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

namespace GB5Shared.DTO.GOP
{
    public class GBGatewayDTO
    {
        /// <summary>
        /// Top-level definition of a mapping. It is versioned – the active version
        /// is the one the runtime uses. Think of this as the "template header".
        /// Example: "SAP Invoice → Canonical Invoice"
        /// </summary>
        public class MappingDefinition
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public int TenantId { get; set; }
            public string Name { get; set; } = string.Empty;
            public string Description { get; set; } = string.Empty;
            public string SourceSchema { get; set; } = string.Empty;  // e.g. "SAP_Invoice_v2"
            public string TargetSchema { get; set; } = string.Empty;  // e.g. "CanonicalInvoice_v1"
            public MappingDirection Direction { get; set; } = MappingDirection.Inbound;
            public string CreatedBy { get; set; } = string.Empty;
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;

            public List<MappingVersion> Versions { get; set; } = new();
        }

        /// <summary>
        /// A snapshot of a MappingDefinition at a point in time.
        /// Only one version per definition can be Active at once.
        /// New drafts are created, tested, then activated.
        /// </summary>
        public class MappingVersion
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid MappingDefinitionId { get; set; }
            public string Label { get; set; } = string.Empty; // e.g. "v1.0.0"
            public VersionStatus Status { get; set; } = VersionStatus.Draft;
            public string CreatedBy { get; set; } = string.Empty;
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
            public DateTime? ActivatedAt { get; set; }

            public List<MappingNode> Nodes { get; set; } = new();
        }

        /// <summary>
        /// A single field-to-field transformation rule within a MappingVersion.
        /// SourcePath  → evaluated expression → TargetPath
        /// Example: "$.invoice.inv_no" → "UPPER(value)" → "$.InvoiceNumber"
        /// </summary>
        public class MappingNode
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid MappingVersionId { get; set; }
            public string SourcePath { get; set; } = string.Empty;  // JSONPath in source document
            public string TargetPath { get; set; } = string.Empty;  // JSONPath in canonical/target
            public string? TransformExpression { get; set; }               // optional C#/JS-like expression
            public int ExecutionOrder { get; set; }                  // lower = runs first
            public bool IsRequired { get; set; } = true;

            // Optional qualifier applied to this field (validate/enrich before mapping)
            public Guid? QualifierVersionId { get; set; }
        }

        public sealed class MappingComponent
        {
            public Guid ComponentId { get; set; }
            public int TenantId { get; set; }
            public string Name { get; set; }
            public string Description { get; set; }
            public DateTime CreatedAt { get; set; }
        }

        public enum ExecutionStatus
        {
            Started,
            Qualifying,
            Mapping,
            Dispatching,
            Paused,          // waiting for human review
            Completed,
            Failed,
            DeadLettered
        }

        /// <summary>How the execution was triggered.</summary>
        public enum ExecutionMode
        {
            RealTime,
            Batch,
            Replay
        }

        /// <summary>Data flow direction.</summary>
        public enum MappingDirection
        {
            Inbound,   // external → canonical
            Outbound   // canonical → external
        }

        /// <summary>Result of a single attempt.</summary>
        public enum AttemptResult
        {
            Success,
            Failure,
            Skipped
        }

        // ─── Mapping ─────────────────────────────────────────────────────────────────

        /// <summary>Draft = editable, Active = locked and in use.</summary>
        public enum VersionStatus
        {
            Draft,
            Active,
            Archived
        }

        // ─── Qualifier ───────────────────────────────────────────────────────────────

        /// <summary>What the qualifier does to the data.</summary>
        public enum QualifierType
        {
            Validator,   // rejects bad data
            Enricher     // adds / transforms data
        }

        // ─── Decision Flow ────────────────────────────────────────────────────────────

        /// <summary>Type of step inside a decision flow.</summary>
        public enum StepType
        {
            Automated,
            ManualReview,
            Approval,
            Notification
        }

        /// <summary>State of a workflow step waiting for a human.</summary>
        public enum WorkflowStepStatus
        {
            Waiting,
            Approved,
            Rejected,
            Escalated,
            Skipped
        }

        // ─── Error Handling ───────────────────────────────────────────────────────────

        /// <summary>What to do when a qualifier fails.</summary>
        public enum OnValidationFailure
        {
            Stop,
            Continue,
            ManualReview
        }

        /// <summary>What to do when dispatching to a target system fails.</summary>
        public enum OnTargetFailure
        {
            Retry,
            ManualReview,
            DeadLetter
        }

        /// <summary>Backoff strategy for retries.</summary>
        public enum BackoffType
        {
            Fixed,
            Linear,
            Exponential
        }

