package payments

import (
	"bytes"
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"math"
	"strconv"
	"strings"
	"time"

	"crussell/clock"
	"crussell/db"
	"crussell/internal/square"

	"github.com/jackc/pgx/v5"
)

// SweepStalePendingPayments resolves pending payment records that are older
// than Square's idempotency-key retention window (~24h). A pending record
// means the DB committed but the Square charge outcome is unknown; it
// normally resolves on a same-key client retry. But if the client abandoned
// the attempt, the record stays pending forever — and retrying it after the
// key expires would ISSUE A SECOND CHARGE (Square no longer dedups). Failing
// stale pendings closes that double-charge window: a late retry finds a
// 'failed' record and stops instead of charging again.
//
// Before failing a row, the sweep reconciles it against Square: a
// genuinely-charged row (Square success, DB post-charge failure) with a
// square_payment_id is rescued to 'completed' instead of being swept to
// 'failed' with no automatic resolution — the money would otherwise be lost
// in limbo (MINOR-R3). Reconciliation is deliberately minimal: status +
// updated_at only, no split/VAT recomputation (that is the handler's job; the
// row is >24h stale and this is a reconciliation rescue). A row with NO
// square_payment_id but a STORED idempotency key (the lost-response case — the
// charge may have completed at Square with the response never received) is
// reconciled at Square by replaying the key (ReplayPaymentByKey) at an EARLIER
// 22h cutoff, while the key is still inside Square's ~24h retention window: a
// COMPLETED charge is rescued to 'completed' with the real square_payment_id
// written back, and a charge Square proves never happened is failed. Rows with
// neither a square_payment_id nor a stored key cannot be reconciled and are
// failed with a WARN exactly as the legacy sweep did.
//
// Only online/till card payments can be pending — cash/giftcard/on_the_house
// are committed synchronously and never enter this state. Both the payments
// table and till_sales carry pending card-sale rows and are swept here.
const stalePendingPaymentAge = 24 * time.Hour

// stalePendingKeyedAge is how old a pending row with a stored idempotency key
// (but no square_payment_id — the lost-response case) must be before the sweep
// reconciles it at Square by replaying the key. It is deliberately 2h EARLIER
// than stalePendingPaymentAge so the replay lands comfortably inside Square's
// ~24h idempotency-key retention window: replaying at exactly 24h risks the key
// already having expired, and an expired key would make the probe rejection
// look like "never charged" even when the charge actually landed. Rows older
// than stalePendingPaymentAge when swept can no longer be replayed
// trustworthily and fall back to the legacy blind-fail + WARN.
const stalePendingKeyedAge = 22 * time.Hour

func SweepStalePendingPayments(ctx context.Context) (int, error) {
	cutoff := clock.Now().Add(-stalePendingPaymentAge)
	keyedCutoff := clock.Now().Add(-stalePendingKeyedAge)

	// Pass 1 (earlier cutoff): rows with a stored idempotency key but NO
	// square_payment_id are the lost-response case — the charge may have landed
	// at Square with the response lost. They are reconciled at Square by
	// replaying the key (ReplayPaymentByKey) while the key is still inside
	// Square's ~24h retention window: a COMPLETED charge is rescued to
	// 'completed' with the real square_payment_id, a charge Square proves never
	// happened is failed (and a till sale's funded gift card clawed back), an
	// ambiguous answer leaves the row pending for the next run, and a row
	// already past the retention window is blind-failed with a WARN exactly as
	// the legacy sweep did (replaying an expired key would misread the probe
	// rejection as "never charged").
	payKeyedCount, payKeyedCompleted, payKeyedUnverified, err := sweepKeyedStaleRows(ctx, "payments", keyedCutoff)
	if err != nil {
		return 0, err
	}
	tillKeyedCount, tillKeyedCompleted, tillKeyedUnverified, err := sweepKeyedStaleRows(ctx, "till_sales", keyedCutoff)
	if err != nil {
		return 0, err
	}

	// Pass 2 (legacy 24h cutoff): rows WITH a square_payment_id are reconciled
	// by payment id; rows with neither a payment id nor a stored key cannot be
	// reconciled and are failed directly (WARN — the charge outcome is unknown).
	payCount, payCompleted, err := sweepStaleRows(ctx, "payments", cutoff)
	if err != nil {
		return 0, err
	}
	tillCount, tillCompleted, err := sweepStaleRows(ctx, "till_sales", cutoff)
	if err != nil {
		return 0, err
	}

	total := payKeyedCount + tillKeyedCount + payCount + tillCount
	payTotal := payKeyedCount + payCount
	tillTotal := tillKeyedCount + tillCount
	completed := payKeyedCompleted + tillKeyedCompleted + payCompleted + tillCompleted
	if total > 0 {
		log.Printf("[SWEEP] Resolved %d stale pending payments (%d payments, %d till sales) older than %s — late retries will be rejected, preventing a second Square charge; %d reconciled to completed against Square (%d payments, %d till sales)", total, payTotal, tillTotal, stalePendingPaymentAge, completed, payKeyedCompleted+payCompleted, tillKeyedCompleted+tillCompleted)
	}
	// Routine sweep bookkeeping, not an incident: failing stale pending rows is
	// the sweep's DESIGNED behaviour. A row swept to failed may still have been
	// charged at Square with a lost response, so note it at WARN level for an
	// admin doing a periodic money reconciliation — but this fires on every
	// normal run and must not be elevated to CRITICAL (which is reserved for
	// genuinely unrecoverable post-charge branches). Rows the keyed reconcile
	// PROVED never charged are deliberately excluded from the WARN (they cannot
	// have moved money); only rows failed without a reconcile proof — keyless
	// rows and keyed rows past the retention window — are counted.
	if payKeyedUnverified > 0 {
		log.Printf("[SWEEP] WARN: %d pending payments with a stored idempotency key but no square_payment_id were marked failed without a replay reconcile (key retention window already closed) — may have been charged at Square with a lost response — verify before refunding/charging", payKeyedUnverified)
	}
	if tillKeyedUnverified > 0 {
		log.Printf("[SWEEP] WARN: %d pending till sales with a stored idempotency key but no square_payment_id were marked failed without a replay reconcile (key retention window already closed) — may have been charged at Square with a lost response", tillKeyedUnverified)
	}
	if payCount > 0 {
		log.Printf("[SWEEP] WARN: %d pending payments marked failed may have been charged at Square with a lost response — verify before refunding/charging", payCount-payCompleted)
	}
	if tillCount > 0 {
		log.Printf("[SWEEP] WARN: %d pending till sales marked failed may have been charged at Square with a lost response", tillCount-tillCompleted)
	}
	return total, nil
}

