implemented fruit shop program logic using solid principles

src/main/java/core/basesyntax/Main.java

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+package core.basesyntax;
+
+import db.Storage;
+import java.io.FileNotFoundException;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import model.FruitTransaction;
+import service.DataConverter;
+import service.FileReader;
+import service.ReportGenerator;
+import service.ShopService;
+import service.impl.DataConverterImpl;
+import service.impl.FileReaderImpl;
+import service.impl.FileWriterImpl;
+import service.impl.OperationStrategyImpl;
+import service.impl.ReportGeneratorImpl;
+import service.impl.ShopServiceImpl;
+import service.operation.BalanceOperation;
+import service.operation.OperationHandler;
+import service.operation.PurchaseOperation;
+import service.operation.ReturnOperation;
+import service.operation.SupplyOperation;
+import strategy.OperationStrategy;
+
+public class Main {
+    private static final String REPORT_TO_READ_FILE = "src/main/resources/reportToRead.csv";
+    private static final String FINAL_REPORT_FILE = "src/main/resources/finalReport.csv";
+
+    public static void main(String[] args) throws FileNotFoundException {
+        FileReader fileReader = new FileReaderImpl();
+        List<String> inputReport = fileReader.read(REPORT_TO_READ_FILE);
+
+        DataConverter dataConverter = new DataConverterImpl();
+
+        Map<FruitTransaction.Operation, OperationHandler> operationHandlers = new HashMap<>();
+        operationHandlers.put(FruitTransaction.Operation.BALANCE, new BalanceOperation());
+        operationHandlers.put(FruitTransaction.Operation.PURCHASE, new PurchaseOperation());
+        operationHandlers.put(FruitTransaction.Operation.RETURN, new ReturnOperation());
+        operationHandlers.put(FruitTransaction.Operation.SUPPLY, new SupplyOperation());
+        OperationStrategy operationStrategy = new OperationStrategyImpl(operationHandlers);
+
+        List<FruitTransaction> transactions = dataConverter.convertToTransaction(inputReport);
+        ShopService shopService = new ShopServiceImpl(operationStrategy);
+        shopService.process(transactions);
+
+        Storage storage = new Storage();
+        ReportGenerator reportGenerator = new ReportGeneratorImpl(storage);
+        String resultingReport = reportGenerator.getReport();
+
+        FileWriterImpl fileWriter = new FileWriterImpl();
+        fileWriter.write(FINAL_REPORT_FILE, resultingReport);
+    }
+}

src/main/java/db/Storage.java

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+package db;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class Storage {
+    private static final Map<String, Integer> fruits = new HashMap<>();
+
+    public static void add(String fruit, Integer amount) {
+        fruits.put(fruit, fruits.getOrDefault(fruit, 0) + amount);
+    }
+
+    public static void remove(String fruit, Integer amount) {
+        if (!fruits.containsKey(fruit) || fruits.get(fruit) < amount) {
+            throw new IllegalArgumentException("Not enough " + fruit + " in storage.");
+        }
+        fruits.put(fruit, fruits.get(fruit) - amount);
+    }
+
+    public static int getAmount(String fruit) {
+        return fruits.getOrDefault(fruit, 0);
+    }
+
+    public Map<String, Integer> getAllFruits() {
+        return new HashMap<>(fruits);
+    }
+}

src/main/java/model/FruitTransaction.java

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+package model;
+
+public class FruitTransaction {
+    private Operation operation;
+    private String fruit;
+    private int quantity;
+
+    public Operation getOperation() {
+        return operation;
+    }
+
+    public void setOperation(Operation operation) {
+        this.operation = operation;
+    }
+
+    public String getFruit() {
+        return fruit;
+    }
+
+    public void setFruit(String fruit) {
+        this.fruit = fruit;
+    }
+
+    public int getQuantity() {
+        return quantity;
+    }
+
+    public void setQuantity(int quantity) {
+        this.quantity = quantity;
+    }
+
+    public enum Operation {
+        BALANCE("b"),
+        SUPPLY("s"),
+        PURCHASE("p"),
+        RETURN("r");
+
+        private String code;
+
+        Operation(String code) {
+            this.code = code;
+        }
+
+        public String getCode() {
+            return code;
+        }
+
+        public static FruitTransaction.Operation getOperationFromCode(String code) {
+            for (FruitTransaction.Operation operation : FruitTransaction.Operation.values()) {
+                if (operation.getCode().equals(code)) {
+                    return operation;
+                }
+            }
+            throw new IllegalArgumentException("Unknown operation: " + code);
+        }
+    }
+}

