package config

import (
	"os"
	"strings"
)

// Config is the payment-broker runtime configuration, all from env.
type Config struct {
	DatabaseURL string
	JWTSecret   string // verifies FlatRender admin JWTs for /v1/admin/* endpoints
	Port        string

	// PublicBaseURL is the broker's externally reachable base (e.g. https://pay.flatrender.ir).
	// ZarinPal callbacks and the user redirect target are built from it.
	PublicBaseURL string

	// ── ZarinPal (shared default merchant) ──────────────────────────────────
	// A client_app may override MerchantId/Sandbox; otherwise these defaults apply.
	ZarinPalMerchantID string
	ZarinPalSandbox    bool
	// AmountUnit is the unit ZarinPal expects in the amount field: "rial" (official
	// v4) or "toman". The broker always stores Rial canonically and converts here.
	ZarinPalAmountUnit string
}

func getEnv(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}

func Load() Config {
	base := strings.TrimRight(getEnv("PUBLIC_BASE_URL", "http://localhost:8080"), "/")
	unit := strings.ToLower(getEnv("ZARINPAL_AMOUNT_UNIT", "rial"))
	if unit != "toman" {
		unit = "rial"
	}
	return Config{
		DatabaseURL:        getEnv("DATABASE_URL", "postgres://postgres:postgres@localhost:5432/flatrender?search_path=payment,public"),
		JWTSecret:          getEnv("JWT_SECRET", "change-me"),
		Port:               getEnv("PORT", "8080"),
		PublicBaseURL:      base,
		ZarinPalMerchantID: getEnv("ZARINPAL_MERCHANT_ID", ""),
		ZarinPalSandbox:    getEnv("ZARINPAL_SANDBOX", "true") == "true",
		ZarinPalAmountUnit: unit,
	}
}

// CallbackURL is the single ZarinPal-verified callback endpoint on this broker.
func (c Config) CallbackURL() string {
	return c.PublicBaseURL + "/callback/zarinpal"
}