package handler

import (
	"html/template"
	"io/ioutil"
	"os"

	"github.com/sirupsen/logrus"
)

// CurrentTheme is the set of template being used.
var CurrentTheme *template.Template

// themeCSS is the CSS of the current theme.
var themeCSS []byte

// SetTheme parses the provided theme name and sets it as the current theme.
func SetTheme(themeName string) error {
	var err error

	folder := "templates/" + themeName + "/"
	CurrentTheme, err = template.ParseFiles(
		folder+"index.tmpl", // Homepage (listing).
		folder+"404.tmpl",   // Post not found.
		folder+"500.tmpl",   // Internal error.
		folder+"post.tmpl",  // Page for posts.
	)

	if err != nil {
		return err
	}

	// Check if the style CSS exists and is not a directory.
	info, err := os.Stat(folder + "style.css")
	if os.IsNotExist(err) || (info != nil && info.IsDir()) {
		return nil
	}
	f, err := os.Open(folder + "style.css")
	if err != nil {
		return err
	}
	defer func() {
		err := f.Close()
		if err != nil {
			logrus.Fatalf("Error while closing theme CSS file: %v", err)
		}
	}()
	themeCSS, err = ioutil.ReadAll(f)
	return err
}