janritter/kvb-api

package adapters

import (
    "context"
    "fmt"
    "log"
    "net/http"
    "strconv"
    "strings"

    "github.com/PuerkitoBio/goquery"
    "github.com/janritter/kvb-api/domains"
    "go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
    "go.opentelemetry.io/otel"
    "go.opentelemetry.io/otel/attribute"
    "go.opentelemetry.io/otel/codes"
    "go.opentelemetry.io/otel/trace"
    "golang.org/x/text/encoding/charmap"
)

type KVBAdapter struct{}

func NewKVBAdapter() *KVBAdapter {
    return &KVBAdapter{}
}

func (adapter *KVBAdapter) GetDeparturesForStationID(ctx context.Context, stationID int) (domains.Departures, error) {
    var span trace.Span
    ctx, span = otel.Tracer("kvb-api").Start(ctx, "GetDeparturesForStationID")
    defer span.End()

    span.SetAttributes(attribute.Int("stationID", stationID))

    url := fmt.Sprintf("https://www.kvb.koeln/generated/?aktion=show&code=%d", stationID)

    client := http.Client{Transport: otelhttp.NewTransport(http.DefaultTransport)}
    req, _ := http.NewRequestWithContext(ctx, "GET", url, nil)
    res, err := client.Do(req)
    if err != nil {
        log.Println(err)
        span.RecordError(err)
        span.SetStatus(codes.Error, err.Error())
        return domains.Departures{}, err
    }

    doc, err := goquery.NewDocumentFromReader(res.Body)
    if err != nil {
        log.Println(err)
        span.RecordError(err)
        span.SetStatus(codes.Error, err.Error())
        return domains.Departures{}, err
    }

    departures := []domains.Departure{}

    _, span = otel.Tracer("kvb-api").Start(ctx, "GetDeparturesForStationID.Parse")
    defer span.End()
    doc.Find("body > div > table:nth-child(2) > tbody > tr").Each(func(i int, s *goquery.Selection) {
        if i != 0 {
            route := strings.Trim(s.Find("td:nth-child(1)").Text(), " ")
            destination := strings.Trim(s.Find("td:nth-child(2)").Text(), " ")
            arrivalTimeString := s.Find("td:nth-child(3)").Text()

            // Build correct time from Sofort and 2 Min
            arrivalTime := -1
            if strings.TrimSpace(arrivalTimeString) == "Sofort" {
                arrivalTime = 0
            } else {
                arrivalTimeString = strings.Replace(arrivalTimeString, "Min", "", -1)
                arrivalTime, err = strconv.Atoi(strings.TrimSpace(arrivalTimeString))
                if err != nil {
                    log.Println(err)
                    span.RecordError(err)
                    span.SetStatus(codes.Error, err.Error())
                }
            }

            // Response is ISO-8859-1, transfer to utf-8
            destination, err = charmap.ISO8859_1.NewDecoder().String(destination)
            if err != nil {
                log.Println(err)
                span.RecordError(err)
                span.SetStatus(codes.Error, err.Error())
            }

            singleDeparture := domains.Departure{
                Line:             strings.TrimSpace(route),
                Destination:      destination,
                ArrivalInMinutes: arrivalTime,
            }
            departures = append(departures, singleDeparture)
        }
    })

    return domains.Departures{
        Departures: departures,
    }, nil
}