388 lines
10 KiB
Go
388 lines
10 KiB
Go
package main
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import (
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"bufio"
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"context"
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"encoding/json"
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"fmt"
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"io"
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"log"
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"net"
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"net/http"
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"net/url"
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"os"
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"strings"
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"sync"
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"time"
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)
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const (
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defaultPort = "79"
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weatherAPIURL = "http://api.worldweatheronline.com/premium/v1/weather.ashx"
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readTimeout = 30 * time.Second
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writeTimeout = 30 * time.Second
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httpTimeout = 15 * time.Second
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forecastDays = 3
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hourlyInterval = 6
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separatorLength = 60
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)
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// Config holds server configuration
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type Config struct {
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Port string
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APIKey string
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}
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// Server represents the weather finger server
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type Server struct {
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config *Config
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client *http.Client
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logger *log.Logger
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shutdown chan struct{}
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wg sync.WaitGroup
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}
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// Weather API response structures
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type WeatherResponse struct {
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Data WeatherData `json:"data"`
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Error []WeatherError `json:"error,omitempty"`
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}
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type WeatherData struct {
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Request []RequestInfo `json:"request"`
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NearestArea []NearestArea `json:"nearest_area"`
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CurrentCondition []CurrentCondition `json:"current_condition"`
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Weather []DailyWeather `json:"weather"`
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}
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type RequestInfo struct {
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Query string `json:"query"`
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Type string `json:"type"`
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}
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type NearestArea struct {
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AreaName []NameValue `json:"areaName"`
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Country []NameValue `json:"country"`
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}
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type NameValue struct {
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Value string `json:"value"`
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}
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type CurrentCondition struct {
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TempC string `json:"temp_C"`
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TempF string `json:"temp_F"`
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WeatherDesc []NameValue `json:"weatherDesc"`
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Humidity string `json:"humidity"`
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Visibility string `json:"visibility"`
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Pressure string `json:"pressure"`
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CloudCover string `json:"cloudcover"`
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FeelsLikeC string `json:"FeelsLikeC"`
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FeelsLikeF string `json:"FeelsLikeF"`
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WindSpeedKmph string `json:"windspeedKmph"`
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WindSpeedMiles string `json:"windspeedMiles"`
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WindDir16Point string `json:"winddir16Point"`
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ObservationTime string `json:"observation_time"`
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}
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type DailyWeather struct {
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Date string `json:"date"`
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MaxTempC string `json:"maxtempC"`
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MaxTempF string `json:"maxtempF"`
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MinTempC string `json:"mintempC"`
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MinTempF string `json:"mintempF"`
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Hourly []HourlyWeather `json:"hourly"`
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}
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type HourlyWeather struct {
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Time string `json:"time"`
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TempC string `json:"tempC"`
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TempF string `json:"tempF"`
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WeatherDesc []NameValue `json:"weatherDesc"`
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ChanceOfRain string `json:"chanceofrain"`
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Humidity string `json:"humidity"`
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}
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type WeatherError struct {
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Msg string `json:"msg"`
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}
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func main() {
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config := &Config{
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Port: getEnvOrDefault("WEATHER_PORT", defaultPort),
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APIKey: os.Getenv("WEATHER_API_KEY"),
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}
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if config.APIKey == "" {
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log.Fatal("WEATHER_API_KEY environment variable is not set")
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}
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server := NewServer(config)
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if err := server.Start(); err != nil {
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log.Fatalf("Server failed to start: %v", err)
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}
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}
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// NewServer creates a new weather finger server instance
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func NewServer(config *Config) *Server {
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return &Server{
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config: config,
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client: &http.Client{
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Timeout: httpTimeout,
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},
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logger: log.New(os.Stdout, "[WeatherServer] ", log.LstdFlags),
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shutdown: make(chan struct{}),
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}
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}
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// Start begins listening for connections
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func (s *Server) Start() error {
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listener, err := net.Listen("tcp", ":"+s.config.Port)
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if err != nil {
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return fmt.Errorf("failed to start listener: %w", err)
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}
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defer listener.Close()
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s.logger.Printf("Weather Finger Server started on port %s", s.config.Port)
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for {
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select {
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case <-s.shutdown:
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s.logger.Println("Shutting down server...")
