۱۵ — قوانین تخفیف (Discount)

---

۱. انواع

type	value	example
percent	0–100	20% off
fixed	toman	10,000 off

---

۲. Scope

scope	vendor_id	who creates
platform	null	admin
vendor	required	admin or vendor (MVP: admin only)

---

۳. Validation rules (به ترتیب)

1. is_active == true
2. now between valid_from and valid_to
3. usage_count < usage_limit_total (if set)
4. user usage < usage_limit_per_user (if set)
5. order.subtotal >= min_order_amount (if set)
6. if vendor scope → order.vendor_id matches
7. compute discount:
   • percent: min(subtotal * rate, max_discount_amount)
   • fixed: min(value, subtotal)
8. total = subtotal - discount (min 0)

---

۴. Stacking

MVP: one code per order — no stack

---

۵. Application timing

When	allowed
Before payment	✅
After paid	❌

---

۶. Examples

Code	Type	Value	Min order	Result on 65K
WELCOME20	percent	20	50K	52,000
FIRST10K	fixed	10K	60K	55,000
VIP30	percent	30	—	45,500

---

۷. Admin UI fields

• code (uppercase auto)
• scope, vendor picker
• type, value
• min_order_amount, max_discount_amount
• usage_limit_total, usage_limit_per_user
• valid_from, valid_to
• is_active toggle

---

۸. Abuse prevention

• normalize code: trim, uppercase
• rate limit validate endpoint
• log failed attempts
• deactivate after N fraud flags (v2)

---

۹. Reporting

• usage_count per code
• total discount given (GMV impact)
• orders with discount vs without