How to Create a FREE WooCommerce Discount Rules Plugin Using Claude AI

Detailed Prompt to create WooCommerce Discount Rules Plugin Using Claude AI

Create a WooCommerce Discount Rules Plugin for WordPress.
The plugin should be production-ready, fully functional, and installable
as a ZIP file. Follow every instruction below exactly.

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PLUGIN DETAILS
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Plugin Name: WC Discount Rules
Version: 1.5.0
Author: Quick Tips
Author URI: https://www.youtube.com/@ParamFreelance
Description: Create powerful, flexible discount rules for WooCommerce.
Text Domain: wc-discount-rules
WC tested up to: 9.0

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FILE STRUCTURE
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Create the following files inside a folder called wc-discount-rules/
and package them into a downloadable ZIP:

wc-discount-rules/
├── wc-discount-rules.php ← Main plugin file
├── includes/
│ ├── class-wcdr-db.php ← Database CRUD
│ ├── class-wcdr-engine.php ← Discount calculation engine
│ └── class-wcdr-admin.php ← Full admin UI
├── admin/
│ ├── css/admin.css ← Admin + frontend styles
│ └── js/admin.js ← Dynamic form behaviour

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MAIN PLUGIN FILE — wc-discount-rules.php
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– Define constants: WCDR_VERSION, WCDR_PLUGIN_DIR, WCDR_PLUGIN_URL, WCDR_TABLE (‘wcdr_rules’)
– On plugins_loaded: check WooCommerce is active, then require and init all three classes
– On register_activation_hook: call WCDR_DB::create_table()
– Declare WooCommerce feature compatibility using before_woocommerce_init hook:
– custom_order_tables (HPOS) → true
– cart_checkout_blocks → true
– On wp_enqueue_scripts: enqueue admin/css/admin.css on is_cart() and is_checkout()
pages so the frontend discount line is styled correctly

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DATABASE — class-wcdr-db.php
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Create a custom table {prefix}wcdr_rules using dbDelta() with these columns:

id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY
rule_name VARCHAR(200)
status TINYINT(1) DEFAULT 1
priority INT DEFAULT 10
discount_type VARCHAR(30) → ‘percentage’, ‘fixed_amount’, ‘fixed_price’, ‘bogo’
discount_value DECIMAL(10,4)
apply_to VARCHAR(30) → ‘all’, ‘products’, ‘categories’
apply_ids LONGTEXT → serialized array of IDs
min_qty INT NULL
max_qty INT NULL
min_cart DECIMAL(10,4) NULL
max_cart DECIMAL(10,4) NULL
user_roles LONGTEXT → serialized (unused but kept for future use)
date_from DATE NULL
date_to DATE NULL
exclusive TINYINT(1) DEFAULT 0
bogo_buy_qty INT NULL
bogo_get_qty INT NULL
bogo_get_discount DECIMAL(10,4) DEFAULT 100
created_at DATETIME DEFAULT CURRENT_TIMESTAMP

Provide these static methods:
– init() → run create_table() if db version option doesn’t match WCDR_VERSION
– create_table() → dbDelta SQL, update wcdr_db_version option
– get_all_rules() → ORDER BY priority ASC, id ASC
– get_active_rules()→ WHERE status = 1 ORDER BY priority ASC, id ASC
– get_rule($id) → single row by id
– save_rule($data) → INSERT or UPDATE based on presence of id field
– delete_rule($id)
– toggle_status($id, $status)

In save_rule(): treat empty string as NULL for min_qty, max_qty, min_cart,
max_cart, bogo_buy_qty, bogo_get_qty fields.

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DISCOUNT ENGINE — class-wcdr-engine.php
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Hook: woocommerce_cart_calculate_fees (priority 20)
Hook: woocommerce_cart_totals_fee_html → wrap negative fees in
<span class=”wcdr-discount-line”> for green styling

CRITICAL RULES — follow these exactly or the discount will not work:

1. NEVER call $product->set_price() or mutate product prices in any way.
Always apply discounts as a NEGATIVE FEE using $cart->add_fee().
This is the only stable WooCommerce approach — set_price() compounds
on every recalculation and breaks the cart total.

2. NEVER use wc_price() in a fee label. wc_price() outputs HTML.
WooCommerce strips HTML from fee names (used as internal keys),
which corrupts the label and causes the fee to be silently dropped.
Use plain text only:
$symbol = html_entity_decode(get_woocommerce_currency_symbol(), ENT_QUOTES, ‘UTF-8’);
$label = $rule->rule_name . ‘ (‘ . $symbol . number_format($amount, 2) . ‘ off)’;

3. Use get_subtotal() for the cart total check — this hook fires AFTER
WooCommerce has calculated item totals so get_subtotal() is accurate here.
Do NOT manually sum prices×qty as a workaround.

