package structs

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"html/template"
	"net/smtp"
	"strings"
	"time"

	"clickandjoin.app/emailserver/modules/cache"
	"clickandjoin.app/emailserver/modules/config"
	"clickandjoin.app/emailserver/modules/escaper"
	gocnjhelper "git.ex.umbach.dev/ClickandJoin/go-cnj-helper"
	"github.com/google/uuid"
)

type Mail struct {
	To         []string
	Subject    string
	TemplateId string
	LanguageId string
	BodyData   interface{}
}

func (m *Mail) Send(htmlBody, textBody string) error {
	cfg := config.Cfg.Mail

	// Generate unique message ID
	messageID := uuid.New().String() + "@" + strings.Split(cfg.FromEmail, "@")[1]

	// Generate unique boundary string
	boundary := "boundary" + uuid.New().String()

	// Create MIME message with multipart/alternative content type
	msg := "From: " + cfg.FromName + " <" + cfg.FromEmail + ">\n" +
		"To: " + strings.Join(m.To, ",") + "\n" +
		"Subject: " + m.Subject + "\n" +
		"Date: " + time.Now().Format("Mon, 02 Jan 2006 15:04:05 -0700") + "\n" +
		"Message-ID: <" + messageID + ">\n" +
		"MIME-version: 1.0;\n" +
		"Content-Type: multipart/alternative; boundary=" + boundary + "\n\n" +
		"--" + boundary + "\n" +
		"Content-Type: text/plain; charset=\"UTF-8\"\n\n" +
		textBody + "\n\n" +
		"--" + boundary + "\n" +
		"Content-Type: text/html; charset=\"UTF-8\"\n\n" +
		htmlBody + "\n\n" +
		"--" + boundary + "--"

	err := smtp.SendMail(cfg.Host+":"+cfg.Port, cache.SmtpAuth, cfg.FromEmail, m.To, []byte(msg))

	if err != nil {
		gocnjhelper.LogErrorf("smtp error: %s", err)
		return err
	}

	return nil
}

/*
func (m *Mail) Send(body string) error {
	cfg := config.Cfg.Mail

	msg := "From: " + cfg.FromName + " <" + cfg.FromEmail + ">\n" +
		"To: " + strings.Join(m.To, ",") + "\n" +
		"Subject: " + m.Subject + "\n" +
		"Date: " + time.Now().Format("Mon, 02 Jan 2006 15:04:05 -0700") + "\n" +
		"Message-ID: <" + uuid.New().String() + "@" + strings.Split(cfg.FromEmail, "@")[1] + ">\n" +
		"MIME-version: 1.0;\nContent-Type: multipart/alternative; charset=\"UTF-8\";\n\n" +
		body

	err := smtp.SendMail(cfg.Host+":"+cfg.Port, cache.SmtpAuth, cfg.FromEmail, m.To, []byte(msg))

	if err != nil {
		gocnjhelper.LogErrorf("smtp error: %s", err)
		return err
	}

	gocnjhelper.LogDebugf("SEND MAIL %s", msg)
	return nil
} */

func (m *Mail) RenderTemplate() (htmlBody, textBody string, err error) {
	body := cache.BodyTemplates[m.TemplateId]

	for templateName, templateData := range cache.Templates.Templates {
		// Skipping templates if the template ID is not the expected one
		if templateName != m.TemplateId {
			continue
		}

		m.Subject = templateData["mailSubject"][m.LanguageId]

		// occurs if the requested language code does not exist
		if m.Subject == "" {
			m.Subject = templateData["mailSubject"][config.Cfg.DefaultLanguageCode]
		}

		// replace body %values% with values in templates config
		for key, value := range templateData {
			if key == "mailSubject" {
				continue
			}

			v := value[m.LanguageId]

			// occurs if the requested language code does not exist
			if v == "" {
				v = value[config.Cfg.DefaultLanguageCode]
			}

			// escaping so that umlauts are displayed correctly
			if m.LanguageId == "de" {
				v = escaper.EscapeHtmlEntites(v)
			}

			body.HTML = []byte(strings.Replace(string(body.HTML), "%"+key+"%", v, -1))
			body.PlainText = []byte(strings.Replace(string(body.PlainText), "%"+key+"%", v, -1))
		}
	}

	// The subject line of an email is an independent header and utf 8 must be set for it
	// https://ncona.com/2011/06/using-utf-8-characters-on-an-e-mail-subject/
	if m.LanguageId == "de" {
		m.Subject = EncodeBase64(m.Subject)
	}

	// Separate rendering for HTML and text bodies
	htmlTemplate := template.Must(template.New("").Parse(string(body.HTML)))
	textTemplate := template.Must(template.New("").Parse(string(body.PlainText)))

	htmlBuf := new(bytes.Buffer)
	textBuf := new(bytes.Buffer)

	if err := htmlTemplate.Execute(htmlBuf, m.BodyData); err != nil {
		return "", "", err
	}

	// the execute function replaces all < and > with &lt; and &gt; in html body
	// so we have to replace them back
	// replace all &lt; and &gt; with < and > in html body

	htmlBody = strings.ReplaceAll(htmlBuf.String(), "&lt;", "<")
	htmlBody = strings.ReplaceAll(htmlBody, "&gt;", ">")

	// Execute text template

	if err := textTemplate.Execute(textBuf, m.BodyData); err != nil {
		return "", "", err
	}

	return htmlBody, textBuf.String(), nil
}

/*
func (m *Mail) RenderTemplate() (string, error) {
	body := cache.BodyTemplates[m.TemplateId]

	for templateName, templateData := range cache.Templates.Templates {
		// Skipping templates if the template ID is not the expected one
		if templateName != m.TemplateId {
			continue
		}

		gocnjhelper.LogDebugf("RENDER TEMPLATE %s %s", templateName, templateData)

		m.Subject = templateData["mailSubject"][m.LanguageId]

		// occurs if the requested language code does not exist
		if m.Subject == "" {
			m.Subject = templateData["mailSubject"][config.Cfg.DefaultLanguageCode]
		}

		// replace body %values% with values in templates config
		for key, value := range templateData {
			if key == "mailSubject" {
				continue
			}

			v := value[m.LanguageId]

			// occurs if the requested language code does not exist
			if v == "" {
				v = value[config.Cfg.DefaultLanguageCode]
			}

			// escaping so that umlauts are displayed correctly
			if m.LanguageId == "de" {
				v = escaper.EscapeHtmlEntites(v)
			}

			body.HTML = []byte(strings.Replace(string(body.HTML), "%"+key+"%", v, -1))
		}
	}

	// The subject line of an email is an independent header and utf 8 must be set for it
	// https://ncona.com/2011/06/using-utf-8-characters-on-an-e-mail-subject/
	if m.LanguageId == "de" {
		m.Subject = EncodeBase64(m.Subject)
	}

	t := template.Must(template.New("").Parse(string(body.HTML)))

	buf := new(bytes.Buffer)

	if err := t.Execute(buf, m.BodyData); err != nil {
		return "", err
	}

	return buf.String(), nil
} */

// https://ncona.com/2011/06/using-utf-8-characters-on-an-e-mail-subject/
func EncodeBase64(s string) string {
	return fmt.Sprintf("=?utf-8?B?%s?=", base64.StdEncoding.EncodeToString([]byte(s)))
}