import { EventEmitter } from 'events';
import { GitHubRepository } from './github-coordinator.js';

// Types and Interfaces
export interface PullRequest {
  id: string;
  number: number;
  title: string;
  description: string;
  author: GitHubUser;
  repository: GitHubRepository;
  sourceBranch: string;
  targetBranch: string;
  status: 'open' | 'closed' | 'merged' | 'draft';
  createdAt: Date;
  updatedAt: Date;
  mergeable: boolean;
  mergeableState: 'clean' | 'unstable' | 'dirty' | 'blocked' | 'behind' | 'unknown';
  labels: string[];
  assignees: GitHubUser[];
  reviewers: GitHubUser[];
  requestedReviewers: GitHubUser[];
  files: PullRequestFile[];
  commits: PullRequestCommit[];
  comments: PullRequestComment[];
  reviews: PullRequestReview[];
  checks: PullRequestCheck[];
  metadata: Record<string, any>;
}

export interface GitHubUser {
  id: string;
  username: string;
  email?: string;
  name?: string;
  avatar?: string;
  type: 'user' | 'bot' | 'organization';
  permissions: string[];
}

export interface PullRequestFile {
  filename: string;
  status: 'added' | 'modified' | 'removed' | 'renamed';
  additions: number;
  deletions: number;
  changes: number;
  patch?: string;
  previousFilename?: string;
  binaryFile: boolean;
}

export interface PullRequestCommit {
  sha: string;
  message: string;
  author: GitHubUser;
  timestamp: Date;
  verified: boolean;
  files: string[];
}

export interface PullRequestComment {
  id: string;
  author: GitHubUser;
  body: string;
  createdAt: Date;
  updatedAt: Date;
  line?: number;
  path?: string;
  position?: number;
  commentType: 'general' | 'inline' | 'review';
  resolved: boolean;
}

export interface PullRequestReview {
  id: string;
  reviewer: GitHubUser;
  state: 'pending' | 'approved' | 'changes_requested' | 'commented' | 'dismissed';
  body: string;
  submittedAt: Date;
  comments: PullRequestComment[];
  aiGenerated: boolean;
  confidence: number;
  recommendations: ReviewRecommendation[];
}

export interface ReviewRecommendation {
  type: 'security' | 'performance' | 'style' | 'logic' | 'testing' | 'documentation';
  severity: 'low' | 'medium' | 'high' | 'critical';
  file: string;
  line?: number;
  message: string;
  suggestion: string;
  autoFixable: boolean;
  references: string[];
}

export interface PullRequestCheck {
  id: string;
  name: string;
  status: 'pending' | 'success' | 'failure' | 'neutral' | 'cancelled' | 'skipped';
  conclusion?: string;
  startedAt: Date;
  completedAt?: Date;
  output: {
    title: string;
    summary: string;
    text?: string;
    annotations: CheckAnnotation[];
  };
  externalId?: string;
  url?: string;
}

export interface CheckAnnotation {
  path: string;
  startLine: number;
  endLine: number;
  startColumn?: number;
  endColumn?: number;
  annotationLevel: 'notice' | 'warning' | 'failure';
  message: string;
  title?: string;
  rawDetails?: string;
}

export interface ReviewStrategy {
  name: string;
  description: string;
  autoAssign: boolean;
  requiredReviewers: number;
  requiredApprovals: number;
  dismissStaleReviews: boolean;
  requireCodeOwnerReviews: boolean;
  restrictDismissals: boolean;
  aiReviewEnabled: boolean;
  aiReviewConfig: AiReviewConfig;
  mergeStrategy: MergeStrategy;
  testingRequirements: TestingRequirements;
}

export interface AiReviewConfig {
  enabled: boolean;
  model: string;
  confidence_threshold: number;
  review_types: ('security' | 'performance' | 'style' | 'logic' | 'testing' | 'documentation')[];
  auto_approve_threshold: number;
  auto_request_changes_threshold: number;
  generate_suggestions: boolean;
  check_best_practices: boolean;
  analyze_complexity: boolean;
}