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s.wg.Wait()
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return nil
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default:
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conn, err := listener.Accept()
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if err != nil {
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s.logger.Printf("Failed to accept connection: %v", err)
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continue
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}
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s.wg.Add(1)
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go s.handleConnection(conn)
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}
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}
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}
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// Stop gracefully shuts down the server
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func (s *Server) Stop() {
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close(s.shutdown)
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}
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// handleConnection processes a single client connection
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func (s *Server) handleConnection(conn net.Conn) {
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defer s.wg.Done()
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defer conn.Close()
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if err := s.processRequest(conn); err != nil {
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s.logger.Printf("Error processing request: %v", err)
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fmt.Fprintf(conn, "Error: %v\n", err)
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}
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}
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// processRequest reads the query and writes the weather response
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func (s *Server) processRequest(conn net.Conn) error {
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// Set timeouts
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conn.SetReadDeadline(time.Now().Add(readTimeout))
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conn.SetWriteDeadline(time.Now().Add(writeTimeout))
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// Read request
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reader := bufio.NewReader(conn)
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request, err := reader.ReadString('\n')
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if err != nil {
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if err == io.EOF {
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return fmt.Errorf("client disconnected")
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}
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return fmt.Errorf("failed to read request: %w", err)
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}
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query := strings.TrimSpace(request)
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if query == "" {
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return fmt.Errorf("empty query")
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}
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clientAddr := conn.RemoteAddr().String()
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s.logger.Printf("Request from %s: '%s'", clientAddr, query)
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// Get weather data
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ctx, cancel := context.WithTimeout(context.Background(), httpTimeout)
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defer cancel()
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forecast, err := s.getWeatherForecast(ctx, query)
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if err != nil {
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return fmt.Errorf("failed to get weather: %w", err)
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}
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// Format and send response
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response := formatWeatherResponse(forecast)
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_, err = conn.Write([]byte(response))
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return err
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}
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// getWeatherForecast fetches weather data from the API
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func (s *Server) getWeatherForecast(ctx context.Context, query string) (*WeatherResponse, error) {
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params := url.Values{
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"key": {s.config.APIKey},
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"q": {query},
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"format": {"json"},
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"num_of_days": {fmt.Sprintf("%d", forecastDays)},
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"tp": {fmt.Sprintf("%d", hourlyInterval)},
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"includelocation": {"yes"},
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}
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apiURL := fmt.Sprintf("%s?%s", weatherAPIURL, params.Encode())
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, apiURL, nil)
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if err != nil {
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return nil, fmt.Errorf("failed to create request: %w", err)
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}
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resp, err := s.client.Do(req)
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if err != nil {
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return nil, fmt.Errorf("API request failed: %w", err)
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}
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defer resp.Body.Close()
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("API returned status %d", resp.StatusCode)
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}
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body, err := io.ReadAll(resp.Body)
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if err != nil {
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return nil, fmt.Errorf("failed to read response: %w", err)
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}
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var weatherData WeatherResponse
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if err := json.Unmarshal(body, &weatherData); err != nil {
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return nil, fmt.Errorf("failed to parse response: %w", err)
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}
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if len(weatherData.Error) > 0 {
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return nil, fmt.Errorf("API error: %s", weatherData.Error[0].Msg)
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}
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return &weatherData, nil
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}
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// formatWeatherResponse creates a human-readable weather report
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func formatWeatherResponse(response *WeatherResponse) string {
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var sb strings.Builder
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data := &response.Data
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// Write header
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writeHeader(&sb, data)
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// Write current conditions
