using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace TMSDAL.DTO.EvaluationInstance
{
    /// <summary>
    /// Maps to DBO.TEVALUATIONINSTANCE
    /// One scheduled evaluation event per employee per plan.
    /// Created when a training completes or a period evaluation is triggered.
    /// Tracks the lifecycle: Pending → Sent → Completed / Overdue / Cancelled.
    /// </summary>
    public class EvaluationInstanceDTO
    {
        // =====================================================
        // PRIMARY KEY
        // =====================================================

        /// <summary>
        /// Unique identifier for this evaluation instance.
        /// Auto-generated via AutoNumber — do not set manually on insert.
        /// </summary>
        public int EvaluationInstanceId { get; set; }


        // =====================================================
        // BUSINESS COLUMNS — FOREIGN KEYS
        // =====================================================

        /// <summary>
        /// FK → MEVALUATIONPLAN.EVALUATIONPLANID
        /// The evaluation plan that governs this instance.
        /// </summary>
        public int EvaluationPlanId { get; set; }

        /// <summary>
        /// Joined from MEVALUATIONPLAN — display reference only.
        /// </summary>
        public string? PlanTitle { get; set; }

        /// <summary>
        /// FK → MEVALUATIONTEMPLATE.EVALUATIONTEMPLATEID
        /// The questionnaire template to be filled by the respondent.
        /// </summary>
        public int EvaluationTemplateId { get; set; }

        /// <summary>
        /// Joined from MEVALUATIONTEMPLATE — display reference only.
        /// </summary>
        public string? TemplateTitle { get; set; }

        /// <summary>
        /// FK → TTRAININGENROLLMENT.ENROLLMENTID
        /// -1 = Multi-programme period evaluation (not tied to a specific enrollment).
        /// </summary>
        public int EnrollmentId { get; set; } = -1;

        /// <summary>
        /// FK → MEMPLOYEE.EMPLOYEEID
        /// The employee being evaluated.
        /// </summary>
        public int EmployeeId { get; set; }

        /// <summary>
        /// Joined from MEMPLOYEE — display reference only.
        /// </summary>
        public string? EmployeeName { get; set; }

        /// <summary>
        /// FK → MEMPLOYEE.EMPLOYEEID
        /// The person responsible for filling the evaluation form.
        /// -1 = Same as EmployeeId (self-evaluation).
        /// </summary>
        public int RespondentId { get; set; } = -1;

        /// <summary>
        /// Joined from MEMPLOYEE — display reference only.
        /// </summary>
        public string? RespondentName { get; set; }


        // =====================================================
        // BUSINESS COLUMNS — PERIOD & SCHEDULE
        // =====================================================

        /// <summary>
        /// Start of the evaluation coverage period.
        /// Null for immediate post-training evaluations.
        /// </summary>
        public DateTime? PeriodCoveredFrom { get; set; }

        /// <summary>
        /// End of the evaluation coverage period.
        /// Null for immediate post-training evaluations.
        /// </summary>
        public DateTime? PeriodCoveredTo { get; set; }

        /// <summary>
        /// Date by which the evaluation must be completed.
        /// Computed from EvalWindowDays in MEVALUATIONPLAN.
        /// </summary>
        public DateTime DueDate { get; set; }


        // =====================================================
        // BUSINESS COLUMNS — STATUS & TRACKING
        // =====================================================

        /// <summary>
        /// Current lifecycle status of this evaluation instance.
        /// 0 = Pending — created, not yet sent to respondent.
        /// 1 = Sent    — form dispatched to respondent.
        /// 2 = Completed — response submitted.
        /// 3 = Overdue — past DueDate with no response.
        /// 4 = Cancelled — manually cancelled by HR/L&D.
        /// BLL enforces: always set to 0 on creation.
        /// </summary>
        public byte EvalStatus { get; set; } = 0;

        /// <summary>
        /// Number of reminder notifications sent so far.
        /// Incremented each time a reminder is dispatched.
        /// </summary>
        public short ReminderSentCount { get; set; } = 0;

        /// <summary>
        /// Timestamp of the most recent reminder sent.
        /// Null if no reminder has been sent yet.
        /// </summary>
        public DateTime? LastReminderSentAt { get; set; }

        /// <summary>
        /// Timestamp when the respondent submitted their response.
        /// Null until EvalStatus = 2 (Completed).
        /// Set automatically by BLL when SubmitEvaluationResponse is called.
        /// </summary>
        public DateTime? CompletedAt { get; set; }


        // =====================================================
        // STANDARD FIELDS
        // =====================================================

        /// <summary>Optimistic concurrency version counter.</summary>
        public short Version { get; set; }

        /// <summary>
        /// Record status.
        /// 0 = Inactive, 1 = Active, 2–5 = Custom workflow states.
        /// </summary>
        public byte Status { get; set; } = 1;

        /// <summary>Display sort order. Default 9999 = append to end.</summary>
        public short SortOrder { get; set; } = 9999;

        /// <summary>
        /// Source of record creation.
        /// 1–4 = Import sources, 5 = Manual entry (default).
        /// </summary>
        public byte SourceType { get; set; } = 5;

        /// <summary>FK → MCLIENT.CLIENTID. Set by BLL from LoginDTO.</summary>
        public int TenantId { get; set; }

        /// <summary>FK → MUSER.USERID. Set by BLL from LoginDTO.</summary>
        public int CreatedById { get; set; }

        /// <summary>Set by BLL to DateTime.UtcNow on insert.</summary>
        public DateTime CreatedOn { get; set; }

        /// <summary>FK → MUSER.USERID. Updated by BLL on every save.</summary>
        public int ModifiedById { get; set; }

        /// <summary>Set by BLL to DateTime.UtcNow on every save.</summary>
        public DateTime ModifiedOn { get; set; }
    }
}