export interface MergeStrategy {
  strategy: 'merge' | 'squash' | 'rebase';
  autoMerge: boolean;
  deleteSourceBranch: boolean;
  requireLinearHistory: boolean;
  conditions: MergeCondition[];
}

export interface MergeCondition {
  type: 'reviews' | 'checks' | 'status' | 'branch' | 'label';
  requirement: string;
  value: any;
}

export interface TestingRequirements {
  runTestsOnPR: boolean;
  requiredTests: string[];
  testTimeout: number;
  parallelExecution: boolean;
  requirePassingTests: boolean;
  performanceThresholds: Record<string, number>;
}

export interface ReviewAssignment {
  pullRequest: PullRequest;
  reviewers: ReviewerAssignment[];
  strategy: ReviewStrategy;
  deadline: Date;
  priority: 'low' | 'medium' | 'high' | 'urgent';
  estimatedReviewTime: number;
}

export interface ReviewerAssignment {
  reviewer: GitHubUser;
  role: 'primary' | 'secondary' | 'optional' | 'ai';
  expertise: string[];
  workload: number;
  averageResponseTime: number;
  availability: ReviewerAvailability;
}

export interface ReviewerAvailability {
  isAvailable: boolean;
  timezone: string;
  workingHours: { start: string; end: string };
  currentWorkload: number;
  maxConcurrentReviews: number;
  outOfOffice: boolean;
}

export interface ReviewCoordination {
  coordinationId: string;
  pullRequests: PullRequest[];
  strategy: 'sequential' | 'parallel' | 'prioritized' | 'load_balanced';
  reviewers: GitHubUser[];
  assignments: ReviewAssignment[];
  metrics: ReviewMetrics;
  notifications: ReviewNotification[];
}

export interface ReviewMetrics {
  totalReviews: number;
  averageReviewTime: number;
  approvalRate: number;
  changeRequestRate: number;
  aiAccuracy: number;
  throughput: number;
  bottlenecks: string[];
}

export interface ReviewNotification {
  type: 'assignment' | 'deadline' | 'completion' | 'escalation';
  recipient: GitHubUser;
  channel: 'email' | 'slack' | 'github' | 'webhook';
  message: string;
  timestamp: Date;
  urgent: boolean;
}

export interface PullRequestManagerConfig {
  aiReviewEnabled: boolean;
  aiModel: string;
  defaultReviewStrategy: ReviewStrategy;
  autoAssignReviewers: boolean;
  enabledIntegrations: string[];
  notificationChannels: string[];
  performanceThresholds: Record<string, number>;
  securityRules: SecurityRule[];
  testingConfig: TestingRequirements;
}

export interface SecurityRule {
  id: string;
  name: string;
  description: string;
  severity: 'low' | 'medium' | 'high' | 'critical';
  pattern: string;
  fileTypes: string[];
  action: 'warn' | 'block' | 'require_review';
  autoFix: boolean;
}

/**
 * Enterprise-grade Pull Request Manager
 * 
 * Provides comprehensive PR management capabilities including:
 * - AI-powered code review with intelligent recommendations
 * - Multi-reviewer coordination with workload balancing
 * - Automated testing integration and quality gates
 * - Intelligent merge strategies with conflict resolution
 * - Enterprise-grade approval workflows and compliance
 */
export class PullRequestManager extends EventEmitter {
  private config: PullRequestManagerConfig;
  private pullRequests: Map<string, PullRequest> = new Map();
  private reviewStrategies: Map<string, ReviewStrategy> = new Map();
  private reviewAssignments: Map<string, ReviewAssignment> = new Map();
  private reviewCoordinations: Map<string, ReviewCoordination> = new Map();
  private reviewerWorkloads: Map<string, number> = new Map();
  private aiReviewCache: Map<string, PullRequestReview> = new Map();
  private performanceMetrics: Map<string, any> = new Map();

