#39 Added basic implementation

src/main/java/de/rwu/easydrop/Main.java

@@ -1,5 +1,8 @@
 package de.rwu.easydrop;
 
+import de.rwu.easydrop.api.client.AmazonProductDataSource;
+import de.rwu.easydrop.util.ConfigUtil;
+
 /**
  * Kickoff point for the service.
  *
@@ -19,6 +22,11 @@ public final class Main {
      * @param args
      */
     public static void main(final String[] args) {
-        System.out.println("I'm alive!");
+        String amznBaseUrl = ConfigUtil.getConfig("AMAZON_API_URL");
+        String amznApiKey = ConfigUtil.getConfig("AMAZON_API_KEY");
+
+        AmazonProductDataSource amznSrc = new AmazonProductDataSource(amznBaseUrl, amznApiKey);
+        System.out.print(amznSrc.getProductDTOById("B096Y2TYKV").toString());
+
     }
 }

src/main/java/de/rwu/easydrop/api/client/AmazonProductDataSource.java

@@ -0,0 +1,121 @@
+package de.rwu.easydrop.api.client;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import de.rwu.easydrop.api.dto.ProductDTO;
+
+/**
+ * Interface to an Amazon data source.
+ *
+ * @since 0.1.0
+ */
+public final class AmazonProductDataSource implements DataSource {
+    /**
+     * Name of this data source.
+     */
+    private static final String DATA_ORIGIN = "Amazon";
+    /**
+     * Base URL to the Amazon data source.
+     */
+    private String baseUrl;
+    /**
+     * Credential key to authorize acccess.
+     */
+    private String apiKey;
+    /**
+     * Product region parameter required for data access.
+     */
+    private static final String PRODUCT_REGION = "DE";
+    /**
+     * Locale parameter required for data access.
+     */
+    private static final String LOCALE = "de_DE";
+
+    /**
+     * Sets up instance with Base URL and API Key.
+     *
+     * @param newBaseUrl
+     * @param newApiKey
+     */
+    public AmazonProductDataSource(final String newBaseUrl, final String newApiKey) {
+        this.baseUrl = newBaseUrl;
+        this.apiKey = newApiKey;
+    }
+
+    @Override
+    public ProductDTO getProductDTOById(final String productId) {
+        JSONObject offer = null;
+        ProductDTO product = new ProductDTO(productId, DATA_ORIGIN);
+
+        try {
+            URL apiUrl = new URL(
+                    baseUrl
+                            + "/products/2020-08-26/products/"
+                            + productId
+                            + "/offers?productRegion="
+                            + PRODUCT_REGION
+                            + "&locale="
+                            + LOCALE);
+
+            HttpURLConnection connection = (HttpURLConnection) apiUrl.openConnection();
+            connection.setRequestMethod("GET");
+            connection.setRequestProperty("Credential", apiKey);
+
+            int responseCode = connection.getResponseCode();
+            BufferedReader reader;
+            if (responseCode == HttpURLConnection.HTTP_OK) {
+                reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
+            } else {
+                return product;
+            }
+
+            String line;
+            StringBuilder response = new StringBuilder();
+            while ((line = reader.readLine()) != null) {
+                response.append(line);
+            }
+            reader.close();
+
+            offer = new JSONObject(response.toString());
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        if (offer == null) {
+            return product;
+        }
+
+        try {
+            offer = offer.getJSONObject("featuredOffer");
+
+            product.setDataOrigin(DATA_ORIGIN);
+            product.setAvailable(offer
+                    .getString("availability")
+                    .equals("available"));
+            product.setCurrentPrice(offer
+                    .getJSONObject("price")
+                    .getJSONObject("value")
+                    .getDouble("amount"));
+            product.setDeliveryPrice(offer
+                    .getJSONArray("shippingOptions")
+                    .getJSONObject(0)
+                    .getJSONObject("shippingCost")
+                    .getJSONObject("value")
+                    .getDouble("amount"));
+            product.setMerchant(offer
+                    .getJSONObject("merchant")
+                    .getString("name"));
+        } catch (JSONException e) {
+            return product;
+        }
+
+        return product;
+    }
+}

src/main/java/de/rwu/easydrop/api/client/DataSource.java

@@ -12,12 +12,5 @@ public interface DataSource {
      * @param productId Identifier
      * @return ProductDTO
      */
-    ProductDTO getProductById(String productId);
+    ProductDTO getProductDTOById(String productId);
-
-    /**
-     * Breaks the connection after specified time.
-     *
-     * @param timeoutSeconds Seconds to time out after
-     */
-    void setConnectionTimeout(int timeoutSeconds);
 }

src/main/java/de/rwu/easydrop/api/dto/ProductDTO.java

@@ -1,8 +1,146 @@
 package de.rwu.easydrop.api.dto;
 
