using System;
using System.Collections.Generic;
using System.Linq;

namespace GB5Shared.DTO.WorkFlow
{
    // ── Workflow Definition ───────────────────────────────────────────────────

    /// <summary>
    /// In-memory representation of a full workflow definition loaded from
    /// MWORKFLOW + MWORKFLOWDETAIL + MWORKFLOWASSIGNMENT.
    /// </summary>
    public class WorkflowDefinition
    {
        public int    WorkflowId            { get; set; }
        public string WorkflowName          { get; set; } = string.Empty;
        public int    EntityId              { get; set; }
        public string? Particulars          { get; set; }
        public int    TenantId              { get; set; }
        public int    SortOrder             { get; set; }
        public int    Version               { get; set; }
        public int    Status                { get; set; }
        public int    SourceType            { get; set; }
        public int    CreatedById           { get; set; }
        public DateTime  CreatedOn          { get; set; }
        public int?   ModifiedById          { get; set; }
        public DateTime? ModifiedOn         { get; set; }

        public List<WorkflowStep> Steps { get; set; } = new();

        // ── Helpers ──────────────────────────────────────────────────────────

        /// <summary>
        /// Returns distinct approval levels present in the definition, sorted ascending.
        /// </summary>
        public List<int> GetApprovalLevels()
            => Steps.Select(s => s.ApprovalLevel)
                    .Distinct()
                    .OrderBy(l => l)
                    .ToList();

        /// <summary>
        /// Returns the next approval level after <paramref name="currentLevel"/>,
        /// or null when <paramref name="currentLevel"/> is the last level.
        /// </summary>
        public int? GetNextApprovalLevel(int currentLevel)
        {
            var levels = GetApprovalLevels();
            int idx = levels.IndexOf(currentLevel);
            if (idx < 0 || idx + 1 >= levels.Count)
                return null;
            return levels[idx + 1];
        }

        /// <summary>Returns all steps at the given approval level, ordered by SLNO.</summary>
        public IReadOnlyList<WorkflowStep> GetStepsAtLevel(int level)
            => Steps.Where(s => s.ApprovalLevel == level)
                    .OrderBy(s => s.SlNo)
                    .ToList();

        /// <summary>Lowest approval level (entry point of the workflow).</summary>
        public int GetFirstApprovalLevel()
            => GetApprovalLevels().FirstOrDefault(1);

        // Keep for backward compat with transition-based paths (not used by new level engine)
        public WorkflowStep? GetInitialStep()
            => Steps.FirstOrDefault(s => s.IsInitial) ?? Steps.OrderBy(s => s.SlNo).FirstOrDefault();
    }

    // ── Action enum ───────────────────────────────────────────────────────────

    public enum WorkflowAction
    {
        Submit   = 0,
        Approve  = 1,
        Reject   = 2,
        Return   = 3,   // send back to previous level / creator
        Escalate = 4,
        Cancel   = 5    // superseded by resubmission, or the record was deleted
    }

    // ── Workflow Step (MWORKFLOWDETAIL + MWORKFLOWASSIGNMENT) ─────────────────

    public class WorkflowStep
    {
        // ── MWORKFLOWDETAIL columns ──────────────────────────────────────────

        public int    WorkflowDetailId      { get; set; }
        public int    WorkflowId            { get; set; }

        /// <summary>Sequence number within the workflow (SLNO).</summary>
        public int    SlNo                  { get; set; }

        /// <summary>
        /// Approval level (APPROVALLEVEL).
        /// Steps with the same level are processed in parallel before advancing.
        /// </summary>
        public int    ApprovalLevel         { get; set; }

        /// <summary>
        /// Unique key derived from WORKFLOWDETAILID (used in history records).
        /// </summary>
        public string StepKey               { get; set; } = string.Empty;

        public string DisplayName           { get; set; } = string.Empty;

        /// <summary>
        /// 0 = Human, 1 = System, 2 = Auto, 3 = End, 4 = ParallelGroup.
        /// </summary>
        public int    StepType              { get; set; }