        // ─── Remediation ──────────────────────────────────────────────────────────────

        public enum RemediationStatus
        {
            Open,
            InProgress,
            Resolved,
            Closed
        }

        // ─── Async / Events ───────────────────────────────────────────────────────────

        public enum ExecutionEventType
        {
            Start,
            Resume,
            Retry,
            Pause,
            Cancel
        }
        public sealed class MappingComponentNode
        {
            public Guid ComponentNodeId { get; set; }
            public Guid ComponentId { get; set; }
            public string NodeType { get; set; }
            public string SourcePath { get; set; }
            public string TargetPath { get; set; }
            public string Expression { get; set; }
            public Guid? QualifierVersionId { get; set; }
            public int ExecutionOrder { get; set; }
        }

        public record CanonicalModelResult(
        Guid Id,
        int TenantId,
        string Name,
        string Description,
        string Version,
        bool IsActive,
        string CreatedBy,
        DateTime CreatedAt,
        IEnumerable<CanonicalFieldResult> Fields
    );

        public class CanonicalModel
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public int TenantId { get; set; }
            public string Name { get; set; } = string.Empty;   // e.g. "Invoice"
            public string Description { get; set; } = string.Empty;
            public string Version { get; set; } = "1.0";          // semantic version of the CDM schema
            public bool IsActive { get; set; } = true;
            public string CreatedBy { get; set; } = string.Empty;
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;

            // Navigation: child fields define the schema structure
            public List<CanonicalField> Fields { get; set; } = new();
        }

        /// <summary>
        /// A single field in a CanonicalModel schema.
        /// Example: InvoiceNumber (string, required), TotalAmount (decimal, required)
        /// </summary>
        public class CanonicalField
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid CanonicalModelId { get; set; }
            public string Name { get; set; } = string.Empty;  // PascalCase e.g. "InvoiceNumber"
            public string DataType { get; set; } = "string";      // string | int | decimal | bool | datetime
            public bool IsRequired { get; set; } = false;
            public string? DefaultValue { get; set; }
            public string? Description { get; set; }
            public int DisplayOrder { get; set; }
        }


        public record CanonicalFieldResult(
            Guid Id,
            string Name,
            string DataType,
            bool IsRequired,
            string? DefaultValue,
            string? Description,
            int DisplayOrder
        );

        // ── Mapping ──────────────────────────────────────────────────────────────────

        public record MappingDefinitionResult(
            Guid Id,
            int TenantId,
            string Name,
            string Description,
            string SourceSchema,
            string TargetSchema,
            string Direction,
            string CreatedBy,
            DateTime CreatedAt,
            IEnumerable<MappingVersionResult> Versions
        );

        public record MappingVersionResult(
            Guid Id,
            Guid MappingDefinitionId,
            string Label,
            string Status,
            string CreatedBy,
            DateTime CreatedAt,
            DateTime? ActivatedAt,
            IEnumerable<MappingNodeResult> Nodes
        );

        public record MappingNodeResult(
            Guid Id,
            string SourcePath,
            string TargetPath,
            string? TransformExpression,
            int ExecutionOrder,
            bool IsRequired,
            Guid? QualifierVersionId
        );

        public class QualifierDefinition
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public int TenantId { get; set; }
            public string Name { get; set; } = string.Empty;
            public string Description { get; set; } = string.Empty;
            public QualifierType Type { get; set; }
            public bool IsSystem { get; set; } = false;  // system-wide vs tenant-specific
            public string CreatedBy { get; set; } = string.Empty;
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;

            public List<QualifierVersion> Versions { get; set; } = new();
        }

        /// <summary>
        /// A snapshot of the qualifier logic at a point in time.
        /// Script contains the validation/enrichment expression or reference.
        /// </summary>
        public class QualifierVersion
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid QualifierDefinitionId { get; set; }
            public string Label { get; set; } = string.Empty;
            public VersionStatus Status { get; set; } = VersionStatus.Draft;
            public string Script { get; set; } = string.Empty; // expression or script body
            public string CreatedBy { get; set; } = string.Empty;
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
            public DateTime? ActivatedAt { get; set; }
        }