// staleRow is one stale pending row read by the sweep so it can reconcile
// rows that carry a Square reference BEFORE failing them. For till_sales rows
// the gift-card context needed to claw back funded money on a definitive
// failure is carried alongside: the card id, who it was redeemed to, whether
// this sale created the card (created_at equality — provable because both
// timestamps are the transaction-start NOW() in the same tx), and the sale
// amount (the exact funding this sale added).
type staleRow struct {
	ID              string
	SquarePaymentID string
	// IdempotencyKey is the deterministic Square idempotency key stored on the
	// pending row ("" when absent). Rows WITH a key but NO square_payment_id are
	// the lost-response case: the sweep replays the key at Square to learn the
	// true charge outcome before declaring failure.
	IdempotencyKey string
	// SquareSourceID is the exact source_id sent in the original CreatePayment
	// call, stored on the row so the replay-by-key can rebuild an IDENTICAL
	// request body (same key + source + amount). Replaying a different body
	// would return IDEMPOTENCY_KEY_REUSED, which proves nothing about whether
	// the charge landed.
	SquareSourceID string
	// SquareRequestSnapshot is the verbatim original CreatePayment request JSON
	// stored on the row at charge time (square_request_snapshot) — the FULL
	// body the replay-by-key must repeat (source, key, amount, customer_id,
	// reference_id, note, buyer_email_address, verification_token, ...).
	// Square's idempotency dedup compares the whole request, so a replay built
	// from partial row data returns IDEMPOTENCY_KEY_REUSED for a RETAINED key
	// and the row stays pending forever (safe but never auto-rescued). Nil for
	// legacy rows — the sweep then rebuilds the minimal body from the stored
	// key + source + amount.
	SquareRequestSnapshot []byte
	// AmountPence is the row's charge amount in pence — the amount the original
	// CreatePayment used. The replay-by-key must repeat it so Square's
	// idempotency dedup returns the original payment.
	AmountPence int64
	// CreatedAt is the pending row's creation time; rows already past Square's
	// idempotency-key retention window cannot be replayed trustworthily.
	CreatedAt time.Time
	// BookingID is the payments row's booking_id ("" when the row has none).
	// A payments row with NO booking is a gift-card purchase (BuyGiftCard
	// inserts without a booking): rescuing it to 'completed' on a Square
	// COMPLETED reconcile would permanently block the same-key retry that
	// delivers the card, so such rows are kept pending instead (C6).
	BookingID *string
	// CreatedBy is the payments row's created_by user id (gift-card purchases
	// always carry the purchaser), used to attribute the critical-payment admin
	// notification.
	CreatedBy     *string
	ItemID        string  // till_sales.item_id — the gift card ("" when NULL / non-gift-card)
	RedeemToUserID  *string // gift_cards.redeemed_by — user credited by a create-with-redeem
	IsCreate        bool    // true when this sale created the gift card (timestamps equal)
	HasGiftCard     bool    // false when the LEFT JOIN found no gift_cards row (gc.id IS NULL)
	TotalAmount     float64 // till_sales.total_amount — the funding this sale added
}

// sweepStaleRows resolves the stale pending rows of one table. Rows with a
// square_payment_id are reconciled at Square first (COMPLETED → 'completed',
// anything else → 'failed' exactly as the legacy bulk UPDATE did); rows
// without one cannot be reconciled and are failed directly. A till_sales row
// whose reconcile PROVES the charge never completed (NOT_FOUND / non-COMPLETED)
// also claws back the funded gift card atomically with the failed mark; the
// blind-fail path (no square_payment_id — the charge may have landed) never
// claws back. Returns the total rows resolved and how many were rescued to
// 'completed'.
func sweepStaleRows(ctx context.Context, table string, cutoff time.Time) (resolved int, completed int, err error) {
	switch table {
	case "payments", "till_sales":
	default:
		return 0, 0, fmt.Errorf("sweep: unknown stale table %q", table)
	}
	stale, err := fetchStaleRows(ctx, table, cutoff, false)
	if err != nil {
		return 0, 0, err
	}
	for _, r := range stale {
		if r.SquarePaymentID != "" {
			switch reconcileStalePaymentAtSquare(ctx, table, r.SquarePaymentID) {
			case staleReconcileCompleted:
				if table == "payments" && r.BookingID == nil {
					// Gift-card purchase row: the charge landed at Square but
					// the gift card was never delivered (C6). Completing the row
					// permanently blocks the same-key retry that delivers the
					// card — leave it pending and alert.
					leaveGiftCardPurchasePending(ctx, r)
					continue
				}
				if rescueStaleRowCompleted(ctx, table, r.ID) {
					resolved++
					completed++
				}
				continue
			case staleReconcileLeavePending:
				// Square's answer was ambiguous (transport/5xx) — the charge
				// may still be in flight at Square. Do NOT touch the row: the
				// next sweep run reconciles it again, and a same-key retry
				// must still be able to reuse the pending row if the charge
				// actually completed.
				log.Printf("Stale pending %s row %s left pending (Square reconcile ambiguous) — will retry next sweep", table, r.ID)
				continue
			}
			// staleReconcileDefinitivelyFailed falls through to the fail path.
		}
		// Fail path. A till-sale reconcile that PROVED the charge never
		// completed (NOT_FOUND / non-COMPLETED) claws back the funded gift
		// card atomically with the failed mark (HIGH-1). The blind-fail path
		// (no square_payment_id — the charge outcome is unknown) NEVER claws
		// back: the money may have landed at Square.
		if table == "till_sales" && r.SquarePaymentID != "" && r.HasGiftCard {
			if clawbackTillSaleFunding(ctx, r) {
				resolved++
			}
			continue
		}
		if failStaleRow(ctx, table, r.ID) {
			resolved++
		}
	}
	return resolved, completed, nil
}

// sweepKeyedStaleRows resolves stale pending rows that carry a stored
// idempotency key but no square_payment_id — the lost-response case, where the
// charge may have completed at Square with the response never reaching the
// app. Such rows are reconciled at Square by replaying the key while it is
// still inside Square's ~24h retention window (the earlier stalePendingKeyedAge
// cutoff guarantees this):
//
//   - a COMPLETED payment under the key → rescued to 'completed' with the real
//     square_payment_id written back (the customer WAS charged);
//   - a payment Square proves never happened (unknown key / FAILED status) →
//     marked 'failed', and a till sale's funded gift card is clawed back
//     (reconcile PROVED the funding has no charge behind it);
//   - an ambiguous answer (transport/5xx) → left pending for the next run;
//   - a row already older than the retention window when swept → cannot be
//     replayed trustworthily (an expired key would misread the probe rejection
//     as "never charged" even when the charge landed), so it is blind-failed
//     with a WARN exactly as the legacy sweep did.
//
// Returns the total rows resolved, how many were rescued to 'completed', and
// how many were marked failed WITHOUT a reconcile proof (blind-fail WARNs).
func sweepKeyedStaleRows(ctx context.Context, table string, cutoff time.Time) (resolved, completed, unverifiable int, err error) {
	switch table {
	case "payments", "till_sales":
	default:
		return 0, 0, 0, fmt.Errorf("sweep: unknown stale table %q", table)
	}
	stale, err := fetchStaleRows(ctx, table, cutoff, true)
	if err != nil {
		return 0, 0, 0, err
	}
	// Square's idempotency-key retention window closes at stalePendingPaymentAge;
	// a row older than that when swept can no longer be replayed trustworthily.
	replayExpired := clock.Now().Add(-stalePendingPaymentAge)
	for _, r := range stale {
		if r.CreatedAt.Before(replayExpired) {
			// Key retention window already closed — replaying would misread an
			// expired key as "never charged". Blind-fail + WARN exactly as the
			// legacy sweep did; a till sale's funded gift card is NOT clawed
			// back (the charge outcome is unknown, the money may have landed).
			if failStaleRow(ctx, table, r.ID) {
				resolved++
				unverifiable++
			}
			log.Printf("Stale pending %s row %s has a stored idempotency key but is already past Square's key retention window — marked failed without a replay reconcile (may have been charged with a lost response)", table, r.ID)
			continue
		}
		switch res, sqPayID := reconcileStalePaymentByKey(ctx, table, r); res {
		case staleReconcileCompleted:
			if table == "payments" && r.BookingID == nil {
				// Gift-card purchase row (C6): the charge landed at Square but
				// the card was never delivered. Completing the row blocks the
				// same-key retry that delivers the card — leave it pending.
				leaveGiftCardPurchasePending(ctx, r)
				continue
			}
			if rescueKeyedStaleRowCompleted(ctx, table, r.ID, sqPayID) {
				resolved++
				completed++
			}
		case staleReconcileLeavePending:
			// Ambiguous replay — the charge may still be in flight. Leave the
			// row pending; the next sweep run reconciles it again.
			log.Printf("Stale pending %s row %s left pending (replay-by-key reconcile ambiguous) — will retry next sweep", table, r.ID)
		case staleReconcileDefinitivelyFailed:
			// Square proved the charge never happened (key unknown / FAILED) —
			// a till sale's funded gift card is clawed back atomically with the
			// failed mark, unlike the blind-fail path where the outcome is unknown.
			if table == "till_sales" && r.HasGiftCard {
				if clawbackTillSaleFunding(ctx, r) {
					resolved++
				}
				continue
			}
			if failStaleRow(ctx, table, r.ID) {
				resolved++
			}
		}
	}
	return resolved, completed, unverifiable, nil
}

