/**
 * Quality Gate
 * 
 * Validates delegation results before returning to users.
 * Implements confidence thresholds and automatic escalation.
 */

import {
  QualityCheck,
  QualityCheckResult,
  QualityIssue,
  QualityGateConfig,
  DelegationResult,
  DelegationContext
} from '../core/types';

// ============================================================================
// Default Configuration
// ============================================================================

const DEFAULT_CONFIG: QualityGateConfig = {
  enabled: true,
  minConfidence: 0.7,
  checks: [],
  escalationThreshold: 0.5,
  autoEscalate: true
};

// ============================================================================
// Built-in Quality Checks
// ============================================================================

const BUILT_IN_CHECKS: QualityCheck[] = [
  {
    id: 'confidence-check',
    name: 'Confidence Threshold',
    description: 'Ensures result meets minimum confidence threshold',
    severity: 'high',
    autoFix: false,
    check: async (result: DelegationResult) => {
      const passed = result.confidence >= 0.7;
      return {
        passed,
        score: result.confidence,
        issues: passed ? [] : [{
          severity: 'high' as const,
          message: `Confidence ${result.confidence.toFixed(2)} below threshold 0.70`
        }],
        recommendations: passed ? [] : ['Consider escalating to main agent']
      };
    }
  },
  {
    id: 'output-validity',
    name: 'Output Validity',
    description: 'Checks that output is non-empty and meaningful',
    severity: 'critical',
    autoFix: false,
    check: async (result: DelegationResult) => {
      const hasOutput = result.output && result.output.trim().length > 0;
      const isNotError = !result.output?.toLowerCase().includes('error');
      
      return {
        passed: hasOutput && isNotError,
        score: hasOutput ? (isNotError ? 1 : 0.5) : 0,
        issues: [
          ...(hasOutput ? [] : [{ severity: 'critical' as const, message: 'Empty output' }]),
          ...(isNotError ? [] : [{ severity: 'high' as const, message: 'Output contains error message' }])
        ],
        recommendations: hasOutput ? [] : ['Regenerate response', 'Escalate to main agent']
      };
    }
  },
  {
    id: 'response-time',
    name: 'Response Time Check',
    description: 'Validates response was generated in reasonable time',
    severity: 'low',
    autoFix: false,
    check: async (result: DelegationResult) => {
      const maxTime = 120000; // 2 minutes
      const passed = result.duration <= maxTime;
      
      return {
        passed,
        score: Math.max(0, 1 - result.duration / maxTime),
        issues: passed ? [] : [{
          severity: 'low' as const,
          message: `Response took ${result.duration}ms (max: ${maxTime}ms)`
        }],
        recommendations: passed ? [] : ['Consider optimizing agent performance']
      };
    }
  },
  {
    id: 'success-verification',
    name: 'Success Verification',
    description: 'Confirms the delegation completed successfully',
    severity: 'critical',
    autoFix: false,
    check: async (result: DelegationResult) => {
      return {
        passed: result.success,
        score: result.success ? 1 : 0,
        issues: result.success ? [] : [{
          severity: 'critical' as const,
          message: result.escalationReason || 'Delegation failed'
        }],
        recommendations: result.success ? [] : ['Retry with different agent', 'Escalate to main agent']
      };
    }
  }
];

// ============================================================================
// Quality Gate Class
// ============================================================================

export class QualityGate {
  private config: QualityGateConfig;
  private checks: Map<string, QualityCheck> = new Map();
  private results: Map<string, QualityCheckResult[]> = new Map();

  constructor(config: Partial<QualityGateConfig> = {}) {
    this.config = { ...DEFAULT_CONFIG, ...config };
    
    // Register built-in checks
    BUILT_IN_CHECKS.forEach(check => this.registerCheck(check));
    
    // Register custom checks
    this.config.checks.forEach(check => this.registerCheck(check));
  }

  // ============================================================================
  // Check Registration
  // ============================================================================

  /**
   * Register a quality check
   */
  registerCheck(check: QualityCheck): void {
    this.checks.set(check.id, check);
  }

  /**
   * Remove a quality check
   */
  removeCheck(checkId: string): void {
    this.checks.delete(checkId);
  }

  /**
   * Get all registered checks
   */
  getChecks(): QualityCheck[] {
    return Array.from(this.checks.values());
  }

  // ============================================================================
  // Result Validation
  // ============================================================================

  /**
   * Validate a delegation result
   */
  async validate(
    result: DelegationResult,
    context: DelegationContext
  ): Promise<{
    passed: boolean;
    overallScore: number;
    checkResults: Map<string, QualityCheckResult>;
    shouldEscalate: boolean;
    issues: QualityIssue[];
  }> {
    if (!this.config.enabled) {
      return {
        passed: result.success,
        overallScore: result.confidence,
        checkResults: new Map(),
        shouldEscalate: false,
        issues: []
      };
    }

    const checkResults = new Map<string, QualityCheckResult>();
    const allIssues: QualityIssue[] = [];
    let totalScore = 0;
    let criticalFailures = 0;

