 'z') ||
                (c >= '0' && c <= '9') ||
                "àèìòùÀÈÌÒÙáéíóúýÁÉÍÓÚÝâêîôûÂÊÎÔÛãñõÃÑÕäëïöüÿÄËÏÖÜŸçÇßØøÅåÆæœ".indexOf(c) !== -1);
        }
        ,checkEnd = function(str, pos, c) {
            while (str[pos]) {
                if (isAlphadec(str[pos]) && str[pos] != c && str[pos +1] == c) {
                    return true;
                }
                pos++;
            }
            return false;
        } ,appendMod = function(mods) {
            if (!Object.keys(currentMods).length)
                return "";
            return '<span class="' +Object.keys(mods).join(' ') +'">';
        };

        // Skip trailing
        while (i < msgLength && (msgContent[i] === ' ' || msgContent[i] === '\t'))
            i++;
        if (msgContent.substr(i, 4) === '&gt;') {
            quote = true;
            i += 4;
        }
        for (; i < msgLength; i++) {
            var c = msgContent[i];

            if (c === '<') {
                do {
                    _msgContent += msgContent[i++];
                } while (msgContent[i -1] !== '>' && msgContent[i]);
                i--;
                continue;
            }
            if (!(currentMods[R.klass.msg.style.bold]) && c === '*' && msgContent[i +1] && checkEnd(msgContent, i, c)) {
                if (Object.keys(currentMods).length)
                    _msgContent += '</span>';
                currentMods[R.klass.msg.style.bold] = true;
                _msgContent += appendMod(currentMods);
            } else if (!(currentMods[R.klass.msg.style.strike]) && c === '~' && msgContent[i +1] && checkEnd(msgContent, i, c)) {
                if (Object.keys(currentMods).length)
                    _msgContent += '</span>';
                currentMods[R.klass.msg.style.strike] = true;
                _msgContent += appendMod(currentMods);
            } else if (!(currentMods[R.klass.msg.style.code]) && c === '`' && msgContent[i +1] && checkEnd(msgContent, i, c)) {
                if (Object.keys(currentMods).length)
                    _msgContent += '</span>';
                currentMods[R.klass.msg.style.code] = true;
                _msgContent += appendMod(currentMods);
            } else if (!(currentMods[R.klass.msg.style.italic]) && c === '_' && msgContent[i +1] && checkEnd(msgContent, i, c)) {
                if (Object.keys(currentMods).length)
                    _msgContent += '</span>';
                currentMods[R.klass.msg.style.italic] = true;
                _msgContent += appendMod(currentMods);
            } else {
                var finalFound = false;
                _msgContent += c;

                do {
                    if ((currentMods[R.klass.msg.style.bold]) && c !== '*' && msgContent[i +1] === '*') {
                        delete currentMods[R.klass.msg.style.bold];
                        finalFound = true;
                    } else if ((currentMods[R.klass.msg.style.strike]) && c !== '~' && msgContent[i +1] === '~') {
                        delete currentMods[R.klass.msg.style.strike];
                        finalFound = true;
                    } else if ((currentMods[R.klass.msg.style.code]) && c !== '`' && msgContent[i +1] === '`') {
                        delete currentMods[R.klass.msg.style.code];
                        finalFound = true;
                    } else if ((currentMods[R.klass.msg.style.italic]) && c !== '_' && msgContent[i +1] === '_') {
                        delete currentMods[R.klass.msg.style.italic];
                        finalFound = true;
                    } else {
                        break;
                    }
                    c = msgContent[++i];
                } while (i < msgLength);
                if (finalFound)
                    _msgContent += '</span>' +appendMod(currentMods);
            }
        }
        if (!isObjectEmpty(currentMods)) {
            // Should not append
            console.warn("formatter warning");
            _msgContent += '</span>';
        }
        if (quote)
            msgContents[msgContentIndex] = '<span class="' +R.klass.msg.style.quote +'">' +_msgContent +'</span>';
        else
            msgContents[msgContentIndex] = _msgContent;
    }
    return msgContents.length === 0 ? "" : msgContents.join('<br/>');
}