package email

import (
	"context"
	"net/http"
	"net/mail"
	"os"
	"strings"
	"time"

	"git.sendico.io/tech/sxchnge/notifications/model"
	merrors "git.sendico.io/tech/sxchnge/shared/errors"
	sharedmodel "git.sendico.io/tech/sxchnge/shared/model"
	"github.com/go-viper/mapstructure/v2"
)

type Driver string

const (
	SendGrid Driver = "sendgrid"
	Resend   Driver = "resend"
)

type Config = sharedmodel.DriverConfig[Driver]
type Settings struct {
	APIKeyEnv     string `mapstructure:"api_key_env"`
	SenderAddress string `mapstructure:"sender_address"`
	SenderName    string `mapstructure:"sender_name"`
}

// Outcome describes provider acceptance, never recipient delivery or reading.
type Outcome struct {
	State      model.State
	Code       string
	RetryAfter time.Duration
	// Provider diagnostics are sanitized operational data, not public failures.
	HTTPStatus      int
	ProviderError   string
	ProviderMessage string
}
type Sender interface {
	Send(context.Context, string, model.Email) Outcome
}

type client struct {
	http     *http.Client
	key      string
	settings Settings
	endpoint string
}

func New(config Config) (Sender, error) {
	var s Settings
	decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{Result: &s, ErrorUnused: true, TagName: "mapstructure"})
	if err != nil {
		return nil, merrors.InternalWrap(err, "create driver settings decoder")
	}
	if err = decoder.Decode(config.Settings); err != nil {
		return nil, merrors.InvalidArgument("invalid email driver settings")
	}
	if !ValidAddress(s.SenderAddress) || strings.ContainsAny(s.SenderName, "\r\n") {
		return nil, merrors.InvalidArgument("invalid sender")
	}
	key := os.Getenv(s.APIKeyEnv)
	if s.APIKeyEnv == "" || strings.TrimSpace(key) == "" || strings.ContainsAny(key, "\r\n") {
		return nil, merrors.FailedPrecondition("email API key environment variable is missing")
	}
	c := client{http: &http.Client{Timeout: 20 * time.Second, CheckRedirect: func(*http.Request, []*http.Request) error { return http.ErrUseLastResponse }}, key: key, settings: s}
	switch config.Driver {
	case SendGrid:
		c.endpoint = "https://api.sendgrid.com/v3/mail/send"
		return &sendgrid{c}, nil
	case Resend:
		c.endpoint = "https://api.resend.com/emails"
		return &resend{c}, nil
	default:
		return nil, merrors.InvalidArgument("unsupported email driver")
	}
}
func ValidAddress(s string) bool {
	a, err := mail.ParseAddress(s)
	return err == nil && a.Address == s && !strings.ContainsAny(s, "\r\n") && len(s) <= 254
}