/**
 * TOM Rules Engine — Control Evaluation
 *
 * Evaluates control applicability based on company context.
 * Core engine class with condition evaluation and TOM derivation.
 */

import {
  ControlLibraryEntry,
  ApplicabilityCondition,
  ControlApplicability,
  RulesEngineResult,
  RulesEngineEvaluationContext,
  DerivedTOM,
  EvidenceDocument,
  GapAnalysisResult,
  ConditionOperator,
} from './types'
import { getAllControls, getControlById } from './controls/loader'

// =============================================================================
// RULES ENGINE CLASS — Evaluation Methods
// =============================================================================

export class TOMRulesEngine {
  private controls: ControlLibraryEntry[]

  constructor() {
    this.controls = getAllControls()
  }

  evaluateControls(context: RulesEngineEvaluationContext): RulesEngineResult[] {
    return this.controls.map((control) => this.evaluateControl(control, context))
  }

  evaluateControl(
    control: ControlLibraryEntry,
    context: RulesEngineEvaluationContext
  ): RulesEngineResult {
    const sortedConditions = [...control.applicabilityConditions].sort(
      (a, b) => b.priority - a.priority
    )

    for (const condition of sortedConditions) {
      const matches = this.evaluateCondition(condition, context)
      if (matches) {
        return {
          controlId: control.id,
          applicability: condition.result,
          reason: this.formatConditionReason(condition, context),
          matchedCondition: condition,
        }
      }
    }

    return {
      controlId: control.id,
      applicability: control.defaultApplicability,
      reason: 'Standard-Anwendbarkeit (keine spezifische Bedingung erfuellt)',
    }
  }

  private evaluateCondition(
    condition: ApplicabilityCondition,
    context: RulesEngineEvaluationContext
  ): boolean {
    const value = this.getFieldValue(condition.field, context)
    if (value === undefined || value === null) return false
    return this.evaluateOperator(condition.operator, value, condition.value)
  }

  private getFieldValue(fieldPath: string, context: RulesEngineEvaluationContext): unknown {
    const parts = fieldPath.split('.')
    let current: unknown = context

    for (const part of parts) {
      if (current === null || current === undefined) return undefined
      if (typeof current === 'object') {
        current = (current as Record<string, unknown>)[part]
      } else {
        return undefined
      }
    }

    return current
  }

  private evaluateOperator(
    operator: ConditionOperator,
    actualValue: unknown,
    expectedValue: unknown
  ): boolean {
    switch (operator) {
      case 'EQUALS':
        return actualValue === expectedValue
      case 'NOT_EQUALS':
        return actualValue !== expectedValue
      case 'CONTAINS':
        if (Array.isArray(actualValue)) return actualValue.includes(expectedValue)
        if (typeof actualValue === 'string' && typeof expectedValue === 'string')
          return actualValue.includes(expectedValue)
        return false
      case 'GREATER_THAN':
        if (typeof actualValue === 'number' && typeof expectedValue === 'number')
          return actualValue > expectedValue
        return false
      case 'IN':
        if (Array.isArray(expectedValue)) return expectedValue.includes(actualValue)
        return false
      default:
        return false
    }
  }

  private formatConditionReason(
    condition: ApplicabilityCondition,
    context: RulesEngineEvaluationContext
  ): string {
    const fieldValue = this.getFieldValue(condition.field, context)
    const fieldLabel = this.getFieldLabel(condition.field)

    switch (condition.operator) {
      case 'EQUALS':
        return `${fieldLabel} ist "${this.formatValue(fieldValue)}"`
      case 'NOT_EQUALS':
        return `${fieldLabel} ist nicht "${this.formatValue(condition.value)}"`
      case 'CONTAINS':
        return `${fieldLabel} enthaelt "${this.formatValue(condition.value)}"`
      case 'GREATER_THAN':
        return `${fieldLabel} ist groesser als ${this.formatValue(condition.value)}`
      case 'IN':
        return `${fieldLabel} ("${this.formatValue(fieldValue)}") ist in [${Array.isArray(condition.value) ? condition.value.join(', ') : condition.value}]`
      default:
        return `Bedingung erfuellt: ${condition.field} ${condition.operator} ${this.formatValue(condition.value)}`
    }
  }