+import de.rwu.easydrop.util.FormattingUtil;
+
 /**
  * Product data transfer object.
+ *
+ * @since 0.1.0
  */
 public class ProductDTO {
+    /**
+     * Data source platform, like "Amazon".
+     */
+    private String dataOrigin;
 
+    /**
+     * @return the dataOrigin
+     */
+    public String getDataOrigin() {
+        return dataOrigin;
+    }
+
+    /**
+     * @param newDataOrigin the dataOrigin to set
+     */
+    public void setDataOrigin(final String newDataOrigin) {
+        this.dataOrigin = newDataOrigin;
+    }
+
+    /**
+     * Platform internal product identifier.
+     */
+    private String productId;
+
+    /**
+     * @return the productId
+     */
+    public String getProductId() {
+        return productId;
+    }
+
+    /**
+     * @param newProductId the productId to set
+     */
+    public void setProductId(final String newProductId) {
+        this.productId = newProductId;
+    }
+
+    /**
+     * Current product price per piece in Euro.
+     */
+    private double currentPrice;
+
+    /**
+     * @return the currentPrice
+     */
+    public double getCurrentPrice() {
+        return currentPrice;
+    }
+
+    /**
+     * @param newCurrentPrice the currentPrice to set
+     */
+    public void setCurrentPrice(final double newCurrentPrice) {
+        this.currentPrice = newCurrentPrice;
+    }
+
+    /**
+     * Name of mercant offering the product on the platform.
+     */
+    private String merchant;
+
+    /**
+     * @return the merchant
+     */
+    public String getMerchant() {
+        return merchant;
+    }
+
+    /**
+     * @param newMerchant the merchant to set
+     */
+    public void setMerchant(final String newMerchant) {
+        this.merchant = newMerchant;
+    }
+
+    /**
+     * Additional Cost for delivery in Euro.
+     */
+    private double deliveryPrice;
+
+    /**
+     * @return the deliveryPrice
+     */
+    public double getDeliveryPrice() {
+        return deliveryPrice;
+    }
+
+    /**
+     * @param newDeliveryPrice the deliveryPrice to set
+     */
+    public void setDeliveryPrice(final double newDeliveryPrice) {
+        this.deliveryPrice = newDeliveryPrice;
+    }
+
+    /**
+     * Whether the product can be purchased at this point.
+     */
+    private boolean available;
+
+    /**
+     * @return the available
+     */
+    public boolean isAvailable() {
+        return available;
+    }
+
+    /**
+     * @param newAvailable the available to set
+     */
+    public void setAvailable(final boolean newAvailable) {
+        this.available = newAvailable;
+    }
+
+    /**
+     * Creates ProductDTO instance.
+     *
+     * @param newProductId  Interal Product indetifier
+     * @param newDataOrigin Data Origin
+     */
+    public ProductDTO(final String newProductId, final String newDataOrigin) {
+        this.productId = newProductId;
+        this.dataOrigin = newDataOrigin;
+    }
+
+    @Override
+    public final String toString() {
+        return "ProductDTO{"
+                + productId + " from "
+                + merchant + " ("
+                + dataOrigin + ")"
+                + " at "
+                + FormattingUtil.formatEuro(currentPrice) + " (available: "
+                + (available ? "yes" : "no") + ")}";
+    }
 }

src/main/java/de/rwu/easydrop/util/FormattingUtil.java

@@ -1,5 +1,39 @@
 package de.rwu.easydrop.util;
 
-public class FormattingUtil {
+import java.text.NumberFormat;
+import java.util.Currency;
+import java.util.Locale;
 
+/**
+ * Helps format a bunch of things.
+ *
+ * @since 0.1.0
+ */
+public final class FormattingUtil {
+
+    /**
+     * Private constructor to prevent unwanted instantiation.
+     *
+     * @throws UnsupportedOperationException always
+     */
+    private FormattingUtil() throws UnsupportedOperationException {
+        throw new UnsupportedOperationException("This is a utility class, don't instantiate it.");
+    }
+
+    /**
+     * Formats a price to the German Euro format.
+     *
+     * @param amount price
+     * @return formatted price
+     */
+    public static String formatEuro(final double amount) {
+        // Set up environment
+        Locale locale = Locale.GERMANY;
+        Currency currency = Currency.getInstance("EUR");
+        NumberFormat numberFormat = NumberFormat.getCurrencyInstance(locale);
+
+        numberFormat.setCurrency(currency);
+
+        return numberFormat.format(amount);
+    }
 }