/**
 * Portable utilities for IRC.
 */

var IrcUtils = {
    /**
     * Completes a single nick.
     *
     * @param candidate What to search for
     * @param nickList Array of current nicks sorted alphabetically
     * @return Completed nick (null if not found)
     */
    _completeSingleNick: function(candidate, nickList) {
        var foundNick = null;

        nickList.some(function(nick) {
            if (nick.search(candidate) == 0) {
                // found!
                foundNick = nick;
                return true;
            }
            return false;
        });

        return foundNick;
    },

    /**
     * Get the next nick when iterating nicks.
     *
     * @param iterCandidate First characters to look at
     * @param currentNick Current selected nick
     * @param nickList Array of current nicks sorted alphabetically
     * @return Next nick (may be the same)
     */
    _nextNick: function(iterCandidate, currentNick, nickList) {
        var firstInGroup = null;
        var matchingNicks = [];
        var at = null;

        // collect matching nicks
        for (var i = 0; i < nickList.length; ++i) {
            if (nickList[i].search(iterCandidate) == 0) {
                matchingNicks.push(nickList[i]);
                if (currentNick == nickList[i]) {
                    at = matchingNicks.length - 1;
                }
            } else if (matchingNicks.length > 0) {
                // end of group, no need to check after this
                break;
            }
        }

        if (at == null || matchingNicks.length == 0) {
            return currentNick;
        } else {
            ++at;
            if (at == matchingNicks.length) {
                // cycle
                at = 0;
            }
            return matchingNicks[at];
        }
    },

    /**
     * Nicks tab completion.
     *
     * @param text Plain text (no colors)
     * @param caretPos Current caret position (0 means before the first character)
     * @param doIterate True to iterate the nicks if possible
     * @param iterCandidate Current iteration candidate (null if not iterating)
     * @param nickList Array of current nicks sorted alphabetically
     * @return Object with following properties:
     *      text: new complete replacement text
     *      caretPos: new caret position within new text
     *      foundNick: completed nick (or null if not possible)
     *      iterCandidate: current iterating candidate
     */
    completeNick: function(text, caretPos, doIterate, iterCandidate, nickList) {
        // text before and after caret
        var beforeCaret = text.substring(0, caretPos);
        var afterCaret = text.substring(caretPos);

        // default: don't change anything
        var ret = {
            text: text,
            caretPos: caretPos,
            foundNick: null,
            iterCandidate: null
        };

        // iterating nicks at the beginning?
        var m = beforeCaret.match(/^([a-zA-Z0-9_\\\[\]{}^`|-]+): $/);
        if (m) {
            if (doIterate) {
                // try iterating
                var newNick = IrcUtils._nextNick(iterCandidate, m[1], nickList);
                beforeCaret = newNick + ': ';
                return {
                    text: beforeCaret + afterCaret,
                    caretPos: beforeCaret.length,
                    foundNick: newNick,
                    iterCandidate: iterCandidate
                };
            } else {
                // if not iterating, don't do anything
                return ret;
            }
        }

        // nick completion in the beginning?
        m = beforeCaret.match(/^([a-zA-Z0-9_\\\[\]{}^`|-]+)$/);
        if (m) {
            // try completing
            var newNick = IrcUtils._completeSingleNick(m[1], nickList);
            if (newNick === null) {
                // no match
                return ret;
            }
            beforeCaret = newNick + ': ';
            if (afterCaret[0] == ' ') {
                // swallow first space after caret if any
                afterCaret = afterCaret.substring(1);
            }
            return {
                text: beforeCaret + afterCaret,
                caretPos: beforeCaret.length,
                foundNick: newNick,
                iterCandidate: m[1]
            };
        }

        // iterating nicks in the middle?
        m = beforeCaret.match(/^(.* )([a-zA-Z0-9_\\\[\]{}^`|-]+) $/);
        if (m) {
            if (doIterate) {
                // try iterating
                var newNick = IrcUtils._nextNick(iterCandidate, m[2], nickList);
                beforeCaret = m[1] + newNick + ' ';
                return {
                    text: beforeCaret + afterCaret,
                    caretPos: beforeCaret.length,
                    foundNick: newNick,
                    iterCandidate: iterCandidate
                };
            } else {
                // if not iterating, don't do anything
                return ret;
            }
        }

        // nick completion elsewhere in the middle?
        m = beforeCaret.match(/^(.* )([a-zA-Z0-9_\\\[\]{}^`|-]+)$/);
        if (m) {
            // try completing
            var newNick = IrcUtils._completeSingleNick(m[2], nickList);
            if (newNick === null) {
                // no match
                return ret;
            }
            beforeCaret = m[1] + newNick + ' ';
            return {
                text: beforeCaret + afterCaret,
                caretPos: beforeCaret.length,
                foundNick: newNick,
                iterCandidate: m[2]
            };
        }

        // completion not possible
        return ret;
    }
};