feat: Implement free issue tracking and scheme discount handling in invoices and Shop POs

Distribution/docs/17_promotions_schemes.md

@@ -76,7 +76,7 @@ order must contain every component in at least its listed `Qty` before the schem
 SchemeRedemption
 ├── Id (Guid)                  — PK
 ├── FK_SchemeId (Guid)         — required
-├── FK_OrderId (Guid?)         — nullable (see FieldInvoiceId below)
+├── FK_ShopPOId (Guid?)        — nullable (see FieldInvoiceId below); the Shop PO the scheme was applied to
 ├── FieldInvoiceId (Guid?)     — placeholder for the future field-invoice module; no FieldInvoice
 │                                 entity exists yet, so this is an unconstrained Guid for now
 ├── DiscountAmount (decimal?)  — set for SlabDiscount/FlatPercent redemptions
@@ -87,8 +87,8 @@ SchemeRedemption
 │                                   later changes
 ├── RedeemedAt (DateTime)
 ```
-At least one of `DiscountAmount` or `FreeQty` is set per redemption; `Scheme`/`Order` restrict-delete
+At least one of `DiscountAmount` or `FreeQty` is set per redemption; `Scheme`/`ShopPO` restrict-delete
-(a scheme or order with redemptions can't be hard-deleted, and soft-delete leaves history intact).
+(a scheme or Shop PO with redemptions can't be hard-deleted, and soft-delete leaves history intact).
 
 ### Item (extended)
 ```
@@ -124,8 +124,10 @@ columns/child table after the first migration had already been applied to the de
 | — | `DELETE /api/schemes/{id}/free-goods-rule` | Clears it |
 | — | `PUT /api/schemes/{id}/bundle-components/{itemId}` | Upserts one FreeBundle required-item row |
 | — | `DELETE /api/schemes/{id}/bundle-components/{itemId}` | Removes one FreeBundle required-item row |
-| `evaluateSchemeEligibility(storeId, orderId)` | `GET /api/schemes/eligible?storeId=...&orderId=...` | Returns eligibility for every in-scope scheme, not just one |
+| — | `POST /api/schemes/suggest` | Body `{ storeId, items:[{itemId, quantity, unitPrice?}] }`; scheme suggestions for a Shop PO that is not saved yet |
+| `evaluateSchemeEligibility(storeId, shopPOId)` | `GET /api/schemes/eligible?storeId=...&orderId=...` (`orderId` is the Shop PO id) | Returns eligibility for every in-scope scheme, not just one |
 | `applySchemeDiscount(orderId, schemeId)` | `POST /api/orders/{id}/apply-scheme` | Adds a zero-price order line for free-goods payouts |
+| — | `POST /api/invoices/{id}/preview-totals` | Draft-editor preview of discount, total and free entitlement for unsaved lines |
 | `trackSchemeSpend(schemeId)` | `GET /api/schemes/{id}/spend` | Discount spend + free-goods cost spend |
 | `getSchemeROI(schemeId)` | `GET /api/schemes/{id}/roi` | Uses `BaselineExpectedSales` |
 
@@ -216,13 +218,18 @@ Use this to add/edit one bundle component after creation.
    [08_sales_agent_controls.md](./08_sales_agent_controls.md) unless `AgentLimitExempt = true`.
    (Enforcement against the actual ceiling is deferred — 08_sales_agent_controls.md's discount
    ceiling isn't implemented in code yet; this is recorded as the target behavior.)
-2. `evaluateSchemeEligibility` matches a scheme to a store/order only if: the scheme's `RegionId` is
+2. `evaluateSchemeEligibility` matches a scheme to a store/Shop PO only if: the scheme's `RegionId` is
    null or matches the store's region; `EligibleSegment` is null or matches `Store.Segment`; and the
-   order's date falls within `[DateRangeFrom, DateRangeTo]`.
+   Shop PO's date falls within `[DateRangeFrom, DateRangeTo]`. `DateRangeTo` is inclusive of the
-3. `BuyXGetY` eligibility: the order must contain at least `TriggerQty` of `TriggerItem`; the payout
+   whole calendar day (compared by date, so a scheme ending `2026-08-31` still applies on the 31st).
+3. `BuyXGetY` eligibility: the Shop PO must contain at least `TriggerQty` of `TriggerItem`; the payout
    scales with how many multiples of `TriggerQty` were bought (`FreeQty × floor(boughtQty / TriggerQty)`).
-4. `FreeBundle` eligibility: the order must contain every `SchemeBundleComponent` in at least its
+   Only **paid** lines (`UnitPrice > 0`) count toward `boughtQty` — free lines added by an earlier
-   listed `Qty`; payout is the flat `FreeQty` of `FreeItem` (no multiplier).
+   redemption never count toward a trigger, so "buy 10 get 1 of the same item" can't self-inflate.
+4. `FreeBundle` eligibility: the Shop PO must contain every `SchemeBundleComponent` in at least its
+   listed `Qty` (paid lines only, same as rule 3); payout is the flat `FreeQty` of `FreeItem` (no multiplier).
+   `FreeQty` must be a whole number (validated on create / `PUT .../free-goods-rule`), because
+   Shop PO lines hold whole units.
 5. `applySchemeDiscount` adds a zero-price `OrderItem` line for the free-goods payout (`UnitPrice = 0`,
    `Quantity = FreeQty`), rather than only recording a discount amount — the free line still needs to
    be picked, delivered, and stock-tracked like any other sold line.
@@ -240,6 +247,80 @@ Use this to add/edit one bundle component after creation.
 