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writeCurrentConditions(&sb, data)
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// Write forecast
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writeForecast(&sb, data)
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return sb.String()
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}
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// writeHeader writes the location header
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func writeHeader(sb *strings.Builder, data *WeatherData) {
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if len(data.NearestArea) > 0 {
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area := data.NearestArea[0]
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areaName := getFirstValue(area.AreaName)
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countryName := getFirstValue(area.Country)
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sb.WriteString(fmt.Sprintf("Weather forecast for: %s, %s\n", areaName, countryName))
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} else {
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sb.WriteString("Weather forecast\n")
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}
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sb.WriteString(strings.Repeat("=", separatorLength))
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sb.WriteString("\n")
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}
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// writeCurrentConditions writes the current weather conditions
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func writeCurrentConditions(sb *strings.Builder, data *WeatherData) {
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if len(data.CurrentCondition) == 0 {
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sb.WriteString("CURRENT CONDITIONS: Not available\n\n")
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return
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}
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current := data.CurrentCondition[0]
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desc := getFirstValue(current.WeatherDesc)
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sb.WriteString("CURRENT CONDITIONS:\n")
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fmt.Fprintf(sb, " Temperature: %s°C (%s°F) - feels like %s°C (%s°F)\n",
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current.TempC, current.TempF, current.FeelsLikeC, current.FeelsLikeF)
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fmt.Fprintf(sb, " Conditions: %s\n", desc)
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fmt.Fprintf(sb, " Humidity: %s%%\n", current.Humidity)
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fmt.Fprintf(sb, " Wind: %s km/h %s (%s mph)\n",
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current.WindSpeedKmph, current.WindDir16Point, current.WindSpeedMiles)
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fmt.Fprintf(sb, " Pressure: %s mb\n", current.Pressure)
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fmt.Fprintf(sb, " Visibility: %s km\n", current.Visibility)
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fmt.Fprintf(sb, " Cloud Cover: %s%%\n", current.CloudCover)
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fmt.Fprintf(sb, " Observed: %s\n", current.ObservationTime)
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sb.WriteString("\n")
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}
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// writeForecast writes the daily forecast
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func writeForecast(sb *strings.Builder, data *WeatherData) {
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if len(data.Weather) == 0 {
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sb.WriteString("FORECAST: Not available\n")
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return
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}
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fmt.Fprintf(sb, "%d-DAY FORECAST:\n", len(data.Weather))
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for _, day := range data.Weather {
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dateStr := formatDate(day.Date)
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fmt.Fprintf(sb, " %s:\n", dateStr)
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fmt.Fprintf(sb, " High: %s°C (%s°F) Low: %s°C (%s°F)\n",
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day.MaxTempC, day.MaxTempF, day.MinTempC, day.MinTempF)
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if len(day.Hourly) > 0 {
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sb.WriteString(" Hourly:\n")
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for _, hour := range day.Hourly {
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timeStr := formatTime(hour.Time)
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desc := getFirstValue(hour.WeatherDesc)
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fmt.Fprintf(sb, " %s: %s°C (%s°F) %s (rain: %s%%, humidity: %s%%)\n",
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timeStr, hour.TempC, hour.TempF, desc, hour.ChanceOfRain, hour.Humidity)
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}
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}
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}
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}
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// Helper functions
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// getFirstValue safely extracts the first value from a NameValue slice
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func getFirstValue(values []NameValue) string {
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if len(values) > 0 {
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return values[0].Value
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}
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return "N/A"
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}
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// formatDate formats a date string for display
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func formatDate(dateStr string) string {
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date, err := time.Parse("2006-01-02", dateStr)
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if err != nil {
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return dateStr
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}
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return date.Format("Mon, Jan 2")
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}
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// formatTime formats API time values to HH:MM format
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func formatTime(timeStr string) string {
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// Normalize to 4-digit format
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padded := fmt.Sprintf("%04s", timeStr)
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if len(padded) >= 4 {
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return padded[:2] + ":" + padded[2:4]
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}
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return timeStr
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}
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// getEnvOrDefault returns environment variable value or default
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func getEnvOrDefault(key, defaultValue string) string {
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if value := os.Getenv(key); value != "" {
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return value
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}
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return defaultValue
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}
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