  constructor(config: PullRequestManagerConfig) {
    super();
    this.config = config;
    this.setupEventHandlers();
    this.initializeDefaultStrategies();
  }

  private setupEventHandlers(): void {
    this.on('pull-request-opened', this.handlePullRequestOpened.bind(this));
    this.on('pull-request-updated', this.handlePullRequestUpdated.bind(this));
    this.on('review-submitted', this.handleReviewSubmitted.bind(this));
    this.on('checks-completed', this.handleChecksCompleted.bind(this));
    this.on('merge-ready', this.handleMergeReady.bind(this));
  }

  private initializeDefaultStrategies(): void {
    // Initialize default review strategies
    const defaultStrategy: ReviewStrategy = {
      name: 'default',
      description: 'Default review strategy with AI assistance',
      autoAssign: true,
      requiredReviewers: 2,
      requiredApprovals: 1,
      dismissStaleReviews: true,
      requireCodeOwnerReviews: true,
      restrictDismissals: false,
      aiReviewEnabled: true,
      aiReviewConfig: {
        enabled: true,
        model: 'claude-3.5-sonnet',
        confidence_threshold: 0.8,
        review_types: ['security', 'performance', 'style', 'logic', 'testing'],
        auto_approve_threshold: 0.95,
        auto_request_changes_threshold: 0.3,
        generate_suggestions: true,
        check_best_practices: true,
        analyze_complexity: true
      },
      mergeStrategy: {
        strategy: 'squash',
        autoMerge: true,
        deleteSourceBranch: true,
        requireLinearHistory: false,
        conditions: [
          { type: 'reviews', requirement: 'approved', value: 1 },
          { type: 'checks', requirement: 'passing', value: true }
        ]
      },
      testingRequirements: {
        runTestsOnPR: true,
        requiredTests: ['unit', 'integration'],
        testTimeout: 1800000, // 30 minutes
        parallelExecution: true,
        requirePassingTests: true,
        performanceThresholds: {
          coverage: 80,
          complexity: 10,
          duplication: 5
        }
      }
    };

    this.reviewStrategies.set('default', defaultStrategy);
  }

  // Pull Request Management
  async registerPullRequest(pr: PullRequest): Promise<void> {
    this.pullRequests.set(pr.id, pr);
    this.emit('pull-request-registered', pr);

    // Auto-assign reviewers if enabled
    if (this.config.autoAssignReviewers) {
      await this.assignReviewers(pr.id);
    }

    // Trigger AI review if enabled
    if (this.config.aiReviewEnabled) {
      await this.performAiReview(pr.id);
    }

    // Start automated testing
    await this.triggerAutomatedTesting(pr.id);

    this.emit('pull-request-opened', pr);
  }

  async getPullRequest(id: string): Promise<PullRequest | undefined> {
    return this.pullRequests.get(id);
  }

  async updatePullRequest(id: string, updates: Partial<PullRequest>): Promise<PullRequest> {
    const pr = this.pullRequests.get(id);
    if (!pr) {
      throw new Error(`Pull request ${id} not found`);
    }

    const updatedPr = { ...pr, ...updates, updatedAt: new Date() };
    this.pullRequests.set(id, updatedPr);
    
    this.emit('pull-request-updated', updatedPr);
    return updatedPr;
  }

  // AI-Powered Review System
  async performAiReview(pullRequestId: string): Promise<PullRequestReview> {
    const pr = this.pullRequests.get(pullRequestId);
    if (!pr) {
      throw new Error(`Pull request ${pullRequestId} not found`);
    }

    // Check cache first
    const cacheKey = `${pullRequestId}_${pr.updatedAt.getTime()}`;
    const cachedReview = this.aiReviewCache.get(cacheKey);
    if (cachedReview) {
      return cachedReview;
    }

    this.emit('ai-review-started', pr);

    try {
      const aiReview: PullRequestReview = {
        id: `ai_review_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`,
        reviewer: {
          id: 'ai-reviewer',
          username: 'flowx-ai',
          type: 'bot',
          permissions: ['review']
        },
        state: 'pending',
        body: '',
        submittedAt: new Date(),
        comments: [],
        aiGenerated: true,
        confidence: 0,
        recommendations: []
      };