        /// <summary>
        /// Binds a qualifier to a specific target (e.g. a MappingNode or a DecisionStep).
        /// This allows reusing the same qualifier across many mappings.
        /// </summary>
        public class QualifierBinding
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid QualifierVersionId { get; set; }
            public string BoundToType { get; set; } = string.Empty; // "MappingNode" | "DecisionStep"
            public Guid BoundToId { get; set; }
            public int ExecutionOrder { get; set; }
        }
        // ── Qualifier ────────────────────────────────────────────────────────────────

        public record QualifierDefinitionResult(
            Guid Id,
            int TenantId,
            string Name,
            string Description,
            string Type,
            bool IsSystem,
            string CreatedBy,
            DateTime CreatedAt,
            IEnumerable<QualifierVersionResult> Versions
        );

        public record QualifierVersionResult(
            Guid Id,
            string Label,
            string Status,
            string Script,
            string CreatedBy,
            DateTime CreatedAt,
            DateTime? ActivatedAt
        );

        // ── Decision Flow ─────────────────────────────────────────────────────────────

        public record DecisionFlowDefinitionResult(
            Guid Id,
            int TenantId,
            string Name,
            string Description,
            string Intent,
            string CreatedBy,
            DateTime CreatedAt,
            IEnumerable<DecisionFlowVersionResult> Versions
        );

        public record DecisionFlowVersionResult(
            Guid Id,
            string Label,
            string Status,
            string CreatedBy,
            DateTime CreatedAt,
            DateTime? ActivatedAt,
            IEnumerable<DecisionStepResult> Steps,
            IEnumerable<DecisionTransitionResult> Transitions
        );

        public record DecisionStepResult(
            Guid Id,
            string Name,
            string Type,
            int ExecutionOrder,
            int SlaHours,
            bool AllowCorrection,
            string? AssignedRole
        );

        public record DecisionTransitionResult(
            Guid Id,
            Guid FromStepId,
            Guid ToStepId,
            string Condition
        );

        public record AssignmentRuleResult(
            Guid Id,
            string Name,
            string MatchField,
            string MatchValue,
            string AssignTo,
            string Department,
            int Priority
        );

        // ── Execution ─────────────────────────────────────────────────────────────────

        public record ExecutionSummaryResult(
            Guid Id,
            int TenantId,
            string Intent,
            string Mode,
            string Direction,
            string Status,
            string CreatedBy,
            DateTime CreatedAt,
            DateTime? CompletedAt,
            string? FailureReason
        );

        public record ExecutionDetailResult(
            Guid Id,
            int TenantId,
            string Intent,
            string Mode,
            string Direction,
            string Status,
            string Payload,
            string CanonicalPayload,
            string CreatedBy,
            DateTime CreatedAt,
            DateTime? CompletedAt,
            string? FailureReason,
            IEnumerable<AttemptResult> Attempts,
            IEnumerable<FailureResult> Failures
        );

        //public record AttemptResult(
        //    int AttemptNumber,
        //    string Stage,
        //    string Result,
        //    string? ErrorMessage,
        //    DateTime StartedAt,
        //    DateTime? CompletedAt
        //);

        public record FailureResult(
            string Category,
            string Code,
            string Message,
            string? FieldPath,
            DateTime OccurredAt
        );

        public record WorkflowStateResult(
            Guid Id,
            Guid DecisionStepId,
            string Status,
            string? AssignedTo,
            string? ReviewerComment,
            DateTime AssignedAt,
            DateTime? ReviewedAt
        );

        // ── Dead Letter & Remediation ─────────────────────────────────────────────────

        public record DeadLetterResult(
            Guid Id,
            Guid ExecutionId,
            string Reason,
            DateTime CreatedAt
        );

        public record RemediationCaseResult(
            Guid Id,
            Guid DeadLetterId,
            string Status,
            string AssignedTo,
            string? Resolution,
            DateTime OpenedAt,
            DateTime? ResolvedAt
        );

        // ── Audit ─────────────────────────────────────────────────────────────────────

        public record AuditLogResult(
            Guid Id,
            string EntityType,
            Guid EntityId,
            string Action,
            string PerformedBy,
            string? OldValue,
            string? NewValue,
            DateTime OccurredAt
        );

        // ── Tenant ───────────────────────────────────────────────────────────────────

        public record TenantResult(
            Guid Id,
            string Name,
            string Slug,
            string Plan,
            bool IsActive,
            int MaxExecutions,
            int MaxMappings,
            string ContactEmail,
            DateTime CreatedAt
        );
        public class AuditLog
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public int TenantId { get; set; }
            public string EntityType { get; set; } = string.Empty;
            public Guid EntityId { get; set; }
            public string Action { get; set; } = string.Empty;
            public string PerformedBy { get; set; } = string.Empty;
            public string? OldValue { get; set; }
            public string? NewValue { get; set; }
            public string? IpAddress { get; set; }
            public DateTime OccurredAt { get; set; } = DateTime.UtcNow;
        }

