package main

import (
	"fmt"
	"html/template"
	"log"
	"net/http"
	"path/filepath"
)

// cache templates on initialization
var templates map[string]*template.Template

// Load templates on program initialisation
func init() {
	if templates == nil {
		templates = make(map[string]*template.Template)
	}

	templatesDir := "tmpl/"

	layouts, err := filepath.Glob(templatesDir + "layouts/*.html")
	if err != nil {
		log.Fatal(err)
	}

	includes, err := filepath.Glob(templatesDir + "includes/*.html")
	if err != nil {
		log.Fatal(err)
	}

	// Generate our templates map from our layouts/ and includes/ directories
	for _, layout := range layouts {
		files := append(includes, layout)
		templates[filepath.Base(layout)] = template.Must(template.ParseFiles(files...))
	}
}

// renderTemplate is a wrapper around template.ExecuteTemplate.
func RenderTemplate(w http.ResponseWriter, name string, p *Page) {
	// Ensure the template exists in the map.
	tmpl, ok := templates[name+".html"]
	if !ok {
		http.Error(w, fmt.Errorf("The template %s does not exist.", name).Error(), http.StatusInternalServerError)
	}

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	err := tmpl.ExecuteTemplate(w, "base", p)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
}