src/main/java/service/DataConverter.java

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+package service;
+
+import java.util.List;
+import model.FruitTransaction;
+
+public interface DataConverter {
+    List<FruitTransaction> convertToTransaction(List<String> reportLines);
+}

src/main/java/service/FileReader.java

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+package service;
+
+import java.io.FileNotFoundException;
+import java.util.List;
+
+public interface FileReader {
+    List<String> read(String fileName) throws FileNotFoundException;
+}

src/main/java/service/ReportGenerator.java

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+package service;
+
+public interface ReportGenerator {
+    String getReport();
+}

src/main/java/service/ShopService.java

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+package service;
+
+import java.util.List;
+import model.FruitTransaction;
+
+public interface ShopService {
+    void process(List<FruitTransaction> fruitTransactionList);
+}

src/main/java/service/impl/DataConverterImpl.java

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+package service.impl;
+
+import java.util.ArrayList;
+import java.util.List;
+import model.FruitTransaction;
+import service.DataConverter;
+
+public class DataConverterImpl implements DataConverter {
+    private static final String COMMA_SEPARATOR = ",";
+
+    @Override
+    public List<FruitTransaction> convertToTransaction(List<String> report) {
+        List<FruitTransaction> fruitTransactionList = new ArrayList<>();
+        for (int i = 1; i < report.size(); i++) {
+            FruitTransaction fruitTransaction = getFromCsvRow(report.get(i));
+            fruitTransactionList.add(fruitTransaction);
+        }
+        return fruitTransactionList;
+    }
+
+    private FruitTransaction getFromCsvRow(String row) {
+        String[] fields = row.split(COMMA_SEPARATOR);
+        FruitTransaction fruitTransaction = new FruitTransaction();
+        fruitTransaction.setOperation(FruitTransaction.Operation.getOperationFromCode(fields[0]));
+        fruitTransaction.setFruit(fields[1]);
+        fruitTransaction.setQuantity(Integer.parseInt(fields[2]));
+        return fruitTransaction;
+    }
+}

src/main/java/service/impl/FileReaderImpl.java

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+package service.impl;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.util.List;
+import service.FileReader;
+
+public class FileReaderImpl implements FileReader {
+
+    public FileReaderImpl() {
+
+    }
+
+    @Override
+    public List<String> read(String fileName) {
+        File file = new File(fileName);
+        if (!file.exists()) {
+            throw new IllegalArgumentException("File not found: " + fileName);
+        }
+        try {
+            return Files.readAllLines(file.toPath());
+        } catch (IOException e) {
+            throw new RuntimeException("Error reading file: " + fileName, e);
+        }
+    }
+}

src/main/java/service/impl/FileWriterImpl.java

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+package service.impl;
+
+import java.io.FileWriter;
+import java.io.IOException;
+
+public class FileWriterImpl {
+    public void write(String filePath, String content) {
+        try (FileWriter fileWriter = new FileWriter(filePath)) {
+            fileWriter.write(content);
+        } catch (IOException e) {
+            throw new RuntimeException("Error writing to file: " + filePath, e);
+        }
+    }
+}

src/main/java/service/impl/OperationStrategyImpl.java

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+package service.impl;
+
+import java.util.Map;
+import model.FruitTransaction;
+import service.operation.OperationHandler;
+import strategy.OperationStrategy;
+
+public class OperationStrategyImpl implements OperationStrategy {
+    private Map<FruitTransaction.Operation, OperationHandler> operationHandlerMap;
+
+    public OperationStrategyImpl(Map<FruitTransaction.Operation,
+            OperationHandler> operationHandlerMap) {
+        this.operationHandlerMap = operationHandlerMap;
+    }
+
+    @Override
+    public OperationHandler get(FruitTransaction.Operation operationType) {
+        return operationHandlerMap.get(operationType);
+    }
+}