        /// <summary>
        /// DB stores: 0 = IS initial, 1 = NOT initial.
        /// Mapped so that a positive value in the column means IsInitial=true
        /// when ISINITIAL column value = 1 (i.e. 1 = yes it IS initial — matches
        /// the existing data where step 18 is flagged).
        /// NOTE: For level-based routing, use ApprovalLevel instead.
        /// </summary>
        public bool   IsInitial             { get; set; }

        /// <summary>Same note as IsInitial. Use ApprovalLevel for routing.</summary>
        public bool   IsFinal               { get; set; }

        /// <summary>0 = User, 1 = Role, 2 = Pool, 3 = Dynamic. Assignment target type.</summary>
        public int    AssignmentType        { get; set; }

        /// <summary>
        /// Boolean expression evaluated against Facts to determine whether
        /// this step is applicable for the current document.
        /// Example: <c>TaskDetailType == 0</c>
        /// Null/empty = always applicable.
        /// </summary>
        public string? EvalCondition        { get; set; }

        /// <summary>FK to MWORKFLOWASSIGNMENT.</summary>
        public int    AssignmentId          { get; set; }

        public string? Particulars          { get; set; }
        public string? ParallelGroupKey     { get; set; }

        /// <summary>SLA hours; 0 = no SLA.</summary>
        public int    SlaHours              { get; set; }

        public int    EscalationRuleGroupId { get; set; }
        public int    PickListId            { get; set; }
        public int    DisplayLabelId        { get; set; }

        // ── MWORKFLOWASSIGNMENT columns (joined) ─────────────────────────────

        public int    WorkflowAssignmentId   { get; set; }
        public string WorkflowAssignmentName { get; set; } = string.Empty;

        /// <summary>
        /// 0 = User (RULEEXPRESSION holds UserId as string),
        /// 1 = UserGroup (RULEEXPRESSION holds UserGroupId as string),
        /// 2 = EnrichQualifier (RULEEXPRESSION is a field name written by a DB_ENRICH
        ///     qualifier into ctx._bag during EnrichForWorkflow; value is the assignee UserId),
        /// 3 = DynamicSQL (RULEEXPRESSION is a SQL query returning a UserId),
        /// 4 = Service (RULEEXPRESSION is a service endpoint / identifier — reserved).
        /// </summary>
        public byte   StrategyType          { get; set; }

        /// <summary>
        /// Content depends on StrategyType:
        /// - 0 (User)            : the UserId as a string, e.g. "42"
        /// - 1 (UserGroup)       : the UserGroupId as a string
        /// - 2 (EnrichQualifier) : field name returned by DB_ENRICH qualifier, e.g. "ReportingToEmployeeId"
        /// - 3 (DynamicSQL)      : parameterised SQL; parameters are injected from Facts
        /// - 4 (Service)         : endpoint/service identifier (reserved)
        /// </summary>
        public string? RuleExpression       { get; set; }

        public string? AssignmentDescription { get; set; }
        public int    AssignmentTenantId    { get; set; }

        // ── Backward compat (was StrategyTypeId in old engine) ───────────────

        /// <summary>
        /// For StrategyType 0/1: direct numeric id parsed from RuleExpression.
        /// Populated at load time in GetActiveDefinitionAsync.
        /// </summary>
        public int    StrategyTypeId        { get; set; }

        /// <summary>Alias kept for backward compatibility.</summary>
        public string? AssignmentValue      { get; set; }
    }

    // ── Rule groups (used by old activation-rule path) ────────────────────────

    public class WorkflowRuleGroup
    {
        public long   RuleGroupId { get; set; }
        public string Name        { get; set; } = string.Empty;
        public string Operator    { get; set; } = "AND";
        public string? Description { get; set; }
        public IList<WorkflowRule> Rules { get; set; } = new List<WorkflowRule>();
    }

    public class WorkflowRule
    {
        public long   RuleId      { get; set; }
        public long   RuleGroupId { get; set; }
        public string FieldPath   { get; set; } = string.Empty;
        public string Operator    { get; set; } = string.Empty;
        public string Value       { get; set; } = string.Empty;
        public string ValueType   { get; set; } = "String";
    }

