package email

import (
	"fmt"
	"net/mail"
	"strings"
	"time"
)

type ComposeRequest struct {
	MessageID   string
	FromAddress string
	FromName    string
	ToAddresses string
	CcAddresses string
	Subject     string
	HTMLBody    string
}

func Compose(request ComposeRequest) []byte {
	var message strings.Builder

	fromHeader := formatMailAddress(request.FromName, request.FromAddress)
	message.WriteString(fmt.Sprintf("From: %s\r\n", fromHeader))
	message.WriteString(fmt.Sprintf("To: %s\r\n", request.ToAddresses))

	if request.CcAddresses != "" {
		message.WriteString(fmt.Sprintf("Cc: %s\r\n", request.CcAddresses))
	}

	message.WriteString(fmt.Sprintf("Subject: %s\r\n", request.Subject))
	message.WriteString(fmt.Sprintf("Date: %s\r\n", time.Now().Format(time.RFC1123Z)))
	message.WriteString(fmt.Sprintf("Message-ID: %s\r\n", request.MessageID))
	message.WriteString("MIME-Version: 1.0\r\n")
	message.WriteString("Content-Type: text/html; charset=UTF-8\r\n")
	message.WriteString("\r\n")
	message.WriteString(request.HTMLBody)

	return []byte(message.String())
}

func EnvelopeRecipients(toAddresses string, ccAddresses string, bccAddresses string) []string {
	var recipients []string

	for _, addressGroup := range []string{toAddresses, ccAddresses, bccAddresses} {
		if addressGroup == "" {
			continue
		}

		parsed, parseError := mail.ParseAddressList(addressGroup)
		if parseError != nil {
			for _, raw := range strings.Split(addressGroup, AddressJoiner) {
				trimmed := strings.TrimSpace(raw)
				if trimmed != "" {
					recipients = append(recipients, trimmed)
				}
			}
			continue
		}

		for _, address := range parsed {
			recipients = append(recipients, address.Address)
		}
	}

	return recipients
}

func formatMailAddress(displayName string, emailAddress string) string {
	if displayName == "" {
		return emailAddress
	}

	return fmt.Sprintf("\"%s\" <%s>", displayName, emailAddress)
}