feat(investment): Interest Entry screen with coupon and provision schedule

Replace the dummy interest calculation tab with the real Interest Entry:
pick Type / Script / Deal No and Retrieve the holding's schedule from
the backend - every half-yearly coupon and every 31 Mar / 30 Sep closing
provision up to maturity, with days (30/360), gross interest, amount
already booked, net income and the Dr/Cr entry per line. Display only;
nothing is posted to GL yet.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/investment/bond-investment/bond-investment.component.html

@@ -626,20 +626,14 @@
     </div>
   }
 
-  <!-- ===================== 03 INTEREST ENTRY / CALCULATION ===================== -->
+  <!-- ===================== 03 INTEREST ENTRY ===================== -->
   @if (activeTab === 'interest') {
     <div class="pg-card">
-      <div class="pos-section-label">Investment - Govt./Bond Interest calculation</div>
+      <div class="pos-section-label">Interest Entry — coupon and 31 Mar / 30 Sep provision schedule</div>
       <div class="inv-form-grid">
-        <label class="inv-form-field"
-          ><span>From Date</span><mifosx-date-ddmmyyyy [(ngModel)]="intCalcFromDate"></mifosx-date-ddmmyyyy
-        ></label>
-        <label class="inv-form-field"
-          ><span>To Date</span><mifosx-date-ddmmyyyy [(ngModel)]="intCalcToDate"></mifosx-date-ddmmyyyy
-        ></label>
         <label class="inv-form-field">
           <span>Type</span>
-          <select [(ngModel)]="intCalcType" (ngModelChange)="onIntCalcTypeChange()">
+          <select [(ngModel)]="intType" (ngModelChange)="onIntFilterChange()">
             <option value="">-- All Types --</option>
             @for (o of bondTypeOptions; track o.value) {
               <option [value]="o.value">{{ o.label }}</option>
@@ -648,67 +642,149 @@
         </label>
         <label class="inv-form-field">
           <span>Script</span>
-          <select [(ngModel)]="intCalcScript">
+          <select [(ngModel)]="intScript" (ngModelChange)="onIntFilterChange()">
             <option value="">-- All Scripts --</option>
-            @for (s of scriptOptions; track s.scriptCode) {
+            @for (s of intScriptOptions; track s.scriptCode) {
               <option [value]="s.scriptCode">{{ s.scriptCode }} — {{ s.scriptName }}</option>
             }
           </select>
         </label>
-        <label class="inv-form-field"><span>Deal No</span><input type="text" [(ngModel)]="intCalcDealNo" /></label>
-        <label class="inv-form-field"
-          ><span>ALL</span><input type="checkbox" [(ngModel)]="intCalcAll" style="height: 18px; width: 18px"
-        /></label>
         <label class="inv-form-field">
-          <span>Post To (Interest Income GL)</span>
-          <select [(ngModel)]="intCalcGlCode">
-            @for (g of interestIncomeGlOptions; track g.glCode) {
-              <option [value]="g.glCode">{{ g.glCode }} — {{ g.glName }}</option>
+          <span>* Deal No</span>
+          <select [(ngModel)]="intPurchaseId" (ngModelChange)="intSchedule = null">
+            <option [ngValue]="null">-- Select --</option>
+            @for (h of intDealOptions; track h.id) {
+              <option [ngValue]="h.id">{{ h.dealNo }} — {{ h.scriptCode }} (Cert {{ h.certNo }})</option>
             }
           </select>
         </label>
+        <label class="inv-form-field"
+          ><span>As On Date</span><mifosx-date-ddmmyyyy [(ngModel)]="intAsOnDate"></mifosx-date-ddmmyyyy
+        ></label>
       </div>
       <div class="inv-form-actions">
-        <button type="button" class="pg-btn pg-btn--primary" (click)="processInterest()">Process</button>
+        <button
+          type="button"
+          class="pg-btn pg-btn--primary"
+          [disabled]="intLoading"
+          (click)="retrieveInterestSchedule()"
+        >
+          {{ intLoading ? 'Retrieving…' : 'Retrieve' }}
+        </button>
         <button type="button" class="pg-btn pg-btn--ghost" (click)="setTab('holdings')">Exit</button>
       </div>
-      @if (intCalcExcludedNpi.length > 0) {
+
+      @if (intSchedule; as sc) {
+        <div class="pos-section-label">Purchase Details</div>
+        <div class="inv-form-grid">
+          <label class="inv-form-field"
+            ><span>Deal No / Cert No</span><input type="text" [value]="sc.dealNo + ' / ' + sc.certNo" readonly
+          /></label>
+          <label class="inv-form-field"
+            ><span>Script</span><input type="text" [value]="sc.scriptCode + ' — ' + sc.scriptDesc" readonly
+          /></label>
+          <label class="inv-form-field"
+            ><span>Face Value Held</span><input type="text" [value]="'₹' + (sc.faceValue | number: '1.2-2')" readonly
+          /></label>
+          <label class="inv-form-field"
+            ><span>Interest Rate</span><input type="text" [value]="sc.intRate + '%'" readonly
+          /></label>
+          <label class="inv-form-field"
+            ><span>Coupon per Half-Year</span
+            ><input type="text" [value]="'₹' + (sc.couponPerHalfYear | number: '1.2-2')" readonly
+          /></label>
+          <label class="inv-form-field"
+            ><span>Deal Date</span><input type="text" [value]="sc.dealDate" readonly
+          /></label>
+          <label class="inv-form-field"
+            ><span>Last Interest Date</span><input type="text" [value]="sc.lastIntDate" readonly
