first version

src/main/java/core/basesyntax/Mail.java

@@ -0,0 +1,19 @@
+package core.basesyntax;
+
+import core.basesyntax.service.Inventory;
+import core.basesyntax.service.InventoryFromCsv;
+import core.basesyntax.service.Report;
+import core.basesyntax.service.ReportToCsv;
+import core.basesyntax.storage.Storage;
+
+public class Mail {
+    public static void main(String[] args) {
+        Storage storage = new Storage();
+
+        Inventory inventory = new InventoryFromCsv();
+        inventory.synchronizeWithTheStorage();
+
+        Report report = new ReportToCsv();
+        report.prepare();
+    }
+}

src/main/java/core/basesyntax/db/StockDao.java

@@ -0,0 +1,18 @@
+package core.basesyntax.db;
+
+import java.util.Set;
+
+public interface StockDao {
+    void set(String product, Integer amount);
+
+    Integer get(String product);
+
+    void decrease(String product, Integer amount);
+
+    void increase(String product, Integer amount);
+
+    boolean contain(String product);
+
+    Set<String> getProductsList();
+
+}

src/main/java/core/basesyntax/db/StockDaoStorageImpl.java

@@ -0,0 +1,50 @@
+package core.basesyntax.db;
+
+import core.basesyntax.storage.Storage;
+import java.util.Set;
+
+public class StockDaoStorageImpl implements StockDao {
+
+    @Override
+    public void set(String product, Integer amount) {
+        Storage.stock.put(product, amount);
+    }
+
+    @Override
+    public Integer get(String product) {
+        return Storage.stock.get(product);
+    }
+
+    @Override
+    public void decrease(String product, Integer amount) {
+        if (contain(product)) {
+            Storage.stock.put(product, get(product) - amount);
+        } else if (get(product) - amount < 0) {
+            throw new RuntimeException(
+                    "the quantity being subtracted is greater than the stock value");
+        } else {
+            throw new RuntimeException("There was no such product before");
+        }
+    }
+
+    @Override
+    public void increase(String product, Integer amount) {
+        if (!contain(product)) {
+            throw new RuntimeException("There was no such product before");
+        } else if (get(product) + amount < 0) {
+            throw new RuntimeException("amount out limit");
+        } else {
+            Storage.stock.put(product, get(product) + amount);
+        }
+    }
+
+    @Override
+    public boolean contain(String product) {
+        return Storage.stock.containsKey(product);
+    }
+
+    @Override
+    public Set<String> getProductsList() {
+        return Storage.stock.keySet();
+    }
+}

src/main/java/core/basesyntax/service/Inventory.java

@@ -0,0 +1,6 @@
+package core.basesyntax.service;
+
+public interface Inventory {
+
+    void synchronizeWithTheStorage();
+}

src/main/java/core/basesyntax/service/InventoryFromCsv.java

@@ -0,0 +1,51 @@
+package core.basesyntax.service;
+
+import core.basesyntax.db.StockDao;
+import core.basesyntax.db.StockDaoStorageImpl;
+import core.basesyntax.service.operations.Balance;
+import core.basesyntax.service.operations.Operation;
+import core.basesyntax.service.operations.Purchase;
+import core.basesyntax.service.operations.Return;
+import core.basesyntax.service.operations.Supply;
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+public class InventoryFromCsv implements Inventory {
+    private static final String FILE_NAME = "inventory.csv";
+    private final StockDao stockDao = new StockDaoStorageImpl();
+
+    @Override
+    public void synchronizeWithTheStorage() {
+        Map<String, Operation> operationMap = new HashMap<>();
+        operationMap.put("b", new Balance());
+        operationMap.put("s", new Supply());
+        operationMap.put("r", new Return());
+        operationMap.put("p", new Purchase());
+
+        OperationStrategy operationStrategy = new OperationStrategyImpl(operationMap);
+
+        try (BufferedReader reader = new BufferedReader(new FileReader(FILE_NAME))) {
+            String line = reader.readLine();
+            while (line != null) {
+                String[] splitDataFromCurrentLine = line.split(",");
+                if (splitDataFromCurrentLine.length != 3) {
+                    throw new RuntimeException("wrong data format");
+                }
+                try {
+                    Integer.parseInt(splitDataFromCurrentLine[2]);
+                } catch (NumberFormatException e) {
+                    throw new RuntimeException("amount is not a number", e);
+                }
+                operationStrategy.getOperation(splitDataFromCurrentLine[0])
+                        .update(splitDataFromCurrentLine[1],
+                                Integer.parseInt(splitDataFromCurrentLine[2]));
+                line = reader.readLine();
+            }
+        } catch (IOException e) {
+            throw new RuntimeException("Cant read from file", e);
+        }
+    }
+}

