Initial implementation of WooCommerce Composable Products plugin

Implemented custom WooCommerce product type allowing customers to build their own
product bundles by selecting from predefined sets of products.

Features:
- Custom "Composable Product" type with admin interface
- Product selection by category, tag, or SKU
- Configurable selection limits (global and per-product)
- Dual pricing modes: fixed price or sum of selected products
- Modern responsive frontend with Twig templates
- AJAX add-to-cart functionality
- Full internationalization support (.pot file)
- WooCommerce settings integration
- Comprehensive documentation

Technical implementation:
- PHP 8.3+ with PSR-4 autoloading
- Twig 3.0 templating engine via Composer
- Vanilla JavaScript with jQuery for frontend interactions
- WordPress and WooCommerce hooks for seamless integration
- Security: input sanitization, validation, and output escaping
- Translation-ready with text domain 'wc-composable-product'

Documentation:
- README.md: Project overview and features
- INSTALL.md: Installation and usage guide
- IMPLEMENTATION.md: Technical architecture
- CHANGELOG.md: Version history

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

assets/css/admin.css

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+/**
+ * Admin Styles for Composable Products
+ *
+ * @package WC_Composable_Product
+ */
+
+#composable_product_data {
+    padding: 12px;
+}
+
+.composable_criteria_group {
+    border-top: 1px solid #eee;
+    padding-top: 12px;
+    margin-top: 12px;
+}
+
+#_composable_categories,
+#_composable_tags {
+    min-height: 150px;
+}
+
+.show_if_composable {
+    display: none;
+}
+
+.product-type-composable .show_if_composable {
+    display: block;
+}
+
+.composable_options.composable_tab a::before {
+    content: '\f323';
+    font-family: 'Dashicons';
+}
+
+/* Enhanced select styling */
+.wc-composable-product-admin .select2-container {
+    min-width: 50%;
+}
+
+/* Help tips */
+.woocommerce-help-tip {
+    color: #666;
+}

assets/css/frontend.css

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+/**
+ * Frontend Styles for Composable Products
+ *
+ * @package WC_Composable_Product
+ */
+
+.wc-composable-product-selector {
+    margin: 2rem 0;
+    padding: 2rem;
+    background: #f9f9f9;
+    border-radius: 8px;
+}
+
+.composable-header {
+    margin-bottom: 2rem;
+    text-align: center;
+}
+
+.composable-header h3 {
+    margin: 0 0 0.5rem;
+    font-size: 1.5rem;
+    color: #333;
+}
+
+.selection-info {
+    margin: 0;
+    color: #666;
+    font-size: 0.95rem;
+}
+
+.composable-products-grid {
+    display: grid;
+    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
+    gap: 1.5rem;
+    margin-bottom: 2rem;
+}
+
+.composable-product-item {
+    position: relative;
+    background: #fff;
+    border: 2px solid #e0e0e0;
+    border-radius: 6px;
+    transition: all 0.3s ease;
+    cursor: pointer;
+}
+
+.composable-product-item:hover {
+    border-color: #999;
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+}
+
+.composable-product-item.selected {
+    border-color: #2c3e50;
+    background: #f0f8ff;
+}
+
+.product-item-label {
+    display: block;
+    padding: 1rem;
+    cursor: pointer;
+    margin: 0;
+}
+
+.composable-product-checkbox {
+    position: absolute;
+    opacity: 0;
+    cursor: pointer;
+}
+
+.product-item-image {
+    margin-bottom: 1rem;
+    text-align: center;
+}
+
+.product-item-image img {
+    max-width: 100%;
+    height: auto;
+    border-radius: 4px;
+}
+
+.product-item-details {
+    text-align: center;
+}
+
+.product-item-name {
+    margin: 0 0 0.5rem;
+    font-size: 1rem;
+    font-weight: 600;
+    color: #333;
+}
+
+.product-item-price {
+    color: #666;
+    font-size: 0.9rem;
+}
+
+.product-item-checkmark {
+    position: absolute;
+    top: 0.5rem;
+    right: 0.5rem;
+    width: 24px;
+    height: 24px;
+    background: #fff;
+    border: 2px solid #ddd;
+    border-radius: 50%;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+}
+
+.composable-product-item.selected .product-item-checkmark::after {
+    content: '✓';
+    color: #2c3e50;
+    font-weight: bold;
+    font-size: 16px;
+}
+
+.composable-total {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 1.5rem;
+    background: #fff;
+    border-radius: 6px;
+    margin-bottom: 1.5rem;
+    font-size: 1.2rem;
+}
+
+.total-label {
+    font-weight: 600;
+    color: #333;
+}
+
+.total-price {
+    font-weight: 700;
+    color: #2c3e50;
+    font-size: 1.5rem;
+}
+
+.composable-actions {
+    text-align: center;
+}
+
+.composable-add-to-cart {
+    padding: 1rem 2rem;
+    font-size: 1.1rem;
+    min-width: 200px;
+}
+
+.composable-add-to-cart.loading {
+    opacity: 0.6;
+    cursor: wait;
+}
+
+.composable-messages {
+    margin-top: 1rem;
+}
+
+.composable-message {
+    padding: 1rem;
+    border-radius: 4px;
+    margin-bottom: 0.5rem;
+}
+
+.composable-message-error {
+    background: #fee;
+    color: #c00;
+    border: 1px solid #fcc;
+}
+
+.composable-message-success {
+    background: #efe;
+    color: #060;
+    border: 1px solid #cfc;
+}
+
+/* Responsive design */
+@media (max-width: 768px) {
+    .composable-products-grid {
+        grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
+        gap: 1rem;
+    }
+
+    .wc-composable-product-selector {
+        padding: 1rem;
+    }
+
+    .composable-total {
+        font-size: 1rem;
+    }
+
+    .total-price {
+        font-size: 1.2rem;
+    }
+}
+
+@media (max-width: 480px) {
+    .composable-products-grid {
+        grid-template-columns: 1fr;
+    }
+}

