package main

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

var (
    	templates = map[string]*template.Template{}
)

// template helper function
func dict (values ...interface{}) (map[string]interface{}, error) {
	if len(values)%2 != 0 {
        return nil, errors.New("invalid dict call")
    }
    dict := make(map[string]interface{}, len(values)/2)
    for i := 0; i < len(values); i+=2 {
        key, ok := values[i].(string)
       if !ok {
           return nil, errors.New("dict keys must be strings")
       }
        dict[key] = values[i+1]
    }
    return dict, nil
}

func stringTimes(times int, str string) string {
    result := ""
    for i := 0; i < times; i ++ {
        result += str
    }
    return result
} 

// Tempalte helper functions
var funcMap = template.FuncMap {
    "add": func (x, y int) int { return x + y },
    "minus": func (x, y int) int { return x - y },
    "dict": dict,
    "stringTimes": stringTimes,
}


func initTemplates() {
	files, _ := filepath.Glob("templates/pages/*.html")
	re := regexp.MustCompile("templates/pages/(.*).html")
	fmt.Println("Loading Templates:")
	for _, t := range files {
		name := re.FindStringSubmatch(t)
		fmt.Println("  ", name[1])
		templates[name[1]] = template.Must(template.New(name[1]).Funcs(funcMap).ParseFiles("templates/layout.html", t))
	}
}

func ShowTemplate(template string, w http.ResponseWriter, data map[string]interface{}) {
	err := templates[template].ExecuteTemplate(w, "layout.html", data)
	if err != nil {
		fmt.Println("Exec err: ", err)
	}
	// TODO: show error 500 page
}