Added weather route and embedded cache system

controller/controller.go

@@ -0,0 +1,81 @@
+package controller
+
+import (
+	"encoding/json"
+	"fmt"
+	"math"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/ceticamarco/zephyr/model"
+	"github.com/ceticamarco/zephyr/types"
+)
+
+func jsonError(res http.ResponseWriter, key string, value string, status int) {
+	res.Header().Set("Content-Type", "application/json")
+	res.WriteHeader(status)
+	json.NewEncoder(res).Encode(map[string]string{key: value})
+}
+
+func jsonValue(res http.ResponseWriter, val any) {
+	res.Header().Set("Content-Type", "application/json")
+	res.WriteHeader(http.StatusOK)
+	json.NewEncoder(res).Encode(val)
+}
+
+func fmtTemperature(temp string, isImperial bool) string {
+	parsedTemp, _ := strconv.ParseFloat(temp, 64)
+
+	if isImperial {
+		return fmt.Sprintf("%d°F", int(math.Round(parsedTemp*(9/5)+32)))
+	}
+
+	return fmt.Sprintf("%d°C", int(math.Round(parsedTemp)))
+}
+
+func GetWeather(res http.ResponseWriter, req *http.Request, cache *types.Cache[types.Weather], vars *types.Variables) {
+	if req.Method != http.MethodGet {
+		jsonError(res, "error", "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	// Extract city name from '/weather/:city'
+	path := strings.TrimPrefix(req.URL.Path, "/weather/")
+	cityName := strings.Trim(path, "/") // Remove trailing slash if present
+
+	// Check whether the 'i' parameter(imperial mode) is specified
+	isImperial := req.URL.Query().Has("i")
+
+	weather, found := cache.GetCache(cityName, vars.TimeToLive)
+	if found {
+		// Format weather values and then return it
+		weather.Temperature = fmtTemperature(weather.Temperature, isImperial)
+		weather.FeelsLike = fmtTemperature(weather.FeelsLike, isImperial)
+
+		jsonValue(res, weather)
+	} else {
+		// Get city coordinates
+		city, err := model.GetCoordinates(cityName, vars.Token)
+		if err != nil {
+			jsonError(res, "error", err.Error(), http.StatusBadRequest)
+			return
+		}
+
+		// Get city weather
+		weather, err := model.GetWeather(&city, vars.Token)
+		if err != nil {
+			jsonError(res, "error", err.Error(), http.StatusBadRequest)
+			return
+		}
+
+		// Add result to cache
+		cache.AddEntry(weather, cityName)
+
+		// Format weather values and then return it
+		weather.Temperature = fmtTemperature(weather.Temperature, isImperial)
+		weather.FeelsLike = fmtTemperature(weather.FeelsLike, isImperial)
+
+		jsonValue(res, weather)
+	}
+}

go.mod

@@ -0,0 +1,3 @@
+module github.com/ceticamarco/zephyr
+
+go 1.24.4

main.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"strconv"
+
+	"github.com/ceticamarco/zephyr/controller"
+	"github.com/ceticamarco/zephyr/types"
+)
+
+func main() {
+	// Retrieve listening port, API token and cache time-to-live from environment variables
+	var (
+		port   = os.Getenv("ZEPHYR_PORT")
+		token  = os.Getenv("ZEPHYR_TOKEN")
+		ttl, _ = strconv.ParseInt(os.Getenv("ZEPHYR_CACHE_TTL"), 10, 8)
+	)
+
+	if port == "" || token == "" || ttl == 0 {
+		log.Fatalf("Environment variables not set")
+	}
+
+	// Initialize cache and vars
+	cache := types.InitCache()
+	vars := types.Variables{
+		Token:      token,
+		TimeToLive: int8(ttl),
+	}
+
+	// API endpoints
+	http.HandleFunc("/weather/", func(res http.ResponseWriter, req *http.Request) {
+		controller.GetWeather(res, req, &cache.WeatherCache, &vars)
+	})
+
+	listenAddr := fmt.Sprintf(":%s", port)
+	log.Printf("Server listening on %s", listenAddr)
+	http.ListenAndServe(listenAddr, nil)
+}

