feat: make scraping much more robust

Sometimes the upstream API will just drop most of the data included. This commit
assumes less of that data will be included, as well as using the most out of the
data.

For example, using line IDs from upstream is entirely avoided, using line names
and titles to determine lines and their directions.

main/main.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"strconv"
 	"strings"
+	"time"
 
 	"git.dvdrw.dev/nsmarter/scraper/scraper"
 )
@@ -24,6 +25,7 @@ var chunkSize = 5
 var apiEndpoint string = "https://online.nsmart.rs/publicapi/v1/announcement/announcement.php"
 var apiKey string
 var limitQuerySize = 0
+var timeoutPeriod = 180
 var fillerUrl string = "localhost"
 
 func parseEnvars() {
@@ -41,6 +43,13 @@ func parseEnvars() {
 				Log.Printf("WARN: Invalid value for CHUNK_SIZE. Falling back to default value (%v)\n", defaultChunkSize)
 				chunkSize = defaultChunkSize
 			}
+		case "TIMEOUT_PERIOD":
+			var err error
+			timeoutPeriod, err = strconv.Atoi(pair[1])
+			if err != nil {
+				Log.Printf("WARN: Invalid value for TIMEOUT_PERIOD. Falling back to default value (%v)\n", 180)
+				timeoutPeriod = 180
+			}
 		case "LIMIT_QUERY_SIZE":
 			var err error
 			limitQuerySize, err = strconv.Atoi(pair[1])
@@ -86,16 +95,19 @@ func main() {
 	}
 
 	results := make(chan []scraper.ScrapeResult, 200)
-	for _, chunk := range stationChunks {
-		go scraper.ScheduleScrape(chunk,
-			results,
-			scraper.ApiConfig{Endpoint: apiEndpoint,
-				Key: apiKey})
-	}
+	go func() {
+		for _, chunk := range stationChunks {
+			go scraper.ScheduleScrape(chunk,
+				results,
+				scraper.ApiConfig{Endpoint: apiEndpoint,
+					Key:     apiKey,
+					Timeout: int64(timeoutPeriod)})
+			// Fan out scrapes over time so as to avoid upstream rate limits
+			time.Sleep(time.Millisecond * 100)
+		}
+	}()
 
 	for r := range results {
-		fmt.Printf("Received data: %#v\n", r)
-
 		json, err := json.Marshal(r)
 		if err != nil {
 			fmt.Print("Couldn't serialise struct to JSON: ", err)

scraper/scrape.go

@@ -31,11 +31,11 @@ type StationInfo struct {
 }
 
 type LineInfo struct {
-	Id       int           `json:"id"`
-	Name     string        `json:"name"`
-	Title    string        `json:"title"`
-	Stations []StationInfo `json:"stations"`
-	Route    []Coords      `json:"route"`
+	Name      string        `json:"name"`
+	Title     string        `json:"title"`
+	Direction int           `json:"direction"`
+	Stations  []StationInfo `json:"stations"`
+	Route     []Coords      `json:"route"`
 }
 
 type ScrapeResult struct {
@@ -60,6 +60,7 @@ func scrapeRange(s []Station) string {
 
 type ApiConfig struct {
 	Endpoint, Key string
+	Timeout       int64
 }
 
 func grabData(stations []Station, c ApiConfig) (map[string][]map[string]interface{}, error) {
@@ -141,25 +142,40 @@ func Scrape(stations []Station, c ApiConfig) ([]ScrapeResult, error) {
 
 			var lineInfo LineInfo
 
-			lineId, err := strconv.Atoi(bus["id"].(string))
-			if err != nil {
-				Log.Printf("WARN: Failed to parse vehicle for stationId=%v\n\t%v", id, err)
-				continue
-			}
-			lineInfo.Id = lineId
-
 			lineName, ok := bus["line_number"].(string)
 			if !ok {
 				lineName = ""
 			}
-			lineInfo.Name = lineName
+			lineInfo.Name = strings.TrimSpace(lineName)
 
 			lineTitle, ok := bus["line_title"].(string)
 			if ok {
 				lineInfo.Title = lineTitle
 			}
 
