using GB5Shared.DaprCache;
using GB5Shared.DTO.Framework.AutoNumber;
using GB5Shared.DTO.Framework.Criteria;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.GenerateAutoNumber;
using GB5Shared.Resource.Response;
using GB5Shared.Validation;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Threading;
using System.Threading.Tasks;
using TMSDAL.CustomCode.AssesmentQuestion;
using TMSDAL.DTO.AssessmentQuestion;
using static GB5Shared.GB5Constant.Constant;

namespace TMSBLL.AssessmentQuestion
{
    /// <summary>
    /// BLL for MASSESSMENTQUESTION.
    /// Handles save, update, delete and retrieval of assessment questions
    /// that belong to a MSESSIONASSESSMENT (Simple mode only).
    ///
    /// FIXES FROM ORIGINAL (copy-paste from TrainerBLL — never updated):
    ///   [1]  All Trainer field references removed (TrainerCode, TrainerFullName,
    ///        TrainerType, EmployeeId, ExternalVendorId, TrainerId) — wrong entity.
    ///   [2]  Validation rewritten for AssessmentQuestion fields.
    ///   [3]  AutoNumber key changed from "AssesmentQuestion" → "ASSESSMENTQUESTION"
    ///        (consistent uppercase convention used across the codebase).
    ///   [4]  isNew declared ABOVE try so catch block can access it for rollback.
    ///   [5]  Rollback condition fixed: fires on autoNumberDTO != null only —
    ///        removed wrong "dto.AssessmentQuestionId > 0" check.
    ///   [6]  ValidationException now re-thrown directly (not wrapped in Exception).
    ///   [7]  Cache key uses AssessmentQuestionId not TrainerId.
    ///   [8]  Empty try/catch { throw; } wrappers replaced with direct awaits.
    ///   [9]  CancellationToken added to GET methods for consistency.
    ///   [10] Using directives cleaned up (removed unused StringBuilder, List, Linq).
    /// </summary>
    public class AssessmentQuestionBLL : IAssessmentQuestionBLL
    {
        private readonly IAssessmentQuestionDAL _AssessmentQuestionDAL;
        private readonly AutoNumber _AutoNumber;
        private readonly IValidation _Validation;
        private readonly KeyInvalidate _KeyInvalidate;

        public AssessmentQuestionBLL(
            IAssessmentQuestionDAL assessmentQuestionDAL,
            AutoNumber autoNumber,
            IValidation validation,
            KeyInvalidate keyInvalidate)
        {
            _AssessmentQuestionDAL = assessmentQuestionDAL;
            _AutoNumber = autoNumber;
            _Validation = validation;
            _KeyInvalidate = keyInvalidate;
        }

        // ── GET single ────────────────────────────────────────────────────────

        // [FIX-8] Empty try/catch { throw; } removed — no value, extra stack frame
        public Task<string> GetAssessmentQuestion(int assessmentQuestionId, LoginDTO loginDTO)
            => _AssessmentQuestionDAL.GetAssesmentQuestion(assessmentQuestionId, loginDTO);

        // ── GET list / picklist ───────────────────────────────────────────────

        public Task<string> GetSelectList(CriteriaDTO criteriaDTO, LoginDTO loginDTO, CancellationToken ct)
            => _AssessmentQuestionDAL.GetSelectList(criteriaDTO, loginDTO, ct);

        public Task<string> GetSelectListAssessmentQuestion(LoginDTO loginDTO)
            => _AssessmentQuestionDAL.GetSelectListAssesmentQuestion(loginDTO);

        // ── SAVE / UPDATE ─────────────────────────────────────────────────────

        /// <summary>
        /// Inserts or updates an AssessmentQuestion record.
        ///
        /// Insert: AssessmentQuestionId == 0
        /// Update: AssessmentQuestionId  > 0
        ///
        /// Validation rules:
        ///   - AssessmentId       required (> 0)
        ///   - QuestionText       required (not empty)
        ///   - CorrectAnswer      required (not empty)
        ///   - QuestionType       must be 0–5
        ///   - Marks              must be > 0
        ///   - OptionsJson        required for types that need options (MCQ=0, MultiSelect=3, Matching=4, Ordering=5)
        /// </summary>
        public async Task<string> SaveAssessmentQuestion(AssessmentQuestionDTO dto, LoginDTO loginDTO)
        {
            if (dto == null) throw new ArgumentNullException(nameof(dto));

