Add statistics endpoint for fetching total spending by category for time period

PersonalFinancesService/src/main/java/dev/mvvasilev/finances/controllers/StatisticsController.java

@@ -1,10 +1,49 @@
 package dev.mvvasilev.finances.controllers;
 
+import dev.mvvasilev.common.controller.AbstractRestController;
+import dev.mvvasilev.common.web.APIResponseDTO;
+import dev.mvvasilev.finances.dtos.SpendingByCategoryDTO;
+import dev.mvvasilev.finances.dtos.SpendingOverTimeByCategoryDTO;
+import dev.mvvasilev.finances.enums.TimePeriod;
+import dev.mvvasilev.finances.services.StatisticsService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.ResponseEntity;
+import org.springframework.security.core.Authentication;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 
+import java.time.LocalDateTime;
+import java.util.Collection;
+
 @RestController("/statistics")
-public class StatisticsController {
+public class StatisticsController extends AbstractRestController {
 
+    private final StatisticsService statisticsService;
 
+    @Autowired
+    public StatisticsController(StatisticsService statisticsService) {
+        this.statisticsService = statisticsService;
+    }
+
+    @GetMapping("/totalSpendingByCategory")
+    public ResponseEntity<APIResponseDTO<SpendingByCategoryDTO>> fetchSpendingByCategory(
+            @RequestParam(defaultValue = "1970-01-01T00:00:00") LocalDateTime from,
+            @RequestParam(defaultValue = "2099-01-01T00:00:00") LocalDateTime to,
+            Authentication authentication
+    ) {
+        return ok(statisticsService.spendingByCategory(from, to, Integer.parseInt(authentication.getName())));
+    }
+
+    @GetMapping("/spendingOverTimeByCategory")
+    public ResponseEntity<APIResponseDTO<SpendingOverTimeByCategoryDTO>> fetchSpendingOverTimeByCategory(
+            Collection<Long> categoryId,
+            TimePeriod period,
+            @RequestParam(defaultValue = "1970-01-01T00:00:00") LocalDateTime from,
+            @RequestParam(defaultValue = "2099-01-01T00:00:00") LocalDateTime to,
+            Authentication authentication
+    ) {
+        throw new UnsupportedOperationException();
+    }
 
 }

PersonalFinancesService/src/main/java/dev/mvvasilev/finances/dtos/SpendingByCategoryDTO.java

@@ -0,0 +1,11 @@
+package dev.mvvasilev.finances.dtos;
+
+import java.util.Collection;
+import java.util.Map;
+
+public record SpendingByCategoryDTO(
+        Collection<CategoryDTO> categories,
+
+        Map<Long, Double> spendingByCategory
+) {
+}

PersonalFinancesService/src/main/java/dev/mvvasilev/finances/dtos/SpendingOverTimeByCategoryDTO.java

@@ -0,0 +1,11 @@
+package dev.mvvasilev.finances.dtos;
+
+import java.util.Collection;
+import java.util.Map;
+
+public record SpendingOverTimeByCategoryDTO(
+        Collection<CategoryDTO> categories,
+
+        Map<Long, Collection<Double>> spendingOverTime
+) {
+}

PersonalFinancesService/src/main/java/dev/mvvasilev/finances/enums/TimePeriod.java

@@ -0,0 +1,13 @@
+package dev.mvvasilev.finances.enums;
+
+public enum TimePeriod {
+    SECONDLY,
+    MINUTELY,
+    HOURLY,
+    DAILY,
+    WEEKLY,
+    BIWEEKLY,
+    MONTHLY,
+    QUARTERLY,
+    YEARLY
+}

PersonalFinancesService/src/main/java/dev/mvvasilev/finances/persistence/StatisticsRepository.java

@@ -0,0 +1,50 @@
+package dev.mvvasilev.finances.persistence;
+
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.Query;
+import jakarta.persistence.Tuple;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Repository;
+
+import java.time.LocalDateTime;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+@Repository
+public class StatisticsRepository {
+
+    private final EntityManager entityManager;
+
+    @Autowired
+    public StatisticsRepository(EntityManager entityManager) {
+        this.entityManager = entityManager;
+    }
+
+    public Map<Long, Double> fetchSpendingByCategory(LocalDateTime from, LocalDateTime to, List<Long> categoryIds) {
+        Query nativeQuery = entityManager.createNativeQuery(
+                """
+                        SELECT ptc.category_id AS category_id, ROUND(CAST(SUM(pt.amount) AS NUMERIC), 2) AS total_spending
+                        FROM transactions.processed_transaction AS pt
+                        JOIN categories.processed_transaction_category AS ptc ON ptc.processed_transaction_id = pt.id
+                        WHERE
+                                pt.is_inflow = FALSE
+                            AND ptc.category_id IN (?1)
+                            AND (pt.timestamp BETWEEN ?2 AND ?3)
+                        GROUP BY ptc.category_id
+                        ORDER BY total_spending DESC;
+                        """,
+                Tuple.class
+        );
+
+        nativeQuery.setParameter(1, categoryIds);
+        nativeQuery.setParameter(2, from);
+        nativeQuery.setParameter(3, to);
+
+        //noinspection unchecked
+        return (Map<Long, Double>) nativeQuery.getResultStream().collect(Collectors.toMap(
+                (Tuple tuple) -> ((Number) tuple.get("category_id")).longValue(),
+                (Tuple tuple) -> ((Number) tuple.get("total_spending")).doubleValue()
+        ));
+    }
+}

PersonalFinancesService/src/main/java/dev/mvvasilev/finances/services/StatisticsService.java

@@ -0,0 +1,37 @@
+package dev.mvvasilev.finances.services;
+
+import dev.mvvasilev.common.data.AbstractEntity;
+import dev.mvvasilev.finances.dtos.CategoryDTO;
+import dev.mvvasilev.finances.dtos.SpendingByCategoryDTO;
+import dev.mvvasilev.finances.persistence.StatisticsRepository;
+import dev.mvvasilev.finances.persistence.TransactionCategoryRepository;
+import org.springframework.stereotype.Service;
+
+import java.time.LocalDateTime;
+
+@Service
+public class StatisticsService {
+
+    private final TransactionCategoryRepository transactionCategoryRepository;
+
+    private final StatisticsRepository statisticsRepository;
+
+    public StatisticsService(TransactionCategoryRepository transactionCategoryRepository, StatisticsRepository statisticsRepository) {
+        this.transactionCategoryRepository = transactionCategoryRepository;
+        this.statisticsRepository = statisticsRepository;
+    }
+
+    public SpendingByCategoryDTO spendingByCategory(LocalDateTime from, LocalDateTime to, int userId) {
+        final var categories = transactionCategoryRepository.fetchTransactionCategoriesWithUserId(userId);
+        final var spendingByCategory = statisticsRepository.fetchSpendingByCategory(
+                from,
+                to,
+                categories.stream().map(AbstractEntity::getId).toList()
+        );
+
+        return new SpendingByCategoryDTO(
+                categories.stream().map(c -> new CategoryDTO(c.getId(), c.getName(), null)).toList(),
+                spendingByCategory
+        );
+    }
+}