// fetchStaleRows reads the stale pending rows of one table that are older than
// cutoff. keyedOnly restricts the query to rows that can be reconciled by
// replaying a stored idempotency key: those with a key but no square_payment_id
// (rows WITH a square_payment_id are reconciled by payment id in the main
// pass). The legacy till_sales sweep only touches card methods — cash and
// on_the_house are committed synchronously and never pending, but the
// predicate is kept so behaviour is byte-identical for any unexpected row.
func fetchStaleRows(ctx context.Context, table string, cutoff time.Time, keyedOnly bool) ([]staleRow, error) {
	keyedPredicate := ""
	if keyedOnly {
		keyedPredicate = ` AND idempotency_key IS NOT NULL AND square_payment_id IS NULL`
	}
	methodFilter := ""
	if table == "till_sales" {
		methodFilter = ` AND payment_method IN ('online_square', 'in_person_card')`
	}
	var rows pgx.Rows
	var err error
	if table == "till_sales" {
		rows, err = db.Conn.Query(ctx, `
			SELECT ts.id, COALESCE(ts.square_payment_id, ''), COALESCE(ts.idempotency_key, ''),
			       COALESCE(ts.square_source_id, ''), COALESCE(ts.square_request_snapshot, ''),
			       ts.created_at, ts.item_id, gc.redeemed_by,
			       (ts.created_at = gc.created_at) AS is_create,
			       (gc.id IS NOT NULL) AS has_gift_card, ts.total_amount
			FROM till_sales ts
			LEFT JOIN gift_cards gc ON gc.id = ts.item_id
			WHERE ts.status = 'pending' AND ts.created_at < $1`+methodFilter+keyedPredicate+`
		`, cutoff)
	} else {
		rows, err = db.Conn.Query(ctx, `
			SELECT id, COALESCE(square_payment_id, ''), COALESCE(idempotency_key, ''),
			       COALESCE(square_source_id, ''), COALESCE(square_request_snapshot, ''),
			       created_at, amount, booking_id, created_by
			FROM `+table+`
			WHERE status = 'pending' AND created_at < $1`+keyedPredicate+`
		`, cutoff)
	}
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var stale []staleRow
	for rows.Next() {
		r, scanErr := scanStaleRow(table, rows)
		if scanErr != nil {
			log.Printf("Failed to scan stale pending row from %s: %v", table, scanErr)
			continue
		}
		stale = append(stale, r)
	}
	return stale, rows.Err()
}

// scanStaleRow scans one row produced by fetchStaleRows into a staleRow,
// deriving the replay amount (in pence) from the stored pound figure — the
// original CreatePayment amount the replay-by-key must repeat.
func scanStaleRow(table string, rows pgx.Rows) (staleRow, error) {
	var r staleRow
	if table == "till_sales" {
		var itemID, redeemedBy, snapshot sql.NullString
		var isCreate *bool
		var hasGiftCard bool
		if err := rows.Scan(&r.ID, &r.SquarePaymentID, &r.IdempotencyKey, &r.SquareSourceID, &snapshot, &r.CreatedAt,
			&itemID, &redeemedBy, &isCreate, &hasGiftCard, &r.TotalAmount); err != nil {
			return r, err
		}
		r.SquareRequestSnapshot = []byte(snapshot.String)
		r.ItemID = itemID.String
		if redeemedBy.Valid && redeemedBy.String != "" {
			r.RedeemToUserID = &redeemedBy.String
		}
		r.IsCreate = isCreate != nil && *isCreate
		r.HasGiftCard = hasGiftCard
		r.AmountPence = int64(math.Round(r.TotalAmount * 100))
		return r, nil
	}
	var amount float64
	var bookingID, createdBy, snapshot sql.NullString
	if err := rows.Scan(&r.ID, &r.SquarePaymentID, &r.IdempotencyKey, &r.SquareSourceID, &snapshot, &r.CreatedAt, &amount, &bookingID, &createdBy); err != nil {
		return r, err
	}
	r.SquareRequestSnapshot = []byte(snapshot.String)
	r.AmountPence = int64(math.Round(amount * 100))
	if bookingID.Valid && bookingID.String != "" {
		b := bookingID.String
		r.BookingID = &b
	}
	if createdBy.Valid && createdBy.String != "" {
		c := createdBy.String
		r.CreatedBy = &c
	}
	return r, nil
}

// failStaleRow marks one stale pending row 'failed'. Returns true when the row
// was updated (status was still 'pending').
func failStaleRow(ctx context.Context, table, id string) bool {
	tag, err := db.Conn.Exec(ctx, `
		UPDATE `+table+` SET status = 'failed', updated_at = NOW()
		WHERE id = $1 AND status = 'pending'
	`, id)
	if err != nil {
		log.Printf("Failed to mark stale pending row %s failed: %v", id, err)
		return false
	}
	return int(tag.RowsAffected()) > 0
}

// rescueStaleRowCompleted marks one stale pending row (whose square_payment_id
// already resolves to a COMPLETED charge) 'completed'. Returns true when the
// row was updated.
func rescueStaleRowCompleted(ctx context.Context, table, id string) bool {
	tag, err := db.Conn.Exec(ctx, `
		UPDATE `+table+` SET status = 'completed', updated_at = NOW()
		WHERE id = $1 AND status = 'pending'
	`, id)
	if err != nil {
		log.Printf("Failed to rescue stale pending row %s to completed: %v", id, err)
		return false
	}
	return int(tag.RowsAffected()) > 0
}

// rescueKeyedStaleRowCompleted marks a keyed stale pending row 'completed' with
// the square_payment_id returned by the replay — the lost-response rescue. The
// reconcile is deliberately minimal (status + square_payment_id + updated_at
// only, no split/VAT recomputation): the row is >22h stale and this is a
// reconciliation rescue, mirroring the F3 by-id rescue's minimality. Returns
// true when the row was updated.
func rescueKeyedStaleRowCompleted(ctx context.Context, table, id, squarePaymentID string) bool {
	tag, err := db.Conn.Exec(ctx, `
		UPDATE `+table+` SET status = 'completed', square_payment_id = $1, updated_at = NOW()
		WHERE id = $2 AND status = 'pending'
	`, squarePaymentID, id)
	if err != nil {
		log.Printf("Failed to rescue stale pending row %s to completed: %v", id, err)
		return false
	}
	return int(tag.RowsAffected()) > 0
}

// clawbackTillSaleFunding claws back a stale pending till sale's funded gift
// card (atomically with the failed mark) after a reconcile PROVED the charge
// never completed — the funding has no charge behind it. A sale with no gift
// card is only marked failed. Returns true when the sale was resolved to
// failed; false when it was already resolved by someone else, had no gift card,
// or the clawback failed (CRITICAL logged).
func clawbackTillSaleFunding(ctx context.Context, r staleRow) bool {
	action := "topup"
	if r.IsCreate {
		action = "create"
	}
	if revErr := revertGiftCardFunding(ctx, action, r.ItemID, r.TotalAmount, r.RedeemToUserID, r.ID); revErr != nil {
		if errors.Is(revErr, errTillSaleNotPending) {
			log.Printf("Stale pending till sale %s was already resolved (not pending) — skipping funding clawback", r.ID)
			return false
		}
		log.Printf("CRITICAL: failed to claw back gift card %s funding for stale till sale %s: %v — MANUAL RECONCILIATION REQUIRED: gift card may still be funded", r.ItemID, r.ID, revErr)
		return false
	}
	return true
}

