add ristretto caching and process daily and rolling data

service_b/internal/domains/meteo/service.go

@@ -2,33 +2,42 @@ package meteo
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"log/slog"
 	"net/http"
-	"sync"
 	"time"
 
 	"github.com/cenkalti/backoff/v5"
+	"github.com/dgraph-io/ristretto/v2"
 )
 
-type inMemory struct {
-	data   any
-	mu     *sync.RWMutex
-	expiry time.Time
-}
 type Service struct {
-	inMemory
+	cache *ristretto.Cache[string, string]
 }
 
 func NewService() *Service {
-	return &Service{}
+	cache, err := ristretto.NewCache(&ristretto.Config[string, string]{
+		NumCounters: 1024,
+		MaxCost:     1 << 30,
+		BufferItems: 64,
+	})
+	if err != nil {
+		slog.Error("cannot init cache", "err", err)
+		return nil
+	}
+
+	return &Service{
+		cache: cache,
+	}
 }
 
-func (s *Service) GetWeatherByCity(ctx context.Context, params GetMeteoData) ([]MeteoData, error) {
+func (s *Service) GetWeatherByCity(ctx context.Context, params GetMeteoData) (MeteoData, error) {
 	fromDate, err := time.Parse("2006-01-02", params.Date)
 	if err != nil {
-		return nil, err
+		return MeteoData{}, err
 	}
 	toDate := fromDate.AddDate(0, 0, params.Days-1)
 
@@ -36,13 +45,15 @@ func (s *Service) GetWeatherByCity(ctx context.Context, params GetMeteoData) ([]
 		url := fmt.Sprintf("http://localhost:8080/data?city=%s&from=%s&to=%s",
 			params.Location, params.Date, toDate.Format("2006-01-02"))
 
+		slog.Info("url", "url", url)
+
 		resp, err := http.Get(url)
 		if err != nil {
 			return nil, err
 		}
-		defer resp.Body.Close()
 
 		if resp.StatusCode == http.StatusBadRequest {
+			resp.Body.Close()
 			return nil, backoff.Permanent(errors.New("bad request"))
 		}
 
@@ -52,11 +63,92 @@ func (s *Service) GetWeatherByCity(ctx context.Context, params GetMeteoData) ([]
 	result, err := backoff.Retry(ctx, operation, backoff.WithBackOff(backoff.NewExponentialBackOff()))
 	if err != nil {
 		slog.Error("somethin happened")
-		return []MeteoData{}, err
+		return MeteoData{}, err
 	}
-	// TODO add ristretto
+	defer result.Body.Close()
 
-	slog.Info("fetched data", "data", result)
+	body, err := io.ReadAll(result.Body)
+	if err != nil {
+		slog.Error("error reading response body", "err", err)
+		return MeteoData{}, err
+	}
 
-	return []MeteoData{}, nil
+	var serviceAResponse struct {
+		MeteoData []MeteoDataFromServiceA `json:"meteo_data"`
+	}
+	if err := json.Unmarshal(body, &serviceAResponse); err != nil {
+		slog.Error("error unmarshaling response", "err", err)
+		return MeteoData{}, err
+	}
+
+	if len(serviceAResponse.MeteoData) == 0 {
+		return MeteoData{}, nil
+	}
+
+	if params.Agg == AggDaily {
+		return s.processDailyData(serviceAResponse.MeteoData, params)
+	}
+
+	return s.processRolling7Data(serviceAResponse.MeteoData, params)
+}
+
+func (s *Service) processDailyData(data []MeteoDataFromServiceA, params GetMeteoData) (MeteoData, error) {
+	days := make([]MeteoDataPerDay, 0, len(data))
+
+	for _, d := range data {
+		avgTemp := (d.MaxTemp + d.MinTemp) / 2
+		day := MeteoDataPerDay{
+			MaxTemp:    d.MaxTemp,
+			MinTemp:    d.MinTemp,
+			AvgTemp:    avgTemp,
+			Rainfall:   d.Rainfall,
+			Cloudiness: d.Cloudiness,
+		}
+
+		if params.Unit == UnitF {
+			day.ConvertValue()
+		}
+
+		days = append(days, day)
+	}
+
+	return MeteoData{
+		Location: params.Location,
+		Unit:     params.Unit,
+		From:     params.Date,
+		Days:     &days,
+	}, nil
+}
+
+func (s *Service) processRolling7Data(data []MeteoDataFromServiceA, params GetMeteoData) (MeteoData, error) {
+	if len(data) < 7 {
+		return MeteoData{}, errors.New("insufficient data for rolling 7-day calculation")
+	}
+
+	var sumTemp, sumRainfall float32
+	var sumCloudiness int
+
+	for i := len(data) - 7; i < len(data); i++ {
+		avgTemp := (data[i].MaxTemp + data[i].MinTemp) / 2
+		sumTemp += avgTemp
+		sumRainfall += data[i].Rainfall
+		sumCloudiness += data[i].Cloudiness
+	}
+
+	rolling7 := &Rolling7Data{
+		AvgTemp:       sumTemp / 7,
+		AvgCloudiness: sumCloudiness / 7,
+		SumRainfall:   sumRainfall,
+	}
+
+	if params.Unit == UnitF {
+		rolling7.AvgTemp = rolling7.AvgTemp*9/5 + 32
+	}
+
+	return MeteoData{
+		Location: params.Location,
+		Unit:     params.Unit,
+		From:     params.Date,
+		Rolling7: rolling7,
+	}, nil
 }