Add CSV download feature for courses, students, and registrations

api/CourseRegistration.API/Controllers/DownloadController.cs

@@ -0,0 +1,143 @@
+using Microsoft.AspNetCore.Mvc;
+using CourseRegistration.Application.Interfaces;
+using System.Text;
+
+namespace CourseRegistration.API.Controllers;
+
+/// <summary>
+/// Controller for downloading course, student, and registration data as CSV files
+/// </summary>
+[ApiController]
+[Route("api/[controller]")]
+public class DownloadController : ControllerBase
+{
+    private readonly ICourseService _courseService;
+    private readonly IStudentService _studentService;
+    private readonly IRegistrationService _registrationService;
+    private readonly ILogger<DownloadController> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the DownloadController
+    /// </summary>
+    public DownloadController(
+        ICourseService courseService,
+        IStudentService studentService,
+        IRegistrationService registrationService,
+        ILogger<DownloadController> logger)
+    {
+        _courseService = courseService ?? throw new ArgumentNullException(nameof(courseService));
+        _studentService = studentService ?? throw new ArgumentNullException(nameof(studentService));
+        _registrationService = registrationService ?? throw new ArgumentNullException(nameof(registrationService));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+    }
+
+    /// <summary>
+    /// Downloads all courses as a CSV file
+    /// </summary>
+    /// <returns>CSV file containing course data</returns>
+    [HttpGet("courses")]
+    [ProducesResponseType(typeof(FileResult), StatusCodes.Status200OK)]
+    public async Task<IActionResult> DownloadCourses()
+    {
+        _logger.LogInformation("Downloading courses as CSV");
+
+        var result = await _courseService.GetCoursesAsync(page: 1, pageSize: int.MaxValue);
+        var courses = result.Items;
+
+        var csv = new StringBuilder();
+        csv.AppendLine("CourseId,CourseName,Description,InstructorName,StartDate,EndDate,Schedule,CurrentEnrollment,IsActive,CreatedAt");
+
+        foreach (var course in courses)
+        {
+            csv.AppendLine(string.Join(",",
+                course.CourseId,
+                EscapeCsvField(course.CourseName),
+                EscapeCsvField(course.Description ?? string.Empty),
+                EscapeCsvField(course.InstructorName),
+                course.StartDate.ToString("yyyy-MM-dd"),
+                course.EndDate.ToString("yyyy-MM-dd"),
+                EscapeCsvField(course.Schedule),
+                course.CurrentEnrollment,
+                course.IsActive,
+                course.CreatedAt.ToString("yyyy-MM-dd")));
+        }
+
+        var bytes = Encoding.UTF8.GetBytes(csv.ToString());
+        return File(bytes, "text/csv", $"courses_{DateTime.UtcNow:yyyyMMdd}.csv");
+    }
+
+    /// <summary>
+    /// Downloads all students as a CSV file
+    /// </summary>
+    /// <returns>CSV file containing student data</returns>
+    [HttpGet("students")]
+    [ProducesResponseType(typeof(FileResult), StatusCodes.Status200OK)]
+    public async Task<IActionResult> DownloadStudents()
+    {
+        _logger.LogInformation("Downloading students as CSV");
+
+        var result = await _studentService.GetStudentsAsync(page: 1, pageSize: int.MaxValue);
+        var students = result.Items;
+
+        var csv = new StringBuilder();
+        csv.AppendLine("StudentId,FirstName,LastName,Email,PhoneNumber,DateOfBirth,CreatedAt");
+
+        foreach (var student in students)
+        {
+            csv.AppendLine(string.Join(",",
+                student.StudentId,
+                EscapeCsvField(student.FirstName),
+                EscapeCsvField(student.LastName),
+                EscapeCsvField(student.Email),
+                EscapeCsvField(student.PhoneNumber ?? string.Empty),
+                student.DateOfBirth.ToString("yyyy-MM-dd"),
+                student.CreatedAt.ToString("yyyy-MM-dd")));
+        }
+
+        var bytes = Encoding.UTF8.GetBytes(csv.ToString());
+        return File(bytes, "text/csv", $"students_{DateTime.UtcNow:yyyyMMdd}.csv");
+    }
+
+    /// <summary>
+    /// Downloads all registrations as a CSV file
+    /// </summary>
+    /// <returns>CSV file containing registration data</returns>
+    [HttpGet("registrations")]
+    [ProducesResponseType(typeof(FileResult), StatusCodes.Status200OK)]
+    public async Task<IActionResult> DownloadRegistrations()
+    {
+        _logger.LogInformation("Downloading registrations as CSV");
+
+        var result = await _registrationService.GetRegistrationsAsync(page: 1, pageSize: int.MaxValue);
+        var registrations = result.Items;
+
+        var csv = new StringBuilder();
+        csv.AppendLine("RegistrationId,StudentId,StudentName,CourseId,CourseName,RegistrationDate,Status,Grade,Notes");
+
+        foreach (var reg in registrations)
+        {
+            csv.AppendLine(string.Join(",",
+                reg.RegistrationId,
+                reg.StudentId,
+                EscapeCsvField(reg.Student != null ? $"{reg.Student.FirstName} {reg.Student.LastName}" : string.Empty),
+                reg.CourseId,
+                EscapeCsvField(reg.Course?.CourseName ?? string.Empty),
+                reg.RegistrationDate.ToString("yyyy-MM-dd"),
+                reg.Status,
+                reg.Grade?.ToString() ?? string.Empty,
+                EscapeCsvField(reg.Notes ?? string.Empty)));
+        }
+
+        var bytes = Encoding.UTF8.GetBytes(csv.ToString());
+        return File(bytes, "text/csv", $"registrations_{DateTime.UtcNow:yyyyMMdd}.csv");
+    }
+
+    private static string EscapeCsvField(string field)
+    {
+        if (field.Contains(',') || field.Contains('"') || field.Contains('\n') || field.Contains('\r'))
+        {
+            return $"\"{field.Replace("\"", "\"\"")}\"";
+        }
+        return field;
+    }
+}