// reconcileStalePaymentByKey asks Square for the authoritative status of the
// charge made under a stale pending row's idempotency key and returns the
// tri-state result. The replay sends an IDENTICAL body to the original charge:
// the stored square_request_snapshot (the FULL request — source_id, key,
// amount and every field the original carried). Replaying a partial body would
// return IDEMPOTENCY_KEY_REUSED for a RETAINED key and strand the row pending
// forever. Square's idempotency guarantee returns the ORIGINAL payment for a
// retained key (never a second charge); a COMPLETED payment rescues the row to
// 'completed' with its real payment id. A definitive 4xx rejection
// (ErrReplayKeyNotRetained — Square attempted a real charge with the
// expired/used source and refused it, so the charge never happened) or a
// FAILED/CANCELED payment proves the charge never completed and fails the row.
// IDEMPOTENCY_KEY_REUSED is NEVER proof of no charge: with an identical body it
// can only mean the stored source differs from the original (a data bug), so
// the row is left pending with a CRITICAL log. Any OTHER error (transport /
// 5xx / ambiguous) leaves the row pending — the charge may still have completed
// at Square. The second return value is the Square payment id of the completed
// payment ("" otherwise), written back on a rescue.
//
// ENV CONTRACT (finding 4): the sweep and the charge process MUST run with the
// SAME SQUARE_ENVIRONMENT and SQUARE_LOCATION_ID. The stored snapshot embeds
// the location_id used at charge time; if the env/location changes between a
// charge and its replay, the replayed wire body differs and a RETAINED key
// returns IDEMPOTENCY_KEY_REUSED — stranding every retained-key row pending
// (safe) until the 24h blind-fail. This is a single-location deployment; the
// contract is enforced by ops (same env for the sweeper and the API), NOT by a
// runtime equality check — deliberately comment-only.
func reconcileStalePaymentByKey(ctx context.Context, table string, r staleRow) (staleReconcileResult, string) {
	snapshot := r.SquareRequestSnapshot
	// fallbackBody is true when the row has NO stored square_request_snapshot
	// and the minimal body (key + source + amount) is rebuilt. The rebuilt body
	// omits reference_id / customer_id / note / buyer_email_address that the
	// original charge carried, so for a RETAINED key real Square compares the
	// WHOLE body, sees the difference and returns IDEMPOTENCY_KEY_REUSED
	// (stranding the row pending) while the dev mock — which compares only the
	// source — returns the original payment (rescuing it). Both are money-safe;
	// the divergence is dev-vs-prod OBSERVABILITY only, and pre-launch there
	// are no prod legacy rows (every charge now stores its snapshot), so the
	// fallback semantics are deliberately left unchanged.
	fallbackBody := false
	if len(bytes.TrimSpace(snapshot)) == 0 {
		fallbackBody = true
		// Legacy row without a stored request snapshot — rebuild the minimal
		// identical body (key + source + amount) exactly as the pre-snapshot
		// replay did. Such rows can still be reconciled as long as the stored
		// source/amount match the original charge.
		fallback, mErr := json.Marshal(square.CreatePaymentReq{
			Amount:         r.AmountPence,
			Currency:       "GBP",
			SourceID:       r.SquareSourceID,
			IdempotencyKey: r.IdempotencyKey,
		})
		if mErr != nil {
			log.Printf("Stale pending %s reconcile by key: failed to rebuild replay body for row %s (%v) — leaving pending", table, r.ID, mErr)
			return staleReconcileLeavePending, ""
		}
		snapshot = fallback
	}
	// The replay repeats the stored request snapshot verbatim so Square's
	// idempotency dedup returns the original payment for a retained key — which
	// requires the sweep to share SQUARE_ENVIRONMENT/SQUARE_LOCATION_ID with the
	// charge process (see the ENV CONTRACT above).
	pr, err := SquareClient.ReplayPaymentByKey(ctx, snapshot)
	if err != nil {
		if errors.Is(err, square.ErrReplayKeyNotRetained) {
			log.Printf("Stale pending %s reconcile by key: Square has no payment under the stored idempotency key (identical-body replay rejected) — marking failed; the charge provably never happened", table)
			return staleReconcileDefinitivelyFailed, ""
		}
		if square.ErrorCode(err) == "IDEMPOTENCY_KEY_REUSED" {
			if fallbackBody {
				// Snapshot-less fallback row: the minimal rebuilt body cannot be
				// identical to the original charge, so real Square rejects the
				// retained-key replay while the dev mock (source-aware only)
				// rescues it. The stranded row would otherwise be invisible
				// until the 24h blind-fail — surface it now (finding 2).
				log.Printf("CRITICAL: stale pending %s reconcile by key hit IDEMPOTENCY_KEY_REUSED via the minimal snapshot-less fallback body (key=%s) — real Square compares the WHOLE request (reference_id/customer_id/note/buyer_email_address absent from the rebuilt body) and rejects the identical-key replay, stranding the row pending; the dev mock would rescue it — dev-vs-prod observability divergence, NOT proof the charge never happened — MANUAL RECONCILIATION REQUIRED", table, r.IdempotencyKey)
			} else {
				log.Printf("CRITICAL: stale pending %s reconcile by key hit IDEMPOTENCY_KEY_REUSED — the stored square_source_id differs from the original charge's source (data bug); this is NOT proof the charge never happened — leaving pending — MANUAL RECONCILIATION REQUIRED", table)
			}
			return staleReconcileLeavePending, ""
		}
		log.Printf("Stale pending %s reconcile by idempotency key hit an ambiguous error (%v) — leaving pending for a later sweep run", table, err)
		return staleReconcileLeavePending, ""
	}
	// Square's terminal payment states are COMPLETED, CANCELED, FAILED;
	// APPROVED (authorization-only, delayed capture) and PENDING are
	// NON-terminal — both can still transition to COMPLETED, so clawing back
	// the funded gift card on either would risk reversing a charge that later
	// lands. This app always creates payments with autocomplete (default true),
	// so it never produces APPROVED/PENDING rows today, but the classification
	// must match Square's documented state machine.
	switch pr.Status {
	case "COMPLETED":
		return staleReconcileCompleted, pr.ID
	case "CANCELED", "FAILED":
		log.Printf("Stale pending %s is %q at Square (replay by key) — marking failed", table, pr.Status)
		return staleReconcileDefinitivelyFailed, ""
	case "APPROVED", "PENDING":
		log.Printf("Stale pending %s is %q at Square (replay by key, non-terminal) — leaving pending for a later sweep run", table, pr.Status)
		return staleReconcileLeavePending, ""
	default:
		log.Printf("Stale pending %s is %q at Square (replay by key) — marking failed", table, pr.Status)
		return staleReconcileDefinitivelyFailed, ""
	}
}

// leaveGiftCardPurchasePending keeps a gift-card-purchase payment row (payments
// table, booking_id NULL) pending after Square confirms the charge COMPLETED,
// instead of rescuing it to 'completed'. Completing the row would permanently
// block the same-key retry (BuyGiftCard) that reuses the pending record to
// deliver the card — the customer would stay charged with no gift card (C6).
// The row is left pending with a CRITICAL log + admin notification so the retry
// can still deliver the card and an admin is alerted to reconcile manually.
func leaveGiftCardPurchasePending(ctx context.Context, r staleRow) {
	log.Printf("CRITICAL: gift card purchase payment %s is COMPLETED at Square but the gift card was never issued (issue transaction failed, retry abandoned) — leaving the payment PENDING so a same-key retry can still deliver the card — MANUAL RECONCILIATION REQUIRED", r.ID)
	insertCriticalPaymentNotification(ctx, nil, r.CreatedBy)
}

// insertCriticalPaymentNotification surfaces an unresolved money event in the
// admin notification centre (reason 'critical_payment_log' — the DB-backed
// stand-in for the un-watched CRITICAL payment logs). bookingID is set when the
// issue ties to a booking (untracked terminal charges); userID is set when it
// ties to a user (gift-card purchases). The NOT EXISTS guard keeps ONE
// notification per issue instead of one per sweep run.
func insertCriticalPaymentNotification(ctx context.Context, bookingID, userID *string) {
	tag, err := db.Conn.Exec(ctx, `
		INSERT INTO admin_notifications (reason, booking_id, user_id, created_at)
		SELECT 'critical_payment_log', $1, $2, NOW()
		WHERE NOT EXISTS (
			SELECT 1 FROM admin_notifications an
			WHERE an.reason = 'critical_payment_log'
			  AND an.booking_id IS NOT DISTINCT FROM $1
			  AND an.user_id IS NOT DISTINCT FROM $2
		)
	`, bookingID, userID)
	if err != nil {
		log.Printf("Failed to insert admin_notifications for critical payment issue (booking=%v user=%v): %v", bookingID, userID, err)
		return
	}
	if int(tag.RowsAffected()) > 0 {
		log.Printf("Inserted critical-payment admin notification (booking=%v user=%v)", bookingID, userID)
	}
}