+          /></label>
+          <label class="inv-form-field"
+            ><span>Maturity Date</span><input type="text" [value]="sc.maturityDate" readonly
+          /></label>
+          <label class="inv-form-field"
+            ><span>Accrued Interest Paid at Purchase</span
+            ><input type="text" [value]="'₹' + (sc.purchasedAccruedInterest | number: '1.2-2')" readonly
+          /></label>
+          <label class="inv-form-field"
+            ><span>Book Value</span><input type="text" [value]="'₹' + (sc.bookValue | number: '1.2-2')" readonly
+          /></label>
+        </div>
+
+        <div class="pos-section-label">
+          Interest Schedule ({{ sc.rows.length }} lines) — due up to {{ sc.asOnDate }}: ₹{{
+            intDueTotal | number: '1.2-2'
+          }}
+        </div>
+        <p class="pg-sub" style="padding: 0 16px">
+          Days are 30/360. A provision books the interest earned since the last coupon; the coupon then clears what is
+          already booked. Display only — nothing is posted to GL yet.
+        </p>
+        <table class="pg-table">
+          <thead>
+            <tr>
+              <th>Type</th>
+              <th>Int Date</th>
+              <th>From</th>
+              <th>To</th>
+              <th class="num">Days</th>
+              <th class="num">Int %</th>
+              <th class="num">Gross Interest</th>
+              <th class="num">Already Booked</th>
+              <th class="num col-in">Amount</th>
+              <th>Accounting</th>
+            </tr>
+          </thead>
+          <tbody>
+            @for (r of sc.rows; track r.intDate) {
+              <tr [style.opacity]="r.due ? 1 : 0.6">
+                <td>
+                  <span class="pg-chip">{{ r.type === 'COUPON' ? 'Coupon' : 'Provision' }}</span>
+                  @if (r.due) {
+                    <span class="pg-chip">Due</span>
+                  }
+                </td>
+                <td>{{ r.intDate }}</td>
+                <td>{{ r.fromDate }}</td>
+                <td>{{ r.toDate }}</td>
+                <td class="num">{{ r.days }}</td>
+                <td class="num">{{ sc.intRate }}</td>
+                <td class="num">₹{{ r.grossInterest | number: '1.2-2' }}</td>
+                <td class="num">₹{{ r.alreadyBooked | number: '1.2-2' }}</td>
+                <td class="num col-in">₹{{ r.amount | number: '1.2-2' }}</td>
+                <td style="white-space: nowrap; font-size: 12px">
+                  @if (r.type === 'COUPON') {
+                    <div>Dr Bank ₹{{ r.grossInterest | number: '1.0-0' }}</div>
+                    @if (r.alreadyBooked > 0) {
+                      <div>
+                        Cr {{ interestReceivableGl.glCode }} Int. Receivable ₹{{ r.alreadyBooked | number: '1.0-0' }}
+                      </div>
+                    }
+                    <div>Cr {{ sc.interestGlCode }} Int. Income ₹{{ r.amount | number: '1.0-0' }}</div>
+                  } @else {
+                    <div>Dr {{ interestReceivableGl.glCode }} Int. Receivable ₹{{ r.amount | number: '1.0-0' }}</div>
+                    <div>Cr {{ sc.interestGlCode }} Int. Income ₹{{ r.amount | number: '1.0-0' }}</div>
+                  }
+                </td>
+              </tr>
+            } @empty {
+              <tr>
+                <td colspan="10" class="pg-empty">
+                  No interest lines — check the rate, last interest date and maturity date.
+                </td>
+              </tr>
+            }
+          </tbody>
+        </table>
+        <p class="pg-sub" style="padding: 8px 16px 12px">
+          Interest income GL: {{ sc.interestGlCode }} — {{ sc.interestGlName }}. Posting to GL will be enabled after
+          approval.
+        </p>
+      } @else {
         <p class="pg-sub" style="padding: 0 16px 12px">
-          {{ intCalcExcludedNpi.length }} holding(s) excluded — classified Non-Performing, interest is not posted on
-          accrual basis (collectible on cash basis only, via Interest Receive in the Investment Interest module).
+          Select a Deal No and press Retrieve to see its interest schedule.
         </p>
       }
-      <div class="pos-section-label">Holdings matching the filter ({{ intCalcTargets.length }})</div>
-      <table class="pg-table">
-        <thead>
-          <tr>
-            <th>Cert No</th>
-            <th>Script</th>
-            <th>Type</th>
-            <th class="num">Rate</th>
-            <th>Frequency</th>
-            <th class="num col-in">Interest to Post</th>
-          </tr>
-        </thead>
-        <tbody>
-          @for (h of intCalcTargets; track h.certNo) {
-            <tr>
-              <td>
-                <span class="pg-chip">{{ h.certNo }}</span>
-              </td>
-              <td>{{ h.scriptName }}</td>
-              <td>{{ instrumentLabel(h.instrumentType) }}</td>
-              <td class="num">{{ h.interestRate }}%</td>
-              <td>{{ h.interestFreq }}</td>
-              <td class="num col-in">₹{{ interestAccrued(h) | number: '1.2-2' }}</td>
-            </tr>
-          } @empty {
-            <tr>
-              <td colspan="6" class="pg-empty">No holdings match the selected filters.</td>
-            </tr>
-          }
-        </tbody>
-      </table>
     </div>
   }
 

