using AutoMapper;
using Entities.Contracts;
using Entities.DTO;
using Microsoft.EntityFrameworkCore;
using SharedDATA.Api;
using SharedDATA.Context;
using TechHelper.Services.Beta;

namespace TechHelper.Services.Beta
{
	/// <summary>
	/// 提交服务实现（Beta版本）
	/// 实现提交相关的业务逻辑操作
	/// </summary>
	public class SubmissionService : ISubmissionService
	{
		private readonly IUnitOfWork _unitOfWork;
		private readonly IMapper _mapper;
		private readonly IRepository<Submission> _submissionRepository;
		private readonly IRepository<SubmissionDetail> _submissionDetailRepository;

		/// <summary>
		/// 初始化提交服务
		/// </summary>
		/// <param name="mapper">AutoMapper实例</param>
		/// <param name="unitOfWork">工作单元</param>
		public SubmissionService(IMapper mapper, IUnitOfWork unitOfWork)
		{
			_mapper = mapper;
			_unitOfWork = unitOfWork;
			_submissionRepository = _unitOfWork.GetRepository<Submission>();
			_submissionDetailRepository = _unitOfWork.GetRepository<SubmissionDetail>();
		}

		#region 基本CRUD操作

		/// <summary>
		/// 获取所有提交记录
		/// </summary>
		/// <param name="query">查询参数</param>
		/// <returns>提交记录列表</returns>
		public async Task<ApiResponse> GetAllAsync(QueryParameter query)
		{
			try
			{
				var pagedSubmissions = await _submissionRepository.GetPagedListAsync(
					pageIndex: query.PageIndex,
					pageSize: query.PageSize,
					orderBy: s => s.OrderByDescending(s => s.SubmissionTime),
					predicate: s => !s.IsDeleted);

				var submissionDtos = _mapper.Map<List<SubmissionListDto>>(pagedSubmissions.Items);

				return ApiResponse.Success("获取所有提交成功。", submissionDtos);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"获取所有提交失败: {ex.Message}");
			}
		}

		/// <summary>
		/// 根据ID获取提交记录
		/// </summary>
		/// <param name="id">提交ID</param>
		/// <returns>提交记录详情</returns>
		public async Task<ApiResponse> GetAsync(Guid id)
		{
			try
			{
				var submission = await _submissionRepository.GetFirstOrDefaultAsync(
					predicate: s => s.Id == id && !s.IsDeleted);

				if (submission == null)
				{
					return ApiResponse.Error("未找到提交记录。", 404);
				}

				var submissionDto = _mapper.Map<SubmissionDto>(submission);
				return ApiResponse.Success("获取提交记录成功。", submissionDto);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"获取提交记录失败: {ex.Message}");
			}
		}

		/// <summary>
		/// 创建提交记录
		/// </summary>
		/// <param name="model">提交数据传输对象</param>
		/// <returns>创建结果</returns>
		public async Task<ApiResponse> AddAsync(SubmissionDto model)
		{
			try
			{
				var submission = _mapper.Map<Submission>(model);
				submission.SubmissionTime = DateTime.Now;
				submission.IsDeleted = false;

				await _submissionRepository.InsertAsync(submission);
				await _unitOfWork.SaveChangesAsync();

				var result = _mapper.Map<SubmissionDto>(submission);
				return ApiResponse.Success("提交成功。", result);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"创建提交失败: {ex.Message}");
			}
		}

		/// <summary>
		/// 更新提交记录
		/// </summary>
		/// <param name="model">提交数据传输对象</param>
		/// <returns>更新结果</returns>
		public async Task<ApiResponse> UpdateAsync(SubmissionDto model)
		{
			try
			{
				var existingSubmission = await _submissionRepository.GetFirstOrDefaultAsync(predicate: s => s.Id == model.Id && !s.IsDeleted);
				if (existingSubmission == null)
				{
					return ApiResponse.Error("未找到要更新的提交记录。", 404);
				}