// staleReconcileResult is the tri-state outcome of reconciling one stale
// pending row against Square. Only a definitively-resolved outcome touches the
// row: an ambiguous answer (transport error / 5xx) leaves it pending so a
// same-key retry can still reuse it if the charge actually completed.
type staleReconcileResult int

const (
	// staleReconcileLeavePending — Square's answer was ambiguous; the row stays
	// pending for the next sweep run.
	staleReconcileLeavePending staleReconcileResult = iota
	// staleReconcileCompleted — Square confirms the charge completed; rescue
	// the row to 'completed'.
	staleReconcileCompleted
	// staleReconcileDefinitivelyFailed — Square proves the charge never
	// completed (payment not found / non-completed status); mark the row
	// 'failed' exactly as the legacy bulk sweep did.
	staleReconcileDefinitivelyFailed
)

// reconcileStalePaymentAtSquare asks Square for the authoritative status of a
// stale pending charge and returns the tri-state result. A COMPLETED payment
// rescues the row to 'completed'; a NOT_FOUND error or any non-COMPLETED status
// proves the charge never completed and fails the row as the legacy bulk sweep
// did. Any OTHER error (transport / 5xx / ambiguous) is NOT treated as a
// definitive failure — the charge may still have completed at Square, and
// marking the row failed would close the double-charge window (blocking a
// same-key retry with a 409) even though the money moved. Such rows stay
// pending for a later run.
func reconcileStalePaymentAtSquare(ctx context.Context, table, squarePaymentID string) staleReconcileResult {
	pr, err := SquareClient.GetPayment(ctx, squarePaymentID)
	if err != nil {
		if squarePaymentErrorIsNotFound(err) {
			log.Printf("Stale pending %s reconcile: Square payment %s not found (%v) — marking failed as the legacy sweep would", table, squarePaymentID, err)
			return staleReconcileDefinitivelyFailed
		}
		log.Printf("Stale pending %s reconcile for Square payment %s hit an ambiguous error (%v) — leaving pending for a later sweep run", table, squarePaymentID, err)
		return staleReconcileLeavePending
	}
	// Square's terminal payment states are COMPLETED, CANCELED, FAILED;
	// APPROVED (authorization-only, delayed capture) and PENDING are
	// NON-terminal — both can still transition to COMPLETED (via
	// CompletePayment or delay_action=COMPLETE), so clawing back the funded
	// gift card on either would risk reversing a charge that later lands.
	// This app always creates payments with autocomplete (default true), so
	// it never produces APPROVED/PENDING rows today, but the classification
	// must match Square's documented state machine (librarian-verified
	// 2026-05-20).
	switch pr.Status {
	case "COMPLETED":
		return staleReconcileCompleted
	case "CANCELED", "FAILED":
		log.Printf("Stale pending %s is %q at Square — marking failed", table, pr.Status)
		return staleReconcileDefinitivelyFailed
	case "APPROVED", "PENDING":
		log.Printf("Stale pending %s is %q at Square (non-terminal) — leaving pending for a later sweep run", table, pr.Status)
		return staleReconcileLeavePending
	default:
		log.Printf("Stale pending %s is %q at Square — marking failed", table, pr.Status)
		return staleReconcileDefinitivelyFailed
	}
}

// squarePaymentErrorIsNotFound reports whether a GetPayment error proves the
// payment does not exist at Square. The structured not-found check is primary
// (square.IsNotFound: NOT_FOUND code / HTTP 404 status / plain "HTTP 404" body);
// the message fallback covers only the dev mock's plain "payment not found"
// error, which carries no structured code.
func squarePaymentErrorIsNotFound(err error) bool {
	if err == nil {
		return false
	}
	if square.IsNotFound(err) {
		return true
	}
	// Any other structured Square error code is authoritative — never
	// substring-match its message.
	if square.ErrorCode(err) != "" {
		return false
	}
	msg := strings.ToUpper(err.Error())
	return strings.Contains(msg, "NOT_FOUND") ||
		strings.Contains(msg, "NOT FOUND")
}

// squareHasCode reports whether err carries a structured Square error code
// equal to any of codes. Errors without a structured code (the dev mock's
// plain errors) match nothing.
func squareHasCode(err error, codes ...string) bool {
	if err == nil {
		return false
	}
	code := square.ErrorCode(err)
	for _, c := range codes {
		if code == c {
			return true
		}
	}
	return false
}

// staleTerminalCheckoutAge is how old a still-pending terminal checkout must
// be before the sweep cancels it. Terminal checkouts normally complete within
// minutes; an hour is far past any legitimate card-reader interaction while
// still short enough that a completed charge can never be misread as stale.
const staleTerminalCheckoutAge = 1 * time.Hour

// SweepStaleTerminalCheckouts cancels terminal (card-machine) checkouts that
// are still PENDING/IN_PROGRESS long after they were created, so the terminal
// stops waiting on a customer who walked away. A checkout created by
// CreateTerminalPayment / CreateTillSale that is never polled would otherwise
// sit live at Square indefinitely; if it later completes it is an invisible,
// untracked charge.
//
// Two tables track live checkout IDs and are both swept:
//   - terminal_checkouts: booking terminal checkouts created by
//     CreateTerminalPayment. PENDING/IN_PROGRESS rows older than the cutoff
//     are resolved at Square first: a checkout still waiting at Square is
//     cancelled and re-checked once — if it completed during the cancel window
//     the row is marked 'completed' (the poll handler records the payment),
//     otherwise 'failed'; a COMPLETED checkout releases the in-flight guard
//     (the poll handler records the payment); a definitively
//     cancelled/expired checkout is marked 'failed'; an ambiguous status is
//     left for a later run.
//   - till_sales.square_checkout_id: card-machine till sales. A checkout still
//     waiting at Square is cancelled and the sale marked 'failed' (the
//     payment_status enum has no 'cancelled' value, and 'failed' is the same
//     terminal state the stale-pending sweep uses, blocking the till
//     pending-retry path); a checkout that completed during the cancel window
//     (or was already COMPLETED when first checked) is RECORDED by the sweep —
//     the sale is marked 'completed' with the returned square_payment_id, the
//     till mirror of the booking path's recordUntrackedTerminalPayment (a
//     never-polled sale would otherwise stay invisible in till reporting until
//     the 24h blind-fail).
//
// Each row is checked at Square FIRST and only cancelled when the checkout is
// provably still waiting (ErrCheckoutPending): a COMPLETED checkout is never
// cancelled, and a checkout whose status is unknown (transport error) is left
// alone for a later run. After a cancel the checkout is re-checked once — the
// customer may have completed the payment in the cancel window, in which case
// the row is resolved to 'completed' rather than 'failed'.
func SweepStaleTerminalCheckouts(ctx context.Context) (int, error) {
	cutoff := clock.Now().Add(-staleTerminalCheckoutAge)

	var pending []staleTerminalCheckoutRow

	// Booking terminal checkouts (CreateTerminalPayment) live in the
	// terminal_checkouts table. A stale PENDING/IN_PROGRESS row means the
	// checkout is still live at Square (or was left after a crash / lost poll).
	rows, err := db.Conn.Query(ctx, `
		SELECT 'terminal_checkout', checkout_id, checkout_id, booking_id
		FROM terminal_checkouts
		WHERE status IN ('PENDING', 'IN_PROGRESS')
		  AND created_at < $1
	`, cutoff)
	if err != nil {
		return 0, err
	}
	for rows.Next() {
		var r staleTerminalCheckoutRow
		if err := rows.Scan(&r.Kind, &r.RowID, &r.CheckoutID, &r.BookingID); err != nil {
			log.Printf("Failed to scan stale terminal checkout row: %v", err)
			continue
		}
		pending = append(pending, r)
	}
	rows.Close()