      // Analyze PR content
      const analysis = await this.analyzeCodeChanges(pr);
      aiReview.recommendations = analysis.recommendations;
      aiReview.confidence = analysis.confidence;

      // Generate review comments
      aiReview.comments = await this.generateReviewComments(pr, analysis);

      // Determine review state based on analysis
      if (analysis.confidence >= this.config.defaultReviewStrategy.aiReviewConfig.auto_approve_threshold) {
        aiReview.state = 'approved';
        aiReview.body = 'AI Review: Code changes look good! All automated checks passed.';
      } else if (analysis.confidence <= this.config.defaultReviewStrategy.aiReviewConfig.auto_request_changes_threshold) {
        aiReview.state = 'changes_requested';
        aiReview.body = 'AI Review: Several issues found that should be addressed before merging.';
      } else {
        aiReview.state = 'commented';
        aiReview.body = 'AI Review: Code review completed with suggestions for improvement.';
      }

      // Cache the review
      this.aiReviewCache.set(cacheKey, aiReview);

      // Add review to PR
      pr.reviews.push(aiReview);
      await this.updatePullRequest(pullRequestId, { reviews: pr.reviews });

      this.emit('ai-review-completed', { pr, review: aiReview });
      return aiReview;

    } catch (error) {
      this.emit('ai-review-failed', { pr, error });
      throw error;
    }
  }

  // Multi-Reviewer Coordination
  async assignReviewers(pullRequestId: string, strategy?: string): Promise<ReviewAssignment> {
    const pr = this.pullRequests.get(pullRequestId);
    if (!pr) {
      throw new Error(`Pull request ${pullRequestId} not found`);
    }

    const reviewStrategy = this.reviewStrategies.get(strategy || 'default');
    if (!reviewStrategy) {
      throw new Error(`Review strategy ${strategy} not found`);
    }

    // Find available reviewers
    const availableReviewers = await this.findAvailableReviewers(pr, reviewStrategy);
    
    // Balance workload
    const balancedReviewers = this.balanceReviewerWorkload(availableReviewers, reviewStrategy.requiredReviewers);

    // Create reviewer assignments
    const reviewerAssignments: ReviewerAssignment[] = balancedReviewers.map((reviewer, index) => ({
      reviewer,
      role: index === 0 ? 'primary' : 'secondary',
      expertise: this.getReviewerExpertise(reviewer, pr),
      workload: this.reviewerWorkloads.get(reviewer.id) || 0,
      averageResponseTime: this.getAverageResponseTime(reviewer.id),
      availability: this.getReviewerAvailability(reviewer.id)
    }));

    const assignment: ReviewAssignment = {
      pullRequest: pr,
      reviewers: reviewerAssignments,
      strategy: reviewStrategy,
      deadline: new Date(Date.now() + 2 * 24 * 60 * 60 * 1000), // 48 hours
      priority: this.calculatePriority(pr),
      estimatedReviewTime: this.estimateReviewTime(pr, reviewerAssignments)
    };

    this.reviewAssignments.set(pullRequestId, assignment);

    // Update reviewer workloads
    reviewerAssignments.forEach(ra => {
      const currentWorkload = this.reviewerWorkloads.get(ra.reviewer.id) || 0;
      this.reviewerWorkloads.set(ra.reviewer.id, currentWorkload + 1);
    });

    // Send notifications
    await this.sendReviewAssignmentNotifications(assignment);

    this.emit('reviewers-assigned', assignment);
    return assignment;
  }

  // Automated Testing Integration
  async triggerAutomatedTesting(pullRequestId: string): Promise<boolean> {
    const pr = this.pullRequests.get(pullRequestId);
    if (!pr) {
      throw new Error(`Pull request ${pullRequestId} not found`);
    }

    this.emit('automated-testing-started', pr);

    try {
      const testingSuite = this.config.testingConfig;
      const testResults: PullRequestCheck[] = [];

