/*\
title: $:/core/modules/filters/x-listops.js
type: application/javascript
module-type: filteroperator

Extended filter operators to manipulate the current list.

\*/
(function () {

    /*jslint node: true, browser: true */
    /*global $tw: false */
    "use strict";

    /*
    Fetch titles from the current list
    */
    var prepare_results = function (source) {
    var results = [];
        source(function (tiddler, title) {
            results.push(title);
        });
        return results;
    };

    /*
    Moves a number of items from the tail of the current list before the item named in the operand
    */
    exports.putbefore = function (source, operator) {
        var results = prepare_results(source),
            index = results.indexOf(operator.operand),
            count = $tw.utils.getInt(operator.suffix,1);
        return (index === -1) ?
            results.slice(0, -1) :
            results.slice(0, index).concat(results.slice(-count)).concat(results.slice(index, -count));
    };

    /*
    Moves a number of items from the tail of the current list after the item named in the operand
    */
    exports.putafter = function (source, operator) {
        var results = prepare_results(source),
            index = results.indexOf(operator.operand),
            count = $tw.utils.getInt(operator.suffix,1);
        return (index === -1) ?
            results.slice(0, -1) :
            results.slice(0, index + 1).concat(results.slice(-count)).concat(results.slice(index + 1, -count));
    };

    /*
    Replaces the item named in the operand with a number of items from the tail of the current list
    */
    exports.replace = function (source, operator) {
        var results = prepare_results(source),
            index = results.indexOf(operator.operand),
            count = $tw.utils.getInt(operator.suffix,1);
        return (index === -1) ?
            results.slice(0, -count) :
            results.slice(0, index).concat(results.slice(-count)).concat(results.slice(index + 1, -count));
    };

    /*
    Moves a number of items from the tail of the current list to the head of the list
    */
    exports.putfirst = function (source, operator) {
        var results = prepare_results(source),
            count = $tw.utils.getInt(operator.suffix,1);
        return results.slice(-count).concat(results.slice(0, -count));
    };

    /*
    Moves a number of items from the head of the current list to the tail of the list
    */
    exports.putlast = function (source, operator) {
        var results = prepare_results(source),
            count = $tw.utils.getInt(operator.suffix,1);
        return results.slice(count).concat(results.slice(0, count));
    };

    /*
    Moves the item named in the operand a number of places forward or backward in the list
    */
    exports.move = function (source, operator) {
        var results = prepare_results(source),
            index = results.indexOf(operator.operand),
            count = $tw.utils.getInt(operator.suffix,1),
            marker = results.splice(index, 1),
            offset =  (index + count) > 0 ? index + count : 0;
        return results.slice(0, offset).concat(marker).concat(results.slice(offset));
    };

    /*
    Returns the items from the current list that are after the item named in the operand
    */
    exports.allafter = function (source, operator) {
        var results = prepare_results(source),
            index = results.indexOf(operator.operand);
        return (index === -1 || index > (results.length - 2)) ? [] :
            (operator.suffix) ? results.slice(index) :
            results.slice(index + 1);
    };

    /*
    Returns the items from the current list that are before the item named in the operand
    */
    exports.allbefore = function (source, operator) {
        var results = prepare_results(source),
            index = results.indexOf(operator.operand);
        return (index < 0) ? [] :
            (operator.suffix) ? results.slice(0, index + 1) :
            results.slice(0, index);
    };

    /*
    Appends the items listed in the operand array to the tail of the current list
    */
    exports.append = function (source, operator) {
        var append = $tw.utils.parseStringArray(operator.operand, "true"),
            results = prepare_results(source),
            count = parseInt(operator.suffix) || append.length;
        return (append.length === 0) ? results :
            (operator.prefix) ? results.concat(append.slice(-count)) :
            results.concat(append.slice(0, count));
    };

    /*
    Prepends the items listed in the operand array to the head of the current list
    */
    exports.prepend = function (source, operator) {
        var prepend = $tw.utils.parseStringArray(operator.operand, "true"),
            results = prepare_results(source),
            count = $tw.utils.getInt(operator.suffix,prepend.length);
        return (prepend.length === 0) ? results :
            (operator.prefix) ? prepend.slice(-count).concat(results) :
            prepend.slice(0, count).concat(results);
    };

    /*
    Returns all items from the current list except the items listed in the operand array
    */
    exports.remove = function (source, operator) {
        var array = $tw.utils.parseStringArray(operator.operand, "true"),
            results = prepare_results(source),
            count = parseInt(operator.suffix) || array.length,
            p,
            len,
            index;
        len = array.length - 1;
        for (p = 0; p < count; ++p) {
            if (operator.prefix) {
                index = results.indexOf(array[len - p]);
            } else {
                index = results.indexOf(array[p]);
            }
            if (index !== -1) {
                results.splice(index, 1);
            }
        }
        return results;
    };

    /*
    Returns all items from the current list sorted in the order of the items in the operand array
    */
    exports.sortby = function (source, operator) {
        var results = prepare_results(source);
        if (!results || results.length < 2) {
            return results;
        }
        var lookup = $tw.utils.parseStringArray(operator.operand, "true");
        results.sort(function (a, b) {
            return lookup.indexOf(a) - lookup.indexOf(b);
        });
        return results;
    };

    /*
    Removes all duplicate items from the current list
    */
    exports.unique = function (source, operator) {
        var results = prepare_results(source);
        var set = results.reduce(function (a, b) {
            if (a.indexOf(b) < 0) {
                a.push(b);
            }
            return a;
        }, []);
        return set;
    };
})();