/**
 * Agentic QE v3 - Root Cause Analyzer Service
 * Analyzes defects to identify root causes and contributing factors
 */

import { Result, ok, err } from '../../../shared/types';
import { MemoryBackend } from '../../../kernel/interfaces';
import {
  RootCauseRequest,
  RootCauseAnalysis,
  ContributingFactor,
  TimelineEvent,
} from '../interfaces';

/**
 * Interface for the root cause analyzer service
 */
export interface IRootCauseAnalyzerService {
  analyzeRootCause(request: RootCauseRequest): Promise<Result<RootCauseAnalysis, Error>>;
  findRelatedDefects(defectId: string): Promise<Result<string[], Error>>;
  generateTimeline(defectId: string): Promise<Result<TimelineEvent[], Error>>;
  suggestRemediation(rootCause: string): Promise<string[]>;
}

/**
 * Configuration for the root cause analyzer
 */
export interface RootCauseAnalyzerConfig {
  maxTimelineEvents: number;
  maxRelatedFiles: number;
  minConfidenceThreshold: number;
  analyzerNamespace: string;
  enableDeepAnalysis: boolean;
}

const DEFAULT_CONFIG: RootCauseAnalyzerConfig = {
  maxTimelineEvents: 20,
  maxRelatedFiles: 10,
  minConfidenceThreshold: 0.3,
  analyzerNamespace: 'defect-intelligence:root-cause',
  enableDeepAnalysis: true,
};

/**
 * Known root cause categories with analysis patterns
 */
const ROOT_CAUSE_CATEGORIES: Record<
  string,
  {
    symptoms: string[];
    causes: string[];
    impact: 'high' | 'medium' | 'low';
    remediation: string[];
  }
> = {
  'logic-error': {
    symptoms: ['wrong result', 'incorrect output', 'unexpected behavior', 'calculation'],
    causes: [
      'Incorrect algorithm implementation',
      'Missing edge case handling',
      'Wrong operator usage',
      'Off-by-one error',
    ],
    impact: 'high',
    remediation: [
      'Review algorithm logic step by step',
      'Add comprehensive unit tests',
      'Use property-based testing for edge cases',
    ],
  },
  'null-reference': {
    symptoms: ['null', 'undefined', 'cannot read property', 'NullPointerException'],
    causes: [
      'Missing null check',
      'Uninitialized variable',
      'Race condition in initialization',
      'API returning null unexpectedly',
    ],
    impact: 'high',
    remediation: [
      'Add defensive null checks',
      'Use Optional/Maybe pattern',
      'Initialize variables at declaration',
    ],
  },
  'concurrency': {
    symptoms: ['race', 'deadlock', 'intermittent', 'timing', 'thread'],
    causes: [
      'Missing synchronization',
      'Shared mutable state',
      'Lock ordering issue',
      'Async operation not awaited',
    ],
    impact: 'high',
    remediation: [
      'Use immutable data structures',
      'Implement proper locking strategy',
      'Add synchronization primitives',
    ],
  },
  'resource-management': {
    symptoms: ['memory', 'leak', 'connection', 'file handle', 'exhausted'],
    causes: [
      'Resource not properly released',
      'Missing cleanup in error path',
      'Connection pool misconfiguration',
      'Circular reference preventing GC',
    ],
    impact: 'medium',
    remediation: [
      'Use try-finally or using blocks',
      'Implement IDisposable pattern',
      'Configure resource pools properly',
    ],
  },
  'configuration': {
    symptoms: ['config', 'environment', 'setting', 'property', 'parameter'],
    causes: [
      'Wrong configuration value',
      'Missing required setting',
      'Environment mismatch',
      'Hardcoded values',
    ],
    impact: 'medium',
    remediation: [
      'Validate configuration at startup',
      'Use configuration schema validation',
      'Document all required settings',
    ],
  },
  'integration': {
    symptoms: ['api', 'service', 'external', 'timeout', 'connection'],
    causes: [
      'External service change',
      'API contract violation',
      'Network configuration issue',
      'Missing retry logic',
    ],
    impact: 'high',
    remediation: [
      'Implement circuit breaker pattern',
      'Add contract tests',
      'Use retry with exponential backoff',
    ],
  },
  'data-integrity': {
    symptoms: ['corrupt', 'invalid', 'constraint', 'duplicate', 'data'],
    causes: [
      'Missing validation',
      'Database constraint violated',
      'Race condition in data update',
      'Inconsistent state transitions',
    ],
    impact: 'high',
    remediation: [
      'Add input validation at all layers',
      'Use database transactions properly',
      'Implement optimistic locking',
    ],
  },
  'security': {
    symptoms: ['injection', 'auth', 'permission', 'access', 'security'],
    causes: [
      'Missing input sanitization',
      'Broken authentication',
      'Insufficient authorization checks',
      'Sensitive data exposure',
    ],
    impact: 'high',
    remediation: [
      'Sanitize all user inputs',
      'Implement proper authentication',
      'Follow principle of least privilege',
    ],
  },
};