src/app/investment/bond-investment/bond-investment.component.ts

@@ -26,8 +26,6 @@ import {
   BOND_RATING_OPTIONS,
   INT_TYPE_OPTIONS,
   AUTHORITY_OPTIONS,
-  INTEREST_INCOME_GL_MASTER,
-  INTEREST_INCOME_GL_BY_TYPE,
   INVESTMENT_GL_BY_TYPE,
   INVESTMENT_GL_LOOKUP,
   INTEREST_RECEIVABLE_GL,
@@ -42,8 +40,6 @@ import {
   InterestFreq,
   INSTRUMENT_LABELS,
   accruedInterest,
-  accruedInterestBetween,
-  canAccrueInterest,
   daysToMaturity,
   maturityAmount,
   addPeriod,
@@ -52,7 +48,13 @@ import {
   todayDDMMYYYY
 } from '../investment-data';
 import { exportWorkbook } from '../investment-export';
-import { InvestmentPurchaseDto, InvestmentService, apiErrorMessage, toHolding } from '../investment.service';
+import {
+  InvestmentInterestScheduleDto,
+  InvestmentPurchaseDto,
+  InvestmentService,
+  apiErrorMessage,
+  toHolding
+} from '../investment.service';
 
 type BondType = 'GOVT_SECURITY' | 'NON_SLR' | 'BOND' | 'MUTUAL_FUND';
 type BondTab =
@@ -286,17 +288,16 @@ export class BondInvestmentComponent implements OnInit {
   redeemDate = this.asOnDate;
   redeemRemarks = '';
 