src/main/java/service/impl/ReportGeneratorImpl.java

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+package service.impl;
+
+import db.Storage;
+import java.util.Map;
+import service.ReportGenerator;
+
+public class ReportGeneratorImpl implements ReportGenerator {
+    private static final String HEADER = "fruit,amount";
+    private static final String COMMA_DELIMITER = ",";
+    private static final String NEW_LINE = System.lineSeparator();
+    private final Storage storage;
+
+    public ReportGeneratorImpl(Storage storage) {
+        this.storage = storage;
+    }
+
+    @Override
+    public String getReport() {
+        StringBuilder report = new StringBuilder();
+        Map<String, Integer> fruits = storage.getAllFruits();
+
+        report.append(HEADER).append(NEW_LINE);
+        for (Map.Entry<String, Integer> entry : fruits.entrySet()) {
+            report.append(entry.getKey())
+                    .append(COMMA_DELIMITER)
+                    .append(entry.getValue())
+                    .append(NEW_LINE);
+        }
+
+        return report.toString();
+    }
+}

src/main/java/service/impl/ShopServiceImpl.java

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+package service.impl;
+
+import java.util.List;
+import model.FruitTransaction;
+import service.ShopService;
+import service.operation.OperationHandler;
+import strategy.OperationStrategy;
+
+public class ShopServiceImpl implements ShopService {
+    private final OperationStrategy operationStrategy;
+
+    public ShopServiceImpl(OperationStrategy operationStrategy) {
+        this.operationStrategy = operationStrategy;
+    }
+
+    @Override
+    public void process(List<FruitTransaction> fruitTransactionList) {
+        for (FruitTransaction transaction : fruitTransactionList) {
+            OperationHandler handler = operationStrategy.get(transaction.getOperation());
+            handler.performOperation(transaction);
+        }
+    }
+}

src/main/java/service/operation/BalanceOperation.java

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+package service.operation;
+
+import db.Storage;
+import model.FruitTransaction;
+
+public class BalanceOperation implements OperationHandler {
+    @Override
+    public void performOperation(FruitTransaction fruitTransaction) {
+        Storage.add(fruitTransaction.getFruit(), fruitTransaction.getQuantity());
+    }
+}

src/main/java/service/operation/OperationHandler.java

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+package service.operation;
+
+import model.FruitTransaction;
+
+public interface OperationHandler {
+    void performOperation(FruitTransaction fruitTransaction);
+}

src/main/java/service/operation/PurchaseOperation.java

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+package service.operation;
+
+import db.Storage;
+import model.FruitTransaction;
+
+public class PurchaseOperation implements OperationHandler {
+    @Override
+    public void performOperation(FruitTransaction fruitTransaction) {
+        Storage.remove(fruitTransaction.getFruit(), fruitTransaction.getQuantity());
+    }
+}

src/main/java/service/operation/ReturnOperation.java

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+package service.operation;
+
+import db.Storage;
+import model.FruitTransaction;
+
+public class ReturnOperation implements OperationHandler {
+    @Override
+    public void performOperation(FruitTransaction fruitTransaction) {
+        Storage.add(fruitTransaction.getFruit(), fruitTransaction.getQuantity());
+    }
+}

src/main/java/service/operation/SupplyOperation.java

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+package service.operation;
+
+import db.Storage;
+import model.FruitTransaction;
+
+public class SupplyOperation implements OperationHandler {
+    @Override
+    public void performOperation(FruitTransaction fruitTransaction) {
+        Storage.add(fruitTransaction.getFruit(), fruitTransaction.getQuantity());
+    }
+}

src/main/java/strategy/OperationStrategy.java

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+package strategy;
+
+import model.FruitTransaction;
+import service.operation.OperationHandler;
+
+public interface OperationStrategy {
+    OperationHandler get(FruitTransaction.Operation operationType);
+}