package mailer

import (
	"bytes"
	htmltemplate "html/template"
	"os"
	"path/filepath"
	texttemplate "text/template"
)

const defaultEmailTemplateDir = "web/emails/templates"

type TemplateData struct {
	AppName   string
	BaseURL   string
	VerifyURL string
	ResetURL  string
	UserEmail string
}

type TemplateRenderer struct {
	templatesDir string
}

func NewTemplateRenderer(templatesDir string) *TemplateRenderer {
	if templatesDir == "" {
		templatesDir = defaultEmailTemplateDir
	}

	return &TemplateRenderer{templatesDir: templatesDir}
}

func (r *TemplateRenderer) RenderVerifyEmail(data TemplateData) (htmlBody string, textBody string, err error) {
	return r.render("verify_email", data)
}

func (r *TemplateRenderer) RenderResetPassword(data TemplateData) (htmlBody string, textBody string, err error) {
	return r.render("reset_password", data)
}

func (r *TemplateRenderer) render(baseName string, data TemplateData) (string, string, error) {
	htmlPath := filepath.Join(r.templatesDir, baseName+".html")
	textPath := filepath.Join(r.templatesDir, baseName+".txt")

	htmlBody, err := renderHTMLFile(htmlPath, data)
	if err != nil {
		return "", "", err
	}

	textBody, err := renderTextFile(textPath, data)
	if err != nil {
		return "", "", err
	}

	return htmlBody, textBody, nil
}

func renderHTMLFile(path string, data TemplateData) (string, error) {
	content, err := os.ReadFile(path)
	if err != nil {
		return "", err
	}

	tmpl, err := htmltemplate.New(filepath.Base(path)).Parse(string(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 renderTextFile(path string, data TemplateData) (string, error) {
	content, err := os.ReadFile(path)
	if err != nil {
		return "", err
	}

	tmpl, err := texttemplate.New(filepath.Base(path)).Parse(string(content))
	if err != nil {
		return "", err
	}

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

	return buf.String(), nil
}