assets/js/admin.js

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+/**
+ * Admin JavaScript for Composable Products
+ *
+ * @package WC_Composable_Product
+ */
+
+(function($) {
+    'use strict';
+
+    $(document).ready(function() {
+        /**
+         * Show/hide product data tab for composable products
+         */
+        $('select#product-type').on('change', function() {
+            const productType = $(this).val();
+
+            if (productType === 'composable') {
+                $('.show_if_composable').show();
+                $('.hide_if_composable').hide();
+                $('#composable_product_data').show();
+                $('.product_data_tabs .composable_options a').show();
+            } else {
+                $('.show_if_composable').hide();
+                $('#composable_product_data').hide();
+                $('.product_data_tabs .composable_options a').hide();
+            }
+        }).trigger('change');
+
+        /**
+         * Toggle criteria groups based on selected type
+         */
+        $('#_composable_criteria_type').on('change', function() {
+            const criteriaType = $(this).val();
+
+            $('.composable_criteria_group').hide();
+            $('#composable_criteria_' + criteriaType).show();
+        }).trigger('change');
+
+        /**
+         * Initialize enhanced select for categories and tags
+         */
+        if ($.fn.selectWoo) {
+            $('#_composable_categories, #_composable_tags').selectWoo({
+                placeholder: 'Select options...',
+                allowClear: true
+            });
+        }
+    });
+
+})(jQuery);