    // ── Runtime instances & tasks ─────────────────────────────────────────────

    public class WorkflowInstance
    {
        public int      WorkflowInstanceId   { get; set; }
        public int      TenantId             { get; set; }
        public int      EntityId             { get; set; }
        public int      ObjectId             { get; set; }
        public int      OUId                 { get; set; }
        public int      BizTransactionTypeId { get; set; }
        public int      WorkflowId           { get; set; }
        public object?  DataJson             { get; set; }

        /// <summary>
        /// JSON-serialized scalar facts from WorkflowStartRequest.Facts (enriched qualifier values).
        /// Stored at workflow start so EnrichQualifier (StrategyType=2) assignments are available
        /// at Level 2, 3, and every subsequent level — not just Level 1.
        /// Merged at lower priority than DataJson; DataJson DTO fields win on key collision.
        /// </summary>
        public string?  FactsJson            { get; set; }

        public long     CurrentStepId        { get; set; }

        /// <summary>
        /// Current approval level being processed (1-based).
        /// Persisted in TWORKFLOWINSTANCE.CURRENTAPPROVALLEVEL.
        /// </summary>
        public int      CurrentApprovalLevel { get; set; } = 1;

        /// <summary>
        /// 0 = Pending, 1 = Completed, 2 = Rejected, 3 = Returned.
        /// </summary>
        public int      WorkflowStatus       { get; set; }

        public int      SortOrder            { get; set; }
        public int      Status               { get; set; }
        public int      Version              { get; set; }
        public int      SourceType           { get; set; }
        public int      CreatedById          { get; set; }
        public DateTime CreatedOn            { get; set; }
        public int      ModifiedById         { get; set; }
        public DateTime ModifiedOn           { get; set; }
    }

    public class WorkflowTask
    {
        public int      WorkflowTaskId       { get; set; }
        public int      WorkflowInstanceId   { get; set; }
        public int      StepId               { get; set; }
        public int      WorkflowTaskStatus   { get; set; }
        public int      AssignedToUserId     { get; set; }
        public int      AssignedRoleId       { get; set; }
        public int      AssignedUserGroupId  { get; set; }
        public DateTime? DueOn               { get; set; }
        public DateTime? CompletedOn         { get; set; }
        public int?     ActionTaken          { get; set; }
        public string?  Comment              { get; set; }
        public long     TenantId             { get; set; }
        public int      SortOrder            { get; set; }
        public int      Status               { get; set; }
        public int      Version              { get; set; }
        public int      SourceType           { get; set; }
        public long     CreatedById          { get; set; }
        public DateTime CreatedOn            { get; set; }
        public long     ModifiedById         { get; set; }
        public DateTime ModifiedOn           { get; set; }
    }

    public enum WorkflowTaskStatus
    {
        Pending   = 0,
        Approved  = 1,
        Rejected  = 2,
        Completed = 3,
        Cancelled = 4
    }

    public class WorkflowHistory
    {
        public int      HistoryId            { get; set; }
        public int      InstanceId           { get; set; }
        public int      ObjectId             { get; set; }
        public object?  DataJson             { get; set; }
        public int      WorkflowId           { get; set; }
        public int      OUID                 { get; set; }
        public int      BiztransactionTypeId { get; set; } = -1;
        public string   EntityName           { get; set; } = string.Empty;
        public int      EntityId             { get; set; }
        public string?  StepKey              { get; set; }
        public int      ApprovalLevel        { get; set; }
        public int      Action               { get; set; }
        public int?     ActionByUserId       { get; set; }
        public string?  Comment              { get; set; }
        public DateTime ActionOn             { get; set; }
    }

    public class UserDelegation
    {
        public long     DelegationId    { get; set; }
        public long     PrincipalUserId { get; set; }
        public long     DelegateUserId  { get; set; }
        public DateTime StartsOn        { get; set; }
        public DateTime EndsOn          { get; set; }
    }

    public class UserPoolMember
    {
        public long   PoolMemberId { get; set; }
        public string PoolName     { get; set; } = string.Empty;
        public long   UserId       { get; set; }
    }

    public enum WorkflowInstanceStatus
    {
        Pending   = 0,
        Completed = 1,
        Rejected  = 2,
        Returned  = 3,
        Cancelled = 4
    }

}