4. In the rule-matching loop, perform ALL condition checks before adding
a rule to $applied_rules:
a) Date range (date_from / date_to)
b) Cart subtotal min/max (min_cart / max_cart)
c) Quantity condition — loop cart items, at least one must satisfy min_qty/max_qty
d) Scope check — if apply_to !== ‘all’, loop cart items and confirm at least
one matches product_matches_scope(). Do this for ALL discount types,
not just bogo/fixed_price.

5. Fee label must be plain text. Build $label_parts[] for each matched rule
and implode with ‘ + ‘ at the end. Cap total_discount at cart subtotal.

DISCOUNT TYPE CALCULATIONS:
– percentage: scoped_subtotal × (discount_value / 100)
scoped_subtotal = sum of (price × qty) for items matching scope only
– fixed_amount: discount_value as a flat amount (e.g. $20 off entire cart)
– fixed_price: per matching item: (unit_price – fixed_price) × qty, summed
– bogo: for each matching item: sets = floor(qty / (buy+get)),
free_qty = sets × get_qty,
discount = free_qty × unit_price × (bogo_get_discount / 100)

SCOPE CHECK — product_matches_scope($product, $rule):
– apply_to = ‘all’ → always true
– apply_to = ‘products’ → product id or parent id in apply_ids array
– apply_to = ‘categories’ → intersection of product’s category IDs and apply_ids

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ADMIN UI — class-wcdr-admin.php
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Register submenu under WooCommerce → Discount Rules (manage_woocommerce cap).

Enqueue on this page only:
– WooCommerce’s own select2 JS and CSS (from WC()->plugin_url())
– admin/css/admin.css
– admin/js/admin.js (depends on jquery, select2)
– wp_localize_script with wcdr object: { ajax_url, nonce: wp_create_nonce(‘wcdr_nonce’) }

Admin POST handlers (check_admin_referer + manage_woocommerce cap):
– wcdr_save_rule → WCDR_DB::save_rule(), redirect with ?saved=1
– wcdr_delete_rule → WCDR_DB::delete_rule(), redirect with ?deleted=1
– wcdr_toggle_rule → WCDR_DB::toggle_status(), redirect back

WP AJAX handlers (wp_ajax_ only, nonce: wcdr_nonce, cap: manage_woocommerce):
– wcdr_search_products → wc_get_products([‘s’=>$term, ‘limit’=>30])
return JSON array of {id, text}
text format: “Product Name (#ID)”
– wcdr_search_categories → get_terms([‘taxonomy’=>’product_cat’,’search’=>$term])
return JSON array of {id, text}

PAGE ROUTER:
– action=list (default) → render rules table
– action=new → render add form
– action=edit&id=X → load rule, render edit form

RULES LIST TABLE columns:
#, Rule Name (+ Exclusive badge if exclusive=1), Type, Discount,
Applies To, Min Cart, Date Range, Priority, Status (toggle button),
Actions (Edit + Delete)

Status toggle: inline form with wcdr_toggle_rule, shows ✅ Active / ⛔ Inactive

ADD/EDIT FORM sections:
1. Basic Settings: rule_name (required), status radio, priority number, exclusive checkbox
2. Discount Settings: discount_type select, discount_value input (hidden when bogo),
bogo row (buy/get/discount inputs, hidden when not bogo)
3. Applies To: apply_to select (all/products/categories),
Select Items row (hidden when all) with #apply_ids select[multiple]
4. Conditions: min_cart/max_cart inputs, min_qty/max_qty inputs
5. Schedule: date_from / date_to date inputs
6. Submit row: “💾 Save Rule” / “💾 Update Rule” button + Cancel link

SELECT ITEMS FIELD — this is critical, do it exactly as follows:
– Render <select id=”apply_ids” name=”apply_ids[]” multiple> with NO static options
– Select2 is initialised in JS with AJAX pointing to wcdr_search_products
or wcdr_search_categories depending on current scope
– minimumInputLength: 0 so results appear on first click without typing
– On edit: pre-load saved selections by injecting Option elements via JS
using a data-preloaded=”[{id,text},…]” attribute on the select element
(build this JSON server-side by fetching product names / category names
for the saved apply_ids)
– When apply_to changes: destroy existing Select2, clear options, reinitialise
with the correct AJAX action for the new scope

FORM DEFAULTS for new rule: status=1, priority=10, discount_type=percentage,
apply_to=all, exclusive=0, bogo_get_discount=100

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JAVASCRIPT — admin/js/admin.js
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On DOM ready (jQuery):

1. DISCOUNT TYPE TOGGLE:
– Watch #discount_type change
– If value = ‘bogo’: hide #row_discount_value, show #row_bogo
– Otherwise: show #row_discount_value, hide #row_bogo
– Run on page load to set initial state

