import { Injectable } from '@angular/core';
import { HttpClient, HttpHeaders, HttpErrorResponse } from '@angular/common/http';
import { environment } from '../../environments/environment';
import { BehaviorSubject, Observable, of, throwError, timer, EMPTY } from 'rxjs';
import { AutheliaAuthService } from './authelia-auth.service';
import { map, catchError, retry, switchMap, tap, delay, timeout } from 'rxjs/operators';
import {
  N8nSyncData,
  SyncStatus,
  SyncError,
  CVAnalysisRequest,
  CVAnalysisResponse,
  QuestionBankResponse,
  SessionSyncRequest,
  SessionSyncResponse,
  AnalyticsRequest,
  AnalyticsResponse,
  AutheliaAuthToken,
  N8nApiConfig,
  N8nDataMapper
} from '../models/n8n-sync.interface';
import { CVProfile } from '../models/cv-profile.interface';
import { QuestionBank } from '../models/question-bank.interface';
import { InterviewSession, SessionSummary, SessionAnalytics } from '../models/interview-session.interface';
import { DataSanitizer } from '../models/validation';

@Injectable({
  providedIn: 'root'
})
export class N8nSyncService implements N8nDataMapper {
  private readonly apiConfig: N8nApiConfig = {
    baseUrl: environment.n8nWebhookUrl.replace('/webhook/cv-analysis', ''),
    authToken: '',
    timeout: 30000,
    retryAttempts: 3
  };

  private authTokenSubject = new BehaviorSubject<AutheliaAuthToken | null>(null);
  private syncStatusSubject = new BehaviorSubject<SyncStatus>(SyncStatus.PENDING);
  private lastSyncSubject = new BehaviorSubject<Date | null>(null);
  private isOnlineSubject = new BehaviorSubject<boolean>(navigator.onLine);

  public authToken$ = this.authTokenSubject.asObservable();
  public syncStatus$ = this.syncStatusSubject.asObservable();
  public lastSync$ = this.lastSyncSubject.asObservable();
  public isOnline$ = this.isOnlineSubject.asObservable();

  private pendingSyncs = new Map<string, N8nSyncData>();
  private syncQueue: string[] = [];

  constructor(
    private http: HttpClient,
    private autheliaAuth: AutheliaAuthService
  ) {
    this.setupNetworkStatusMonitoring();
    this.initializeAuthToken();
    this.startSyncQueueProcessor();
  }

  // Authentication Methods
  public async authenticateWithAuthelia(username: string, password: string): Promise<boolean> {
    try {
      const authEndpoint = `${this.apiConfig.baseUrl}/api/verify`;

      const response = await this.http.post<any>(authEndpoint, {
        username,
        password
      }, {
        headers: new HttpHeaders({
          'Content-Type': 'application/json'
        }),
        withCredentials: true
      }).toPromise();

      if (response && response.token) {
        const authToken: AutheliaAuthToken = {
          token: response.token,
          expiresAt: new Date(Date.now() + (response.expires_in || 3600) * 1000),
          refreshToken: response.refresh_token
        };

        this.authTokenSubject.next(authToken);
        this.apiConfig.authToken = response.token;
        this.storeAuthToken(authToken);

        return true;
      }

      return false;
    } catch (error) {
      console.error('Authelia authentication failed:', error);
      return false;
    }
  }

  public async refreshAuthToken(): Promise<boolean> {
    const currentToken = this.authTokenSubject.value;
    if (!currentToken?.refreshToken) {
      return false;
    }

    try {
      const refreshEndpoint = `${this.apiConfig.baseUrl}/api/refresh`;

      const response = await this.http.post<any>(refreshEndpoint, {
        refresh_token: currentToken.refreshToken
      }, {
        headers: new HttpHeaders({
          'Content-Type': 'application/json',
          'Authorization': `Bearer ${currentToken.token}`
        })
      }).toPromise();

      if (response && response.token) {
        const newAuthToken: AutheliaAuthToken = {
          token: response.token,
          expiresAt: new Date(Date.now() + (response.expires_in || 3600) * 1000),
          refreshToken: response.refresh_token || currentToken.refreshToken
        };

        this.authTokenSubject.next(newAuthToken);
        this.apiConfig.authToken = response.token;
        this.storeAuthToken(newAuthToken);

        return true;
      }

      return false;
    } catch (error) {
      console.error('Token refresh failed:', error);
      this.clearAuthToken();
      return false;
    }
  }