  private getFieldLabel(fieldPath: string): string {
    const labels: Record<string, string> = {
      'companyProfile.role': 'Unternehmensrolle',
      'companyProfile.size': 'Unternehmensgroesse',
      'dataProfile.hasSpecialCategories': 'Besondere Datenkategorien',
      'dataProfile.processesMinors': 'Verarbeitung von Minderjaehrigen-Daten',
      'dataProfile.dataVolume': 'Datenvolumen',
      'dataProfile.thirdCountryTransfers': 'Drittlanduebermittlungen',
      'architectureProfile.hostingModel': 'Hosting-Modell',
      'architectureProfile.hostingLocation': 'Hosting-Standort',
      'architectureProfile.multiTenancy': 'Mandantentrennung',
      'architectureProfile.hasSubprocessors': 'Unterauftragsverarbeiter',
      'architectureProfile.encryptionAtRest': 'Verschluesselung ruhender Daten',
      'securityProfile.hasMFA': 'Multi-Faktor-Authentifizierung',
      'securityProfile.hasSSO': 'Single Sign-On',
      'securityProfile.hasPAM': 'Privileged Access Management',
      'riskProfile.protectionLevel': 'Schutzbedarf',
      'riskProfile.dsfaRequired': 'DSFA erforderlich',
      'riskProfile.ciaAssessment.confidentiality': 'Vertraulichkeit',
      'riskProfile.ciaAssessment.integrity': 'Integritaet',
      'riskProfile.ciaAssessment.availability': 'Verfuegbarkeit',
    }
    return labels[fieldPath] || fieldPath
  }

  private formatValue(value: unknown): string {
    if (value === true) return 'Ja'
    if (value === false) return 'Nein'
    if (value === null || value === undefined) return 'nicht gesetzt'
    if (Array.isArray(value)) return value.join(', ')
    return String(value)
  }

  deriveAllTOMs(context: RulesEngineEvaluationContext): DerivedTOM[] {
    const results = this.evaluateControls(context)

    return results.map((result) => {
      const control = getControlById(result.controlId)
      if (!control) throw new Error(`Control not found: ${result.controlId}`)

      return {
        id: `derived-${result.controlId}`,
        controlId: result.controlId,
        name: control.name.de,
        description: control.description.de,
        applicability: result.applicability,
        applicabilityReason: result.reason,
        implementationStatus: 'NOT_IMPLEMENTED',
        responsiblePerson: null,
        responsibleDepartment: null,
        implementationDate: null,
        reviewDate: null,
        linkedEvidence: [],
        evidenceGaps: [...control.evidenceRequirements],
        aiGeneratedDescription: null,
        aiRecommendations: [],
      }
    })
  }

  getApplicableTOMs(context: RulesEngineEvaluationContext): DerivedTOM[] {
    return this.deriveAllTOMs(context).filter(
      (tom) => tom.applicability === 'REQUIRED' || tom.applicability === 'RECOMMENDED'
    )
  }

  getRequiredTOMs(context: RulesEngineEvaluationContext): DerivedTOM[] {
    return this.deriveAllTOMs(context).filter((tom) => tom.applicability === 'REQUIRED')
  }

  getControlsByApplicability(
    context: RulesEngineEvaluationContext,
    applicability: ControlApplicability
  ): ControlLibraryEntry[] {
    return this.evaluateControls(context)
      .filter((r) => r.applicability === applicability)
      .map((r) => getControlById(r.controlId))
      .filter((c): c is ControlLibraryEntry => c !== undefined)
  }

  getSummaryStatistics(context: RulesEngineEvaluationContext): {
    total: number; required: number; recommended: number; optional: number; notApplicable: number
    byCategory: Map<string, { required: number; recommended: number }>
  } {
    const results = this.evaluateControls(context)
    const stats = {
      total: results.length, required: 0, recommended: 0, optional: 0, notApplicable: 0,
      byCategory: new Map<string, { required: number; recommended: number }>(),
    }

    for (const result of results) {
      switch (result.applicability) {
        case 'REQUIRED': stats.required++; break
        case 'RECOMMENDED': stats.recommended++; break
        case 'OPTIONAL': stats.optional++; break
        case 'NOT_APPLICABLE': stats.notApplicable++; break
      }

      const control = getControlById(result.controlId)
      if (control) {
        const existing = stats.byCategory.get(control.category) || { required: 0, recommended: 0 }
        if (result.applicability === 'REQUIRED') existing.required++
        else if (result.applicability === 'RECOMMENDED') existing.recommended++
        stats.byCategory.set(control.category, existing)
      }
    }

    return stats
  }

  isControlApplicable(controlId: string, context: RulesEngineEvaluationContext): boolean {
    const control = getControlById(controlId)
    if (!control) return false
    const result = this.evaluateControl(control, context)
    return result.applicability === 'REQUIRED' || result.applicability === 'RECOMMENDED'
  }

  getControlsByTagWithApplicability(
    tag: string,
    context: RulesEngineEvaluationContext
  ): Array<{ control: ControlLibraryEntry; result: RulesEngineResult }> {
    return this.controls
      .filter((control) => control.tags.includes(tag))
      .map((control) => ({ control, result: this.evaluateControl(control, context) }))
  }

  performGapAnalysis(
    derivedTOMs: DerivedTOM[],
    documents: EvidenceDocument[]
  ): GapAnalysisResult {
    // Delegate to standalone function to keep this class focused on evaluation
    const { performGapAnalysis: doGapAnalysis } = require('./gap-analysis')
    return doGapAnalysis(derivedTOMs, documents)
  }

  reloadControls(): void {
    this.controls = getAllControls()
  }
}