    // Run all checks
    for (const [id, check] of this.checks) {
      try {
        const checkResult = await check.check(result, context);
        checkResults.set(id, checkResult);
        totalScore += checkResult.score;

        // Collect issues
        checkResult.issues.forEach(issue => {
          allIssues.push({
            ...issue,
            location: issue.location || check.name
          });
        });

        // Count critical failures
        if (!checkResult.passed && check.severity === 'critical') {
          criticalFailures++;
        }

      } catch (error) {
        console.error(`Quality check ${id} failed:`, error);
        checkResults.set(id, {
          passed: false,
          score: 0,
          issues: [{
            severity: 'medium',
            message: `Check failed: ${error instanceof Error ? error.message : 'Unknown error'}`
          }],
          recommendations: []
        });
      }
    }

    // Calculate overall score
    const overallScore = totalScore / this.checks.size;

    // Determine if passed
    const passed = criticalFailures === 0 && overallScore >= this.config.minConfidence;

    // Determine if should escalate
    const shouldEscalate = this.config.autoEscalate && (
      overallScore < this.config.escalationThreshold ||
      criticalFailures > 0 ||
      allIssues.some(i => i.severity === 'critical')
    );

    // Store results
    if (context.requestId) {
      this.results.set(context.requestId, Array.from(checkResults.values()));
    }

    return {
      passed,
      overallScore,
      checkResults,
      shouldEscalate,
      issues: allIssues
    };
  }

  /**
   * Quick validation for fast path
   */
  quickValidate(result: DelegationResult): {
    passed: boolean;
    shouldEscalate: boolean;
  } {
    if (!this.config.enabled) {
      return { passed: result.success, shouldEscalate: false };
    }

    const passed = result.success && 
                   result.confidence >= this.config.minConfidence &&
                   !!result.output;

    const shouldEscalate = this.config.autoEscalate && (
      !result.success ||
      result.confidence < this.config.escalationThreshold
    );

    return { passed, shouldEscalate };
  }

  // ============================================================================
  // Escalation Decision
  // ============================================================================

  /**
   * Decide if result should be escalated to main agent
   */
  shouldEscalate(
    result: DelegationResult,
    validation: { overallScore: number; issues: QualityIssue[] }
  ): {
    escalate: boolean;
    reason: string;
    recommendedAction: string;
  } {
    if (!this.config.autoEscalate) {
      return {
        escalate: false,
        reason: 'Auto-escalation disabled',
        recommendedAction: 'Return result as-is'
      };
    }

    // Check confidence
    if (result.confidence < this.config.escalationThreshold) {
      return {
        escalate: true,
        reason: `Confidence ${result.confidence.toFixed(2)} below threshold ${this.config.escalationThreshold}`,
        recommendedAction: 'Forward to main agent for review'
      };
    }

    // Check for critical issues
    const criticalIssues = validation.issues.filter(i => i.severity === 'critical');
    if (criticalIssues.length > 0) {
      return {
        escalate: true,
        reason: `Critical issues: ${criticalIssues.map(i => i.message).join(', ')}`,
        recommendedAction: 'Escalate with context for resolution'
      };
    }

    // Check for high severity issues
    const highIssues = validation.issues.filter(i => i.severity === 'high');
    if (highIssues.length > 2) {
      return {
        escalate: true,
        reason: `Multiple high-severity issues: ${highIssues.length}`,
        recommendedAction: 'Consider escalation for quality assurance'
      };
    }

    return {
      escalate: false,
      reason: 'Result meets quality standards',
      recommendedAction: 'Return result to user'
    };
  }

  // ============================================================================
  // Statistics
  // ============================================================================

  getStats(): {
    totalChecks: number;
    validationHistory: number;
    averageScore: number;
    escalationRate: number;
  } {
    const allResults = Array.from(this.results.values()).flat();
    const totalChecks = this.checks.size;
    const averageScore = allResults.length > 0
      ? allResults.reduce((sum, r) => sum + r.score, 0) / allResults.length
      : 0;

    return {
      totalChecks,
      validationHistory: this.results.size,
      averageScore,
      escalationRate: 0 // Would need to track escalations
    };
  }

  /**
   * Clear validation history
   */
  clearHistory(): void {
    this.results.clear();
  }
}

// ============================================================================
// Factory Function
// ============================================================================

export function createQualityGate(config?: Partial<QualityGateConfig>): QualityGate {
  return new QualityGate(config);
}

// ============================================================================
// Export
// ============================================================================

export default QualityGate;