/**
 * Root Cause Analyzer Service Implementation
 * Uses symptom analysis and heuristics to identify root causes
 */
export class RootCauseAnalyzerService implements IRootCauseAnalyzerService {
  private readonly config: RootCauseAnalyzerConfig;

  constructor(
    private readonly memory: MemoryBackend,
    config: Partial<RootCauseAnalyzerConfig> = {}
  ) {
    this.config = { ...DEFAULT_CONFIG, ...config };
  }

  /**
   * Analyze root cause of a defect
   */
  async analyzeRootCause(
    request: RootCauseRequest
  ): Promise<Result<RootCauseAnalysis, Error>> {
    try {
      const { defectId, symptoms, context = {} } = request;

      if (symptoms.length === 0) {
        return err(new Error('No symptoms provided for analysis'));
      }

      // Identify the root cause category
      const categoryAnalysis = this.identifyRootCauseCategory(symptoms);

      // Calculate confidence based on symptom matches
      const confidence = this.calculateConfidence(categoryAnalysis, symptoms);

      if (confidence < this.config.minConfidenceThreshold) {
        return ok({
          defectId,
          rootCause: 'Unable to determine root cause with sufficient confidence',
          confidence,
          contributingFactors: [],
          relatedFiles: [],
          recommendations: ['Provide more symptoms for better analysis'],
          timeline: [],
        });
      }

      // Identify contributing factors
      const contributingFactors = await this.identifyContributingFactors(
        categoryAnalysis.category,
        symptoms,
        context
      );

      // Find related files
      const relatedFiles = await this.findRelatedFiles(defectId, symptoms);

      // Generate recommendations
      const recommendations = this.generateRecommendations(
        categoryAnalysis,
        contributingFactors
      );

      // Build timeline
      const timeline = await this.generateTimeline(defectId);

      // Store analysis for future reference
      await this.storeAnalysis({
        defectId,
        rootCause: categoryAnalysis.rootCause,
        category: categoryAnalysis.category,
        confidence,
        symptoms,
        timestamp: new Date(),
      });

      return ok({
        defectId,
        rootCause: categoryAnalysis.rootCause,
        confidence,
        contributingFactors,
        relatedFiles,
        recommendations,
        timeline: timeline.success ? timeline.value : [],
      });
    } catch (error) {
      return err(error instanceof Error ? error : new Error(String(error)));
    }
  }

  /**
   * Find defects related to a given defect
   */
  async findRelatedDefects(defectId: string): Promise<Result<string[], Error>> {
    try {
      // Look for defects with similar root causes
      const analysis = await this.memory.get<{ category: string }>(
        `${this.config.analyzerNamespace}:analysis:${defectId}`
      );

      if (!analysis) {
        return ok([]);
      }

      // Search for other defects in the same category
      const keys = await this.memory.search(
        `${this.config.analyzerNamespace}:analysis:*`,
        50
      );

      const relatedDefects: string[] = [];
      for (const key of keys) {
        const otherAnalysis = await this.memory.get<{
          defectId: string;
          category: string;
        }>(key);

        if (
          otherAnalysis &&
          otherAnalysis.defectId !== defectId &&
          otherAnalysis.category === analysis.category
        ) {
          relatedDefects.push(otherAnalysis.defectId);
        }
      }

      return ok(relatedDefects);
    } catch (error) {
      return err(error instanceof Error ? error : new Error(String(error)));
    }
  }

  /**
   * Generate timeline of events related to a defect
   */
  async generateTimeline(defectId: string): Promise<Result<TimelineEvent[], Error>> {
    try {
      const timeline: TimelineEvent[] = [];