        // ── Execution Context (runtime state) ─────────────────────────────────────

        /// <summary>
        /// The runtime state of one document/payload being processed.
        /// Flow: Created → Qualifying → Mapping → Dispatching → Completed | Failed | Paused
        /// </summary>
        public class ExecutionContext
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public int TenantId { get; set; }
            public string Intent { get; set; } = string.Empty;
            public ExecutionMode Mode { get; set; } = ExecutionMode.RealTime;
            public MappingDirection Direction { get; set; } = MappingDirection.Inbound;
            public ExecutionStatus Status { get; set; } = ExecutionStatus.Started;
            public string Payload { get; set; } = string.Empty;
            public string CanonicalPayload { get; set; } = string.Empty;
            public Guid? MappingVersionId { get; set; }
            public Guid? DecisionFlowVersionId { get; set; }
            public string CreatedBy { get; set; } = string.Empty;
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
            public DateTime? CompletedAt { get; set; }
            public string? FailureReason { get; set; }
        }

        /// <summary>One retry/attempt of an execution.</summary>
        public class ExecutionAttempt
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid ExecutionId { get; set; }
            public int AttemptNumber { get; set; } = 1;
            public AttemptResult Result { get; set; }
            public string? ErrorMessage { get; set; }
            public string Stage { get; set; } = string.Empty; // "Qualify" | "Map" | "Dispatch"
            public DateTime StartedAt { get; set; } = DateTime.UtcNow;
            public DateTime? CompletedAt { get; set; }
        }

        /// <summary>Structured failure captured during an execution.</summary>
        public class ExecutionFailure
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid ExecutionId { get; set; }
            public string Category { get; set; } = string.Empty; // "Validation" | "Mapping" | "Target"
            public string Code { get; set; } = string.Empty;
            public string Message { get; set; } = string.Empty;
            public string? FieldPath { get; set; }
            public DateTime OccurredAt { get; set; } = DateTime.UtcNow;
        }

        /// <summary>State of a manual step inside an execution's workflow.</summary>
        public class WorkflowState
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid ExecutionId { get; set; }
            public Guid DecisionStepId { get; set; }
            public WorkflowStepStatus Status { get; set; } = WorkflowStepStatus.Waiting;
            public string? AssignedTo { get; set; }
            public string? ReviewerComment { get; set; }
            public DateTime AssignedAt { get; set; } = DateTime.UtcNow;
            public DateTime? ReviewedAt { get; set; }
        }

        /// <summary>Dead-lettered execution that cannot be retried automatically.</summary>
        public class DeadLetter
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid ExecutionId { get; set; }
            public string Reason { get; set; } = string.Empty;
            public string? Payload { get; set; }
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
        }

        /// <summary>A case opened to track resolution of a dead-lettered execution.</summary>
        public class RemediationCase
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid DeadLetterId { get; set; }
            public int TenantId { get; set; }
            public RemediationStatus Status { get; set; } = RemediationStatus.Open;
            public string AssignedTo { get; set; } = string.Empty;
            public string? Resolution { get; set; }
            public DateTime OpenedAt { get; set; } = DateTime.UtcNow;
            public DateTime? ResolvedAt { get; set; }
        }

        /// <summary>Async event to trigger or control an execution.</summary>
        public class ExecutionEvent
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid ExecutionId { get; set; }
            public ExecutionEventType EventType { get; set; }
            public string? Payload { get; set; }
            public DateTime PublishedAt { get; set; } = DateTime.UtcNow;
        }

        // ── Target System ─────────────────────────────────────────────────────────

        /// <summary>An external system that receives processed data.</summary>
        public class TargetSystem
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public int TenantId { get; set; }
            public string Name { get; set; } = string.Empty;
            public string SystemType { get; set; } = string.Empty; // "ERP" | "CRM" | "Webhook" | "Database"
            public string BaseUrl { get; set; } = string.Empty;
            public string AuthType { get; set; } = "ApiKey";      // ApiKey | OAuth2 | BasicAuth | None
            public string? ApiKey { get; set; }
            public string? OAuthClientId { get; set; }
            public string? OAuthSecret { get; set; }
            public int RateLimit { get; set; } = 100;
            public int TimeoutMs { get; set; } = 30000;
            public bool IsActive { get; set; } = true;
            public string CreatedBy { get; set; } = string.Empty;
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
        }

        /// <summary>An operation (endpoint) on a TargetSystem.</summary>
        public class TargetOperation
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid TargetSystemId { get; set; }
            public string Name { get; set; } = string.Empty;
            public string HttpMethod { get; set; } = "POST";
            public string Path { get; set; } = string.Empty;
            public string? BodyTemplate { get; set; }
            public string Intent { get; set; } = string.Empty;
        }

