package order

import (
	"context"
	"fmt"
	"net/mail"
	"strings"

	"github.com/mailersend/mailersend-go"
)

// MailerSendEmailSender sends email through the MailerSend API using the
// official Go SDK. It implements the EmailSender interface.
type MailerSendEmailSender struct {
	client      *mailersend.Mailersend
	defaultFrom mail.Address
}

// NewMailerSendEmailSender creates a new MailerSend-backed sender.
func NewMailerSendEmailSender(apiKey string, defaultFrom mail.Address) (*MailerSendEmailSender, error) {
	if strings.TrimSpace(apiKey) == "" {
		return nil, fmt.Errorf("mailersend sender: missing API key")
	}
	if strings.TrimSpace(defaultFrom.Address) == "" {
		return nil, fmt.Errorf("mailersend sender: missing default from address")
	}
	return &MailerSendEmailSender{
		client:      mailersend.NewMailersend(apiKey),
		defaultFrom: defaultFrom,
	}, nil
}

// DefaultFrom returns the default sender address configured for this sender.
func (s *MailerSendEmailSender) DefaultFrom() mail.Address { return s.defaultFrom }

// Send delivers the rendered email message through the MailerSend API.
func (s *MailerSendEmailSender) Send(ctx context.Context, msg EmailMessage) error {
	if strings.TrimSpace(msg.From.Address) == "" {
		return fmt.Errorf("mailersend sender: missing from address")
	}
	if len(msg.To) == 0 {
		return fmt.Errorf("mailersend sender: missing recipients")
	}
	if strings.TrimSpace(msg.Subject) == "" {
		return fmt.Errorf("mailersend sender: missing subject")
	}
	if strings.TrimSpace(msg.TextBody) == "" && strings.TrimSpace(msg.HTMLBody) == "" {
		return fmt.Errorf("mailersend sender: missing body")
	}

	message := s.client.Email.NewMessage()

	fromName := msg.From.Name
	if fromName == "" {
		fromName = s.defaultFrom.Name
	}
	message.SetFrom(mailersend.From{
		Name:  fromName,
		Email: msg.From.Address,
	})

	recipients := make([]mailersend.Recipient, 0, len(msg.To))
	for _, rcpt := range msg.To {
		recipients = append(recipients, mailersend.Recipient{
			Name:  rcpt.Name,
			Email: rcpt.Address,
		})
	}
	message.SetRecipients(recipients)
	message.SetSubject(msg.Subject)

	if strings.TrimSpace(msg.HTMLBody) != "" {
		message.SetHTML(msg.HTMLBody)
	}
	if strings.TrimSpace(msg.TextBody) != "" {
		message.SetText(msg.TextBody)
	}

	_, err := s.client.Email.Send(ctx, message)
	if err != nil {
		return fmt.Errorf("mailersend sender: %w", err)
	}
	return nil
}