#25 Initial implementation of the JsonGardenPlan

Updated and renamed the Crop type to accommodate storage

src/main/java/ch/zhaw/gartenverwaltung/io/GardenPlan.java

@@ -1,12 +1,42 @@
 package ch.zhaw.gartenverwaltung.io;
 
-import ch.zhaw.gartenverwaltung.types.UserPlanting;
+import ch.zhaw.gartenverwaltung.types.Crop;
 
 import java.io.IOException;
 import java.util.List;
+import java.util.Optional;
 
 public interface GardenPlan {
-    List<UserPlanting> getPlantings();
+    /**
-    void savePlanting(UserPlanting planting) throws IOException;
+     * Yields a list of all {@link Crop}s in the database.
-    void removePlanting(UserPlanting planting) throws IOException;
+     *
+     * @return A list of all {@link Crop}s in the database
+     * @throws IOException If there is a problem reading from or writing to the database
+     */
+    List<Crop> getCrops() throws IOException;
+
+    /**
+     * Attempts to retrieve the {@link Crop} with the specified cropId.
+     *
+     * @param id The {@link Crop#cropId} to look for
+     * @return {@link Optional} of the found {@link Crop}, {@link Optional#empty()} if no entry matched the criteria
+     * @throws IOException If there is a problem reading from or writing to the database
+     */
+    Optional<Crop> getCropById(long id) throws IOException;
+
+    /**
+     * Saves a Crop to the Database.
+     *
+     * @param crop The {@link Crop} to be saved
+     * @throws IOException If there is a problem reading from or writing to the database
+     */
+    void saveCrop(Crop crop) throws IOException;
+
+    /**
+     * Removes a Crop from the Database.
+     *
+     * @param crop The {@link Crop} to be removed
+     * @throws IOException If there is a problem reading from or writing to the database
+     */
+    void removeCrop(Crop crop) throws IOException;
 }

src/main/java/ch/zhaw/gartenverwaltung/io/InvalidJsonException.java

@@ -0,0 +1,9 @@
+package ch.zhaw.gartenverwaltung.io;
+
+import java.io.IOException;
+
+class InvalidJsonException extends IOException {
+    public InvalidJsonException(String reason) {
+        super(reason);
+    }
+}

src/main/java/ch/zhaw/gartenverwaltung/io/JsonGardenPlan.java

@@ -0,0 +1,134 @@
+package ch.zhaw.gartenverwaltung.io;
+
+import ch.zhaw.gartenverwaltung.types.Crop;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
+import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+public class JsonGardenPlan implements GardenPlan {
+    private final URL dataSource = getClass().getResource("user-crops.json");
+
+    private IdProvider idProvider;
+    private Map<Long, Crop> cropMap = Collections.emptyMap();
+
+    /**
+     * Creating constant objects required to deserialize the {@link LocalDate} classes
+     */
+    private final static JavaTimeModule timeModule = new JavaTimeModule();
+    private final static String INVALID_DATASOURCE_MSG = "Invalid datasource specified!";
+    static {
+        DateTimeFormatter dateFormat = DateTimeFormatter.ofPattern("yy-MM-dd");
+        LocalDateDeserializer dateDeserializer = new LocalDateDeserializer(dateFormat);
+        timeModule.addDeserializer(LocalDate.class, dateDeserializer);
+    }
+
+    /**
+     * @see GardenPlan#getCrops()
+     */
+    @Override
+    public List<Crop> getCrops() throws IOException {
+        if (idProvider == null) {
+            loadCropList();
+        }
+        return cropMap.values().stream().toList();
+    }
+
+    /**
+     * @see GardenPlan#getCropById(long)
+     */
+    @Override
+    public Optional<Crop> getCropById(long id) throws IOException {
+        if (idProvider == null) {
+            loadCropList();
+        }
+        return Optional.ofNullable(cropMap.get(id));
+    }
+
+    /**
+     * @see GardenPlan#saveCrop(Crop)
+     *
+     * Saves a crop to the database.
+     * If no {@link Crop#cropId} is set, one will be generated and
+     * the Crop is stored as a new entry.
+     */
+    @Override
+    public void saveCrop(Crop crop) throws IOException {
+        if (idProvider == null) {
+            loadCropList();
+        }
+        Long cropId = crop.getCropId().orElse(idProvider.incrementAndGet());
+        cropMap.put(cropId, crop.withId(cropId));
+        writeCropList();
+    }
+
+    /**
+     * @see GardenPlan#removeCrop(Crop)
+     */
+    @Override
+    public void removeCrop(Crop crop) throws IOException {
+        if (idProvider == null) {
+            loadCropList();
+        }
+        Optional<Long> cropId = crop.getCropId();
+        if (cropId.isPresent()) {
+            cropMap.remove(cropId.get());
+            writeCropList();
+        }
+    }
+
+    /**
+     * Loads the database from {@link #dataSource} and updates the cached data.
+     *
+     * @throws IOException If the database cannot be accessed or invalid data was read.
+     */
+    private void loadCropList() throws IOException {
+        if (dataSource != null) {
+            ObjectMapper mapper = new ObjectMapper();
+            mapper.registerModule(timeModule);
+
+            List<Crop> result;
+            result = mapper.readerForListOf(Crop.class).readValue(dataSource);
+
+            // Turn list into a HashMap with structure cropId => Crop
+            cropMap = new HashMap<>(result.size());
+            for (Crop crop : result) {
+                Long id = crop.getCropId()
+                        .orElseThrow(() -> new InvalidJsonException(String.format("Invalid value for \"cropId\" in %s!", crop)));
+                cropMap.put(id, crop);
+            }
+            Long maxId = cropMap.isEmpty() ? 0L : Collections.max(cropMap.keySet());
+            idProvider = new IdProvider(maxId);
+        }
+    }
+
+    /**
+     * Writes the values from {@link #cropMap} to the {@link #dataSource}
+     *
+     * @throws IOException If the database cannot be accessed
+     */
+    private void writeCropList() throws IOException {
+        if (dataSource != null) {
+            try {
+                new ObjectMapper()
+                        .registerModule(timeModule)
+                        .writeValue(new File(dataSource.toURI()), cropMap.values());
+            } catch (URISyntaxException e) {
+                // TODO: Log
+                throw new IOException(INVALID_DATASOURCE_MSG, e);
+            }
+        }
+    }
+
+}

src/main/java/ch/zhaw/gartenverwaltung/types/Crop.java

@@ -0,0 +1,35 @@
+package ch.zhaw.gartenverwaltung.types;
+
+import java.time.LocalDate;
+import java.util.Optional;
+
+public class Crop {
+    private Long cropId = null;
+    private final long plantId;
+    private final LocalDate startDate;
+    private int area = 1;
+
+    public Crop(long plantId, LocalDate startDate) {
+        this.plantId = plantId;
+        this.startDate = startDate;
+    }
+
+    // Builder-Style setter
+    public Crop withId(long cropId) {
+        this.cropId = cropId;
+        return this;
+    }
+    public Crop withArea(int area) {
+        this.area = area;
+        return this;
+    }
+
+    // Getters
+    public Optional<Long> getCropId() {
+        return Optional.ofNullable(cropId);
+    }
+
+    public long getPlantId() { return plantId; }
+    public LocalDate getStartDate() { return startDate; }
+    public int getArea() { return area; }
+}

src/main/java/ch/zhaw/gartenverwaltung/types/UserPlanting.java

@@ -1,10 +0,0 @@
-package ch.zhaw.gartenverwaltung.types;
-
-import java.util.Date;
-
-public record UserPlanting(
-        long plantId,
-        Date startDate,
-        int area
-) {
-}