				_mapper.Map(model, existingSubmission);
				_submissionRepository.Update(existingSubmission);
				await _unitOfWork.SaveChangesAsync();

				var result = _mapper.Map<SubmissionDto>(existingSubmission);
				return ApiResponse.Success("更新提交记录成功。", result);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"更新提交记录失败: {ex.Message}");
			}
		}

		/// <summary>
		/// 删除提交记录
		/// </summary>
		/// <param name="id">提交ID</param>
		/// <returns>删除结果</returns>
		public async Task<ApiResponse> DeleteAsync(Guid id)
		{
			try
			{
				var submission = await _submissionRepository.GetFirstOrDefaultAsync(predicate: s => s.Id == id && !s.IsDeleted);
				if (submission == null)
				{
					return ApiResponse.Error("未找到要删除的提交记录。", 404);
				}

				submission.IsDeleted = true;
				_submissionRepository.Update(submission);

				var submissionDetails = await _submissionDetailRepository.GetPagedListAsync(predicate: sd => sd.SubmissionId == id);
				foreach (var detail in submissionDetails.Items)
				{
					detail.IsDeleted = true;
					_submissionDetailRepository.Update(detail);
				}

				await _unitOfWork.SaveChangesAsync();
				return ApiResponse.Success("提交记录及相关详情删除成功。", null);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"删除提交记录失败: {ex.Message}");
			}
		}

		#endregion

		#region 错题相关操作

		/// <summary>
		/// 获取用户的错题列表
		/// </summary>
		/// <param name="userId">用户ID</param>
		/// <returns>错题列表</returns>
		public async Task<ApiResponse> GetAllErrorQuestionsAsync(Guid userId)
		{
			try
			{
				var errorSDs = await _submissionDetailRepository.GetPagedListAsync(
					predicate: sd => sd.StudentId == userId && sd.IsCorrect == false,
					include: i => i
						.Include(s => s.ExamQuestion)
							.ThenInclude(aq => aq.Question));

				var errorQuestions = errorSDs.Items.Select(sd => sd.ExamQuestion.Question)
											.Where(q => q != null)
											.DistinctBy(q => q.Id)
											.ToList();

				var result = _mapper.Map<List<QuestionDto>>(errorQuestions);
				return ApiResponse.Success("获取所有错题成功。", result);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"获取所有错题失败: {ex.Message}");
			}
		}

		/// <summary>
		/// 获取指定作业的错题列表
		/// </summary>
		/// <param name="assignmentId">作业ID</param>
		/// <param name="userId">用户ID</param>
		/// <returns>错题列表</returns>
		public async Task<ApiResponse> GetAssignmentErrorQuestionsAsync(Guid assignmentId, Guid userId)
		{
			try
			{
				var errorSDs = await _submissionDetailRepository.GetPagedListAsync(
					predicate: sd => sd.Submission.ExamId == assignmentId &&
									 sd.StudentId == userId &&
									 sd.IsCorrect == false,
					include: i => i
						.Include(s => s.ExamQuestion)
							.ThenInclude(aq => aq.Question));

				var errorQuestions = errorSDs.Items.Select(sd => sd.ExamQuestion.Question)
											.Where(q => q != null)
											.DistinctBy(q => q.Id)
											.ToList();

				var result = _mapper.Map<List<QuestionDto>>(errorQuestions);
				return ApiResponse.Success("获取指定作业错题成功。", result);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"获取指定作业错题失败: {ex.Message}");
			}
		}

		/// <summary>
		/// 获取错题类型分布
		/// </summary>
		/// <param name="assignmentId">作业ID</param>
		/// <param name="userId">用户ID</param>
		/// <returns>错题类型分布</returns>
		public async Task<ApiResponse> GetAssignmentErrorQuestionTypeDisAsync(Guid assignmentId, Guid userId)
		{
			try
			{
				var errorSDs = await _submissionDetailRepository.GetPagedListAsync(
					predicate: sd => sd.Submission.ExamId == assignmentId &&
									 sd.StudentId == userId &&
									 sd.IsCorrect == false,
					include: i => i
						.Include(s => s.ExamQuestion)
							.ThenInclude(aq => aq.Question));

				var errorTypeDistribution = errorSDs.Items
					.Where(sd => sd.ExamQuestion?.Question?.QuestionType != null)
					.GroupBy(sd => sd.ExamQuestion.Question.QuestionType.Name)
					.Select(g => new
					{
						QuestionType = g.Key.ToString(),
						Count = g.Count()
					})
					.ToList();

				return ApiResponse.Success("获取指定作业错题类型分布成功。", errorTypeDistribution);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"获取指定作业错题类型分布失败: {ex.Message}");
			}
		}

