From e0113bf06718ae2e9e4518ea5160cc7fc8494b2c Mon Sep 17 00:00:00 2001
From: vinayak3010 <rvinayak108@gmail.com>
Date: Sat, 5 Oct 2024 22:18:39 +0530
Subject: [PATCH] feat: Add caching mechanism to optimize weather data fetching
 from OpenMeteo API

---
 backends/open-meteo.com.go     | 34 +++++++++++++++++++++++++---
 backends/openweathermap.org.go | 41 +++++++++++++++++++++++++++-------
 2 files changed, 64 insertions(+), 11 deletions(-)

diff --git a/backends/open-meteo.com.go b/backends/open-meteo.com.go
index 696ba1e..e6a2696 100644
--- a/backends/open-meteo.com.go
+++ b/backends/open-meteo.com.go
@@ -9,15 +9,23 @@ import (
 	"net/http"
 	"regexp"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/schachmat/wego/iface"
 )
 
+type cachedData struct {
+	Data      iface.Data
+	Timestamp time.Time
+}
+
 type openmeteoConfig struct {
-	apiKey   string
-	language string
-	debug    bool
+	apiKey        string
+	language      string
+	debug         bool
+	cache         map[string]cachedData // adding a cache map
+	cacheDuration time.Duration         // adding the duration for which the data will be valid
 }
 
 type curCond struct {
@@ -110,6 +118,8 @@ var (
 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
 }
 
 func (opmeteo *openmeteoConfig) parseDaily(dailyInfo Hourly) []iface.Day {
@@ -161,11 +171,22 @@ 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 ")
 	}
@@ -219,6 +240,13 @@ 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()
+
 	return ret
 }
 
diff --git a/backends/openweathermap.org.go b/backends/openweathermap.org.go
index 1eae102..091be8c 100644
--- a/backends/openweathermap.org.go
+++ b/backends/openweathermap.org.go
@@ -4,30 +4,39 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
-	"github.com/schachmat/wego/iface"
 	"io"
 	"log"
 	"net/http"
 	"regexp"
 	"strings"
+	"sync"
 	"time"
+
+	"github.com/schachmat/wego/iface"
 )
 
 type openWeatherConfig struct {
-	apiKey string
-	lang   string
-	debug  bool
+	apiKey   string
+	lang     string
+	debug    bool
+	cache    map[string]cacheEntry
+	cacheMux sync.Mutex
+}
+
+type cacheEntry struct {
+	data      iface.Data
+	Timestamp time.Time
 }
 
 type openWeatherResponse struct {
 	Cod  string `json:"cod"`
 	City struct {
-		Name    string `json:"name"`
-		Country string `json:"country"`
-		TimeZone int64 `json: "timezone"`
+		Name     string `json:"name"`
+		Country  string `json:"country"`
+		TimeZone int64  `json: "timezone"`
 		// sunrise/sunset are once per call
 		SunRise int64 `json: "sunrise"`
-		SunSet int64 `json: "sunset"`
+		SunSet  int64 `json: "sunset"`
 	} `json:"city"`
 	List []dataBlock `json:"list"`
 }
@@ -57,12 +66,15 @@ type dataBlock struct {
 
 const (
 	openweatherURI = "http://api.openweathermap.org/data/2.5/forecast?%s&appid=%s&units=metric&lang=%s"
+	cacheDuration = 1 * time.Hour
 )
 
 func (c *openWeatherConfig) Setup() {
 	flag.StringVar(&c.apiKey, "owm-api-key", "", "openweathermap backend: the api `KEY` to use")
 	flag.StringVar(&c.lang, "owm-lang", "en", "openweathermap backend: the `LANGUAGE` to request from openweathermap")
 	flag.BoolVar(&c.debug, "owm-debug", false, "openweathermap backend: print raw requests and responses")
+
+	c.cache = make(map[string]cacheEntry) // initializing the cache
 }
 
 func (c *openWeatherConfig) fetch(url string) (*openWeatherResponse, error) {
@@ -236,6 +248,14 @@ func (c *openWeatherConfig) Fetch(location string, numdays int) iface.Data {
 	if len(c.apiKey) == 0 {
 		log.Fatal("No openweathermap.org API key specified.\nYou have to register for one at https://home.openweathermap.org/users/sign_up")
 	}
+
+	c.cacheMux.Lock()
+	if entry, found := c.cache[location]; found && time.Since(entry.Timestamp)<cacheDuration {
+		c.cacheMux.Unlock()
+		return entry.data
+	}
+	c.cacheMux.Unlock()
+
 	if matched, err := regexp.MatchString(`^-?[0-9]*(\.[0-9]+)?,-?[0-9]*(\.[0-9]+)?$`, location); matched && err == nil {
 		s := strings.Split(location, ",")
 		loc = fmt.Sprintf("lat=%s&lon=%s", s[0], s[1])
@@ -257,6 +277,11 @@ func (c *openWeatherConfig) Fetch(location string, numdays int) iface.Data {
 	}
 
 	if numdays == 0 {
+		c.cacheMux.Lock()
+		c.cache[location] = cacheEntry{
+			data: ret, 
+			Timestamp: time.Now(),
+		}
 		return ret
 	}
 	ret.Forecast = c.parseDaily(resp.List, numdays)