-  // Interest Calculation (legacy: From/To Date / Type / Script / Deal No / ALL + Process) —
-  // posts interest accrued strictly within [intCalcFromDate, intCalcToDate], same period-based
-  // basis as the Investment Interest module's Govt./Bond Interest Calculation.
-  intCalcFromDate = addPeriod(this.asOnDate, 0, -3);
-  intCalcToDate = this.asOnDate;
-  intCalcType: BondType | '' = '';
-  intCalcScript = '';
-  intCalcDealNo = '';
-  intCalcAll = false;
-  intCalcGlCode = INTEREST_INCOME_GL_BY_TYPE.GOVT_SECURITY;
-  readonly interestIncomeGlOptions = INTEREST_INCOME_GL_MASTER;
+  // 03 Interest Entry (legacy: Type / Script / Deal No + Retrieve) — the backend works out every
+  // half-yearly coupon and 31 Mar / 30 Sep closing provision of the holding. Display only:
+  // nothing is posted to GL until the posting rules are approved.
+  intType: BondType | '' = '';
+  intScript = '';
+  intPurchaseId: number | null = null;
+  intAsOnDate = this.asOnDate;
+  intSchedule: InvestmentInterestScheduleDto | null = null;
+  intLoading = false;
+  readonly interestReceivableGl = INTEREST_RECEIVABLE_GL;
 
   // Write-off
   writeoffCertNo = '';
@@ -892,78 +893,53 @@ export class BondInvestmentComponent implements OnInit {
   }
 
   // -------------------- Interest calculation --------------------
-  /** Holdings the Interest Calculation "Process" run would cover, given the filters. A
-   *  Non-Performing holding is always excluded — same accrual-basis rule as the Investment
-   *  Interest module (it's still collectible on cash basis via Interest Receive there). */
-  get intCalcTargets(): InvestmentHolding[] {
-    const base = this.holdings.filter((h) => h.status === 'ACTIVE' && canAccrueInterest(h));
-    if (this.intCalcAll) {
-      return base;
+  /** Saved holdings for the Deal No dropdown, narrowed by Type and Script. */
+  get intDealOptions(): InvestmentHolding[] {
+    return this.holdings.filter(
+      (h) =>
+        h.id != null &&
+        h.status === 'ACTIVE' &&
+        (!this.intType || h.instrumentType === this.intType) &&
+        (!this.intScript || h.scriptCode === this.intScript)
+    );
+  }
+
+  get intScriptOptions(): typeof SCRIPT_MASTER {
+    return this.scriptOptions.filter((s) => !this.intType || s.instrumentType === this.intType);
+  }
+
+  onIntFilterChange(): void {
+    if (this.intScript && !this.intScriptOptions.some((s) => s.scriptCode === this.intScript)) {
+      this.intScript = '';
     }
-    return base.filter((h) => {
-      if (this.intCalcType && h.instrumentType !== this.intCalcType) return false;
-      if (this.intCalcScript && h.scriptCode !== this.intCalcScript) return false;
-      if (this.intCalcDealNo && h.certNo !== this.intCalcDealNo.trim()) return false;
-      return true;
-    });
-  }
-
-  get intCalcExcludedNpi(): InvestmentHolding[] {
-    return this.holdings.filter((h) => h.status === 'ACTIVE' && !canAccrueInterest(h));
-  }
-
-  /** Re-suggests the Interest Income GL when the Type filter changes — still overridable. */
-  onIntCalcTypeChange(): void {
-    if (this.intCalcType) {
-      this.intCalcGlCode = INTEREST_INCOME_GL_BY_TYPE[this.intCalcType];
+    if (this.intPurchaseId != null && !this.intDealOptions.some((h) => h.id === this.intPurchaseId)) {
+      this.intPurchaseId = null;
     }
+    this.intSchedule = null;
   }
 
