Feature/delete question option endpoint

src/api/VoteMonitor.Api.Form/Commands/DeleteQuestionOptionCommand.cs

@@ -0,0 +1,17 @@
+using MediatR;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace VoteMonitor.Api.Form.Commands
+{
+    public class DeleteQuestionOptionCommand : IRequest<bool>
+    {
+        public int SectionId { get; set; }
+
+        public int QuestionId { get; set; }
+
+        public int OptionId { get; set; }
+    }
+}

src/api/VoteMonitor.Api.Form/Controllers/FormController.cs

@@ -174,5 +174,28 @@ public async Task<IActionResult> DeleteQuestionAsync(int sectionId, int question
 
             return Ok();
         }
+
+        [HttpDelete("section/{sectionId}/question/{questionId}/option/{optionId}")]
+        [Authorize("Organizer")]
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        [ProducesResponseType(StatusCodes.Status400BadRequest)]
+        public async Task<IActionResult> DeleteQuestionOptionAsync(int sectionId, int questionId, int optionId)
+        {
+
+            var deleted = await _mediator.Send(new DeleteQuestionOptionCommand()
+            {
+                QuestionId = questionId,
+                SectionId = sectionId,
+                OptionId = optionId
+            });
+
+            if (!deleted)
+            {
+                return BadRequest("The option could not be deleted. Make sure the option exists.");
+            }
+
+            return Ok();
+        }
+
     }
 }

src/api/VoteMonitor.Api.Form/Handlers/DeleteQuestionOptionHandler.cs

@@ -0,0 +1,94 @@
+using MediatR;
+using Microsoft.EntityFrameworkCore;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using VoteMonitor.Api.Form.Commands;
+using VoteMonitor.Entities;
+
+namespace VoteMonitor.Api.Form.Handlers
+{
+    public class DeleteQuestionOptionHandler : IRequestHandler<DeleteQuestionOptionCommand, bool>
+    {
+        private readonly VoteMonitorContext _context;
+        public DeleteQuestionOptionHandler(VoteMonitorContext context)
+        {
+            _context = context;
+        }
+
+        public async Task<bool> Handle(DeleteQuestionOptionCommand request, CancellationToken cancellationToken)
+        {
+            using (var transaction = await _context.Database.BeginTransactionAsync(cancellationToken))
+            {
+
+                var optionToBeRemoved = _context.Options.FirstOrDefault(o => o.Id == request.OptionId);
+
+                if (optionToBeRemoved == null)
+                {
+                    return false;
+                }
+
+
+                if (await OptionToBeDeleted(request.OptionId))
+                {
+                    if (await OptionHasAnswers(request.OptionId))
+                    {
+                        return false;
+                    }
+
+                    await DeleteQuestionsToOption(request.OptionId);
+                    DeleteOption(optionToBeRemoved);
+
+                }
+                else
+                {
+                    RemoveOptionFromQuestion(request.SectionId, request.QuestionId, request.OptionId);
+                }
+
+                await _context.SaveChangesAsync();
+                await transaction.CommitAsync(cancellationToken);
+
+                return true;
+            }
+        }
+
+        private void RemoveOptionFromQuestion(int sectionId, int questionId, int optionId)
+        {
+            var questionOptionLinkToBeRemoved = _context.Questions.Where(q => q.IdSection == sectionId && q.Id == questionId)
+            .SelectMany(q => q.OptionsToQuestions)
+            .Where(otq => otq.IdOption == optionId).FirstOrDefault();
+
+            _context.Remove(questionOptionLinkToBeRemoved);
+        }
+
+        private async Task<bool> OptionToBeDeleted(int optiondId)
+        {
+            var atMostOnOneQuestion = await _context.OptionsToQuestions
+            .Where(o => o.IdOption == optiondId).CountAsync() <= 1;
+
+            return atMostOnOneQuestion;
+
+        }
+
+
+        private async Task<bool> OptionHasAnswers(int optionId)
+        {
+            return await _context
+            .Answers.Where(a => a.OptionAnswered.IdOption == optionId).AnyAsync();
+        }
+
+        private async Task DeleteQuestionsToOption(int optionId)
+        {
+            var questionsToOptions = await _context.OptionsToQuestions.Where(otq => otq.IdOption == optionId).ToListAsync();
+
+            _context.RemoveRange(questionsToOptions);
+        }
+
+        private void DeleteOption(Option option)
+        {
+            _context.Remove(option);
+        }
+    }
+}