package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"

	"github.com/PuerkitoBio/goquery"
)

type (
	// Meal contains the info about a meals
	Meal struct {
		Category string `json:"category"`
		Price    string `json:"price"`
		Title    string `json:"title"`
	}
	// Menu contains all info to menues in a mensa on one day
	Menu struct {
		Day   string `json:"day"`
		Mensa string `json:"mensa"`
		Meals []Meal `json:"meals"`
	}
)

var (
	mensen = []string{
		"Zentralmensa",
		"Nordmensa",
	}
	days = []string{
		"heute",
		"morgen",
		"uebermorgen",
	}
)

func main() {
	menus := []Menu{}

	for _, mensa := range mensen {
		for _, day := range days {
			menu, err := operate(mensa, day)
			if err != nil {
				fmt.Println(err.Error())
			}
			menus = append(menus, menu)
		}
	}

	bytes, err := json.Marshal(menus)
	if err != nil {
		fmt.Println(err.Error())
	}

	if len(os.Args) == 2 {
		err = writeToFile(bytes)
		if err != nil {
			fmt.Println(err.Error())
		}
	} else {
		fmt.Println(string(bytes))
	}
}

func writeToFile(content []byte) error {
	err := ioutil.WriteFile(os.Args[1], content, 0644)
	if err != nil {
		return err
	}
	return nil
}

func operate(mensa, day string) (Menu, error) {
	meals, err := parseHTML(fmt.Sprintf("https://phpapp2.zvw.uni-goettingen.de/portlet_mensaplan/public/ajaxresponse/getgerichte?mensa=%s&tag=%s&preis=stu&vegetarisch=true&schweinefleisch=true&vegan=true&fisch=true&gefluegel=true&rind=true&wild=true&lamm=true&alkohol=true&knoblauch=true&sonstige_gerichte=true", mensa, day))
	if err != nil {
		return Menu{}, err
	}

	return Menu{Day: day, Mensa: mensa, Meals: meals}, nil
}

func parseHTML(url string) ([]Meal, error) {
	doc, err := goquery.NewDocument(url)
	if err != nil {
		return nil, err
	}

	meals := []Meal{}
	doc.Find("table tr").Each(func(i int, s *goquery.Selection) {
		meal := Meal{
			Category: s.Find(".gericht_kategorie").Text(),
			Price:    s.Find(".gericht_preis").Text(),
			Title:    s.Find(".spalte_gericht").Text(),
		}
		meals = append(meals, meal)
	})
	return meals, nil
}