model/weatherModel.go

@@ -0,0 +1,155 @@
+package model
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/ceticamarco/zephyr/types"
+)
+
+const (
+	GEO_URL = "https://api.openweathermap.org/geo/1.0/direct"
+	WTR_URL = "https://api.openweathermap.org/data/3.0/onecall"
+)
+
+func getEmoji(condition string, isNight bool) string {
+	switch condition {
+	case "Thunderstorm":
+		return "⛈️"
+	case "Drizzle":
+		return "🌦️"
+	case "Rain":
+		return "🌧️"
+	case "Snow":
+		return "☃️"
+	case "Mist", "Smoke", "Haze", "Dust", "Fog", "Sand", "Ash", "Squall":
+		return "🌫️"
+	case "Tornado":
+		return "🌪️"
+	case "Clear":
+		{
+			if isNight {
+				return "🌙"
+			} else {
+				return "☀️"
+			}
+		}
+	case "Clouds":
+		return "☁️"
+	case "SunWithCloud":
+		return "🌤️"
+	case "CloudWithSun":
+		return "🌥️"
+	}
+
+	return "❓"
+}
+
+func GetCoordinates(cityName string, apiKey string) (types.City, error) {
+	url, err := url.Parse(GEO_URL)
+	if err != nil {
+		return types.City{}, err
+	}
+
+	params := url.Query()
+	params.Set("q", cityName)
+	params.Set("limit", "1")
+	params.Set("appid", apiKey)
+
+	url.RawQuery = params.Encode()
+
+	res, err := http.Get(url.String())
+	if err != nil {
+		return types.City{}, err
+	}
+
+	var geoArr []types.City
+	if err := json.NewDecoder(res.Body).Decode(&geoArr); err != nil {
+		return types.City{}, err
+	}
+
+	if len(geoArr) == 0 {
+		return types.City{}, errors.New("Cannot find this city")
+	}
+
+	return types.City{
+		Name: geoArr[0].Name,
+		Lat:  geoArr[0].Lat,
+		Lon:  geoArr[0].Lon,
+	}, nil
+}
+
+func GetWeather(city *types.City, apiKey string) (types.Weather, error) {
+	url, err := url.Parse(WTR_URL)
+	if err != nil {
+		return types.Weather{}, err
+	}
+
+	params := url.Query()
+	params.Set("lat", strconv.FormatFloat(city.Lat, 'E', -1, 64))
+	params.Set("lon", strconv.FormatFloat(city.Lon, 'E', -1, 64))
+	params.Set("appid", apiKey)
+	params.Set("units", "metric")
+	params.Set("exclude", "minutely,hourly,daily,alerts")
+
+	url.RawQuery = params.Encode()
+
+	res, err := http.Get(url.String())
+	if err != nil {
+		return types.Weather{}, err
+	}
+
+	// Structures representing the JSON response
+	type InfoRes struct {
+		Title       string `json:"main"`
+		Description string `json:"description"`
+		Icon        string `json:"icon"`
+	}
+	type CurrentRes struct {
+		FeelsLike   float64   `json:"feels_like"`
+		Temperature float64   `json:"temp"`
+		Timestamp   int64     `json:"dt"`
+		Weather     []InfoRes `json:"weather"`
+	}
+	type WeatherRes struct {
+		Current CurrentRes `json:"current"`
+	}
+
+	var weather WeatherRes
+	if err := json.NewDecoder(res.Body).Decode(&weather); err != nil {
+		return types.Weather{}, err
+	}
+
+	// Format UNIX timestamp as 'YYYY-MM-DD'
+	// unixTs, _ := strconv.Atoi(weather.Current.Timestamp)
+	utcTime := time.Unix(int64(weather.Current.Timestamp), 0)
+	weatherDate := utcTime.UTC()
+
+	// Set condition accordingly to weather description
+	var condition string
+	switch weather.Current.Weather[0].Description {
+	case "few clouds":
+		condition = "SunWithCloud"
+	case "broken clouds":
+		condition = "CloudWithSun"
+	default:
+		condition = weather.Current.Weather[0].Title
+	}
+
+	// Get emoji from weather condition
+	isNight := strings.HasSuffix(weather.Current.Weather[0].Icon, "n")
+	emoji := getEmoji(condition, isNight)
+
+	return types.Weather{
+		Date:        weatherDate,
+		Temperature: strconv.FormatFloat(weather.Current.Temperature, 'E', -1, 64),
+		FeelsLike:   strconv.FormatFloat(weather.Current.FeelsLike, 'E', -1, 64),
+		Condition:   weather.Current.Weather[0].Title,
+		Emoji:       emoji,
+	}, nil
+}