		/// <summary>
		/// 获取所有错题类型分布
		/// </summary>
		/// <param name="assignmentId">作业ID</param>
		/// <param name="userId">用户ID</param>
		/// <returns>错题类型分布</returns>
		public async Task<ApiResponse> GetAllErrorQuestionTypeDisAsync(Guid assignmentId, Guid userId)
		{
			try
			{
				var errorSDs = await _submissionDetailRepository.GetPagedListAsync(
					predicate: sd => sd.Submission.ExamId == assignmentId &&
									 sd.StudentId == userId &&
									 sd.IsCorrect == false,
					include: i => i
						.Include(s => s.ExamQuestion)
							.ThenInclude(aq => aq.Question));

				var errorTypeDistribution = errorSDs.Items
					.Where(sd => sd.ExamQuestion?.Question?.QuestionType != null)
					.GroupBy(sd => sd.ExamQuestion.Question.QuestionType.Name)
					.Select(g => new
					{
						QuestionType = g.Key.ToString(),
						Count = g.Count()
					})
					.ToList();

				return ApiResponse.Success("获取错题类型分布成功。", errorTypeDistribution);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"获取错题类型分布失败: {ex.Message}");
			}
		}

		/// <summary>
		/// 获取作业中所有学生的错题情况
		/// </summary>
		/// <param name="assignmentId">作业ID</param>
		/// <param name="teacherId">教师ID</param>
		/// <returns>学生错题情况</returns>
		public async Task<ApiResponse> GetAssignmentAllStudentsError(Guid assignmentId, Guid teacherId)
		{
			try
			{
				var submissionDetails = await _submissionDetailRepository.GetPagedListAsync(
					predicate: sd => sd.Submission.ExamId == assignmentId &&
									 sd.IsCorrect == false,
					include: i => i.Include(sd => sd.Student));

				var studentsErrorSummary = submissionDetails.Items
					.Where(sd => sd.Student != null)
					.GroupBy(sd => new { sd.StudentId, sd.Student.UserName })
					.Select(g => new
					{
						StudentId = g.Key.StudentId,
						StudentName = g.Key.UserName,
						ErrorQuestionCount = g.Count()
					})
					.ToList();

				return ApiResponse.Success("获取作业中所有学生的错题情况成功。", studentsErrorSummary);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"获取作业中所有学生的错题情况失败: {ex.Message}");
			}
		}

		/// <summary>
		/// 获取出现错题的学生列表
		/// </summary>
		/// <param name="assignmentQuestionId">作业题目ID</param>
		/// <returns>错题学生列表</returns>
		public async Task<ApiResponse> GetQuestionErrorStudents(Guid assignmentQuestionId)
		{
			try
			{
				var errorSubmissionDetails = await _submissionDetailRepository.GetPagedListAsync(
					predicate: sd => sd.ExamQuestionId == assignmentQuestionId &&
									 sd.IsCorrect == false,
					include: i => i
						.Include(sd => sd.Student)
						.Include(sd => sd.ExamQuestion)
							.ThenInclude(aq => aq.Question));

				var errorStudentsByQuestion = errorSubmissionDetails.Items
					.Where(sd => sd.ExamQuestion?.Question != null && sd.Student != null)
					.GroupBy(sd => new { sd.ExamQuestionId, sd.ExamQuestion.Question.Title })
					.Select(g => new
					{
						AssignmentQuestionId = g.Key.ExamQuestionId,
						QuestionTitle = g.Key.Title,
						ErrorStudents = g.Select(sd => new
						{
							StudentId = sd.StudentId,
							StudentName = sd.Student.UserName
						}).Distinct().ToList()
					})
					.ToList();

				return ApiResponse.Success("获取出现错题的学生成功。", errorStudentsByQuestion);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"获取出现错题的学生失败: {ex.Message}");
			}
		}

