/**
 * БИТ.WMS Child Theme — js/ajax-filter.js
 *
 * Handles filter button clicks and "Load more" for the content feed section.
 * Communicates with the WordPress AJAX handler (bitwms_ajax_filter_handler).
 *
 * Global: bitwmsAjax  { url: string, nonce: string }
 */

( function () {
    'use strict';

    document.addEventListener( 'DOMContentLoaded', function () {
        var filterBar   = document.querySelector( '.filter-bar' );
        var contentGrid = document.getElementById( 'content-grid' );
        var loadMoreBtn = document.getElementById( 'load-more-btn' );

        if ( ! filterBar || ! contentGrid ) {
            return;
        }

        var currentFilter = 'all';
        var currentPage   = 1;
        var isLoading     = false;

        // ---------------------------------------------------------------
        // Filter button click
        // ---------------------------------------------------------------
        filterBar.addEventListener( 'click', function ( e ) {
            var btn = e.target.closest( '.filter-bar__btn' );
            if ( ! btn ) return;

            var filter = btn.getAttribute( 'data-filter' );
            if ( filter === currentFilter ) return;

            // Update active state.
            filterBar.querySelectorAll( '.filter-bar__btn' ).forEach( function ( b ) {
                b.classList.remove( 'filter-bar__btn--active' );
                b.setAttribute( 'aria-selected', 'false' );
            } );
            btn.classList.add( 'filter-bar__btn--active' );
            btn.setAttribute( 'aria-selected', 'true' );

            currentFilter = filter;
            currentPage   = 1;

            loadContent( false );
        } );

        // ---------------------------------------------------------------
        // Load more button click
        // ---------------------------------------------------------------
        if ( loadMoreBtn ) {
            loadMoreBtn.addEventListener( 'click', function () {
                if ( isLoading ) return;
                currentPage += 1;
                loadContent( true );
            } );
        }

        // ---------------------------------------------------------------
        // loadContent( append )
        //   append === false: replace grid content
        //   append === true:  append to existing grid content
        // ---------------------------------------------------------------
        function loadContent( append ) {
            if ( isLoading ) return;
            isLoading = true;

            if ( loadMoreBtn ) {
                loadMoreBtn.disabled = true;
                loadMoreBtn.textContent = loadMoreBtn.getAttribute( 'data-loading' ) || 'Загрузка…';
            }

            var formData = new FormData();
            formData.append( 'action',    'bitwms_filter' );
            formData.append( 'nonce',     bitwmsAjax.nonce );
            formData.append( 'post_type', currentFilter );
            formData.append( 'page',      currentPage );

            fetch( bitwmsAjax.url, {
                method: 'POST',
                body:   formData,
            } )
                .then( function ( response ) {
                    return response.json();
                } )
                .then( function ( data ) {
                    if ( ! data.success ) return;

                    var html    = data.data.html;
                    var hasMore = data.data.has_more;

                    if ( append ) {
                        contentGrid.insertAdjacentHTML( 'beforeend', html );
                    } else {
                        contentGrid.innerHTML = html || '<p>Материалы не найдены.</p>';
                    }

                    // Show/hide load-more button.
                    if ( loadMoreBtn ) {
                        if ( hasMore ) {
                            loadMoreBtn.style.display = '';
                            loadMoreBtn.disabled      = false;
                            loadMoreBtn.textContent   = 'Загрузить ещё';
                        } else {
                            loadMoreBtn.style.display = 'none';
                        }
                    }
                } )
                .catch( function ( err ) {
                    console.error( 'bitwms filter error:', err );
                    if ( loadMoreBtn ) {
                        loadMoreBtn.disabled    = false;
                        loadMoreBtn.textContent = 'Загрузить ещё';
                    }
                } )
                .finally( function () {
                    isLoading = false;
                } );
        }
    } );
} )();