 ---
 
+## Offers on the PO and Invoice (implemented)
+
+Nothing is added silently: the system **suggests**, the user **accepts**, and what was accepted stays **editable**.
+
+### 1. On the Shop PO (new and edit screens)
+1. While paid lines are entered, the screen calls `POST /api/schemes/suggest` (`{ storeId, items:[{itemId, quantity, unitPrice?}] }`).
+   The server returns the in-scope schemes (region, segment, date) the lines qualify for, plus Buy & get free /
+   Combo gift schemes the cart is part-way to (`reason` doubles as a nudge, e.g. "Requires 10 of the trigger item;
+   ShopPO has 6").
+2. The **Offers & Free Issues** panel shows:
+   - **Free goods** (BuyXGetY / FreeBundle): "Qualifies for N free X" with **Add free**. The accepted free line is
+     editable (qty, remove) and is saved as a line with `isFree = true` and the `schemeId`.
+   - **Percentage discount** (FlatPercent / SlabDiscount): "Saves Rs. X" with **Apply discount**. Only one discount
+     per order. The accepted scheme ids are sent as `discountSchemeIds` on create / update-items.
+3. If a later paid-qty change shrinks what the order earns, the screen trims the free qty / drops the discount and
+   says so. The server enforces the same rules on save: free qty within the entitlement, free item in stock, scheme
+   active and in scope, at most one discount, order still qualifies.
+4. Saving keeps `SchemeRedemption` in step with the lines: created or resized per free line, removed with its line,
+   and discount redemptions created, recomputed, or dropped if the order stops qualifying.
+5. `GET /api/shop-pos/{id}` returns `discounts[]` (scheme, amount) so the edit screen starts with the right state and
+   the PO view shows a "Scheme discount" row above the total. `PO.TotalAmount` stays the full lines total.
+
+### 2. On the invoice
+- The invoice copies the PO lines, including free lines (`IsFree`, `FK_SchemeId`, `SchemeName`). Free lines show in a
+  **Free Issue** column (a "-" in the cell that does not apply), are listed **after all paid lines**, are zero-priced
+  (price cannot be edited) and can be lowered like any line while the invoice is Draft.
+- `Invoice.TotalAmount = billable lines - DiscountAmount`. When the invoice is created from a PO it starts at the
+  discounted total.
+- **Draft invoice editor** (`/sales/invoices/{id}/edit`):
+  - A **Scheme discount** box lists the flat / slab discounts the current lines qualify for with **Apply discount** /
+    **Remove**. This also covers a PO that was confirmed before a discount was applied. `PUT /api/invoices/{id}/items`
+    accepts `discountSchemeIds` (null = leave as is).
+  - `POST /api/invoices/{id}/preview-totals` (`{ items:[{itemId, quantity, unitPrice, isFree, isRemoved, schemeId}], discountSchemeIds? }`)
+    returns the discount, total and per-scheme free entitlement for the unsaved lines; the editor calls it (debounced)
+    so the Scheme discount row and Total update while typing. It changes nothing.
+- **Recalculation.** On every line change (add, remove, restore, re-price, quantity) and again at print and finalize,
+  `InvoiceService.ApplyTotalsAsync` first reconciles free lines, then re-evaluates the discount against the current lines:
+  - FlatPercent stays the set % of the current lines total; SlabDiscount can move up or down a level, or drop to 0 and
+    return if the lines requalify. Free lines and struck-out lines are ignored. The redemption's `DiscountAmount` is
+    updated with it, so scheme spend / ROI stay correct.
+  - **Free lines only shrink automatically.** If the paid quantity that earned a free issue is lowered or removed, the free
+    quantity is reduced to what is still earned (a line that earns nothing is struck out, keeping its quantity so it can be
+    restored) and the PO's free-goods redemption is resized. Free quantity is never raised automatically; a person raises it,
+    up to what the scheme earns.
+- The invoice page's Items table ends with **Subtotal / Scheme discount / Total**, and the printed A4 and receipt copies show
+  Subtotal, Scheme discount, Total (Paid / Balance Due use the discounted total).
+- The older `POST /api/orders/{id}/apply-scheme` endpoint still works for an already-saved PO and flags the line the same way
+  (and mirrors a free line onto a still-Draft invoice).
+
+### 3. Scheme setup screens
+`/pricing/schemes/new`, `/pricing/schemes/{id}` (read-only) and `/pricing/schemes/{id}/edit` are full pages (no modal) built on one
+form. Rule types are shown in plain words: **Buy & get free** (BuyXGetY), **Combo gift** (FreeBundle), **Flat discount**
+(FlatPercent), **Spend more, save more** (SlabDiscount); the fields adapt to the type (product dropdowns, quantities, % and
+levels) with a live summary sentence. Required fields come first; Active, then the optional Region / Store segment last. The scheme
+name is optional (generated from the offer when blank). The rule type cannot change after creation.
+
+### Data
+`ShopPOItem` and `InvoiceItem` gained `IsFree`, `FK_SchemeId` (plain Guid, no FK constraint) and a `SchemeName` snapshot. Migration
+`AddFreeIssueLines` also back-fills existing zero-priced redemption lines.
+
+### Not done yet
+`SchemeRedemption.FK_InvoiceId` (`FieldInvoiceId` is still an unused placeholder); invoice-version snapshots do not record `IsFree`;
+no hint or one-click "add more free units" when the paid quantity rises; scope (date / region) is checked when a discount is first
+applied, not re-checked on later invoice edits; Slab "close to the next level" hints are not shown.
+
+## Known Gaps vs. Enterprise Practice
+
+Scheme code, lifecycle (Draft/Approved/Active/Expired), priority and stackable/exclusive flags;
+budget and per-store caps; triggers on product groups/brands/categories or order value; tiered
+free-goods slabs; funding source (company vs supplier — ties into SupplierClaims and GRN
+`FreeQuantity`); stock reservation for the free item (the current check only sums balances).
+
+---
+
 ## Open Questions
 