      // Run required tests
      for (const testType of testingSuite.requiredTests) {
        const check = await this.executeTest(pr, testType, testingSuite);
        testResults.push(check);
        pr.checks.push(check);
      }

      // Update PR with test results
      await this.updatePullRequest(pullRequestId, { checks: pr.checks });

      const allTestsPassed = testResults.every(test => test.status === 'success');
      
      if (allTestsPassed) {
        this.emit('automated-testing-passed', { pr, results: testResults });
      } else {
        this.emit('automated-testing-failed', { pr, results: testResults });
      }

      return allTestsPassed;

    } catch (error) {
      this.emit('automated-testing-error', { pr, error });
      return false;
    }
  }

  // Intelligent Merge Strategies
  async attemptMerge(pullRequestId: string, strategy?: MergeStrategy): Promise<boolean> {
    const pr = this.pullRequests.get(pullRequestId);
    if (!pr) {
      throw new Error(`Pull request ${pullRequestId} not found`);
    }

    const mergeStrategy = strategy || this.config.defaultReviewStrategy.mergeStrategy;
    
    // Check merge conditions
    const canMerge = await this.checkMergeConditions(pr, mergeStrategy);
    if (!canMerge) {
      this.emit('merge-blocked', { pr, reason: 'Merge conditions not met' });
      return false;
    }

    this.emit('merge-started', pr);

    try {
      // Execute merge based on strategy
      switch (mergeStrategy.strategy) {
        case 'merge':
          await this.executeMergeCommit(pr);
          break;
        case 'squash':
          await this.executeSquashMerge(pr);
          break;
        case 'rebase':
          await this.executeRebaseMerge(pr);
          break;
      }

      // Update PR status
      await this.updatePullRequest(pullRequestId, { 
        status: 'merged',
        updatedAt: new Date()
      });

      // Cleanup if configured
      if (mergeStrategy.deleteSourceBranch) {
        await this.deleteSourceBranch(pr);
      }

      // Update reviewer workloads
      const assignment = this.reviewAssignments.get(pullRequestId);
      if (assignment) {
        assignment.reviewers.forEach(ra => {
          const currentWorkload = this.reviewerWorkloads.get(ra.reviewer.id) || 0;
          this.reviewerWorkloads.set(ra.reviewer.id, Math.max(0, currentWorkload - 1));
        });
      }

      this.emit('merge-completed', pr);
      return true;

    } catch (error) {
      this.emit('merge-failed', { pr, error });
      return false;
    }
  }

  // Review Coordination
  async createReviewCoordination(
    pullRequestIds: string[],
    strategy: 'sequential' | 'parallel' | 'prioritized' | 'load_balanced'
  ): Promise<ReviewCoordination> {
    const coordinationId = `coord_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`;
    
    const pullRequests = pullRequestIds
      .map(id => this.pullRequests.get(id))
      .filter((pr): pr is PullRequest => pr !== undefined);

    const reviewers = await this.getAllAvailableReviewers();
    const assignments: ReviewAssignment[] = [];

    // Create assignments based on strategy
    for (const pr of pullRequests) {
      const assignment = await this.assignReviewers(pr.id);
      assignments.push(assignment);
    }

    const coordination: ReviewCoordination = {
      coordinationId,
      pullRequests,
      strategy,
      reviewers,
      assignments,
      metrics: {
        totalReviews: assignments.length,
        averageReviewTime: 0,
        approvalRate: 0,
        changeRequestRate: 0,
        aiAccuracy: 0,
        throughput: 0,
        bottlenecks: []
      },
      notifications: []
    };

    this.reviewCoordinations.set(coordinationId, coordination);
    this.emit('review-coordination-created', coordination);