	// Till-sale card-machine checkouts are tracked on the till_sales row.
	rows, err = db.Conn.Query(ctx, `
		SELECT 'till_sale', id, square_checkout_id, ''
		FROM till_sales
		WHERE status = 'pending' AND square_checkout_id IS NOT NULL
		  AND created_at < $1
	`, cutoff)
	if err != nil {
		return 0, err
	}
	for rows.Next() {
		var r staleTerminalCheckoutRow
		if err := rows.Scan(&r.Kind, &r.RowID, &r.CheckoutID, &r.BookingID); err != nil {
			log.Printf("Failed to scan stale terminal checkout row: %v", err)
			continue
		}
		pending = append(pending, r)
	}
	rows.Close()

	resolved := 0
	for _, r := range pending {
		// A provisional (pre-Square) terminal_checkouts row carries a synthetic
		// "tmp-" checkout_id (or an empty one) — no checkout was ever created
		// at Square for it, so it is PROVABLY not live (R3). Resolve it to
		// failed directly without a Square round-trip; a hard crash between the
		// row insert and the Square CreateCheckout call is the only way one
		// exists.
		if r.CheckoutID == "" || strings.HasPrefix(r.CheckoutID, "tmp-") {
			if markTerminalCheckoutRowFailed(ctx, r) {
				resolved++
			}
			log.Printf("Provisional (pre-Square) terminal checkout row %s (%s) resolved as failed — no live checkout at Square", r.RowID, r.Kind)
			continue
		}

		// Conservative status check: only cancel a checkout that is provably
		// still waiting at Square. A COMPLETED checkout must never be
		// cancelled, and an ambiguous status (network error) is left alone for
		// the next run.
		pr, gErr := SquareClient.GetCheckout(ctx, r.CheckoutID)
		switch {
		case errors.Is(gErr, square.ErrCheckoutPending):
			// Still live at the terminal — cancel it. A customer can complete
			// the payment in the small window between the GetCheckout above and
			// the cancel, so re-check once before marking the row failed: a
			// COMPLETED charge must never be recorded as failed.
			if cErr := SquareClient.CancelCheckout(ctx, r.CheckoutID); cErr != nil {
				log.Printf("Failed to cancel stale terminal checkout %s (%s %s): %v", r.CheckoutID, r.Kind, r.RowID, cErr)
				continue
			}
			recheck, rErr := SquareClient.GetCheckout(ctx, r.CheckoutID)
			switch {
			case rErr == nil && recheck.Status == "COMPLETED":
				// The customer completed the payment during the cancel window.
				// Record it if it was never polled/recorded — a COMPLETED
				// checkout must not stay an untracked charge (H4). Booking
				// checkouts record full payments rows; till-sale checkouts
				// record the sale row (finding 3).
				if r.Kind == "terminal_checkout" {
					if recordUntrackedTerminalPayment(ctx, r.CheckoutID, r.BookingID, recheck) {
						resolved++
					}
				} else if recordUntrackedTillSalePayment(ctx, r.RowID, recheck) {
					resolved++
				}
				log.Printf("Cancelled stale terminal checkout %s (%s %s, pending >%s) but re-check shows COMPLETED — payment recorded by the sweep", r.CheckoutID, r.Kind, r.RowID, staleTerminalCheckoutAge)
			case isTerminalCheckoutError(rErr) || errors.Is(rErr, square.ErrCheckoutPending):
				// The cancel landed (CANCELED / cancel-requested / expired /
				// still-reporting-pending-but-now-cancelled) — it can never
				// complete, so resolve the row to the terminal 'failed' state.
				// A till sale's funded gift card is clawed back (a cancel that
				// landed cannot later complete); a booking terminal_checkout
				// has no gift card.
				if r.Kind == "till_sale" {
					if clawBackTillSaleFunding(ctx, r.RowID) {
						resolved++
					}
				} else if markTerminalCheckoutRowFailed(ctx, r) {
					resolved++
				}
				log.Printf("Cancelled stale terminal checkout %s (%s %s, pending >%s) — marked failed", r.CheckoutID, r.Kind, r.RowID, staleTerminalCheckoutAge)
			default:
				// The cancel succeeded but the re-check itself is ambiguous —
				// leave the row for a later run.
				log.Printf("Terminal checkout %s was cancelled but its re-check is ambiguous (%v) — leaving %s %s pending for a later sweep", r.CheckoutID, rErr, r.Kind, r.RowID)
			}
		case gErr == nil && pr.Status == "COMPLETED":
			if r.Kind == "terminal_checkout" {
				// The checkout completed at Square but was never polled/recorded
				// (the frontend never called GetCheckoutStatus). Record the
				// payment rows now — otherwise the charge stays invisible to
				// refunds and TotalPaid (H4).
				if recordUntrackedTerminalPayment(ctx, r.CheckoutID, r.BookingID, pr) {
					resolved++
				}
			} else if recordUntrackedTillSalePayment(ctx, r.RowID, pr) {
				// A never-polled COMPLETED till-sale checkout must not stay
				// pending until the 24h blind-fail (finding 3) — the charge is
				// real, so the sale is recorded completed with the payment id.
				resolved++
			}
		case isTerminalCheckoutError(gErr):
			// The checkout is cancelled / cancel-requested / expired at Square.
			switch {
			case r.Kind == "till_sale" && isCheckoutDefinitivelyDead(gErr):
				// The error PROVES the checkout can never complete (CANCELED /
				// NOT_FOUND, and no bare CANCEL_REQUESTED) — claw back the
				// funded gift card along with the failed mark.
				if clawBackTillSaleFunding(ctx, r.RowID) {
					resolved++
				}
				log.Printf("Terminal checkout %s is definitively terminal (%v) — marked till sale %s failed, gift-card funding clawed back", r.CheckoutID, gErr, r.RowID)
			case r.Kind == "till_sale":
				// CANCEL_REQUESTED-only: Square does not promise non-completion
				// in that state, so the charge may still land. Mark the sale
				// failed but DO NOT claw back the funded gift card.
				if markTerminalCheckoutRowFailed(ctx, r) {
					resolved++
				}
				log.Printf("CRITICAL: terminal checkout %s reports only CANCEL_REQUESTED (not provably dead) — till sale %s marked failed WITHOUT clawing back the funded gift card; verify at Square before re-issuing — MANUAL RECONCILIATION REQUIRED", r.CheckoutID, r.RowID)
			default:
				if markTerminalCheckoutRowFailed(ctx, r) {
					resolved++
				}
				log.Printf("Terminal checkout %s is definitively terminal (%v) — marked %s %s failed", r.CheckoutID, gErr, r.Kind, r.RowID)
			}
		default:
			// Ambiguous transport/unknown status — leave for a later run.
			log.Printf("Terminal checkout %s status unknown (%v) — leaving %s %s pending for a later sweep", r.CheckoutID, gErr, r.Kind, r.RowID)
		}
	}
	return resolved, nil
}

// staleTerminalCheckoutRow is one live-checkout row the sweep reads from
// either table so it can resolve the checkout at Square before touching the
// row. Kind is "terminal_checkout" (booking, terminal_checkouts table) or
// "till_sale" (till_sales.square_checkout_id). BookingID is the booking the
// terminal_checkouts row belongs to ("" for till sales) — needed to record an
// untracked COMPLETED terminal charge (H4).
type staleTerminalCheckoutRow struct {
	Kind       string
	RowID      string
	CheckoutID string
	BookingID  string
}

// markTerminalCheckoutRowFailed moves one tracked row to the terminal 'failed'
// state after its checkout is cancelled or proven terminal at Square. Returns
// true when the row was updated (status was still active).
func markTerminalCheckoutRowFailed(ctx context.Context, r staleTerminalCheckoutRow) bool {
	var table, where string
	if r.Kind == "till_sale" {
		table = "till_sales"
		where = "id = $1 AND status = 'pending'"
	} else {
		table = "terminal_checkouts"
		where = "checkout_id = $1 AND status IN ('PENDING', 'IN_PROGRESS')"
	}
	tag, err := db.Conn.Exec(ctx, `
		UPDATE `+table+` SET status = 'failed', updated_at = NOW()
		WHERE `+where, r.RowID)
	if err != nil {
		log.Printf("Failed to mark %s %s failed: %v", r.Kind, r.RowID, err)
		return false
	}
	return int(tag.RowsAffected()) > 0
}

