Implement domain services

Implement core business logic for working with Student, Test, and TestResult.

1 files changed, 143 insertions, 5 deletions

diff --git a/src/main/java/com/stileeducation/markr/service/TestResultsService.java b/src/main/java/com/stileeducation/markr/service/TestResultsService.java
index 2740e50..8d1b314 100644
--- a/src/main/java/com/stileeducation/markr/service/TestResultsService.java
+++ b/src/main/java/com/stileeducation/markr/service/TestResultsService.java
@@ -1,10 +1,148 @@
 package com.stileeducation.markr.service;
 
 import com.stileeducation.markr.dto.AggregatedTestResultsDTO;
-import com.stileeducation.markr.dto.MCQTestResultsDTO;
+import com.stileeducation.markr.entity.Student;
+import com.stileeducation.markr.entity.Test;
+import com.stileeducation.markr.entity.TestResult;
+import com.stileeducation.markr.repository.StudentRepository;
+import com.stileeducation.markr.repository.TestRepository;
+import com.stileeducation.markr.repository.TestResultRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
 
-public interface TestResultsService {
-  MCQTestResultsDTO importTestResults(MCQTestResultsDTO mcqTestResults);
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
 
-  AggregatedTestResultsDTO aggregateTestResults(String testId);
-}
+@Service
+public class TestResultsService {
+
+  @Autowired
+  private TestResultRepository testResultRepository;
+
+  @Autowired
+  private StudentRepository studentRepository;
+
+  @Autowired
+  private TestRepository testRepository;
+
+  public TestResult findOrCreateTestResult(Long studentId, Long testId, Integer marksAwarded) {
+    Student student = studentRepository.findById(studentId).orElseThrow(() -> new RuntimeException("Student not found"));
+    Test test = testRepository.findById(testId).orElseThrow(() -> new RuntimeException("Test not found"));
+
+    Optional<TestResult> optionalTestResult = testResultRepository.findByStudentAndTest(student, test);
+    if (optionalTestResult.isPresent()) {
+      return optionalTestResult.get();
+    } else {
+      TestResult testResult = new TestResult();
+      testResult.setStudent(student);
+      testResult.setTest(test);
+      testResult.setMarksAwarded(marksAwarded);
+      return testResultRepository.save(testResult);
+    }
+  }
+
+  public List<TestResult> findAllByTestId(String testId) {
+    return testResultRepository.findAllByTestId(testId);
+  }
+
+  public double calculateMeanOfTestResults(List<TestResult> results) {
+    if (results.isEmpty()) {
+      return 0.0;
+    }
+    return results.stream()
+        .mapToInt(TestResult::getMarksAwarded)
+        .average()
+        .orElse(0.0);
+  }
+
+  public double calculateMinOfTestResults(List<TestResult> results) {
+    if (results.isEmpty()) {
+      return 0.0;
+    }
+    return results
+        .stream()
+        .mapToDouble(TestResult::getMarksAwarded)
+        .min()
+        .orElse(0.0);
+  }
+
+  public double calculateMaxOfTestResults(List<TestResult> results) {
+    if (results.isEmpty()) {
+      return 0.0;
+    }
+    return results
+        .stream()
+        .mapToDouble(TestResult::getMarksAwarded)
+        .max()
+        .orElse(0.0);
+  }
+
+  public double calculateStandardDeviationOfTestResults(List<TestResult> results, double mean) {
+    if (results.isEmpty()) {
+      return 0.0; // or throw an exception if no results are found
+    }
+
+    // Calculate the variance
+    double variance = results.stream()
+        .mapToDouble(result -> Math.pow(result.getMarksAwarded() - mean, 2))
+        .average()
+        .orElse(0.0);
+
+    // Return the standard deviation
+    return Math.sqrt(variance);
+  }
+
+  public double calculatePercentile(List<Integer> sortedMarks, double percentile) {
+    if (sortedMarks.isEmpty()) {
+      return 0.0;
+    }
+    int index = (int) Math.floor(percentile / 100.0 * sortedMarks.size()) - 1;
+    return sortedMarks.get(Math.min(index, sortedMarks.size() - 1));
+  }
+
+  public List<Integer> getSortedMarks(List<TestResult> testResults) {
+    return testResults.stream()
+        .map(TestResult::getMarksAwarded)
+        .sorted()
+        .collect(Collectors.toList());
+  }
+
+  public double calculate25thPercentile(List<Integer> sortedMarks) {
+    return calculatePercentile(sortedMarks, 25.0);
+  }
+
+  public double calculate50thPercentile(List<Integer> sortedMarks) {
+    return calculatePercentile(sortedMarks, 50.0);
+  }
+
+  public double calculate75thPercentile(List<Integer> sortedMarks) {
+    return calculatePercentile(sortedMarks, 75.0);
+  }
+
+  public AggregatedTestResultsDTO aggregateTestResults(String testId) {
+    List<TestResult> testResults = findAllByTestId(testId);
+    List<Integer> sortedMarks = getSortedMarks(testResults);
+
+    AggregatedTestResultsDTO results = new AggregatedTestResultsDTO();
+
+    results.setMean(calculateMeanOfTestResults(testResults));
+
+    results.setStddev(calculateStandardDeviationOfTestResults(testResults, results.getMean()));
+
+    results.setMin(calculateMinOfTestResults(testResults));
+
+    results.setMax(calculateMaxOfTestResults(testResults));
+
+    results.setP25(calculate25thPercentile(sortedMarks));
+
+    results.setP50(calculate50thPercentile(sortedMarks));
+
+    results.setP75(calculate75thPercentile(sortedMarks));
+
+    results.setCount(testResults.size());
+
+    return results;
+  }
+
+}
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