src/main/java/core/basesyntax/service/OperationStrategy.java

@@ -0,0 +1,7 @@
+package core.basesyntax.service;
+
+import core.basesyntax.service.operations.Operation;
+
+public interface OperationStrategy {
+    Operation getOperation(String operationSymbol);
+}

src/main/java/core/basesyntax/service/OperationStrategyImpl.java

@@ -0,0 +1,21 @@
+package core.basesyntax.service;
+
+import core.basesyntax.service.operations.Operation;
+import java.util.Map;
+
+public class OperationStrategyImpl implements OperationStrategy {
+    private Map<String, Operation> operationMap;
+
+    public OperationStrategyImpl(Map<String, Operation> operationMap) {
+        this.operationMap = operationMap;
+    }
+
+    @Override
+    public Operation getOperation(String operationSymbol) {
+        if (operationMap.containsKey(operationSymbol)) {
+            return operationMap.get(operationSymbol);
+        } else {
+            throw new RuntimeException("unknown operation symbol");
+        }
+    }
+}

src/main/java/core/basesyntax/service/Report.java

@@ -0,0 +1,5 @@
+package core.basesyntax.service;
+
+public interface Report {
+    void prepare();
+}

src/main/java/core/basesyntax/service/ReportToCsv.java

@@ -0,0 +1,23 @@
+package core.basesyntax.service;
+
+import core.basesyntax.db.StockDao;
+import core.basesyntax.db.StockDaoStorageImpl;
+import java.io.BufferedWriter;
+import java.io.FileWriter;
+import java.io.IOException;
+
+public class ReportToCsv implements Report {
+    private static final String FILE_NAME = "report.csv";
+    private final StockDao stockDao = new StockDaoStorageImpl();
+
+    @Override
+    public void prepare() {
+        try (BufferedWriter writer = new BufferedWriter(new FileWriter(FILE_NAME))) {
+            for (String product : stockDao.getProductsList()) {
+                writer.write(product + "," + stockDao.get(product) + System.lineSeparator());
+            }
+        } catch (IOException e) {
+            throw new RuntimeException("Cant print to file", e);
+        }
+    }
+}

src/main/java/core/basesyntax/service/operations/Balance.java

@@ -0,0 +1,13 @@
+package core.basesyntax.service.operations;
+
+import core.basesyntax.db.StockDao;
+import core.basesyntax.db.StockDaoStorageImpl;
+
+public class Balance implements Operation {
+    private final StockDao stockDao = new StockDaoStorageImpl();
+
+    @Override
+    public void update(String product, Integer amount) {
+        stockDao.set(product, amount);
+    }
+}

src/main/java/core/basesyntax/service/operations/Operation.java

@@ -0,0 +1,5 @@
+package core.basesyntax.service.operations;
+
+public interface Operation {
+    void update(String product, Integer amount);
+}

src/main/java/core/basesyntax/service/operations/Purchase.java

@@ -0,0 +1,13 @@
+package core.basesyntax.service.operations;
+
+import core.basesyntax.db.StockDao;
+import core.basesyntax.db.StockDaoStorageImpl;
+
+public class Purchase implements Operation {
+    private final StockDao stockDao = new StockDaoStorageImpl();
+
+    @Override
+    public void update(String product, Integer amount) {
+        stockDao.decrease(product, amount);
+    }
+}

src/main/java/core/basesyntax/service/operations/Return.java

@@ -0,0 +1,13 @@
+package core.basesyntax.service.operations;
+
+import core.basesyntax.db.StockDao;
+import core.basesyntax.db.StockDaoStorageImpl;
+
+public class Return implements Operation {
+    private final StockDao stockDao = new StockDaoStorageImpl();
+
+    @Override
+    public void update(String product, Integer amount) {
+        stockDao.increase(product, amount);
+    }
+}

src/main/java/core/basesyntax/service/operations/Supply.java

@@ -0,0 +1,13 @@
+package core.basesyntax.service.operations;
+
+import core.basesyntax.db.StockDao;
+import core.basesyntax.db.StockDaoStorageImpl;
+
+public class Supply implements Operation {
+    private final StockDao stockDao = new StockDaoStorageImpl();
+
+    @Override
+    public void update(String product, Integer amount) {
+        stockDao.increase(product, amount);
+    }
+}

src/main/java/core/basesyntax/storage/Storage.java

@@ -0,0 +1,7 @@
+package core.basesyntax.storage;
+
+import java.util.HashMap;
+
+public class Storage {
+    public static final HashMap<String, Integer> stock = new HashMap<>();
+}