// recordUntrackedTerminalPayment records the payments row(s) for a terminal
// checkout that COMPLETED at Square but was never polled/recorded, then marks
// the terminal_checkouts row COMPLETED. The stale sweep otherwise leaves a real
// charge with NO payments row — invisible to refunds and TotalPaid (H4). It
// reuses the exact insert convention of GetCheckoutStatus: the same advisory
// lock key (serializes against a concurrent poll), the same dedup by
// booking_id + square_payment_id, the same PaymentRecord shape and derived
// idempotency key, and the same deposit/balance/tip split for a charge above
// the remaining booking value. Returns true when the checkout row was resolved
// (payment recorded or already recorded); false when recording failed (the
// row is left pending so the next sweep re-runs the whole reconcile).
func recordUntrackedTerminalPayment(ctx context.Context, checkoutID, bookingID string, pr *square.PaymentResult) bool {
	if pr == nil || pr.SquarePayID == "" {
		log.Printf("CRITICAL: terminal checkout %s is COMPLETED at Square but carries no Square payment ID — cannot record the payment — MANUAL RECONCILIATION REQUIRED", checkoutID)
		return false
	}
	service := NewPaymentService()

	// Serialize with the poll handler (GetCheckoutStatus): both record the same
	// Square payment, so the advisory lock + dedup SELECT prevent a double
	// insert (the idempotency_key UNIQUE constraint is the backstop).
	pinConn, err := db.Conn.Acquire(ctx)
	if err != nil {
		log.Printf("Failed to acquire connection for terminal-completion lock: %v", err)
		return false
	}
	defer pinConn.Release()
	lockOK, err := acquireAdvisoryLock(ctx, pinConn, "crussell:terminal:"+pr.SquarePayID)
	if err != nil {
		log.Printf("Failed to acquire terminal-completion serialization lock for %s: %v", pr.SquarePayID, err)
		return false
	}
	if !lockOK {
		log.Printf("Terminal-completion serialization lock for %s not acquired within bound — a poll is already recording this checkout", pr.SquarePayID)
		return false
	}
	defer func() {
		if _, err := pinConn.Exec(context.Background(), `SELECT pg_advisory_unlock(hashtext('crussell:terminal:' || $1))`, pr.SquarePayID); err != nil {
			log.Printf("Failed to release terminal-completion serialization lock for %s: %v", pr.SquarePayID, err)
		}
	}()

	tx, err := db.Conn.Begin(ctx)
	if err != nil {
		log.Printf("Failed to begin terminal-completion transaction: %v", err)
		return false
	}
	defer func() {
		if err := tx.Rollback(ctx); err != nil && !errors.Is(err, pgx.ErrTxClosed) {
			log.Printf("Failed to rollback terminal-completion transaction: %v", err)
		}
	}()

	// Dedup by Square payment ID: a concurrent poll (or a prior sweep run)
	// already recorded this charge — just release the in-flight guard.
	var existingID string
	if err := tx.QueryRow(ctx, `
		SELECT id FROM payments
		WHERE booking_id = $1 AND square_payment_id = $2
	`, bookingID, pr.SquarePayID).Scan(&existingID); err == nil {
		if _, upErr := tx.Exec(ctx, `
			UPDATE terminal_checkouts SET status = 'COMPLETED', updated_at = NOW()
			WHERE checkout_id = $1 AND status IN ('PENDING', 'IN_PROGRESS')
		`, checkoutID); upErr != nil {
			log.Printf("Failed to mark terminal checkout %s completed: %v", checkoutID, upErr)
			return false
		}
		if cErr := tx.Commit(ctx); cErr != nil {
			log.Printf("Failed to commit terminal-completion transaction: %v", cErr)
			return false
		}
		return true
	} else if !errors.Is(err, pgx.ErrNoRows) {
		log.Printf("Failed to check for existing terminal payment: %v", err)
		return false
	}

	// The payment type the admin charged is recorded on the checkout row by
	// CreateTerminalPayment; fall back to 'full' for legacy rows.
	var checkoutPaymentType string
	if err := tx.QueryRow(ctx, `
		SELECT payment_type FROM terminal_checkouts WHERE checkout_id = $1
	`, checkoutID).Scan(&checkoutPaymentType); err != nil {
		if !errors.Is(err, pgx.ErrNoRows) {
			log.Printf("Failed to read payment type for checkout %s: %v", checkoutID, err)
		}
		checkoutPaymentType = "full"
	}

	idempotencyKey := bookingID + "-terminal-" + strconv.FormatInt(pr.Amount, 10) + "-" + pr.SquarePayID
	record := PaymentRecord{
		BookingID:       bookingID,
		PaymentType:     checkoutPaymentType,
		PaymentMethod:   "in_person_card",
		Status:          "completed",
		Amount:          float64(pr.Amount) / 100.0,
		SquarePaymentID: &pr.SquarePayID,
		IdempotencyKey:  &idempotencyKey,
		Fees:            float64(pr.Fees) / 100.0,
		CreatedAt:       clock.Now(),
		UpdatedAt:       clock.Now(),
	}

	// M4 split: a terminal charge above the remaining booking value is a tip —
	// record it as its own record so only the booking portion is refundable.
	var records []PaymentRecord
	bookingInfo, bErr := service.GetBookingPaymentInfo(ctx, bookingID)
	if bErr == nil && bookingInfo != nil {
		charged := float64(pr.Amount) / 100.0
		remainingBookingValue := math.Max(0, bookingInfo.TotalAmount-bookingInfo.TotalPaid)
		bookingPortion := math.Min(charged, remainingBookingValue)
		bookingPortion = math.Round(bookingPortion*100) / 100
		tipAmount := math.Round((charged-bookingPortion)*100) / 100
		if tipAmount > 0.004 {
			records = buildTerminalSplitRecords(record, bookingInfo, bookingPortion, tipAmount)
		}
	}
	if len(records) == 0 {
		records = []PaymentRecord{record}
	}

	primary := records[0]
	paymentID, err := service.CreatePaymentRecordTx(ctx, tx, primary, nil)
	if err != nil {
		log.Printf("Failed to create payment record for untracked terminal charge %s: %v", pr.SquarePayID, err)
		return false
	}
	ApplyVATToBookingPayment(ctx, tx, paymentID)
	for _, rec := range records[1:] {
		pid, cErr := service.CreatePaymentRecordTx(ctx, tx, rec, nil)
		if cErr != nil {
			log.Printf("Failed to create terminal tip split record: %v", cErr)
			return false
		}
		ApplyVATToBookingPayment(ctx, tx, pid)
	}

	// Release the in-flight guard: this checkout is now recorded.
	if _, err := tx.Exec(ctx, `
		UPDATE terminal_checkouts SET status = 'COMPLETED', updated_at = NOW()
		WHERE checkout_id = $1 AND status IN ('PENDING', 'IN_PROGRESS')
	`, checkoutID); err != nil {
		log.Printf("Failed to mark terminal checkout %s completed: %v", checkoutID, err)
		return false
	}
	if err := tx.Commit(ctx); err != nil {
		log.Printf("Failed to commit terminal-completion transaction: %v", err)
		return false
	}

	// The booking may now be fully paid — complete it like the poll handler does.
	completeFullyPaidBooking(ctx, bookingID)
	log.Printf("CRITICAL: recorded untracked terminal charge %s (booking %s) from stale checkout %s — payment row %s created (never polled by the frontend)", pr.SquarePayID, bookingID, checkoutID, paymentID)
	return true
}