+			mainLineTitle, ok := bus["main_line_title"].(string)
+			if ok {
+				if mainLineTitle == lineTitle {
+					lineInfo.Direction = 1
+				} else {
+					lineInfo.Direction = 0
+				}
+			} else {
+				lineInfo.Direction = -1
+			}
+
 			var vehicles []Vehicle
+
+			garageNoStr, ok := bus["garage_no"].(string)
+			if ok {
+				vehicles = append(vehicles, Vehicle{
+					GarageId:      garageNoStr,
+					Coords:        Coords{},
+					AtStationId:   -1,
+					AtStationName: "",
+				})
+			}
+
 			vehiclesJson, ok := bus["vehicles"].([]interface{})
 
 			if !ok {
@@ -174,34 +190,38 @@ func Scrape(stations []Station, c ApiConfig) ([]ScrapeResult, error) {
 						continue
 					}
 
-					stationNumber, err := strconv.Atoi(vehicle["station_number"].(string))
-					if err != nil {
-						Log.Printf("WARN: Failed to parse vehicle for stationId=%v\n\t%v", id, err)
-						continue
+					stationNumberString, ok := vehicle["station_number"].(string)
+					var stationNumber int = -1
+					if ok {
+						stationNumber, err = strconv.Atoi(stationNumberString)
+						if err != nil {
+							Log.Printf("WARN: No station number for vehicle stationId=%v\n\t%v", id, err)
+							continue
+						}
 					}
 
 					lat, err := strconv.ParseFloat(vehicle["lat"].(string), 64)
 					if err != nil {
-						Log.Printf("WARN: Failed to parse vehicle for stationId=%v\n\t%v", id, err)
+						Log.Printf("WARN: Failed to parse vehicle lat for stationId=%v\n\t%v", id, err)
 						continue
 					}
 
 					lon, err := strconv.ParseFloat(vehicle["lng"].(string), 64)
 					if err != nil {
-						Log.Printf("WARN: Failed to parse vehicle for stationId=%v\n\t%v", id, err)
+						Log.Printf("WARN: Failed to parse vehicle lng for stationId=%v\n\t%v", id, err)
 						continue
 					}
 
 					garageId, ok := vehicle["garageNo"].(string)
 					if !ok {
-						Log.Printf("WARN: Failed to parse vehicle for stationId=%v\n\tVehicle's garageNo invalid or missing: %v", id, vehicle)
+						Log.Printf("WARN: Failed to parse vehicle garageNo for stationId=%v\n\tVehicle's garageNo invalid or missing: %v", id, vehicle)
 						continue
 					}
 
 					atStationName, ok := vehicle["station_name"].(string)
 					if !ok {
-						Log.Printf("WARN: Failed to parse vehicle for stationId=%v\n\tVehicle's station_name invalid or missing: %v", id, vehicle)
-						continue
+						Log.Printf("WARN: Failed to parse station_name for vehicle at stationId=%v\n\tVehicle's station_name invalid or missing: %v", id, vehicle)
+						atStationName = ""
 					}
 
 					vehicles = append(vehicles, Vehicle{
@@ -212,7 +232,12 @@ func Scrape(stations []Station, c ApiConfig) ([]ScrapeResult, error) {
 					})
 				}
 
-				lineInfo.Route = scrapeLineRoute(bus["line_route"].([]interface{}))
+				lineRouteJson, ok := bus["line_route"].([]interface{})
+				if ok {
+					lineInfo.Route = scrapeLineRoute(lineRouteJson)
+				} else {
+					lineInfo.Route = []Coords{}
+				}
 
 				all_stations, ok := bus["all_stations"].([]interface{})
 				if !ok {
@@ -274,6 +299,14 @@ func Scrape(stations []Station, c ApiConfig) ([]ScrapeResult, error) {
 			}
 
 		SKIP_AUX_INFO:
+			// Sometimes we don't get the vehicles array in the upstream response.
+			// In that case, we grab the only info about the bus we can get
+			//  (its garageNo from the toplevel garage_no field).
+			// In case we parse *both* buses, pick the one last added.
+			if len(vehicles) > 1 {
+				vehicles = []Vehicle{vehicles[len(vehicles)-1]}
+			}
+
 			results = append(results, ScrapeResult{
 				Success:     true,
 				Id:          id,
@@ -296,6 +329,7 @@ func ScheduleScrape(chunk []Station, c chan []ScrapeResult, a ApiConfig) {
 	}
 
 	c <- r
-	time.Sleep(time.Minute * 3)
+	duration := time.Duration(a.Timeout) * time.Second
+	time.Sleep(duration)
 	ScheduleScrape(chunk, c, a)
 }