import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { fmt } from "@/lib/format";
import type { RemitDetail } from "@/hooks/useRemitDetail";

type ClaimPaymentsTableProps = {
  remit: RemitDetail;
};

/**
 * Format a CARC reason code as `GROUP-REASON` (e.g. `CO-45`). Both
 * halves come straight off the backend `CasAdjustment` row; the group
 * is the 2-letter ANSI code (CO/PR/OA/PI/CR) and the reason is the
 * numeric code within that group.
 */
function carcKey(group: string, reason: string): string {
  return `${group}-${reason}`;
}

/**
 * Aggregate per-CARC adjustment totals so the table footer can show
 * the dollar impact per reason code. The remit's flat `adjustments`
 * array is summed in-place — no server round-trip.
 */
function summarizeAdjustments(remit: RemitDetail): Array<{
  group: string;
  reason: string;
  label: string;
  total: number;
  count: number;
}> {
  const byKey = new Map<
    string,
    { group: string; reason: string; label: string; total: number; count: number }
  >();
  for (const adj of remit.adjustments ?? []) {
    const key = carcKey(adj.group, adj.reason);
    const existing = byKey.get(key);
    if (existing) {
      existing.total += adj.amount;
      existing.count += 1;
    } else {
      byKey.set(key, {
        group: adj.group,
        reason: adj.reason,
        label: adj.label,
        total: adj.amount,
        count: 1,
      });
    }
  }
  // Largest dollar impact first — easy to scan for the biggest hit.
  return Array.from(byKey.values()).sort((a, b) => Math.abs(b.total) - Math.abs(a.total));
}

/**
 * Claim payments table for the remittance detail drawer.
 *
 * The current backend `/api/remittances/{id}` payload exposes one
 * `ClaimPayment` per remit (the persistence layer keys adjustments by
 * remittance, not by claim), so the table renders one row carrying the
 * remit's claim identity (PCN + claim id) plus the headline figures
 * (paid + adjustments). Below the headline row we surface a per-CARC
 * breakdown — one row per (group, reason) pair, with the cumulative
 * amount and the reason-code label — so the user can see WHY the
 * adjustment totals moved without leaving the drawer.
 *
 * When the backend grows to expose per-`ClaimPayment.service_payment`
 * rows in the detail payload, the table grows naturally: a parent row
 * per claim, expandable to per-service-payment children. The current
 * single-row layout is the v1 shape that works against the v1 API.
 */
export function ClaimPaymentsTable({ remit }: ClaimPaymentsTableProps) {
  const summary = summarizeAdjustments(remit);

  const claimLabel = remit.payerClaimControlNumber ?? remit.claimId ?? remit.id;
  const hasCharge = typeof remit.totalCharge === "number" && Number.isFinite(remit.totalCharge);

  return (
    <section className="flex flex-col gap-3 px-6 py-4" data-testid="claim-payments-table-section">
      <h3
        data-testid="section-label"
        className="text-[10.5px] font-semibold uppercase tracking-[0.18em] text-[color:var(--m-ink-tertiary)]"
      >
        Claim Payments (1)
      </h3>

      <Table data-testid="claim-payments-table">
        <TableHeader>
          <TableRow>
            <TableHead className="w-44">Claim</TableHead>
            <TableHead className="w-28">Status</TableHead>
            <TableHead className="text-right">Charge</TableHead>
            <TableHead className="text-right">Paid</TableHead>
            <TableHead className="text-right">Adjustments</TableHead>
          </TableRow>
        </TableHeader>
        <TableBody>
          <TableRow data-testid="claim-payments-row">
            <TableCell className="font-mono text-[color:var(--m-ink-primary)]">
              {claimLabel}
            </TableCell>
            <TableCell className="font-mono text-[color:var(--m-ink-secondary)]">
              {remit.status}
            </TableCell>
            <TableCell
              className="text-right font-mono text-base tabular-nums text-[color:var(--m-ink-primary)]"
              style={{ fontFamily: "var(--m-font-mono)" }}
            >
              {hasCharge ? fmt.usdPrecise(remit.totalCharge as number) : "—"}
            </TableCell>
            <TableCell
              className="text-right font-mono text-base tabular-nums text-[color:var(--m-ink-primary)]"
              style={{ fontFamily: "var(--m-font-mono)" }}
            >
              {fmt.usdPrecise(remit.paidAmount)}
            </TableCell>
            <TableCell
              className="text-right font-mono text-base tabular-nums text-[color:var(--m-ink-primary)]"
              style={{ fontFamily: "var(--m-font-mono)" }}
            >
              {Math.abs(remit.adjustmentAmount) > 0
                ? fmt.usdPrecise(remit.adjustmentAmount)
                : "—"}
            </TableCell>
          </TableRow>
        </TableBody>
      </Table>

      {summary.length > 0 ? (
        <div className="flex flex-col gap-2 pt-2" data-testid="claim-payments-carc-summary">
          <h4 className="text-[10.5px] font-semibold uppercase tracking-[0.18em] text-[color:var(--m-ink-tertiary)]">
            CARC breakdown
          </h4>
          <Table>
            <TableHeader>
              <TableRow>
                <TableHead className="w-20">CARC</TableHead>
                <TableHead>Reason</TableHead>
                <TableHead className="w-16 text-right">Hits</TableHead>
                <TableHead className="w-32 text-right">Amount</TableHead>
              </TableRow>
            </TableHeader>
            <TableBody>
              {summary.map((row) => (
                <TableRow
                  key={carcKey(row.group, row.reason)}
                  data-testid="carc-row"
                  data-carc={carcKey(row.group, row.reason)}
                >
                  <TableCell className="font-mono text-[color:var(--m-ink-primary)]">
                    {carcKey(row.group, row.reason)}
                  </TableCell>
                  <TableCell className="text-sm text-[color:var(--m-ink-secondary)]">
                    {row.label}
                  </TableCell>
                  <TableCell
                    className="text-right font-mono tabular-nums text-[color:var(--m-ink-secondary)]"
                    data-testid="carc-count"
                  >
                    ×{row.count}
                  </TableCell>
                  <TableCell
                    className="text-right font-mono tabular-nums text-[color:var(--m-ink-primary)]"
                    style={{ fontFamily: "var(--m-font-mono)" }}
                  >
                    {fmt.usdPrecise(row.total)}
                  </TableCell>
                </TableRow>
              ))}
            </TableBody>
          </Table>
        </div>
      ) : null}
    </section>
  );
}