 - What counts as "incremental sales" for `getSchemeROI` — **resolved for v1**: a manual

Distribution/docs/refactor_docs/order_invoice_lifecycle.md

@@ -95,6 +95,7 @@ InvoiceItem                          — the live billing lines
 ├── FK_InvoiceId, FK_ShopPOItemId, FK_ItemId
 ├── Quantity (int)                   — what is billed now (0..ShopPOItem.Quantity)
 ├── UnitPrice (decimal)
+├── IsFree, FK_SchemeId, SchemeName  — free issue copied from the PO line (UnitPrice 0); see 17_promotions_schemes.md
 └── IsActive, CreatedAt              — from Template
 
 InvoiceVersion                       — immutable snapshot of the invoice
@@ -145,7 +146,8 @@ invoice for the preview, the draft editor and the print tab:
   `*** PRINTED ***`, `qty x price` lines, heavy-ruled TOTAL, Paid/Balance, payments, "Thank you!").
 - Money `Rs. 12,450.00`, quantities up to 3 decimals, dates `dd/MM/yyyy`.
 - Deleted lines are shown **struck through in every status** and excluded from all totals.
-- Not included (no data in the app): company/"From" block, logo, bank details, discount, tax, due date.
+- Scheme discount: shown as Subtotal / Scheme discount / Total (`Invoice.DiscountAmount`), re-derived from the current lines on every edit, print and finalize (see 17_promotions_schemes.md). Free-issue lines get a **Free Issue** column and come after the paid lines.
+- Not included (no data in the app): company/"From" block, logo, bank details, tax, due date.
 
