guestguard/internal/notification/suppressions.go

package notification

import (
	"context"
	"errors"
	"strings"

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

	"github.com/alchemistkay/guestguard/internal/storage"
)

// SuppressionSource categorises why an address landed on the suppression
// list. Bounces + complaints come from provider webhooks; "user" is set
// when a guest clicks an unsubscribe link.
type SuppressionSource string

const (
	SuppressionBounce    SuppressionSource = "bounce"
	SuppressionComplaint SuppressionSource = "complaint"
	SuppressionManual    SuppressionSource = "manual"
	SuppressionUser      SuppressionSource = "user"
)

// SuppressionRepo manages the unsubscribes table — a flat suppression list
// of email addresses that must never receive another email regardless of
// notification type.
type SuppressionRepo struct {
	pool *pgxpool.Pool
}

func NewSuppressionRepo(db *storage.DB) *SuppressionRepo {
	return &SuppressionRepo{pool: db.Pool}
}

// IsSuppressed returns true if `email` is on the suppression list.
// Empty / unparseable addresses are treated as not-suppressed; the caller
// is expected to validate before sending.
func (r *SuppressionRepo) IsSuppressed(ctx context.Context, email string) (bool, error) {
	email = normaliseEmail(email)
	if email == "" {
		return false, nil
	}
	var exists bool
	err := r.pool.QueryRow(ctx,
		`SELECT EXISTS (SELECT 1 FROM unsubscribes WHERE email = $1)`,
		email,
	).Scan(&exists)
	if err != nil {
		return false, err
	}
	return exists, nil
}

// Add records `email` on the suppression list. Idempotent — repeated calls
// keep the earliest entry's timestamp.
func (r *SuppressionRepo) Add(ctx context.Context, email, reason string, src SuppressionSource) error {
	email = normaliseEmail(email)
	if email == "" {
		return errors.New("empty email")
	}
	_, err := r.pool.Exec(ctx, `
        INSERT INTO unsubscribes (email, reason, source)
        VALUES ($1, NULLIF($2, ''), $3)
        ON CONFLICT (email) DO NOTHING
    `, email, reason, string(src))
	return err
}

// Get returns the suppression record for `email`, or pgx.ErrNoRows if not
// found. Mostly used by tests / admin tooling.
func (r *SuppressionRepo) Get(ctx context.Context, email string) (string, SuppressionSource, error) {
	var reason *string
	var source string
	err := r.pool.QueryRow(ctx,
		`SELECT reason, source FROM unsubscribes WHERE email = $1`,
		normaliseEmail(email),
	).Scan(&reason, &source)
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return "", "", err
		}
		return "", "", err
	}
	r2 := ""
	if reason != nil {
		r2 = *reason
	}
	return r2, SuppressionSource(source), nil
}

func normaliseEmail(s string) string {
	return strings.ToLower(strings.TrimSpace(s))
}