      // Look for stored events
      const eventsKey = `${this.config.analyzerNamespace}:events:${defectId}`;
      const storedEvents = await this.memory.get<TimelineEvent[]>(eventsKey);

      if (storedEvents) {
        timeline.push(...storedEvents);
      }

      // Look for related changes in code intelligence
      const changes = await this.memory.search(
        `code-intelligence:change:*`,
        this.config.maxTimelineEvents
      );

      for (const changeKey of changes) {
        const change = await this.memory.get<{
          timestamp: string;
          description: string;
          file: string;
        }>(changeKey);

        if (change) {
          timeline.push({
            timestamp: new Date(change.timestamp),
            event: `Code change: ${change.description}`,
            relevance: 0.5,
          });
        }
      }

      // Sort by timestamp and limit
      const sortedTimeline = timeline
        .sort((a, b) => b.timestamp.getTime() - a.timestamp.getTime())
        .slice(0, this.config.maxTimelineEvents);

      return ok(sortedTimeline);
    } catch (error) {
      return err(error instanceof Error ? error : new Error(String(error)));
    }
  }

  /**
   * Suggest remediation steps for a root cause
   */
  async suggestRemediation(rootCause: string): Promise<string[]> {
    const remediation: string[] = [];

    // Match root cause to known categories
    for (const [category, data] of Object.entries(ROOT_CAUSE_CATEGORIES)) {
      if (
        rootCause.toLowerCase().includes(category) ||
        data.causes.some((c) => rootCause.toLowerCase().includes(c.toLowerCase()))
      ) {
        remediation.push(...data.remediation);
      }
    }

    if (remediation.length === 0) {
      remediation.push('Review the affected code thoroughly');
      remediation.push('Add tests to prevent regression');
      remediation.push('Document the fix for future reference');
    }

    return [...new Set(remediation)];
  }

  // ============================================================================
  // Private Helper Methods
  // ============================================================================

  private identifyRootCauseCategory(
    symptoms: string[]
  ): { category: string; rootCause: string; matchScore: number } {
    let bestMatch = {
      category: 'unknown',
      rootCause: 'Undetermined root cause',
      matchScore: 0,
    };

    const symptomText = symptoms.join(' ').toLowerCase();

    for (const [category, data] of Object.entries(ROOT_CAUSE_CATEGORIES)) {
      let matchScore = 0;

      for (const symptom of data.symptoms) {
        if (symptomText.includes(symptom.toLowerCase())) {
          matchScore += 1;
        }
      }

      // Normalize by number of symptoms
      matchScore = matchScore / data.symptoms.length;

      if (matchScore > bestMatch.matchScore) {
        // Select the most likely cause from the category
        const likelyCause = this.selectLikelyCause(data.causes, symptomText);
        bestMatch = {
          category,
          rootCause: likelyCause,
          matchScore,
        };
      }
    }

    return bestMatch;
  }

  private selectLikelyCause(causes: string[], symptomText: string): string {
    // Score each cause by word overlap with symptoms
    let bestCause = causes[0];
    let bestScore = 0;

    for (const cause of causes) {
      const words = cause.toLowerCase().split(/\s+/);
      let score = 0;
      for (const word of words) {
        if (word.length > 3 && symptomText.includes(word)) {
          score += 1;
        }
      }
      if (score > bestScore) {
        bestScore = score;
        bestCause = cause;
      }
    }

    return bestCause;
  }

  private calculateConfidence(
    categoryAnalysis: { matchScore: number },
    symptoms: string[]
  ): number {
    // Base confidence from match score
    let confidence = categoryAnalysis.matchScore;

    // Adjust based on number of symptoms
    if (symptoms.length >= 3) {
      confidence *= 1.1;
    } else if (symptoms.length === 1) {
      confidence *= 0.8;
    }

    // Cap at 1.0
    return Math.min(1, Math.max(0, confidence));
  }

  private async identifyContributingFactors(
    category: string,
    symptoms: string[],
    context: Record<string, unknown>
  ): Promise<ContributingFactor[]> {
    const factors: ContributingFactor[] = [];
    const categoryData = ROOT_CAUSE_CATEGORIES[category];

    if (!categoryData) {
      return factors;
    }

    // Add factors based on category
    factors.push({
      factor: `Category: ${category}`,
      impact: categoryData.impact,
      evidence: symptoms.slice(0, 3),
    });