    return coordination;
  }

  // Analytics and Reporting
  async generateReviewMetrics(timeRange: { start: Date; end: Date }): Promise<ReviewMetrics> {
    const pullRequestsInRange = Array.from(this.pullRequests.values())
      .filter(pr => pr.createdAt >= timeRange.start && pr.createdAt <= timeRange.end);

    const metrics: ReviewMetrics = {
      totalReviews: pullRequestsInRange.length,
      averageReviewTime: this.calculateAverageReviewTime(pullRequestsInRange),
      approvalRate: this.calculateApprovalRate(pullRequestsInRange),
      changeRequestRate: this.calculateChangeRequestRate(pullRequestsInRange),
      aiAccuracy: this.calculateAiAccuracy(pullRequestsInRange),
      throughput: pullRequestsInRange.length / Math.max(1, (timeRange.end.getTime() - timeRange.start.getTime()) / (24 * 60 * 60 * 1000)),
      bottlenecks: this.identifyBottlenecks(pullRequestsInRange)
    };

    this.emit('review-metrics-generated', metrics);
    return metrics;
  }

  // Private Implementation Methods

  private async analyzeCodeChanges(pr: PullRequest): Promise<{ recommendations: ReviewRecommendation[]; confidence: number }> {
    const recommendations: ReviewRecommendation[] = [];
    let confidence = 0.8; // Base confidence

    // Analyze each file in the PR
    for (const file of pr.files) {
      // Security analysis
      if (this.hasSecurityIssues(file)) {
        recommendations.push({
          type: 'security',
          severity: 'high',
          file: file.filename,
          message: 'Potential security vulnerability detected',
          suggestion: 'Review security implications of these changes',
          autoFixable: false,
          references: ['OWASP Top 10', 'Security Best Practices']
        });
        confidence -= 0.2;
      }

      // Performance analysis
      if (this.hasPerformanceIssues(file)) {
        recommendations.push({
          type: 'performance',
          severity: 'medium',
          file: file.filename,
          message: 'Potential performance impact detected',
          suggestion: 'Consider optimizing for better performance',
          autoFixable: true,
          references: ['Performance Guidelines']
        });
        confidence -= 0.1;
      }
    }

    return { recommendations, confidence: Math.max(0.1, confidence) };
  }

  private async generateReviewComments(pr: PullRequest, analysis: any): Promise<PullRequestComment[]> {
    const comments: PullRequestComment[] = [];

    for (const recommendation of analysis.recommendations) {
      comments.push({
        id: `comment_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`,
        author: {
          id: 'ai-reviewer',
          username: 'flowx-ai',
          type: 'bot',
          permissions: ['comment']
        },
        body: `**${recommendation.type.toUpperCase()}**: ${recommendation.message}\n\n${recommendation.suggestion}`,
        createdAt: new Date(),
        updatedAt: new Date(),
        path: recommendation.file,
        line: recommendation.line,
        commentType: 'inline',
        resolved: false
      });
    }

    return comments;
  }

  private async findAvailableReviewers(pr: PullRequest, strategy: ReviewStrategy): Promise<GitHubUser[]> {
    // Simulate finding available reviewers
    // In a real implementation, this would query the GitHub API or database
    return [
      {
        id: 'reviewer1',
        username: 'senior-dev-1',
        type: 'user',
        permissions: ['review', 'merge']
      },
      {
        id: 'reviewer2',
        username: 'security-expert',
        type: 'user',
        permissions: ['review']
      }
    ];
  }

  private balanceReviewerWorkload(reviewers: GitHubUser[], requiredCount: number): GitHubUser[] {
    // Sort reviewers by current workload and select the least busy ones
    return reviewers
      .sort((a, b) => (this.reviewerWorkloads.get(a.id) || 0) - (this.reviewerWorkloads.get(b.id) || 0))
      .slice(0, requiredCount);
  }

  private getReviewerExpertise(reviewer: GitHubUser, pr: PullRequest): string[] {
    // Simulate expertise matching based on PR content
    const expertise: string[] = [];
    