assets/js/frontend.js

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+/**
+ * Frontend JavaScript for Composable Products
+ *
+ * @package WC_Composable_Product
+ */
+
+(function($) {
+    'use strict';
+
+    const ComposableProduct = {
+        /**
+         * Initialize
+         */
+        init: function() {
+            this.bindEvents();
+        },
+
+        /**
+         * Bind events
+         */
+        bindEvents: function() {
+            const self = this;
+
+            // Handle checkbox changes
+            $(document).on('change', '.composable-product-checkbox', function() {
+                self.handleCheckboxChange($(this));
+            });
+
+            // Handle add to cart button
+            $(document).on('click', '.composable-add-to-cart', function(e) {
+                e.preventDefault();
+                self.addToCart($(this));
+            });
+        },
+
+        /**
+         * Handle checkbox change
+         *
+         * @param {jQuery} $checkbox Checkbox element
+         */
+        handleCheckboxChange: function($checkbox) {
+            const $container = $checkbox.closest('.wc-composable-product-selector');
+            const selectionLimit = parseInt($container.data('selection-limit'));
+            const pricingMode = $container.data('pricing-mode');
+            const $checked = $container.find('.composable-product-checkbox:checked');
+
+            // Enforce selection limit
+            if ($checked.length > selectionLimit) {
+                $checkbox.prop('checked', false);
+                this.showMessage($container, wcComposableProduct.i18n.max_items, 'error');
+                return;
+            }
+
+            // Update visual state
+            $checkbox.closest('.composable-product-item').toggleClass('selected', $checkbox.is(':checked'));
+
+            // Update total price if in sum mode
+            if (pricingMode === 'sum') {
+                this.updateTotalPrice($container);
+            }
+
+            // Clear messages
+            this.clearMessages($container);
+        },
+
+        /**
+         * Update total price
+         *
+         * @param {jQuery} $container Container element
+         */
+        updateTotalPrice: function($container) {
+            const $checked = $container.find('.composable-product-checkbox:checked');
+            let total = 0;
+
+            $checked.each(function() {
+                const price = parseFloat($(this).data('price'));
+                if (!isNaN(price)) {
+                    total += price;
+                }
+            });
+
+            const currencySymbol = $container.find('.total-price').data('currency');
+            $container.find('.calculated-total').text(currencySymbol + total.toFixed(2));
+        },
+
+        /**
+         * Add to cart
+         *
+         * @param {jQuery} $button Button element
+         */
+        addToCart: function($button) {
+            const $container = $button.closest('.wc-composable-product-selector');
+            const $checked = $container.find('.composable-product-checkbox:checked');
+            const productId = $button.data('product-id');
+
+            // Validate selection
+            if ($checked.length === 0) {
+                this.showMessage($container, wcComposableProduct.i18n.min_items, 'error');
+                return;
+            }
+
+            // Collect selected product IDs
+            const selectedProducts = [];
+            $checked.each(function() {
+                selectedProducts.push($(this).val());
+            });
+
+            // Disable button
+            $button.prop('disabled', true).addClass('loading');
+
+            // Add to cart via AJAX
+            $.ajax({
+                url: wc_add_to_cart_params.wc_ajax_url.toString().replace('%%endpoint%%', 'add_to_cart'),
+                type: 'POST',
+                data: {
+                    product_id: productId,
+                    quantity: 1,
+                    composable_products: selectedProducts
+                },
+                success: function(response) {
+                    if (response.error) {
+                        this.showMessage($container, response.error, 'error');
+                    } else {
+                        // Trigger WooCommerce event
+                        $(document.body).trigger('added_to_cart', [response.fragments, response.cart_hash, $button]);
+
+                        // Show success message
+                        this.showMessage($container, 'Product added to cart!', 'success');
+
+                        // Reset selection
+                        setTimeout(function() {
+                            $checked.prop('checked', false);
+                            $container.find('.composable-product-item').removeClass('selected');
+                            this.updateTotalPrice($container);
+                        }.bind(this), 1500);
+                    }
+                }.bind(this),
+                error: function() {
+                    this.showMessage($container, 'An error occurred. Please try again.', 'error');
+                }.bind(this),
+                complete: function() {
+                    $button.prop('disabled', false).removeClass('loading');
+                }
+            });
+        },
+
+        /**
+         * Show message
+         *
+         * @param {jQuery} $container Container element
+         * @param {string} message Message text
+         * @param {string} type Message type (error, success)
+         */
+        showMessage: function($container, message, type) {
+            const $messages = $container.find('.composable-messages');
+            const $message = $('<div>')
+                .addClass('composable-message')
+                .addClass('composable-message-' + type)
+                .text(message);
+
+            $messages.empty().append($message);
+
+            // Auto-hide after 5 seconds
+            setTimeout(function() {
+                $message.fadeOut(function() {
+                    $(this).remove();
+                });
+            }, 5000);
+        },
+
+        /**
+         * Clear messages
+         *
+         * @param {jQuery} $container Container element
+         */
+        clearMessages: function($container) {
+            $container.find('.composable-messages').empty();
+        }
+    };
+
+    // Initialize on document ready
+    $(document).ready(function() {
+        ComposableProduct.init();
+    });
+
+})(jQuery);