 **Print tab** — `/invoices/{id}/print` (own route group `(print)`, no dashboard chrome). Has a
 paper-size selector (A4 / 80mm / 58mm), sets `@page` with `margin: 0` (so the browser's own
@@ -290,8 +292,9 @@ Draft → Printed → Finalized
    also unresolved. Both cases need explicit cascade rules before implementation.
 6. **Exact adjustment payload for `POST /finalize`** — *partly resolved:* quantity adjustments
    (`{ shopPOItemId, adjustedQuantity }`) are implemented and persisted on the invoice lines.
-   Returns, damage and discounts are still open, as is the payload shape for them. "Free issues" handling (items
+   Returns and damage are still open, as is the payload shape for them. Scheme discounts and free issues are now handled
-   given to the shop at no charge) is a known case that needs its own field(s) in the payload.
+   by the invoice itself (re-evaluated on every edit, print and finalize; free lines only ever shrink automatically) — see
+   [17_promotions_schemes.md](../17_promotions_schemes.md).
 
 ---
 

distribution_fe/components/invoice/invoice-template.tsx

@@ -34,9 +34,11 @@ const statusLabel = (invoice: InvoiceResponse) =>
 
 // Removed lines stay on the document (struck through) but are excluded from every total.
 function totals(invoice: InvoiceResponse, payments: PaymentResponse[]) {
-  const total = invoice.items.filter((i) => !i.isRemoved).reduce((s, i) => s + i.quantity * i.unitPrice, 0)
+  const subtotal = invoice.items.filter((i) => !i.isRemoved).reduce((s, i) => s + i.quantity * i.unitPrice, 0)
+  const discount = Math.min(invoice.discountAmount ?? 0, subtotal)
+  const total = subtotal - discount
   const paid = payments.reduce((s, p) => s + p.amount, 0)
-  return { total, paid, balance: total - paid }
+  return { subtotal, discount, total, paid, balance: total - paid }
 }
 
 export function InvoiceTemplate({ paper = 'A4', ...props }: InvoiceTemplateProps) {
@@ -56,9 +58,12 @@ function A4Sheet({
   showAgentEdits,
   className,
 }: Omit<InvoiceTemplateProps, 'paper'>) {
-  const { total, paid, balance } = totals(invoice, payments)
+  const { subtotal, discount, total, paid, balance } = totals(invoice, payments)
   const status = statusLabel(invoice)
   const hasRemoved = invoice.items.some((i) => i.isRemoved)
+  const hasFree = invoice.items.some((i) => i.isFree)
+  // Free issues are listed after every paid line.
+  const rows = [...invoice.items].sort((a, b) => Number(a.isFree) - Number(b.isFree))
 
