package emailtemplates

import (
	"Yimaru-Backend/internal/domain"
	"bytes"
)

var defaultTemplates = map[string]domain.EmailTemplate{
	domain.EmailTemplateSlugOTP: {
		Slug:      domain.EmailTemplateSlugOTP,
		Name:      "One-Time Password",
		Subject:   defaultOTPSubject,
		BodyText:  defaultOTPText,
		BodyHTML:  defaultOTPHTML,
		Variables: []string{"OTP", "FirstName", "ExpiresMinutes"},
		Status:    domain.EmailTemplateStatusActive,
	},
	domain.EmailTemplateSlugInvitation: {
		Slug:      domain.EmailTemplateSlugInvitation,
		Name:      "User Invitation",
		Subject:   defaultInvitationSubject,
		BodyText:  defaultInvitationText,
		BodyHTML:  defaultInvitationHTML,
		Variables: []string{"FirstName", "InviterName", "InviteLink"},
		Status:    domain.EmailTemplateStatusActive,
	},
	domain.EmailTemplateSlugPasswordReset: {
		Slug:      domain.EmailTemplateSlugPasswordReset,
		Name:      "Password Reset",
		Subject:   defaultPasswordResetSubject,
		BodyText:  defaultPasswordResetText,
		BodyHTML:  defaultPasswordResetHTML,
		Variables: []string{"FirstName", "ResetLink", "ExpiresMinutes"},
		Status:    domain.EmailTemplateStatusActive,
	},
	domain.EmailTemplateSlugWelcome: {
		Slug:      domain.EmailTemplateSlugWelcome,
		Name:      "Welcome Email",
		Subject:   defaultWelcomeSubject,
		BodyText:  defaultWelcomeText,
		BodyHTML:  defaultWelcomeHTML,
		Variables: []string{"FirstName", "LoginURL"},
		Status:    domain.EmailTemplateStatusActive,
	},
	domain.EmailTemplateSlugCustomMessage: {
		Slug:      domain.EmailTemplateSlugCustomMessage,
		Name:      "Custom Message",
		Subject:   "{{.Subject}}",
		BodyText:  "{{.Message}}",
		BodyHTML:  defaultCustomMessageHTML,
		Variables: []string{"Subject", "Message"},
		Status:    domain.EmailTemplateStatusActive,
	},
}

func defaultTemplate(slug string) (domain.EmailTemplate, bool) {
	tmpl, ok := defaultTemplates[slug]
	return tmpl, ok
}

func renderTemplateFields(tmpl domain.EmailTemplate, data map[string]any) (domain.RenderedEmail, error) {
	if data == nil {
		data = map[string]any{}
	}

	subject, err := executeTextTemplate("subject:"+tmpl.Slug, tmpl.Subject, data)
	if err != nil {
		return domain.RenderedEmail{}, err
	}

	text, err := executeTextTemplate("text:"+tmpl.Slug, tmpl.BodyText, data)
	if err != nil {
		return domain.RenderedEmail{}, err
	}

	html, err := executeHTMLTemplate("html:"+tmpl.Slug, tmpl.BodyHTML, data)
	if err != nil {
		return domain.RenderedEmail{}, err
	}

	return domain.RenderedEmail{
		Subject: subject,
		Text:    text,
		HTML:    html,
	}, nil
}

func executeTextTemplate(name, content string, data map[string]any) (string, error) {
	tmpl, err := newTextTemplate(name, content)
	if err != nil {
		return "", err
	}

	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, data); err != nil {
		return "", err
	}
	return buf.String(), nil
}

func executeHTMLTemplate(name, content string, data map[string]any) (string, error) {
	tmpl, err := newHTMLTemplate(name, content)
	if err != nil {
		return "", err
	}

	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, data); err != nil {
		return "", err
	}
	return buf.String(), nil
}