feat: seed secure demo merchant identity

internal/identity/seed.go

@@ -0,0 +1,39 @@
+package identity
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+type SeedResult struct {
+	Username          string
+	MerchantSourceKey string
+	MerchantName      string
+}
+
+func SeedDemo(ctx context.Context, pool *pgxpool.Pool, username, password string) (SeedResult, error) {
+	hash, err := HashPassword(password)
+	if err != nil {
+		return SeedResult{}, err
+	}
+	var result SeedResult
+	var merchantID int64
+	err = pool.QueryRow(ctx, `SELECT m.id,m.source_key,m.display_name
+		FROM merchants m JOIN payment_sessions ps ON ps.merchant_id=m.id
+		GROUP BY m.id ORDER BY count(*) DESC,m.source_key LIMIT 1`).Scan(
+		&merchantID, &result.MerchantSourceKey, &result.MerchantName,
+	)
+	if err != nil {
+		return SeedResult{}, fmt.Errorf("selecting demo merchant: %w", err)
+	}
+	_, err = pool.Exec(ctx, `INSERT INTO merchant_users(merchant_id,username,password_hash)
+		VALUES ($1,$2,$3) ON CONFLICT (username) DO UPDATE
+		SET merchant_id=excluded.merchant_id,password_hash=excluded.password_hash,is_active=true`, merchantID, username, hash)
+	if err != nil {
+		return SeedResult{}, fmt.Errorf("seeding demo merchant user: %w", err)
+	}
+	result.Username = username
+	return result, nil
+}