types/Weather.go

@@ -0,0 +1,12 @@
+package types
+
+import "time"
+
+// The Weather data type, representing the weather of a certain city
+type Weather struct {
+	Date        time.Time `json:"date"`
+	Temperature string    `json:"temperature"`
+	Condition   string    `json:"condition"`
+	FeelsLike   string    `json:"feelsLike"`
+	Emoji       string    `json:"emoji"`
+}

types/cache.go

@@ -0,0 +1,66 @@
+package types
+
+import (
+	"time"
+)
+
+// CacheType, representing the abstract value of a CacheEntity
+type CacheType interface {
+	Weather | Metrics
+}
+
+// CacheEntity, representing the value of the cache
+type CacheEntity[T CacheType] struct {
+	Element   T
+	Timestamp time.Time
+}
+
+// Cache, representing a mapping between a key(str) and a CacheEntity
+type Cache[T CacheType] struct {
+	Data map[string]CacheEntity[T]
+}
+
+// Caches, representing a grouping of the various caches
+type Caches struct {
+	WeatherCache Cache[Weather]
+	MetricsCache Cache[Metrics]
+}
+
+func InitCache() *Caches {
+	return &Caches{
+		WeatherCache: Cache[Weather]{Data: make(map[string]CacheEntity[Weather])},
+		MetricsCache: Cache[Metrics]{Data: make(map[string]CacheEntity[Metrics])},
+	}
+}
+
+func (cache *Cache[T]) GetCache(key string, ttl int8) (T, bool) {
+	val, isPresent := cache.Data[key+"_weather"]
+
+	// If key is not present, return a zero value
+	if !isPresent {
+		return val.Element, false
+	}
+
+	// Otherwise check whether cache element is expired
+	currentTime := time.Now()
+	expired := currentTime.Sub(val.Timestamp) > (time.Duration(ttl) * time.Hour)
+	if expired {
+		return val.Element, false
+	}
+
+	return val.Element, true
+}
+
+func (cache *Cache[T]) AddEntry(entry T, cityName string) {
+	currentTime := time.Now()
+
+	switch any(entry).(type) {
+	case Weather:
+		{
+			cache.Data[cityName+"_weather"] = CacheEntity[T]{
+				Element:   entry,
+				Timestamp: currentTime,
+			}
+		}
+	}
+}

types/city.go

@@ -0,0 +1,9 @@
+package types
+
+// The City data type, representing the name, the latitude and the longitude
+// of a location
+type City struct {
+	Name string  `json:"name"`
+	Lat  float64 `json:"lat"`
+	Lon  float64 `json:"lon"`
+}

types/metrics.go

@@ -0,0 +1,11 @@
+package types
+
+// The Metrics data type, representing the humidity, pressure and
+// similar miscellaneous values
+type Metrics struct {
+	Humidity   string `json:"humidity"`
+	Pressure   string `json:"pressure"`
+	DewPoint   string `json:"dewPoint"`
+	UvIndex    int8   `json:"uvIndex"`
+	Visibility string `json:"visibility"`
+}

types/variables.go

@@ -0,0 +1,7 @@
+package types
+
+// Variables type, representing values read from environment variables
+type Variables struct {
+	Token      string
+	TimeToLive int8
+}