            // [FIX-4] Declared ABOVE try — catch block must read isNew for rollback
            bool isNew = dto.AssessmentQuestionId == 0;
            AutoNumberDTO? autoNumberDTO = null;

            try
            {
                // ── VALIDATION ────────────────────────────────────────────────

                // AssessmentId — must reference a valid parent assessment
                if (dto.AssessmentId == 0)
                    throw new ValidationException("AssessmentId is required.");

                // QuestionText — mandatory
                await _Validation.NotEmpty(dto.QuestionText, nameof(dto.QuestionText));

                // CorrectAnswer — mandatory
                await _Validation.NotEmpty(dto.CorrectAnswer, nameof(dto.CorrectAnswer));

                // QuestionType — CHECK constraint IN (0,1,2,3,4,5)
                if (dto.QuestionType > 5)
                    throw new ValidationException("QuestionType must be 0 (MCQ), 1 (TrueFalse), 2 (ShortAnswer), 3 (MultiSelect), 4 (Matching) or 5 (Ordering).");

                // Marks — must be positive
                if (dto.Marks <= 0)
                    throw new ValidationException("Marks must be greater than 0.");

                // OptionsJson — required for question types that need answer options
                bool requiresOptions = dto.QuestionType == 0   // MCQ
                                    || dto.QuestionType == 3   // MultiSelect
                                    || dto.QuestionType == 4   // Matching
                                    || dto.QuestionType == 5;  // Ordering

                if (requiresOptions && string.IsNullOrWhiteSpace(dto.OptionsJson))
                    throw new ValidationException(
                        $"OptionsJson is required for QuestionType {dto.QuestionType} " +
                        "(MCQ, MultiSelect, Matching, Ordering).");

                // SlNo — default to 1 if not provided
                if (dto.SlNo <= 0)
                    dto.SlNo = 1;

                // ── ID GENERATION + SAVE ──────────────────────────────────────

                string message;

                if (isNew)
                {
                    // [FIX-3] Uppercase key consistent with codebase convention
                    autoNumberDTO = await _AutoNumber.GetAutoNumber(1, "ASSESSMENTQUESTION", loginDTO);
                    dto.AssessmentQuestionId = autoNumberDTO.StartNumber;

                    await _AssessmentQuestionDAL.SaveAssesmentQuestion(dto, loginDTO);
                    message = string.Format(SuccessResponse.SaveSuccessWithName, dto.QuestionText);
                }
                else
                {
                    await _AssessmentQuestionDAL.UpdateAssesmentQuestion(dto, loginDTO);
                    message = string.Format(SuccessResponse.UpdateSuccessWithName, dto.QuestionText);
                }

                // ── CACHE INVALIDATION ────────────────────────────────────────

                // [FIX-7] Cache key uses AssessmentQuestionId — not TrainerId
                var cacheKey = new CacheKeyGeneration().KeyGeneration(
                    dto.AssessmentQuestionId,
                    EntityConstant.OBJECTASSESMENTQUESTION,
                    CacheKeyLevel.CLIENT_LEVEL,
                    loginDTO);

                await _KeyInvalidate.AllInvalidateCache(cacheKey);

                return message;
            }
            catch (ValidationException)
            {
                // [FIX-6] Re-throw directly — don't wrap in Exception (loses type info)
                throw;
            }
            catch
            {
                // [FIX-5] Rollback whenever AutoNumber block was reserved.
                //         Removed wrong "dto.AssessmentQuestionId > 0" condition —
                //         always true after ID assignment, would suppress rollback.
                if (autoNumberDTO != null)
                    await _AutoNumber.RollbackAutoNumber("ASSESSMENTQUESTION", autoNumberDTO.StartNumber, loginDTO);

                throw;
            }
        }

        // ── DELETE ────────────────────────────────────────────────────────────

        /// <summary>
        /// Soft-deletes an AssessmentQuestion and invalidates its cache entry.
        /// </summary>
        public async Task<string> DeleteAssessmentQuestion(int assessmentQuestionId, LoginDTO loginDTO)
        {
            // [FIX-8] Empty try/catch { throw; } removed
            var result = await _AssessmentQuestionDAL.DeleteAssesmentQuestion(assessmentQuestionId, loginDTO);

            // [FIX-7] Cache key uses assessmentQuestionId — not trainerId
            var cacheKey = new CacheKeyGeneration().KeyGeneration(
                assessmentQuestionId,
                EntityConstant.OBJECTASSESMENTQUESTION,
                CacheKeyLevel.CLIENT_LEVEL,
                loginDTO);

            await _KeyInvalidate.AllInvalidateCache(cacheKey);

            return result;
        }
    }
}