Add genre to concerts - WIP

Fixes #36

controllers/eventController.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/gofiber/fiber/v2"
 	"github.com/jakopako/event-api/config"
+	"github.com/jakopako/event-api/genre"
 	"github.com/jakopako/event-api/geo"
 	"github.com/jakopako/event-api/models"
 	"go.mongodb.org/mongo-driver/bson"
@@ -110,7 +111,7 @@ func AddEvents(c *fiber.Ctx) error {
 			continue
 		}
 
-		// check geolocation
+		// lookup geolocation if not given
 		if len(event.Geolocation) != 2 {
 			// lookup location based on city AND cache this info to not flood the geoloc service
 			// It's the client's responsibility to provide enough info (ie country if necessary)
@@ -130,6 +131,18 @@ func AddEvents(c *fiber.Ctx) error {
 			event.MongoGeolocation.Coordinates = event.Geolocation[:]
 		}
 
+		// lookup genres if not given
+		if len(event.Genres) == 0 {
+			genres, err := genre.LookupGenres(event.Title)
+			if err != nil {
+				errors = append(errors, fiber.Map{
+					"message": fmt.Sprintf("failed to find genre for event %+v", event),
+					"error":   err.Error(),
+				})
+			}
+			event.Genres = genres
+		}
+
 		// add offset
 		_, offset := event.Date.Zone()
 		event.Offset = offset

genre/genreLookup.go

@@ -0,0 +1,96 @@
+package genre
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/jakopako/event-api/config"
+	"go.mongodb.org/mongo-driver/mongo"
+)
+
+type GenreCache struct {
+	lookupSpotifyGenre bool
+	spotifyToken       string
+	spotifyTokenExpiry time.Time
+	mu                 sync.RWMutex
+	eventsColl         *mongo.Collection
+	spotifyErrorCount  int // do we need this? if the spotify responds with an error we probably don't want to hammer it with 1000s of requests, so might need to stop querying the api after a certain error count
+}
+
+type spotifyTokenResponse struct {
+	AccessToken string `json:access_token"`
+	TokenType   string `json:token_type"`
+	ExpiresIn   int    `json:expires_in"` // minutes
+}
+
+var GC *GenreCache
+
+func (gc *GenreCache) renewSpotifyToken() error {
+	client := http.Client{}
+	if gc.spotifyToken == "" || gc.spotifyTokenExpiry.After(time.Now().UTC()) {
+		tokenUrl := "https://accounts.spotify.com/api/token"
+		clientId := os.Getenv("SPOTIFY_CLIENT_ID")
+		clientSecret := os.Getenv("SPOTIFY_CLIENT_SECRET")
+		if clientId == "" || clientSecret == "" {
+			return fmt.Errorf("env vars SPOTIFY_CLIENT_ID and/or SPOTIFY_CLIENT_SECRET are empty")
+		}
+
+		form := url.Values{}
+		form.Add("grant_type", "client_credentials")
+		form.Add("client_id", clientId)
+		form.Add("client_secret", clientSecret)
+
+		req, _ := http.NewRequest("POST", tokenUrl, strings.NewReader(form.Encode()))
+		// req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+		resp, err := client.Do(req)
+		if err != nil {
+			return err
+		}
+		defer resp.Body.Close()
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return err
+		}
+
+		var tokenResp spotifyTokenResponse
+		if err := json.Unmarshal(body, &tokenResp); err != nil {
+			return err
+		}
+
+		gc.spotifyToken = tokenResp.AccessToken
+		gc.spotifyTokenExpiry = time.Now().UTC().Add(time.Minute * time.Duration(tokenResp.ExpiresIn-1))
+	}
+	return nil
+}
+
+func (gc *GenreCache) getSpoticyGenres(artist string) ([]string, error) {
+	genres := []string{}
+
+	if gc.lookupSpotifyGenre {
+		gc.renewSpotifyToken()
+
+		// find genres
+	}
+
+	return genres, nil
+}
+
+func InitGenreCache() {
+	// this code assumes that the DB has already been initialized
+
+	GC = &GenreCache{
+		lookupSpotifyGenre: os.Getenv("LOOKUP_SPOTIFY_GENRE") == "true",
+		eventsColl:         config.MI.DB.Collection("events"),
+	}
+}
+
+func LookupGenres(artist string) ([]string, error) {
+	return GC.getSpoticyGenres(artist)
+}

geo/geoLookup.go

@@ -46,17 +46,21 @@ func LookupCityCoordinates(city, country string) (*models.MongoGeolocation, erro
 		searchKey += fmt.Sprintf("+%s", country)
 	}
 	searchKey = strings.ReplaceAll(searchKey, " ", "+")
+
+	// check memory cache
 	GC.mu.RLock()
 	coords, found := GC.memCache[searchKey]
 	GC.mu.RUnlock()
 	if found {
 		return coords, nil
 	}
+
 	// check database
 	filter := bson.D{{"name", city}, {"country", country}}
 	var result models.City
 	ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)
 	err := GC.cityColl.FindOne(ctx, filter).Decode(&result)
+
 	// fetch if not in database and write
 	if err != nil {
 		if err == mongo.ErrNoDocuments {

main.go

@@ -14,6 +14,7 @@ import (
 	"github.com/gofiber/fiber/v2/utils"
 	"github.com/jakopako/event-api/config"
 	_ "github.com/jakopako/event-api/docs"
+	"github.com/jakopako/event-api/genre"
 	"github.com/jakopako/event-api/geo"
 	"github.com/jakopako/event-api/routes"
 	_ "github.com/joho/godotenv/autoload"
@@ -56,6 +57,7 @@ func main() {
 	// initialize DB and geoloc cache
 	config.ConnectDB()
 	geo.InitGeolocCache()
+	genre.InitGenreCache()
 
 	setupRoutes(app)
 

models/models.go

@@ -18,6 +18,7 @@ type Event struct {
 	SourceURL        string           `bson:"sourceUrl,omitempty" json:"sourceUrl,omitempty" validate:"required,url" example:"http://link.to/source"`
 	Geolocation      []float64        `bson:"-" json:"geolocation,omitempty" example:"7.4514512,46.9482713"`
 	MongoGeolocation MongoGeolocation `bson:"geolocation,omitempty" json:"-"`
+	Genres           []string         `bson:"genres,omitempty", json:"genres,omitempty" example:"german trap"`
 }
 
 type MongoGeolocation struct {