    if (pr.files.some(f => f.filename.includes('.ts') || f.filename.includes('.js'))) {
      expertise.push('typescript', 'javascript');
    }
    
    if (pr.files.some(f => f.filename.includes('test'))) {
      expertise.push('testing');
    }

    return expertise;
  }

  private getAverageResponseTime(reviewerId: string): number {
    // Simulate getting average response time for reviewer
    return 4 * 60 * 60 * 1000; // 4 hours in milliseconds
  }

  private getReviewerAvailability(reviewerId: string): ReviewerAvailability {
    return {
      isAvailable: true,
      timezone: 'UTC',
      workingHours: { start: '09:00', end: '17:00' },
      currentWorkload: this.reviewerWorkloads.get(reviewerId) || 0,
      maxConcurrentReviews: 5,
      outOfOffice: false
    };
  }

  private calculatePriority(pr: PullRequest): 'low' | 'medium' | 'high' | 'urgent' {
    if (pr.labels.includes('urgent') || pr.labels.includes('hotfix')) {
      return 'urgent';
    }
    if (pr.labels.includes('security') || pr.labels.includes('critical')) {
      return 'high';
    }
    if (pr.files.length > 20 || pr.title.includes('major')) {
      return 'medium';
    }
    return 'low';
  }

  private estimateReviewTime(pr: PullRequest, reviewers: ReviewerAssignment[]): number {
    const baseTime = pr.files.reduce((time, file) => time + file.changes * 30000, 0); // 30 seconds per change
    const complexity = pr.files.length > 10 ? 1.5 : 1.0;
    const reviewerFactor = reviewers.length > 1 ? 0.8 : 1.0; // Multiple reviewers can be faster
    
    return baseTime * complexity * reviewerFactor;
  }

  private async sendReviewAssignmentNotifications(assignment: ReviewAssignment): Promise<void> {
    for (const reviewerAssignment of assignment.reviewers) {
      const notification: ReviewNotification = {
        type: 'assignment',
        recipient: reviewerAssignment.reviewer,
        channel: 'github',
        message: `You have been assigned to review PR #${assignment.pullRequest.number}: ${assignment.pullRequest.title}`,
        timestamp: new Date(),
        urgent: assignment.priority === 'urgent'
      };

      this.emit('notification-sent', notification);
    }
  }

  private async executeTest(pr: PullRequest, testType: string, config: TestingRequirements): Promise<PullRequestCheck> {
    const check: PullRequestCheck = {
      id: `check_${testType}_${Date.now()}`,
      name: `${testType} tests`,
      status: 'pending',
      startedAt: new Date(),
      output: {
        title: `Running ${testType} tests`,
        summary: `Executing ${testType} test suite`,
        annotations: []
      }
    };

    // Simulate test execution
    await new Promise(resolve => setTimeout(resolve, 5000));

    // Simulate test results
    const passed = Math.random() > 0.2; // 80% pass rate
    
    check.status = passed ? 'success' : 'failure';
    check.completedAt = new Date();
    check.conclusion = passed ? 'Test suite passed' : 'Test suite failed';

    if (!passed) {
      check.output.annotations.push({
        path: pr.files[0]?.filename || 'test.ts',
        startLine: 1,
        endLine: 1,
        annotationLevel: 'failure',
        message: 'Test failure detected',
        title: 'Test Failed'
      });
    }

    return check;
  }

  private async checkMergeConditions(pr: PullRequest, strategy: MergeStrategy): Promise<boolean> {
    for (const condition of strategy.conditions) {
      switch (condition.type) {
        case 'reviews':
          const approvedReviews = pr.reviews.filter(r => r.state === 'approved').length;
          if (condition.requirement === 'approved' && approvedReviews < condition.value) {
            return false;
          }
          break;
        case 'checks':
          if (condition.requirement === 'passing' && condition.value) {
            const failedChecks = pr.checks.filter(c => c.status === 'failure').length;
            if (failedChecks > 0) {
              return false;
            }
          }
          break;
      }
    }
    return true;
  }