    // Add context-based factors
    if (context.recentChanges) {
      factors.push({
        factor: 'Recent code changes',
        impact: 'high',
        evidence: ['Code was recently modified'],
      });
    }

    if (context.highTraffic) {
      factors.push({
        factor: 'High traffic conditions',
        impact: 'medium',
        evidence: ['Occurred during peak load'],
      });
    }

    if (context.environment) {
      factors.push({
        factor: `Environment: ${context.environment}`,
        impact: 'medium',
        evidence: [`Observed in ${context.environment} environment`],
      });
    }

    // Look for historical patterns
    const historicalFactors = await this.getHistoricalFactors(category);
    factors.push(...historicalFactors);

    return factors;
  }

  private async getHistoricalFactors(
    category: string
  ): Promise<ContributingFactor[]> {
    const factors: ContributingFactor[] = [];

    // Search for historical analyses in the same category
    const historicalKey = `${this.config.analyzerNamespace}:history:${category}`;
    const history = await this.memory.get<{
      occurrences: number;
      commonFactors: string[];
    }>(historicalKey);

    if (history && history.occurrences > 1) {
      factors.push({
        factor: 'Recurring issue pattern',
        impact: 'high',
        evidence: [
          `Similar issues occurred ${history.occurrences} times`,
          ...history.commonFactors.slice(0, 2),
        ],
      });
    }

    return factors;
  }

  private async findRelatedFiles(
    _defectId: string,
    symptoms: string[]
  ): Promise<string[]> {
    const files: Set<string> = new Set();

    // Extract file paths from symptoms
    for (const symptom of symptoms) {
      const filePatterns = symptom.match(/[\w\-]+\.(ts|js|tsx|jsx|py|java|go)/g);
      if (filePatterns) {
        filePatterns.forEach((f) => files.add(f));
      }

      // Look for path-like patterns
      const pathPatterns = symptom.match(/(?:src|lib|app)\/[\w\/\-]+/g);
      if (pathPatterns) {
        pathPatterns.forEach((p) => files.add(p));
      }
    }

    // Look for files from code intelligence
    const codeIntelKeys = await this.memory.search(
      'code-intelligence:file:*',
      this.config.maxRelatedFiles
    );

    for (const key of codeIntelKeys.slice(0, this.config.maxRelatedFiles - files.size)) {
      const fileInfo = await this.memory.get<{ path: string }>(key);
      if (fileInfo) {
        files.add(fileInfo.path);
      }
    }

    return Array.from(files).slice(0, this.config.maxRelatedFiles);
  }

  private generateRecommendations(
    categoryAnalysis: { category: string; rootCause: string },
    contributingFactors: ContributingFactor[]
  ): string[] {
    const recommendations: string[] = [];
    const categoryData = ROOT_CAUSE_CATEGORIES[categoryAnalysis.category];

    // Add category-specific remediation
    if (categoryData) {
      recommendations.push(...categoryData.remediation);
    }

    // Add factor-specific recommendations
    for (const factor of contributingFactors) {
      if (factor.impact === 'high') {
        recommendations.push(`Address: ${factor.factor}`);
      }
    }

    // Add general recommendations
    recommendations.push('Add regression tests for this scenario');
    recommendations.push('Document the root cause and fix');

    return [...new Set(recommendations)].slice(0, 8);
  }

  private async storeAnalysis(analysis: {
    defectId: string;
    rootCause: string;
    category: string;
    confidence: number;
    symptoms: string[];
    timestamp: Date;
  }): Promise<void> {
    // Store the analysis
    await this.memory.set(
      `${this.config.analyzerNamespace}:analysis:${analysis.defectId}`,
      analysis,
      { namespace: 'defect-intelligence', persist: true }
    );

    // Update historical data for the category
    const historyKey = `${this.config.analyzerNamespace}:history:${analysis.category}`;
    const history = (await this.memory.get<{
      occurrences: number;
      commonFactors: string[];
    }>(historyKey)) || { occurrences: 0, commonFactors: [] };

    history.occurrences += 1;
    // Add new symptoms to common factors
    for (const symptom of analysis.symptoms.slice(0, 2)) {
      if (!history.commonFactors.includes(symptom)) {
        history.commonFactors.push(symptom);
      }
    }
    history.commonFactors = history.commonFactors.slice(0, 10);

    await this.memory.set(historyKey, history, {
      namespace: 'defect-intelligence',
      persist: true,
    });
  }
}