Reapply "feat(loyalty): EnakPoint & EnakCoin" (#32)

This reverts commit 4e24f9bbb0.

internal/repository/wallet_expiry_repository.go

@@ -0,0 +1,118 @@
+package repository
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/google/uuid"
+	"gorm.io/gorm"
+)
+
+// DueLot is a lot whose expiry has passed and that still holds something.
+type DueLot struct {
+	ID         uuid.UUID
+	CustomerID uuid.UUID
+	Currency   string
+	Remaining  int64
+	ExpiresAt  time.Time
+	// The description of the row that created the lot, for the EXPIRE row's.
+	SourceDescription string
+}
+
+// UpcomingExpiry is how much of a customer's balance expires on one day.
+type UpcomingExpiry struct {
+	CustomerID uuid.UUID
+	// A calendar date in walletDisplayTimeZone, formatted YYYY-MM-DD.
+	Date   string
+	Amount int64
+}
+
+// WalletExpiryRepository finds what the expiry job has to do (docs/prd-point-coin.md
+// F12). Balances only change through WalletProcessor.
+type WalletExpiryRepository interface {
+	// ListDueLots returns up to limit lots due at asOf, the longest overdue first. It
+	// takes no lock: locking a lot before its wallet would deadlock against payments,
+	// which lock the wallet first. WalletProcessor.ExpireLot locks and reads again.
+	ListDueLots(ctx context.Context, asOf time.Time, limit int) ([]DueLot, error)
+
+	// OrganizationsWithUpcomingExpiry lists the organizations that have balance
+	// expiring after asOf.
+	OrganizationsWithUpcomingExpiry(ctx context.Context, asOf time.Time) ([]uuid.UUID, error)
+	// UpcomingUnreminded sums, per customer and expiry day, the balance of one currency
+	// of an organization expiring after asOf and up to until, leaving out the days the
+	// customer has already been reminded of.
+	UpcomingUnreminded(ctx context.Context, organizationID uuid.UUID, currency string, asOf, until time.Time) ([]UpcomingExpiry, error)
+	// MarkReminded records a reminder, and reports false when it was already recorded,
+	// by this run or another.
+	MarkReminded(ctx context.Context, reminder UpcomingExpiry, currency string) (bool, error)
+}
+
+type walletExpiryRepository struct {
+	db *gorm.DB
+}
+
+func NewWalletExpiryRepository(db *gorm.DB) WalletExpiryRepository {
+	return &walletExpiryRepository{db: db}
+}
+
+func (r *walletExpiryRepository) ListDueLots(ctx context.Context, asOf time.Time, limit int) ([]DueLot, error) {
+	var lots []DueLot
+	err := DBFromContext(ctx, r.db).WithContext(ctx).Raw(`
+		SELECT l.id, l.customer_id, l.currency, l.remaining_amount AS remaining, l.expires_at,
+			t.description AS source_description
+		FROM wallet_lots l
+		JOIN wallet_transactions t ON t.id = l.source_transaction_id
+		WHERE l.remaining_amount > 0 AND l.expires_at <= ?
+		ORDER BY l.expires_at, l.id
+		LIMIT ?`, asOf, limit).Scan(&lots).Error
+	if err != nil {
+		return nil, fmt.Errorf("failed to list due wallet lots: %w", err)
+	}
+	return lots, nil
+}
+
+func (r *walletExpiryRepository) OrganizationsWithUpcomingExpiry(ctx context.Context, asOf time.Time) ([]uuid.UUID, error) {
+	var ids []uuid.UUID
+	err := DBFromContext(ctx, r.db).WithContext(ctx).Raw(`
+		SELECT DISTINCT organization_id FROM wallet_lots
+		WHERE remaining_amount > 0 AND expires_at > ?`, asOf).Scan(&ids).Error
+	if err != nil {
+		return nil, fmt.Errorf("failed to list organizations with expiring balances: %w", err)
+	}
+	return ids, nil
+}
+
+func (r *walletExpiryRepository) UpcomingUnreminded(ctx context.Context, organizationID uuid.UUID, currency string, asOf, until time.Time) ([]UpcomingExpiry, error) {
+	var rows []UpcomingExpiry
+	err := DBFromContext(ctx, r.db).WithContext(ctx).Raw(`
+		WITH by_day AS (
+			SELECT customer_id, (expires_at AT TIME ZONE ?)::date AS day, SUM(remaining_amount) AS amount
+			FROM wallet_lots
+			WHERE organization_id = ? AND currency = ? AND remaining_amount > 0
+				AND expires_at > ? AND expires_at <= ?
+			GROUP BY customer_id, day
+		)
+		SELECT d.customer_id, to_char(d.day, 'YYYY-MM-DD') AS date, d.amount
+		FROM by_day d
+		LEFT JOIN wallet_expiry_reminders w
+			ON w.customer_id = d.customer_id AND w.currency = ? AND w.expiry_date = d.day
+		WHERE w.customer_id IS NULL
+		ORDER BY d.day, d.customer_id`,
+		walletDisplayTimeZone, organizationID, currency, asOf, until, currency).Scan(&rows).Error
+	if err != nil {
+		return nil, fmt.Errorf("failed to list upcoming expiry: %w", err)
+	}
+	return rows, nil
+}
+
+func (r *walletExpiryRepository) MarkReminded(ctx context.Context, reminder UpcomingExpiry, currency string) (bool, error) {
+	res := DBFromContext(ctx, r.db).WithContext(ctx).Exec(`
+		INSERT INTO wallet_expiry_reminders (customer_id, currency, expiry_date, amount)
+		VALUES (?, ?, ?::date, ?)
+		ON CONFLICT DO NOTHING`, reminder.CustomerID, currency, reminder.Date, reminder.Amount)
+	if res.Error != nil {
+		return false, fmt.Errorf("failed to record expiry reminder: %w", res.Error)
+	}
+	return res.RowsAffected == 1, nil
+}