Since im not that deep into the project i seperated it from the rest, its in "backend/sport/main.go". I added the task which are still needed to do.

Added Package "github.com/PuerkitoBio/goquery"

backend/sport/main.go

@@ -0,0 +1,185 @@
+package main
+
+import (
+	"errors"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/PuerkitoBio/goquery"
+)
+
+// just to test the code
+// @TODO: remove this
+// @TODO: add tests
+// @TODO: add it to the service
+// @TODO: make it like a cron job to fetch the sport courses once a week
+func main() {
+	events := fetchAllHtwkSportCourses()
+	for _, event := range events {
+		print(event.Title)
+	}
+}
+
+// fetchAllHtwkSportCourses fetches all sport courses from the htwk sport website.
+// It iterates over all ids from 0 to 9999 and tries to fetch the sport course.
+// If the sport course does not exist, it will continue with the next id.
+// If the sport course exists, it will be added to the events slice.
+// Since the ids are not consecutive, it will take a while to fetch all sport courses.
+// @TODO: find the highest id and iterate over all ids from 0 to highest id
+func fetchAllHtwkSportCourses() []Event {
+	var events []Event
+	for i := 0; i <= 9999; i++ {
+		newEvent, err := fetchHtwkSportCourse("https://sport.htwk-leipzig.de/sportangebote/detail/sport/", i)
+		if err != nil {
+			continue
+		}
+		events = append(events, newEvent...)
+
+	}
+	return events
+}
+
+// fetchHtwkSportCourse fetches the sport course from the given url and id.
+// If the sport course does not exist, it will return an error.
+// If the sport course exists, it will return the sport course.
+// goquery is used to parse the html. The html structure is not very consistent, so it is hard to parse.
+// May be improved in the future.
+func fetchHtwkSportCourse(url string, id int) ([]Event, error) {
+	var events []Event
+
+	resp, err := http.Get(url + strconv.Itoa(id))
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	doc, err := goquery.NewDocumentFromReader(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	if doc.Find("h1").Text() == "Aktuelle Sportangebote" {
+		return nil, errors.New("not a sport course page")
+	}
+
+	doc.Find(".eventHead").Each(func(i int, s *goquery.Selection) {
+		var event Event
+		var details EventDetails
+
+		fullTitle := strings.TrimSpace(s.Find("h3").Text())
+		titleParts := strings.Split(fullTitle, "-")
+		if len(titleParts) > 0 {
+			event.Title = strings.TrimSpace(titleParts[0])
+		}
+		s.NextFiltered("table.eventDetails").Find("tr").Each(func(i int, s *goquery.Selection) {
+			key := strings.TrimSpace(s.Find("td").First().Text())
+			value := strings.TrimSpace(s.Find("td").Last().Text())
+
+			switch key {
+			case "Zeitraum":
+				dates := strings.Split(value, "-")
+				if len(dates) == 2 {
+					startDate, _ := time.Parse("02.01.2006", strings.TrimSpace(dates[0]))
+					endDate, _ := time.Parse("02.01.2006", strings.TrimSpace(dates[1]))
+					details.DateRange = DateRange{Start: startDate, End: endDate}
+				}
+			case "Zyklus":
+				details.Cycle = value
+			case "Geschlecht":
+				details.Gender = value
+			case "Leiter":
+				leaderName := strings.TrimSpace(s.Find("td a").Text())
+				leadersSlice := strings.Split(leaderName, "\n")
+				for i, leader := range leadersSlice {
+					leadersSlice[i] = strings.TrimSpace(leader)
+				}
+				formattedLeaders := strings.Join(leadersSlice, ", ")
+				leaderLink, _ := s.Find("td a").Attr("href")
+				details.CourseLead = CourseLead{Name: formattedLeaders, Link: leaderLink}
+			case "Ort":
+				locationDetails := strings.Split(value, "(")
+				if len(locationDetails) == 2 {
+					details.Location = Location{
+						Name:    strings.TrimSpace(locationDetails[0]),
+						Address: strings.TrimRight(strings.TrimSpace(locationDetails[1]), ")"),
+					}
+				}
+			case "Teilnehmer":
+				parts := strings.Split(value, "/")
+				if len(parts) >= 3 {
+					bookings, _ := strconv.Atoi(strings.TrimSpace(parts[0]))
+					totalPlaces, _ := strconv.Atoi(strings.TrimSpace(parts[1]))
+					waitList, _ := strconv.Atoi(strings.TrimSpace(parts[2]))
+					details.Participants = Participants{Bookings: bookings, TotalPlaces: totalPlaces, WaitList: waitList}
+				}
+			case "Kosten":
+				details.Cost = value // makes no sense since you need to be logged in to see the price
+			case "Hinweis":
+				var allNotes []string
+
+				s.Find("td").Last().Contents().Each(func(i int, s *goquery.Selection) {
+					if s.Is("h4.eventAdvice") || goquery.NodeName(s) == "#text" {
+						note := strings.TrimSpace(s.Text())
+						if note != "" {
+							allNotes = append(allNotes, note)
+						}
+					}
+				})
+
+				event.AdditionalNote = strings.Join(allNotes, " ")
+			}
+		})
+
+		event.Details = details
+		events = append(events, event)
+	})
+
+	return events, nil
+}
+
+// MODELS
+
+// Event represents the overall event details.
+type Event struct {
+	Title          string
+	Details        EventDetails
+	AdditionalNote string
+}
+
+// EventDetails represents detailed information about the event.
+type EventDetails struct {
+	DateRange    DateRange
+	Cycle        string
+	Gender       string
+	CourseLead   CourseLead
+	Location     Location
+	Participants Participants
+	Cost         string
+}
+
+// DateRange represents a start and end date.
+type DateRange struct {
+	Start time.Time
+	End   time.Time
+}
+
+// CourseLead represents a person with a name and a contact link.
+type CourseLead struct {
+	Name string
+	Link string
+}
+
+// Location represents the location of the event.
+type Location struct {
+	Name    string
+	Address string
+}
+
+// Participants represents the participants' details.
+type Participants struct {
+	Bookings    int
+	TotalPlaces int
+	WaitList    int
+}