        // ── Tenant ────────────────────────────────────────────────────────────────

        /// <summary>An isolated organisation using the platform.</summary>
        public class Tenant
        {
            public int TenantId { get; set; } = -1;
            public string Name { get; set; } = string.Empty;
            public string Slug { get; set; } = string.Empty;
            public string Plan { get; set; } = "Standard"; // Free | Standard | Enterprise
            public bool IsActive { get; set; } = true;
            public int MaxExecutions { get; set; } = 10000;
            public int MaxMappings { get; set; } = 100;
            public string ContactEmail { get; set; } = string.Empty;
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
            public DateTime? DeactivatedAt { get; set; }
        }

        // ── Execution Result DTOs ─────────────────────────────────────────────────

        public record ExecutionAttemptResult(
            int AttemptNumber,
            string Stage,
            string Result,
            string? ErrorMessage,
            DateTime StartedAt,
            DateTime? CompletedAt
        );


        public class CanonicalModelField
        {
            public string Id { get; set; } = string.Empty;
            public string Name { get; set; } = string.Empty;
            public string DataType { get; set; } = string.Empty;
            public bool IsRequired { get; set; }
            public string? Description { get; set; }
            public Dictionary<string, string>? Attributes { get; set; }
        }


        public class Provenance
        {
            public string? CreatedBy { get; set; }
            public DateTime? CreatedAt { get; set; }
            public string? UpdatedBy { get; set; }
            public DateTime? UpdatedAt { get; set; }
            public string? ApprovedBy { get; set; }
            public DateTime? ApprovedAt { get; set; }
            public string? ApprovalNotes { get; set; }
        }

        public class DecisionFlowDefinition
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public int TenantId { get; set; }
            public string Name { get; set; } = string.Empty;
            public string Description { get; set; } = string.Empty;
            public string Intent { get; set; } = string.Empty;  // business intent e.g. "InvoiceApproval"
            public string CreatedBy { get; set; } = string.Empty;
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;

            public List<DecisionFlowVersion> Versions { get; set; } = new();
        }

        /// <summary>
        /// A versioned snapshot of the decision flow (steps + transitions).
        /// </summary>
        public class DecisionFlowVersion
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid DecisionFlowDefinitionId { get; set; }
            public string Label { get; set; } = string.Empty;
            public VersionStatus Status { get; set; } = VersionStatus.Draft;
            public string CreatedBy { get; set; } = string.Empty;
            public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
            public DateTime? ActivatedAt { get; set; }

            public List<DecisionStep> Steps { get; set; } = new();
            public List<DecisionTransition> Transitions { get; set; } = new();
        }

        /// <summary>
        /// A step within a DecisionFlowVersion.
        /// ManualReview/Approval steps pause the execution until a human acts.
        /// SlaHours defines how long before the step is escalated.
        /// </summary>
        public class DecisionStep
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid DecisionFlowVersionId { get; set; }
            public string Name { get; set; } = string.Empty;
            public StepType Type { get; set; } = StepType.Automated;
            public int ExecutionOrder { get; set; }
            public int SlaHours { get; set; } = 24;
            public bool AllowCorrection { get; set; } = false;  // reviewer can edit data
            public string? AssignedRole { get; set; }            // e.g. "finance.manager"
        }

        /// <summary>
        /// Defines the allowed transitions between steps.
        /// For Approval steps: OnApprove → NextStep, OnReject → RejectionStep.
        /// </summary>
        public class DecisionTransition
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public Guid DecisionFlowVersionId { get; set; }
            public Guid FromStepId { get; set; }
            public Guid ToStepId { get; set; }
            public string Condition { get; set; } = "OnApprove"; // OnApprove | OnReject | OnTimeout | Always
        }

        /// <summary>
        /// Assignment rule that routes a manual step to the right person/team.
        /// Rules are evaluated in priority order; first match wins.
        /// </summary>
        public class AssignmentRule
        {
            public Guid Id { get; set; } = Guid.NewGuid();
            public int TenantId { get; set; }
            public string Name { get; set; } = string.Empty;
            public string MatchField { get; set; } = string.Empty;  // field on payload to match
            public string MatchValue { get; set; } = string.Empty;  // expected value
            public string AssignTo { get; set; } = string.Empty;  // user / group / email
            public string Department { get; set; } = string.Empty;
            public int Priority { get; set; } = 10;
            public bool IsActive { get; set; } = true;
        }
    }
}