package mail

import (
	"fmt"
	"os"
	"strconv"
)

// Config holds SMTP relay settings from the environment.
type Config struct {
	Host     string
	Port     int
	User     string
	Password string
	From     string
	To       string
	// TLS: "auto" (STARTTLS on 587, plain on 25), "tls" (implicit TLS, e.g. 465), "plain"
	TLS string
}

// Load reads SMTP settings from environment variables.
//
// Required: SMTP_HOST, SMTP_FROM, SMTP_TO
// Optional: SMTP_PORT (587), SMTP_USER, SMTP_PASSWORD, SMTP_TLS (auto)
func Load() (Config, error) {
	host := os.Getenv("SMTP_HOST")
	if host == "" {
		return Config{}, fmt.Errorf("SMTP_HOST is required")
	}

	from := os.Getenv("SMTP_FROM")
	if from == "" {
		return Config{}, fmt.Errorf("SMTP_FROM is required")
	}

	to := os.Getenv("SMTP_TO")
	if to == "" {
		return Config{}, fmt.Errorf("SMTP_TO is required")
	}

	port := 587
	if p := os.Getenv("SMTP_PORT"); p != "" {
		n, err := strconv.Atoi(p)
		if err != nil {
			return Config{}, fmt.Errorf("SMTP_PORT: %w", err)
		}
		port = n
	}

	tls := os.Getenv("SMTP_TLS")
	if tls == "" {
		tls = "auto"
	}

	return Config{
		Host:     host,
		Port:     port,
		User:     os.Getenv("SMTP_USER"),
		Password: os.Getenv("SMTP_PASSWORD"),
		From:     from,
		To:       to,
		TLS:      tls,
	}, nil
}

// Enabled reports whether relay settings are present.
func Enabled() bool {
	return os.Getenv("SMTP_HOST") != "" &&
		os.Getenv("SMTP_FROM") != "" &&
		os.Getenv("SMTP_TO") != ""
}