mensa/server/server.go

package main

import (
    "encoding/json"
    "fmt"
    "io/ioutil"
    "os"
    "regexp"
    "strings"
    "time"

    "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"`
        Diet     string `json:"diet"`
    }
    // Menu contains all info to menues in a mensa on one day
    Menu struct {
        Day   int    `json:"day"`
        Mensa string `json:"mensa"`
        Meals []Meal `json:"meals"`
        Date  string `json:"date"`
    }
)

var (
    mensen = map[string]string{
        "Zentralmensa":  "zentralmensa",
        "Nordmensa":     "nordmensa",
        "Mensa+am+Turm": "turmmensa",
        "Mensa+Italia":  "mensaitalia",
        "Bistro+HAWK":   "bistrohawk",
    }
    trimRegex = regexp.MustCompile(`\s{2,}`)
)

func main() {
    path := "./"
    if len(os.Args) == 2 {
        path = os.Args[1] + "/"
    }

    for mensa := range mensen {
        for day := 1; day < 8; day = day + 1 {
            menu, err := operate(mensa, day)
            if err != nil {
                fmt.Println(err.Error())
                return
            }

            content, err := json.Marshal(menu)
            if err != nil {
                fmt.Println(err.Error())
                return
            }

            err = ioutil.WriteFile(fmt.Sprintf("%s/%s.%v.json", path, mensen[mensa], day), content, 0644)
            if err != nil {
                fmt.Println(err.Error())
                return
            }
        }
    }
}

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

func operate(mensa string, day int) (Menu, error) {
    currentDay := int(time.Now().Weekday())		// week starts on sunday in go, but thats not relevant, because the canteen is closed on sunday
    push := 0
    if currentDay > day {
        push = 1
    }

    document, err := goquery.NewDocument(fmt.Sprintf("http://www.studentenwerk-goettingen.de/speiseplan.html?no_cache=1&day=%v&push=%v&selectmensa=%s", day, push, mensa))

    if err != nil {
        return Menu{}, err
    }

    meals, err := parseMeals(document)
    if err != nil {
        return Menu{}, err
    }

    date := parseDate(document)
    return Menu{Day: day, Mensa: mensa, Meals: meals, Date: date}, nil
}

func parseDate(doc *goquery.Document) string {
    return strip(doc.Find("#speise-head2_datum").Text())
}

func strip(old string) string {
    return strings.TrimSpace(trimRegex.ReplaceAllString(old, " "))
}

func parseMeals(doc *goquery.Document) ([]Meal, error) {
    meals := []Meal{}
    doc.Find("table.speise-tblmain tbody tr").Each(func(i int, s *goquery.Selection) {
	diet, _ := s.Find(".ext_sits_speiseplan_icon").Children().Attr("alt")
        meal := Meal{
            Category: strip(s.Find(".ext_sits_preis").Text()), // yes, really preis
            Title:    strip(s.Find(".ext_sits_essen").Text()),
            Diet:     strip(diet),
        }
        meals = append(meals, meal)
    })
    return meals, nil
}