/**
 * @file signature.ts
 * @description Signature data structures and types
 * Supports drawn, typed, click, digital, qualified, and biometric signatures
 */

import type {
  TSignatureType,
  TSignatureLegalLevel,
  TSignatureStatus,
  TSignatureAuditAction,
  THashAlgorithm,
  TSignatureAlgorithm,
} from './types.js';

// ============================================================================
// SIGNATURE DATA STRUCTURES (Discriminated Union)
// ============================================================================

/**
 * Base signature data common to all types
 */
export interface ISignatureDataBase {
  id: string;
  schemaVersion: '1.0.0';
  capturedAt: number;
}

/**
 * Individual stroke point from signature_pad
 */
export interface ISignatureStrokePoint {
  x: number;
  y: number;
  pressure: number;
  time: number;
}

/**
 * Drawn signature data (canvas-based)
 * Compatible with signature_pad library output
 */
export interface ISignatureDataDrawn extends ISignatureDataBase {
  type: 'drawn';
  strokeData: ISignatureStrokePoint[][];
  svg: string;
  pngBase64?: string;
  canvasDimensions: {
    width: number;
    height: number;
    devicePixelRatio: number;
  };
  drawingMetrics?: {
    totalStrokes: number;
    totalPoints: number;
    averageVelocity: number;
    drawingDurationMs: number;
  };
}

/**
 * Typed signature data
 */
export interface ISignatureDataTyped extends ISignatureDataBase {
  type: 'typed';
  text: string;
  fontFamily: string;
  fontSize: number;
  svg: string;
  pngBase64?: string;
}

/**
 * Click-to-sign acknowledgment
 */
export interface ISignatureDataClick extends ISignatureDataBase {
  type: 'click';
  acknowledgmentText: string;
  acknowledged: boolean;
  fullNameEntered?: string;
  jobTitle?: string;
}

/**
 * Certificate information for digital signatures
 */
export interface ICertificateInfo {
  certificatePem: string;
  serialNumber: string;
  issuer: string;
  subject: string;
  validity: {
    notBefore: number;
    notAfter: number;
  };
  fingerprint: string;
}

/**
 * Digital certificate-based signature (X.509/PKI)
 */
export interface ISignatureDataDigital extends ISignatureDataBase {
  type: 'digital';
  certificate: ICertificateInfo;
  signatureValue: string;
  signatureAlgorithm: TSignatureAlgorithm;
  contentHash: string;
  hashAlgorithm: THashAlgorithm;
}

/**
 * Qualified Trust Service Provider information
 */
export interface IQtspInfo {
  name: string;
  providerId: string;
  serviceId: string;
  country: string;
}

/**
 * Signature creation device information
 */
export interface ISignatureCreationDevice {
  type: 'local' | 'remote';
  deviceId?: string;
  certification?: string;
}

/**
 * Qualified Electronic Signature (eIDAS QES)
 */
export interface ISignatureDataQualified extends ISignatureDataBase {
  type: 'qualified';
  digitalSignature: Omit<ISignatureDataDigital, 'type' | 'id' | 'schemaVersion' | 'capturedAt'>;
  qtsp: IQtspInfo;
  trustedListReference?: string;
  signatureCreationDevice?: ISignatureCreationDevice;
}

/**
 * Biometric signature data (extensible for future)
 */
export interface ISignatureDataBiometric extends ISignatureDataBase {
  type: 'biometric';
  biometricType: 'fingerprint' | 'facial' | 'voice' | 'iris';
  templateReference: string;
  confidenceScore: number;
  provider: string;
}

/**
 * Union type of all signature data types
 */
export type TSignatureData =
  | ISignatureDataDrawn
  | ISignatureDataTyped
  | ISignatureDataClick
  | ISignatureDataDigital
  | ISignatureDataQualified
  | ISignatureDataBiometric;

// ============================================================================
// SIGNATURE METADATA
// ============================================================================

/**
 * IP geolocation information
 */
export interface IIpGeolocation {
  country: string;
  countryCode: string;
  region?: string;
  city?: string;
}

/**
 * Device fingerprint for fraud detection
 */
export interface IDeviceFingerprint {
  hash: string;
  components: {
    screenResolution?: string;
    timezone?: string;
    language?: string;
    platform?: string;
    colorDepth?: number;
    touchSupport?: boolean;
    canvasFingerprint?: string;
    webglFingerprint?: string;
  };
  confidence: number;
}

/**
 * Session information
 */
export interface ISigningSession {
  sessionId: string;
  sessionStarted: number;
  pageViews: number;
  documentsViewed: string[];
}

/**
 * Comprehensive signature metadata capturing context
 */
export interface ISignatureMetadata {
  timestamps: {
    clientCaptured: number;
    serverReceived?: number;
    blockchainTimestamped?: number;
    tsaTimestamped?: number;
  };
  geolocation?: {
    latitude: number;
    longitude: number;
    accuracy: number;
    altitude?: number;
    timestamp: number;
    source: 'gps' | 'network' | 'ip-based';
  };
  network: {
    ipAddress: string;
    ipGeolocation?: IIpGeolocation;
    userAgent: string;
  };
  deviceFingerprint?: IDeviceFingerprint;
  session?: ISigningSession;
}