2. SCOPE TOGGLE + SELECT2 INIT:
Function handleScopeChange(scope, animate):
– If scope = ‘all’: hide #row_apply_ids (slideUp if animate, hide if not)
– Otherwise: show #row_apply_ids (slideDown if animate, show if not)
– Call initSelect2(scope)

Function initSelect2(scope):
– If #apply_ids already has Select2: destroy it and empty() the select
– If scope = ‘all’: return early
– Determine AJAX action: scope=’products’ → ‘wcdr_search_products’,
scope=’categories’ → ‘wcdr_search_categories’
– Init Select2 with:
ajax.url: wcdr.ajax_url
ajax.data: { action, nonce: wcdr.nonce, q: params.term || ” }
ajax.processResults: return { results: data }
minimumInputLength: 0
placeholder: ‘Type to search products…’ or ‘Type to search categories…’
allowClear: true, width: ‘100%’
– After init, read data-preloaded attribute, loop items,
append Option(text, id, true, true) for each, trigger(‘change’)

On page load: call handleScopeChange($(‘#apply_to’).val(), false)
On #apply_to change: call handleScopeChange($(this).val(), true)

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CSS — admin/css/admin.css
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Frontend (cart/checkout):
.wcdr-discount-line { color: #2e7d32; font-weight: 600; }

Admin general:
– .wcdr-wrap h1 .dashicons: color #7f54b3, font-size 26px
– .wcdr-version: small grey version label
– .wcdr-table: vertically centered cells
– .wcdr-badge.exclusive: orange background, white text
– .wcdr-toggle.active: green tinted button
– .wcdr-toggle.inactive: red tinted button
– .wcdr-empty: centered, padded empty state cell

Form:
– .wcdr-section: white card, 1px border, border-radius 6px, box-shadow
– .wcdr-section h3: bottom border separator
– .wcdr-optional: small grey helper text
– .wcdr-submit-row with .button-hero: large prominent save button
– .required: red asterisk color

Select2:
– Selected tags: background #7f54b3 (WooCommerce purple), white text
– Highlighted option: background #7f54b3
– Border-color matching WP admin inputs

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KNOWN BUGS TO AVOID — these were discovered and fixed during development.
Do NOT reproduce these mistakes:
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BUG 1 — Discount not applying (cart total always 0)
WRONG: hook into woocommerce_before_calculate_totals and call get_subtotal()
RIGHT: hook into woocommerce_cart_calculate_fees — get_subtotal() is
accurate at this point because WC has already summed item totals.

BUG 2 — Discount compounds on every page reload
WRONG: $product->set_price($new_price) inside any cart hook
RIGHT: $cart->add_fee($label, -$amount, false) — negative fee is
idempotent and never mutates stored product data.

BUG 3 — Fixed amount fee is silently dropped
WRONG: $label = $rule->rule_name . ‘ (‘ . wc_price($amount) . ‘ off)’;
RIGHT: $symbol = html_entity_decode(get_woocommerce_currency_symbol());
$label = $rule->rule_name . ‘ (‘ . $symbol . number_format($amount,2) . ‘ off)’;

BUG 4 — Scope check missing for fixed_amount rules
WRONG: only call product_matches_scope() inside per-type calculation helpers
RIGHT: check scope in the main rule-matching loop for ALL discount types
before adding any rule to $applied_rules

BUG 5 — Select Items field blank when changing scope
WRONG: render <option> elements server-side and show/hide the row via JS
RIGHT: use Select2 with AJAX (wp_ajax_ handlers) — reinitialise Select2
with the correct AJAX action each time scope changes

BUG 6 — Critical error from wp_roles()
WRONG: call wp_roles() directly in the admin form render method
RIGHT: remove user roles field entirely OR call it only inside an
admin_init or later hook where WordPress has fully initialised

BUG 7 — WooCommerce compatibility warning on activation
WRONG: no compatibility declaration
RIGHT: use before_woocommerce_init hook to call
FeaturesUtil::declare_compatibility() for both
‘custom_order_tables’ and ‘cart_checkout_blocks’

BUG 8 — Edit form has no visible Save button
WRONG: submit button inside a nested container with overflow or display issues
RIGHT: place the submit button in its own .wcdr-submit-row div outside
all .wcdr-section cards, directly before closing </form>

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FINAL OUTPUT
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– Create all files listed above with complete, working code
– Package everything into a ZIP file named wc-discount-rules.zip
– The ZIP should extract to a single folder: wc-discount-rules/
– The plugin must be installable directly via WordPress Admin →
Plugins → Add New → Upload Plugin with no additional setup required
– After activation, WooCommerce → Discount Rules menu must appear
with a working rules list, add form, edit form, and toggle controls