survey-beta/survey-beta/Services/AnalyticsServices.cs

using Microsoft.AspNetCore.Http.HttpResults;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using survey_beta.DataBaseContext;
using survey_beta.DTOs.Update;
using survey_beta.Models;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

public class AnalyticsServices
{
    private readonly AppDbContext _context;
    public AnalyticsServices(AppDbContext context)
    {
        _context = context;
    }
    public void UpdateAnalytics(string surveyId)
    {
        var responses = _context.Responses
            .Where(r => r.SurveyId == surveyId)
            .Include(r => r.Answers)
                .ThenInclude(a => a.Choice) 
            .ToList();

        var analyticsData = CalculateAnalytics(responses);

        SaveAnalytics(surveyId, analyticsData);
    }
    private SurveyStats CalculateAnalytics(List<Response> responses)
    {
        var answerFrequency = new Dictionary<string, int>();
        var questionFrequency = new Dictionary<string, int>();

        foreach (var response in responses)
        {
            foreach (var answer in response.Answers)
            {
                var choiceText = answer.Choice?.Letter;
                if (choiceText != null)
                {
                    if (answerFrequency.ContainsKey(choiceText))
                    {
                        answerFrequency[choiceText]++;
                    }
                    else
                    {
                        answerFrequency[choiceText] = 1;
                    }
                }
                if (questionFrequency.ContainsKey(answer.Question?.Text))
                {
                    questionFrequency[answer.Question.Text]++;
                }
                else
                {
                    questionFrequency[answer.Question.Text] = 1;
                }
            }
        }

        return new SurveyStats
        {
            SurveyId = responses.FirstOrDefault()?.SurveyId,
            TotalResponses = responses.Count,
            AnswerFrequency = answerFrequency,
            QuestionFrequency = questionFrequency
        };
    }
    private void SaveAnalytics(string surveyId, SurveyStats analyticsData)
    {
        var analytics = new SurveyAnalytics
        {
            SurveyId = surveyId,
            TotalResponses = analyticsData.TotalResponses,
            CreatedAt = DateTime.UtcNow,
        };

        _context.Add(analytics);
        _context.SaveChanges();
    }
    public SurveyStats GetAggregatedSurveyResponses(string surveyId)
    {
        var responses = _context.Responses
            .Where(r => r.SurveyId == surveyId)
            .Include(r => r.Answers)
                .ThenInclude(a => a.Choice)
            .ToList();

        return CalculateAnalytics(responses);
    }
    public IActionResult ExportSurveyDataToCsv(string surveyId)
    {
        var responses = _context.Responses
            .Where(r => r.SurveyId == surveyId)
            .Include(r => r.Answers)
                .ThenInclude(a => a.Choice)
            .ToList();
        if (responses == null || responses.Count == 0)
        {
            return new ObjectResult("No responses found for this survey.")
            {
                StatusCode = 404 
            };
        }

        var csvData = new StringWriter();
        var csvHeader = "ResponseId,Question,ChoiceText";
        csvData.WriteLine(csvHeader);

        foreach (var response in responses)
        {
            foreach (var answer in response.Answers)
            {
                var choiceText = answer.Choice?.Letter ?? "No Choice";
                var csvLine = $"{response.Id},{answer.Question?.Text},{choiceText}";
                csvData.WriteLine(csvLine);
            }
        }

        var fileName = $"{surveyId}_responses.csv";
        var fileBytes = System.Text.Encoding.UTF8.GetBytes(csvData.ToString());
        return new FileContentResult(fileBytes, "text/csv")
        {
            FileDownloadName = fileName
        };
    }
}