// ============================================================================
// CONSENT AND VERIFICATION
// ============================================================================

/**
 * Legal consent record
 */
export interface IConsent {
  type: 'terms_accepted' | 'electronic_signature' | 'data_processing' | 'custom';
  text: string;
  accepted: boolean;
  timestamp?: number;
}

/**
 * Signature audit trail entry
 */
export interface ISignatureAuditEntry {
  timestamp: number;
  action: TSignatureAuditAction;
  actor: {
    type: 'user' | 'system' | 'service';
    id: string;
    name?: string;
  };
  details: Record<string, unknown>;
  ipAddress?: string;
}

// ============================================================================
// COMPLETE SIGNATURE OBJECT
// ============================================================================

/**
 * Forward declaration for identity verification (defined in identity.ts)
 */
export interface IIdentityVerificationResultRef {
  id: string;
  status: string;
  confidence: string;
}

/**
 * Forward declaration for legal compliance proof (defined in legal.ts)
 */
export interface ILegalComplianceProofRef {
  id: string;
  eidasLevel?: TSignatureLegalLevel;
}

/**
 * Complete signature with data, metadata, and verification status
 */
export interface ISignature {
  id: string;
  schemaVersion: '1.0.0';
  signatureType: TSignatureType;
  legalLevel: TSignatureLegalLevel;
  data: TSignatureData;
  metadata: ISignatureMetadata;
  identityVerificationId?: string;
  legalComplianceProofId?: string;
  consents: IConsent[];
  auditTrail: ISignatureAuditEntry[];
  status: TSignatureStatus;
}

// ============================================================================
// SIGNATURE FIELD PLACEMENT
// ============================================================================

/**
 * Paragraph-based placement
 */
export interface IPlacementParagraph {
  paragraphId: string;
  position: 'before' | 'after' | 'inline';
  inlineOffset?: number;
}

/**
 * Page-based placement (PDF coordinates)
 */
export interface IPlacementPage {
  pageNumber: number;
  coordinates: {
    x: number;
    y: number;
    width: number;
    height: number;
  };
}

/**
 * Anchor-based placement
 */
export interface IPlacementAnchor {
  anchorText: string;
  occurrence: number;
  offset: {
    x: number;
    y: number;
  };
  size: {
    width: number;
    height: number;
  };
}

/**
 * Signature field placement configuration
 */
export interface ISignatureFieldPlacement {
  type: 'paragraph' | 'page' | 'anchor' | 'append';
  paragraph?: IPlacementParagraph;
  page?: IPlacementPage;
  anchor?: IPlacementAnchor;
  displayOrder: number;
}

// ============================================================================
// SIGNATURE FIELD REQUIREMENTS
// ============================================================================

import type { TIdentityVerificationMethod, TVerificationConfidence } from './types.js';

/**
 * Requirements for a signature field
 */
export interface ISignatureFieldRequirements {
  required: boolean;
  allowedSignatureTypes: TSignatureType[];
  minimumLegalLevel: TSignatureLegalLevel;
  identityVerification: {
    required: boolean;
    allowedMethods?: TIdentityVerificationMethod[];
    minimumConfidence?: TVerificationConfidence;
  };
  timestamping: {
    required: boolean;
    types?: ('tsa' | 'qualified_tsa' | 'blockchain')[];
  };
  deadline?: {
    timestamp?: number;
    relativeSeconds?: number;
  };
  customValidation?: {
    ruleId: string;
    params: Record<string, unknown>;
  }[];
}

// ============================================================================
// SIGNATURE DEPENDENCIES
// ============================================================================

import type { TFieldDependencyType } from './types.js';

/**
 * Defines dependencies between signature fields
 */
export interface ISignatureDependency {
  type: TFieldDependencyType;
  dependsOn: string[];
  timeConstraint?: {
    minSecondsAfter?: number;
    maxSecondsAfter?: number;
  };
}

// ============================================================================
// FACTORY FUNCTIONS
// ============================================================================

/**
 * Create empty signature metadata
 */
export function createEmptySignatureMetadata(): ISignatureMetadata {
  return {
    timestamps: {
      clientCaptured: Date.now(),
    },
    network: {
      ipAddress: '',
      userAgent: '',
    },
  };
}

/**
 * Create default signature field requirements
 */
export function createDefaultSignatureFieldRequirements(): ISignatureFieldRequirements {
  return {
    required: true,
    allowedSignatureTypes: ['drawn', 'typed', 'click'],
    minimumLegalLevel: 'simple',
    identityVerification: {
      required: false,
    },
    timestamping: {
      required: false,
    },
  };
}