Added caching mechanism and cache duration flag to openmeteo backend.

backends/open-meteo.com.go

@@ -7,9 +7,9 @@ import (
 	"io"
 	"log"
 	"net/http"
+	"os"
 	"regexp"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/schachmat/wego/iface"
@@ -119,7 +119,39 @@ func (opmeteo *openmeteoConfig) Setup() {
 	flag.StringVar(&opmeteo.apiKey, "openmeteo-api-key", "", "openmeteo backend: the api `KEY` to use if commercial usage")
 	flag.BoolVar(&opmeteo.debug, "openmeteo-debug", false, "openmeteo backend: print raw requests and responses")
 	opmeteo.cache = make(map[string]cachedData) // initializing a cache
-	opmeteo.cacheDuration = 1 * time.Hour       // setting the cache duation to 1 hour
+	flag.DurationVar(&opmeteo.cacheDuration, "openmeteo-cache-duration", 1*time.Hour, "openmeteo backend: duration for caching weather data") // adding the cache duration flag
+	opmeteo.LoadCacheFromDisk()
+}
+
+func (opmeteo *openmeteoConfig) SaveCacheToDisk() {
+	file, err := os.Create("/tmp/wego_cache.json")
+
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	defer file.Close()
+
+	json.NewEncoder(file).Encode(opmeteo.cache)
+}
+
+func (opmeteo *openmeteoConfig) LoadCacheFromDisk() {
+	file, err := os.Open("/tmp/wego_cache.json")
+
+	if os.IsNotExist(err) {
+		log.Println("Cache file not found")
+		return
+	}
+
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	defer file.Close()
+
+	if err := json.NewDecoder(file).Decode(&opmeteo.cache); err != nil {
+		log.Println("Failed to load cache from disk, starting with an empty cache:", err)
+	}
 }
 
 func (opmeteo *openmeteoConfig) parseDaily(dailyInfo Hourly) []iface.Day {
@@ -171,21 +203,17 @@ func parseCurCond(current curCond) (ret iface.Cond) {
 
 }
 
-var mu sync.Mutex
-
 func (opmeteo *openmeteoConfig) Fetch(location string, numdays int) iface.Data {
 	var ret iface.Data
 	var params []string
 	var loc string
 
 	//checking cache before fething the data
-	mu.Lock()
 	if cached, ok := opmeteo.cache[location]; ok {
 		if time.Since(cached.Timestamp) < opmeteo.cacheDuration {
 			return cached.Data
 		}
 	}
-	mu.Unlock()
 
 	if numdays <= 0 {
 		log.Fatal("Number of days less than 1 ")
@@ -207,9 +235,11 @@ func (opmeteo *openmeteoConfig) Fetch(location string, numdays int) iface.Data {
 
 	res, err := http.Get(requri)
 	if err != nil {
-		log.Fatal("Unable to get weather data: ", err)
+		log.Println("Unable to get weather data: ", err)
+		return ret
 	} else if res.StatusCode != 200 {
-		log.Fatal("Unable to get weather data: http status ", res.StatusCode)
+		log.Println("Unable to get weather data: http status ", res.StatusCode)
+		return ret
 	}
 	defer res.Body.Close()
 
@@ -226,7 +256,8 @@ func (opmeteo *openmeteoConfig) Fetch(location string, numdays int) iface.Data {
 
 	var resp openmeteoResponse
 	if err = json.Unmarshal(body, &resp); err != nil {
-		log.Println(err)
+		log.Println("Failed to unmarshal weather data:", err)
+		return ret
 	}
 
 	ret.Current = parseCurCond(resp.Current)
@@ -240,12 +271,12 @@ func (opmeteo *openmeteoConfig) Fetch(location string, numdays int) iface.Data {
 		ret.Forecast = forecast
 	}
 
-	mu.Lock()
 	opmeteo.cache[location] = cachedData{
 		Data:      ret,        //store the fetched data in the cache
 		Timestamp: time.Now(), // store the current time in the cache
 	}
-	mu.Unlock()
+
+	opmeteo.SaveCacheToDisk()
 
 	return ret
 }