		#endregion

		#region 特殊操作

		/// <summary>
		/// 判断是否已经存在提交记录
		/// </summary>
		/// <param name="assignmentId">作业ID</param>
		/// <param name="studentId">学生ID</param>
		/// <returns>提交记录数量</returns>
		public async Task<byte> IsHasSubmissionAsync(Guid assignmentId, Guid studentId)
		{
			try
			{
				var result = await _unitOfWork.GetRepository<Submission>().GetAllAsync(predicate: s => s.ExamId == assignmentId && s.StudentId == studentId);
				return (byte)result.Count;
			}
			catch (Exception ex)
			{
				throw;
			}
		}

		/// <summary>
		/// 获取学生提交摘要
		/// </summary>
		/// <param name="userId">用户ID</param>
		/// <returns>学生提交摘要列表</returns>
		public async Task<ApiResponse> GetStudentSubmissionSummariesAsync(Guid userId)
		{
			try
			{
				var submissions = await _submissionRepository.GetPagedListAsync(
					predicate: s => s.StudentId == userId && !s.IsDeleted,
					orderBy: s => s.OrderByDescending(s => s.SubmissionTime));

				var summaries = submissions.Items.Select(s => new StudentSubmissionSummaryDto
				{
					Id = s.Id,
					AssignmentName = s.Exam?.Title ?? "未知作业",
					CreatedDate = s.SubmissionTime,
					Score = s.OverallGrade,
					StudentName = s.Student?.UserName ?? "未知学生",
					Status = s.Status.GetDisplayName()
				}).ToList();

				return ApiResponse.Success("获取学生提交摘要成功。", new StudentSubmissionSummaryResponseDto
				{
					Submissions = summaries,
					TotalCount = submissions.TotalCount
				});
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"获取学生提交摘要失败: {ex.Message}");
			}
		}

		/// <summary>
		/// 获取学生提交详情
		/// </summary>
		/// <param name="submissionId">提交ID</param>
		/// <returns>学生提交详情</returns>
		public async Task<ApiResponse> GetStudentSubmissionDetailAsync(Guid submissionId)
		{
			try
			{
				var submission = await _submissionRepository.GetFirstOrDefaultAsync(
					predicate: s => s.Id == submissionId && !s.IsDeleted);

				if (submission == null)
				{
					return ApiResponse.Error("未找到提交记录。", 404);
				}

				var detail = _mapper.Map<StudentSubmissionDetailDto>(submission);


				return ApiResponse.Success("获取学生提交详情成功。", detail);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"获取学生提交详情失败: {ex.Message}");
			}
		}

		public async Task<ApiResponse> GradeExam(SubmissionTeacherUpdateDto model)
		{

			try
			{
				var existingSubmission = await _submissionRepository.GetFirstOrDefaultAsync(predicate: s => s.Id == model.Id && !s.IsDeleted);
				if (existingSubmission == null)
				{
					return ApiResponse.Error("未找到要批改的试卷记录。", 404);
				}

				_mapper.Map(model, existingSubmission);

				foreach (var item in existingSubmission.SubmissionDetails)
				{
					var sdd = model.SubmissionUpdateDetails.FirstOrDefault(d => d.Id == item.Id);
					if (sdd == null) continue;
					_mapper.Map(sdd, item);
				}
				_submissionRepository.Update(existingSubmission);
				await _unitOfWork.SaveChangesAsync();

				var result = _mapper.Map<SubmissionDto>(existingSubmission);
				return ApiResponse.Success("批改试卷记录成功。", result);
			}
			catch (Exception ex)
			{
				return ApiResponse.Error($"批改试卷记录失败: {ex.Message}");
			}
		}

		#endregion
	}
}
