import { Invoice } from "../billing/entities/invoice.entity";
import {
  InvoiceDocumentModel,
  pngDataUrl,
} from "../billing/documents/invoice-document.service";
import { EimsReceipt, EimsReceiptStatus } from "./entities/eims-receipt.entity";
import { EimsSalesReceiptRequest, EimsWithholdReceiptRequest } from "./eims-receipt.types";

/**
 * Maps a filed `EimsReceipt` onto the shared invoice/receipt document layout — mirrors
 * `eims-invoice.mapper.ts`'s role for `/v1/register`: a pure function, no I/O.
 *
 * The amounts (collected amount, mode of payment, withholding amount) live only in
 * `receipt.request` — the exact body this app sent, typed and written in exactly one place
 * (`EimsReceiptService`). Reading it back is a cast, not a new source of truth; real columns
 * would mean a migration + backfill for data already present in a stable shape.
 *
 * Throws rather than returning a model for anything not actually filed: a sealed, stamped PDF
 * for a receipt MoR rejected, never acknowledged, or whose request was somehow never recorded
 * would read as a genuine tax document. Callers (`EimsReceiptService.document`) let this throw
 * surface as a 400 — there is nothing sensible to render instead.
 */
export function toReceiptDocumentModel(receipt: EimsReceipt, invoice: Invoice): InvoiceDocumentModel {
  if (receipt.status !== EimsReceiptStatus.Registered) {
    throw new Error(
      `Receipt ${receipt.receiptNumber} is ${receipt.status}, not REGISTERED — refusing to print an unfiled receipt.`,
    );
  }
  if (!receipt.request) {
    throw new Error(`Receipt ${receipt.receiptNumber} has no stored request body — cannot render its amounts.`);
  }

  const isSales = receipt.kind === "SALES";

  if (isSales) {
    const req = receipt.request as unknown as EimsSalesReceiptRequest;
    return build(receipt, invoice, {
      title: "Sales Receipt",
      currency: req.ReceiptCurrency,
      amountLabel: "Collected",
      lineDescription: `Payment received against invoice ${invoice.invoiceNumber}`,
      amount: req.CollectedAmount,
      // A sales receipt is a real payment — this is the one case the shared layout's own default
      // ("EDR PAID" for kind RECEIPT) is already correct, but set it explicitly so it never drifts
      // if that default changes for an unrelated reason.
      sealText: "EDR PAID",
      extraSummary: [{ label: "Mode of payment", value: req.TransactionDetails.ModeOfPayment }],
    });
  }

  const req = receipt.request as unknown as EimsWithholdReceiptRequest;
  return build(receipt, invoice, {
    title: "Withholding Receipt",
    currency: req.InvoiceDetail.Currency,
    amountLabel: "Withheld",
    lineDescription: `Withholding (${req.WithholdDetail.Type}) against invoice ${invoice.invoiceNumber}`,
    amount: req.WithholdDetail.WithholdingAmount,
    // A withholding receipt is not a payment — the shared layout's "EDR PAID" default would be
    // wrong here, so this is the one case that MUST override it.
    sealText: "EDR",
    extraSummary: [{ label: "Withholding type", value: req.WithholdDetail.Type }],
  });
}

function build(
  receipt: EimsReceipt,
  invoice: Invoice,
  opts: {
    title: string;
    currency: string;
    amountLabel: string;
    lineDescription: string;
    amount: number;
    sealText: string;
    extraSummary: Array<{ label: string; value: string | null }>;
  },
): InvoiceDocumentModel {
  return {
    kind: "RECEIPT",
    title: opts.title,
    documentNumber: receipt.receiptNumber,
    issuedAt: receipt.submittedAt ?? null,
    status: receipt.status,
    currency: opts.currency,
    summary: [
      { label: "Invoice", value: invoice.invoiceNumber },
      { label: "Invoice IRN", value: invoice.eimsIrn ?? null },
      { label: "RRN", value: receipt.rrn ?? null },
      { label: "Ack status", value: receipt.ackStatus ?? null },
      ...opts.extraSummary,
    ],
    // No line items on a receipt — one synthetic line, since buildHtml renders the line table
    // unconditionally and an empty `lines: []` would print a header-only empty table.
    lines: [
      {
        description: opts.lineDescription,
        quantity: 1,
        unitRate: opts.amount,
        amount: opts.amount,
        currency: opts.currency,
      },
    ],
    totals: [{ label: opts.amountLabel, amount: opts.amount, grand: true }],
    sealText: opts.sealText,
    qrImageUrl: receipt.qr ? pngDataUrl(receipt.qr) : null,
  };
}