feat(WeatherAPI): WeatherAPI API implementation

src/main/java/eirb/pg203/WeatherAPI.java

@@ -1,4 +1,68 @@
 package eirb.pg203;
 
-public class WeatherAPI {
+import org.json.JSONArray;
+import org.json.JSONObject;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URI;
+import java.net.URL;
+import java.time.Instant;
+import java.util.ArrayList;
+
+public class WeatherAPI implements WeatherDataAPI{
+    private final String weatherAPIKey;
+
+    WeatherAPI(String weatherAPIKey) {
+        this.weatherAPIKey = weatherAPIKey;
+    }
+
+    private JSONObject fetchWeather(int days, String city) throws IOException {
+        StringBuilder result = new StringBuilder();
+        URL url = URI.create(
+                String.format("https://api.weatherapi.com/v1/forecast.json?key=%s&q=%s&days=%d",
+                        this.weatherAPIKey,
+                        city,
+                        days
+                )
+        ).toURL();
+        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
+        conn.setRequestMethod("GET");
+        try (BufferedReader reader = new BufferedReader(
+                new InputStreamReader(conn.getInputStream()))) {
+            for (String line; (line = reader.readLine()) != null; ) {
+                result.append(line);
+            }
+        }
+
+        return new JSONObject(result.toString());
+    }
+
+    @Override
+    public Temperature getTemperature(int day, String city) throws IOException {
+        JSONObject result = fetchWeather(day+1, city);
+        JSONArray forecast = result.getJSONObject("forecast").getJSONArray("forecastday");
+        float temp_c = forecast.getJSONObject(day).getJSONObject("day").getFloat("avgtemp_c");
+
+        return new Temperature(temp_c, city, Instant.now());
+    }
+
+    @Override
+    public Temperature getTemperature(int day, int hour, String city) throws IOException{
+        return getTemperature(day, city);
+    }
+
+    @Override
+    public ArrayList<Temperature> getTemperatures(int days, String city) throws IOException {
+        JSONObject result = fetchWeather(days, city);
+        ArrayList<Temperature> temperatures = new ArrayList<>();
+        for (int day = 0; day < days; ++day) {
+            JSONArray forecast = result.getJSONObject("forecast").getJSONArray("forecastday");
+            float temp_c = forecast.getJSONObject(day).getJSONObject("day").getFloat("avgtemp_c");
+            temperatures.add(new Temperature(temp_c, city, Instant.now()));
+        }
+        return temperatures;
+    }
 }