// recordUntrackedTillSalePayment records a stale card-machine till sale whose
// checkout COMPLETED at Square but was never polled/recorded: the sale is
// marked 'completed' with the returned square_payment_id written back. A
// never-polled COMPLETED checkout would otherwise leave the sale pending until
// the 24h blind-fail — the charge is real but invisible in till reporting
// (money-safe: the gift card was funded pre-charge, a blind-fail never claws
// back, and failed rows reject retries — but the till reporting would be wrong,
// finding 3). There is no split/deposit concept for till sales — a single
// completed row, exactly the update the till poll handler (GetTillCheckoutStatus)
// performs. The WHERE status = 'pending' guard makes it safe against a
// concurrent poll: only one of them wins the update, the loser sees 0 rows and
// backs off. Returns true when the sale was updated; false when the checkout
// carries no Square payment id (the sale is left PENDING — never blind-failed
// — with a CRITICAL log for manual reconciliation) or the sale was already
// resolved by someone else.
func recordUntrackedTillSalePayment(ctx context.Context, saleID string, pr *square.PaymentResult) bool {
	if pr == nil || pr.SquarePayID == "" {
		log.Printf("CRITICAL: terminal checkout is COMPLETED at Square but carries no Square payment ID — cannot record till sale %s — leaving it PENDING — MANUAL RECONCILIATION REQUIRED", saleID)
		return false
	}
	tag, err := db.Conn.Exec(ctx, `
		UPDATE till_sales SET status = 'completed', square_payment_id = $1, updated_at = NOW()
		WHERE id = $2 AND status = 'pending'
	`, pr.SquarePayID, saleID)
	if err != nil {
		log.Printf("Failed to record untracked terminal till sale %s as completed: %v", saleID, err)
		return false
	}
	if int(tag.RowsAffected()) == 0 {
		// A concurrent poll (or a prior sweep run) already recorded the sale —
		// nothing left for this run to do.
		log.Printf("Terminal till sale %s was already resolved — skipping untracked terminal completion record", saleID)
		return false
	}
	log.Printf("CRITICAL: recorded untracked terminal till-sale charge %s (sale %s) from a stale checkout — sale marked completed (never polled by the frontend)", pr.SquarePayID, saleID)
	return true
}

// isTerminalCheckoutError reports whether a GetCheckout error proves the
// checkout can never complete. Square's HTTP client returns ErrCheckoutPending
// for a still-live checkout and surfaces a definitively CANCELED status as a
// "square: checkout <id> is CANCELED (not COMPLETED)" error; an expired
// checkout returns a structured NOT_FOUND API error (the mock uses a plain
// "checkout not found"). Any other error (timeout, 5xx) leaves the money state
// ambiguous, so the checkout must stay in flight.
//
// Structured codes are authoritative when present: NOT_FOUND (via
// square.IsNotFound) and an explicit CANCELED / CANCEL_REQUESTED code classify
// as terminal. The formatted-message match applies only to errors that carry
// no structured code — the dev mock's plain errors and the real client's
// client-side "is <status> (not COMPLETED)" error, which it synthesizes
// without a squareAPIError.
func isTerminalCheckoutError(err error) bool {
	if err == nil || errors.Is(err, square.ErrCheckoutPending) {
		return false
	}
	if square.IsNotFound(err) || squareHasCode(err, "CANCELED", "CANCEL_REQUESTED") {
		return true
	}
	// Any other structured Square error code is authoritative — never
	// substring-match its message.
	if square.ErrorCode(err) != "" {
		return false
	}
	msg := strings.ToUpper(err.Error())
	return strings.Contains(msg, "CANCELED") ||
		strings.Contains(msg, "CANCEL_REQUESTED") ||
		strings.Contains(msg, "NOT_FOUND") ||
		strings.Contains(msg, "NOT FOUND")
}

// isCheckoutDefinitivelyDead reports whether a GetCheckout error PROVES the
// checkout can never complete — the condition under which a till sale's funded
// gift card may be clawed back. It is stricter than isTerminalCheckoutError:
// a CANCEL_REQUESTED-only classification (Square does not promise non-completion
// in that state) is NOT definitive proof, so the charge may still land and the
// funding must stay put. Only an explicit CANCELED or NOT_FOUND status is
// definitive; a CANCEL_REQUESTED message counts only when it ALSO carries
// CANCELED.
//
// Structured codes are authoritative when present: CANCELED and NOT_FOUND are
// definitive, a bare CANCEL_REQUESTED code is not. The formatted-message match
// applies only to errors that carry no structured code (dev mock plain errors,
// and the real client's client-side "is <status> (not COMPLETED)" error).
func isCheckoutDefinitivelyDead(err error) bool {
	if err == nil || errors.Is(err, square.ErrCheckoutPending) {
		return false
	}
	if code := square.ErrorCode(err); code != "" {
		return code == "CANCELED" || code == "NOT_FOUND"
	}
	// Non-structured errors: an HTTP 404 / plain 404 body is definitive
	// (IsNotFound); the message match covers the client-side CANCELED status
	// error and the mock's plain not-found errors.
	if square.IsNotFound(err) {
		return true
	}
	msg := strings.ToUpper(err.Error())
	if !strings.Contains(msg, "CANCELED") && !strings.Contains(msg, "NOT_FOUND") && !strings.Contains(msg, "NOT FOUND") {
		return false
	}
	if strings.Contains(msg, "CANCEL_REQUESTED") && !strings.Contains(msg, "CANCELED") {
		return false
	}
	return true
}

// clawBackTillSaleFunding reverts the gift-card funding of a till sale whose
// card-machine checkout is provably dead, marking the sale failed at the same
// time. The terminal-checkout sweep's rows carry no gift-card context, so the
// sale's item/amount/redeem target are looked up here (is_create via the
// created_at equality with the gift card) and handed to the claim-first
// revertGiftCardFunding. A sale with no gift card (future retail product /
// orphaned item) is only marked failed. Returns true when the sale was
// resolved to failed; false when it was already resolved by someone else, had
// no gift card, or the clawback failed (CRITICAL logged).
func clawBackTillSaleFunding(ctx context.Context, tillSaleID string) bool {
	var itemType string
	var itemID sql.NullString
	var totalAmount float64
	var redeemedBy sql.NullString
	var isCreate *bool
	err := db.Conn.QueryRow(ctx, `
		SELECT ts.item_type, ts.item_id, ts.total_amount, gc.redeemed_by,
		       (ts.created_at = gc.created_at) AS is_create
		FROM till_sales ts
		LEFT JOIN gift_cards gc ON gc.id = ts.item_id
		WHERE ts.id = $1
	`, tillSaleID).Scan(&itemType, &itemID, &totalAmount, &redeemedBy, &isCreate)
	if err != nil {
		log.Printf("CRITICAL: failed to look up till sale %s for funding clawback: %v — MANUAL RECONCILIATION REQUIRED", tillSaleID, err)
		return false
	}
	if itemType != "gift_card" || !itemID.Valid || itemID.String == "" || isCreate == nil {
		// No gift card to claw back — mark the sale failed without touching
		// any card.
		tag, upErr := db.Conn.Exec(ctx, `
			UPDATE till_sales SET status = 'failed', updated_at = NOW()
			WHERE id = $1 AND status = 'pending'
		`, tillSaleID)
		if upErr != nil {
			log.Printf("Failed to mark till sale %s failed: %v", tillSaleID, upErr)
			return false
		}
		return int(tag.RowsAffected()) > 0
	}
	action := "topup"
	if *isCreate {
		action = "create"
	}
	var redeem *string
	if redeemedBy.Valid && redeemedBy.String != "" {
		redeem = &redeemedBy.String
	}
	if revErr := revertGiftCardFunding(ctx, action, itemID.String, totalAmount, redeem, tillSaleID); revErr != nil {
		if errors.Is(revErr, errTillSaleNotPending) {
			log.Printf("Till sale %s was already resolved (not pending) — skipping funding clawback", tillSaleID)
			return false
		}
		log.Printf("CRITICAL: funding clawback for till sale %s (gift card %s) failed: %v — MANUAL RECONCILIATION REQUIRED: gift card may still be funded", tillSaleID, itemID.String, revErr)
		return false
	}
	return true
}