-  glName(glCode: string): string {
-    return this.interestIncomeGlOptions.find((g) => g.glCode === glCode)?.glName ?? glCode;
-  }
-
-  /** Interest accrued strictly within [intCalcFromDate, intCalcToDate] — a period-based
-   *  Interest Calculation & Post run, same basis as the Investment Interest module. */
-  interestAccrued(h: InvestmentHolding): number {
-    return accruedInterestBetween(h, this.intCalcFromDate || h.purchaseDate, this.intCalcToDate || this.asOnDate);
-  }
-
-  processInterest(): void {
-    const targets = this.intCalcTargets.filter((h) => this.interestAccrued(h) > 0);
-    if (targets.length === 0) {
-      this.toast('No holdings have interest due to be posted for this period.');
+  retrieveInterestSchedule(): void {
+    if (this.intPurchaseId == null) {
+      this.toast('Select a Deal No first.');
       return;
     }
-    const toDate = this.intCalcToDate || this.asOnDate;
-    const fromDate = this.intCalcFromDate || toDate;
-    const glCode = this.intCalcGlCode;
-    const glName = this.glName(glCode);
-    const newTxns: InvestmentTxn[] = targets.map((h, i) => {
-      const amt = this.interestAccrued(h);
-      h.interestPosted = (h.interestPosted ?? 0) + amt;
-      h.interestPostedTillDate = toDate;
-      return {
-        certNo: h.certNo,
-        instrumentType: h.instrumentType,
-        txnType: 'INTEREST',
-        voucherNo: `INV/INT/${h.certNo}-${this.txns.length + i + 1}`,
-        txnDate: toDate,
-        amount: amt,
-        particulars: `Interest calculated (accrual) for period ${fromDate} to ${toDate} - ${h.scriptName}`,
-        glCode,
-        glName
-      };
+    this.intLoading = true;
+    this.investmentService.getInterestSchedule(this.intPurchaseId, this.intAsOnDate || undefined).subscribe({
+      next: (schedule) => {
+        this.intSchedule = schedule;
+        this.intLoading = false;
+      },
+      error: (err) => {
+        this.intSchedule = null;
+        this.intLoading = false;
+        this.toast(apiErrorMessage(err));
+      }
     });
-    this.txns = [
-      ...newTxns,
-      ...this.txns
-    ];
-    this.intCalcFromDate = toDate;
-    const total = newTxns.reduce((s, t) => s + t.amount, 0);
-    this.toast(
-      `Interest processed for ${targets.length} holding(s) to ${glCode} - ${glName}. Total ₹${total.toLocaleString('en-IN')}.`
-    );
+  }
+
+  /** Total of the lines falling due up to the as-on date. */
+  get intDueTotal(): number {
+    return (this.intSchedule?.rows ?? []).filter((r) => r.due).reduce((sum, r) => sum + r.amount, 0);
   }
 
   // -------------------- Sell / Redeem Entry --------------------

src/app/investment/investment.service.ts

@@ -169,6 +169,14 @@ export class InvestmentService {
     return this.http.get<InvestmentPurchaseDto[]>('/investment/purchases');
   }
 
+  /** Coupon and 31 Mar / 30 Sep provision lines of a holding up to maturity (calculated, not posted). */
+  getInterestSchedule(purchaseId: number, asOnDate?: string): Observable<InvestmentInterestScheduleDto> {
+    const params = asOnDate ? `?asOnDate=${encodeURIComponent(asOnDate)}` : '';
+    return this.http.get<InvestmentInterestScheduleDto>(
+      `/investment/purchases/${purchaseId}/interest-schedule${params}`
+    );
+  }
+
   createPurchase(body: object): Observable<{ resourceId: number; resourceIdentifier: string }> {
     return this.http.post<{ resourceId: number; resourceIdentifier: string }>('/investment/purchases', body);
   }
@@ -292,6 +300,42 @@ export function toHolding(p: InvestmentPurchaseDto): InvestmentHolding {
   };
 }
 
+/** One line of a holding's interest schedule (see InvestmentInterestScheduleData in the backend). */
+export interface InvestmentInterestRowDto {
+  type: 'COUPON' | 'PROVISION';
+  intDate: string;
+  fromDate: string;
+  toDate: string;
+  days: number;
+  grossInterest: number;
+  alreadyBooked: number;
+  amount: number;
+  due: boolean;
+}
+
+export interface InvestmentInterestScheduleDto {
+  purchaseId: number;
+  dealNo: string;
+  certNo: string;
+  scriptCode: string;
+  scriptDesc: string;
+  faceValue: number;
+  unitValue: number;
+  balanceUnits: number;
+  purchaseRate: number;
+  bookValue: number;
+  intRate: number;
+  dealDate: string;
+  lastIntDate: string;
+  maturityDate: string;
+  purchasedAccruedInterest: number;
+  couponPerHalfYear: number;
+  asOnDate: string;
+  interestGlCode: string;
+  interestGlName: string;
+  rows: InvestmentInterestRowDto[];
+}
+
 /** The first validation / domain-rule message from a Fineract error response, for a toast. */
 export function apiErrorMessage(err: unknown): string {
   const e = err as HttpErrorResponse;