(function (window) {
    'use strict';

    function isEmptyValue(value) {
        return value === null || value === undefined || value === '';
    }

    /**
     * Build a GET URL from a filter form, omitting empty / unselected fields.
     *
     * @param {HTMLFormElement|jQuery} formEl
     * @param {object} [opts]
     * @returns {string}
     */
    window.pmsBuildCleanGetQuery = function (formEl, opts) {
        opts = opts || {};
        var form = formEl && formEl.jquery ? formEl[0] : formEl;
        if (!form) {
            return window.location.pathname;
        }

        var action = form.getAttribute('action') || window.location.pathname;
        var pairs = [];
        var seen = {};

        function add(name, value) {
            if (!name || isEmptyValue(value)) {
                return;
            }
            if (name === 'project_id' && seen.project_id) {
                return;
            }
            if (name === 'visit_date_from' || name === 'visit_date_to') {
                var rangeEl = form.querySelector('[name="visit_date_range"]');
                if (rangeEl && isEmptyValue(rangeEl.value)) {
                    return;
                }
            }
            seen[name] = true;
            pairs.push(encodeURIComponent(name) + '=' + encodeURIComponent(String(value)));
        }

        if (typeof opts.beforeCollect === 'function') {
            opts.beforeCollect(form, add);
        }

        Array.prototype.forEach.call(form.elements, function (el) {
            if (!el.name || el.disabled) {
                return;
            }

            var tag = el.tagName;
            var type = (el.type || '').toLowerCase();

            if (type === 'checkbox') {
                if (el.checked) {
                    add(el.name, el.value || '1');
                } else if (typeof opts.onUncheckedCheckbox === 'function') {
                    opts.onUncheckedCheckbox(el.name, el, add);
                }
                return;
            }

            if (type === 'radio') {
                if (el.checked) {
                    add(el.name, el.value);
                }
                return;
            }

            if (tag === 'SELECT') {
                if (el.multiple) {
                    Array.prototype.forEach.call(el.selectedOptions, function (opt) {
                        add(el.name, opt.value);
                    });
                } else {
                    add(el.name, el.value);
                }
                return;
            }

            if (type === 'button' || type === 'submit' || type === 'reset' || type === 'file') {
                return;
            }

            add(el.name, el.value);
        });

        return action + (pairs.length ? '?' + pairs.join('&') : '');
    };

    window.pmsBindCleanFilterFormSubmit = function (selector, opts) {
        $(document).on('submit', selector, function (e) {
            e.preventDefault();
            window.location.href = window.pmsBuildCleanGetQuery(this, opts || {});
        });
    };
}(window));