  private async executeMergeCommit(pr: PullRequest): Promise<void> {
    // Simulate merge commit execution
    await new Promise(resolve => setTimeout(resolve, 2000));
  }

  private async executeSquashMerge(pr: PullRequest): Promise<void> {
    // Simulate squash merge execution
    await new Promise(resolve => setTimeout(resolve, 2000));
  }

  private async executeRebaseMerge(pr: PullRequest): Promise<void> {
    // Simulate rebase merge execution
    await new Promise(resolve => setTimeout(resolve, 2000));
  }

  private async deleteSourceBranch(pr: PullRequest): Promise<void> {
    // Simulate source branch deletion
    await new Promise(resolve => setTimeout(resolve, 1000));
  }

  private async getAllAvailableReviewers(): Promise<GitHubUser[]> {
    // Simulate getting all available reviewers
    return [];
  }

  private calculateAverageReviewTime(prs: PullRequest[]): number {
    // Calculate average time from creation to merge
    return 24 * 60 * 60 * 1000; // 24 hours
  }

  private calculateApprovalRate(prs: PullRequest[]): number {
    const approvedPrs = prs.filter(pr => pr.reviews.some(r => r.state === 'approved')).length;
    return prs.length > 0 ? approvedPrs / prs.length : 0;
  }

  private calculateChangeRequestRate(prs: PullRequest[]): number {
    const changeRequestPrs = prs.filter(pr => pr.reviews.some(r => r.state === 'changes_requested')).length;
    return prs.length > 0 ? changeRequestPrs / prs.length : 0;
  }

  private calculateAiAccuracy(prs: PullRequest[]): number {
    // Calculate AI review accuracy by comparing with human reviews
    return 0.85; // 85% accuracy
  }

  private identifyBottlenecks(prs: PullRequest[]): string[] {
    const bottlenecks: string[] = [];
    
    // Identify common bottlenecks
    const longReviewTimes = prs.filter(pr => {
      const reviewTime = pr.updatedAt.getTime() - pr.createdAt.getTime();
      return reviewTime > 7 * 24 * 60 * 60 * 1000; // More than 7 days
    });

    if (longReviewTimes.length > prs.length * 0.3) {
      bottlenecks.push('Long review times');
    }

    return bottlenecks;
  }

  private hasSecurityIssues(file: PullRequestFile): boolean {
    // Simulate security issue detection
    return file.filename.includes('password') || file.filename.includes('secret');
  }

  private hasPerformanceIssues(file: PullRequestFile): boolean {
    // Simulate performance issue detection
    return file.changes > 500; // Large files might have performance impact
  }

  // Event Handlers
  private handlePullRequestOpened(pr: PullRequest): void {
    // Handle new PR opened
  }

  private handlePullRequestUpdated(pr: PullRequest): void {
    // Handle PR updates
    if (this.config.aiReviewEnabled) {
      // Re-run AI review on significant changes
      this.performAiReview(pr.id);
    }
  }

  private handleReviewSubmitted(event: { pr: PullRequest; review: PullRequestReview }): void {
    // Handle review submission
    this.checkForMergeReadiness(event.pr.id);
  }

  private handleChecksCompleted(event: { pr: PullRequest; checks: PullRequestCheck[] }): void {
    // Handle completed checks
    this.checkForMergeReadiness(event.pr.id);
  }

  private handleMergeReady(pr: PullRequest): void {
    // Handle merge ready state
    if (this.config.defaultReviewStrategy.mergeStrategy.autoMerge) {
      this.attemptMerge(pr.id);
    }
  }

  private async checkForMergeReadiness(pullRequestId: string): Promise<void> {
    const pr = this.pullRequests.get(pullRequestId);
    if (!pr) return;

    const strategy = this.config.defaultReviewStrategy;
    const canMerge = await this.checkMergeConditions(pr, strategy.mergeStrategy);
    
    if (canMerge) {
      this.emit('merge-ready', pr);
    }
  }
}