   return (
     <div
@@ -107,6 +112,7 @@ function A4Sheet({
             <tr className="border-b border-neutral-300 text-xs uppercase tracking-wide text-neutral-500">
               <th className="px-2 py-2 text-left font-medium">Item</th>
               <th className="w-24 px-2 py-2 text-right font-medium">Qty</th>
+              {hasFree && <th className="w-24 px-2 py-2 text-right font-medium">Free Issue</th>}
               <th className="w-36 px-2 py-2 text-right font-medium">Unit Price</th>
               <th className="w-40 px-2 py-2 text-right font-medium">Amount</th>
               {renderActions && <th className="w-24 px-2 py-2 print:hidden" />}
@@ -118,15 +124,25 @@ function A4Sheet({
                 <td colSpan={4} className="px-2 py-6 text-center text-neutral-500">No items.</td>
               </tr>
             ) : (
-              invoice.items.map((item) => (
+              rows.map((item) => (
                 <tr
                   key={item.id}
                   className={cn('break-inside-avoid border-b border-neutral-200', item.isRemoved && 'text-neutral-400 line-through')}
                 >
-                  <td className="px-2 py-2.5">{item.itemName}</td>
+                  <td className="px-2 py-2.5">
-                  <td className="px-2 py-2.5 text-right">
+                    {item.itemName}
-                    {renderQuantity && !item.isRemoved ? renderQuantity(item) : fmtQty(item.quantity)}
+                    {item.isFree && item.schemeName && (
+                      <span className="block text-xs text-neutral-500 no-underline">Free issue · {item.schemeName}</span>
+                    )}
                   </td>
+                  <td className="px-2 py-2.5 text-right">
+                    {item.isFree ? '-' : renderQuantity && !item.isRemoved ? renderQuantity(item) : fmtQty(item.quantity)}
+                  </td>
+                  {hasFree && (
+                    <td className="px-2 py-2.5 text-right">
+                      {item.isFree ? (renderQuantity && !item.isRemoved ? renderQuantity(item) : fmtQty(item.quantity)) : '-'}
+                    </td>
+                  )}
                   <td className="px-2 py-2.5 text-right">
                     {renderUnitPrice && !item.isRemoved ? renderUnitPrice(item) : fmtMoney(item.unitPrice)}
                   </td>
@@ -160,8 +176,14 @@ function A4Sheet({
         <dl className="w-72 break-inside-avoid text-sm">
           <div className="flex justify-between border-b py-1.5">
             <dt className="text-neutral-500">Subtotal</dt>
-            <dd>{fmtMoney(total)}</dd>
+            <dd>{fmtMoney(subtotal)}</dd>
           </div>
+          {discount > 0 && (
+            <div className="flex justify-between border-b py-1.5">
+              <dt className="text-neutral-500">Scheme discount</dt>
+              <dd>-{fmtMoney(discount)}</dd>
+            </div>
+          )}
           <div className="flex justify-between border-y py-2 text-base font-bold" style={{ borderColor: RULE }}>
             <dt>Total</dt>
             <dd>{fmtMoney(total)}</dd>
@@ -225,7 +247,7 @@ function ReceiptSheet({
   showAgentEdits,
   className,
 }: Omit<InvoiceTemplateProps, 'paper'> & { paper: Exclude<InvoicePaper, 'A4'> }) {
-  const { total, paid, balance } = totals(invoice, payments)
+  const { subtotal, discount, total, paid, balance } = totals(invoice, payments)
   const status = statusLabel(invoice)
   const narrow = paper === '58mm'
   const rule = <div className="my-2 border-t border-dashed border-black" />
@@ -252,12 +274,21 @@ function ReceiptSheet({
       </div>
       {rule}
       <div className="space-y-1.5">
-        {invoice.items.map((i) => (
+        {[...invoice.items].sort((a, b) => Number(a.isFree) - Number(b.isFree)).map((i) => (
           <div key={i.id} className={cn(i.isRemoved && 'line-through opacity-60')}>
             <p>{i.itemName}</p>
             <p className="flex justify-between">
+              {i.isFree ? (
+                <>
+                  <span>{fmtQty(i.quantity)} FREE{i.schemeName ? ` (${i.schemeName})` : ''}</span>
+                  <span>{num(0)}</span>
+                </>
+              ) : (
+                <>
                   <span>{fmtQty(i.quantity)} x {num(i.unitPrice)}</span>
                   <span>{num(i.quantity * i.unitPrice)}</span>
+                </>
+              )}
             </p>
           </div>
         ))}
@@ -265,8 +296,14 @@ function ReceiptSheet({
       {rule}
       <p className="flex justify-between">
         <span>Subtotal</span>
-        <span>{fmtMoney(total)}</span>
+        <span>{fmtMoney(subtotal)}</span>
       </p>
+      {discount > 0 && (
+        <p className="flex justify-between">
+          <span>Scheme discount</span>
+          <span>-{fmtMoney(discount)}</span>
+        </p>
+      )}
       <div className="my-1 border-y-2 border-black py-1 text-sm font-bold">
         <p className="flex justify-between">
           <span>TOTAL</span>

distribution_fe/types/api.ts

@@ -661,6 +661,18 @@ export interface SchemeResponse {
   createdAt: string
 }
 
+export interface SchemeSuggestion {
+  schemeId: string
+  schemeName: string
+  ruleType: SchemeRuleType
+  eligible: boolean
+  reason: string | null
+  discountAmount: number | null
+  freeItemId: string | null
+  freeQty: number | null
+  freeItemName: string | null
+}
+
 // ─── Suppliers ────────────────────────────────────────────────────────────────
 
 export interface SupplierResponse {
@@ -973,6 +985,15 @@ export interface ShopPOItemResponse {
   quantityFulfilled: number
   unitPrice: number
   isActive: boolean
+  isFree: boolean
+  schemeId: string | null
+  schemeName: string | null
+}
+
+export interface ShopPODiscount {
+  schemeId: string
+  schemeName: string
+  amount: number
 }
 
 export interface ShopPOResponse {
@@ -1000,6 +1021,7 @@ export interface ShopPOResponse {
   cancelReason: string | null
   cancelledByName: string | null
   cancelledByRole: string | null
+  discounts: ShopPODiscount[]
 }
 
 export interface InvoiceItemResponse {
@@ -1011,6 +1033,9 @@ export interface InvoiceItemResponse {
   quantity: number
   unitPrice: number
   isRemoved: boolean
+  isFree: boolean
+  schemeId: string | null
+  schemeName: string | null
 }
 
 export interface InvoiceVersionItemResponse {
@@ -1050,6 +1075,7 @@ export interface InvoiceResponse {
   isActive: boolean
   createdAt: string
   items: InvoiceItemResponse[]
+  discounts: ShopPODiscount[]
 }
 
 export interface OutstandingPaymentsResponse {