  // CV Analysis Methods
  public submitCVForAnalysis(cvProfile: CVProfile): Observable<CVAnalysisResponse> {
    this.syncStatusSubject.next(SyncStatus.IN_PROGRESS);

    const request = this.mapCVProfileToRequest(cvProfile);
    const endpoint = environment.apiEndpoints.cvAnalysis;

    console.log('🚀 Submitting CV for analysis with N8N API key auth');

    // Use direct HTTP with API key authentication
    return this.http.post<any>(endpoint, request, {
      headers: this.getN8nApiHeaders()
    }).pipe(
      retry(this.apiConfig.retryAttempts),
      map(response => {
        // Handle empty response from N8N (when no workflow is configured)
        if (!response || typeof response !== 'object') {
          console.log('⚠️ N8N returned empty response, generating fallback');
          return this.generateFallbackResponse(cvProfile);
        }
        
        // Handle proper N8N workflow response
        if (response.analysisId) {
          console.log('✅ CV analysis submitted:', response.analysisId);
          return response as CVAnalysisResponse;
        }
        
        // Handle unexpected response format
        console.log('⚠️ N8N response missing analysisId, generating fallback');
        return this.generateFallbackResponse(cvProfile);
      }),
      tap(response => {
        this.syncStatusSubject.next(SyncStatus.SUCCESS);
      }),
      catchError(error => {
        console.error('❌ CV analysis failed:', error);
        this.syncStatusSubject.next(SyncStatus.FAILED);
        return throwError(() => error);
      })
    );
  }

  public pollAnalysisStatus(analysisId: string): Observable<CVAnalysisResponse> {
    const statusEndpoint = `${this.apiConfig.baseUrl}/webhook/cv-analysis/${analysisId}/status`;

    return timer(0, 5000).pipe( // Poll every 5 seconds
      switchMap(() =>
        this.http.get<CVAnalysisResponse>(statusEndpoint, {
          headers: this.getN8nApiHeaders()
        }).pipe(
          catchError(error => {
            console.warn('Status polling error:', error);
            return of({ status: 'failed' } as CVAnalysisResponse);
          })
        )
      ),
      tap(response => {
        if (response.status === 'completed' || response.status === 'failed') {
          this.syncStatusSubject.next(
            response.status === 'completed' ? SyncStatus.SUCCESS : SyncStatus.FAILED
          );
        }
      })
    );
  }

  public getGeneratedQuestionBank(questionBankId: string): Observable<QuestionBank> {
    const endpoint = `${this.apiConfig.baseUrl}/webhook/question-bank/${questionBankId}`;

    return this.http.get<QuestionBankResponse>(endpoint, {
      headers: this.getN8nApiHeaders()
    }).pipe(
      map(response => this.mapResponseToQuestionBank(response)),
      retry(this.apiConfig.retryAttempts),
      catchError(this.handleHttpError.bind(this))
    );
  }

  // Session Synchronization Methods
  public syncInterviewSession(session: InterviewSession): Observable<SessionSyncResponse> {
    this.syncStatusSubject.next(SyncStatus.IN_PROGRESS);

    const request = this.mapSessionToSyncRequest(session);
    const endpoint = `${this.apiConfig.baseUrl}/webhook/session-sync`;

    return this.http.post<SessionSyncResponse>(endpoint, request, {
      headers: this.getN8nApiHeaders(),
      timeout: this.apiConfig.timeout
    }).pipe(
      retry(this.apiConfig.retryAttempts),
      tap(response => {
        this.syncStatusSubject.next(
          response.status === 'success' ? SyncStatus.SUCCESS : SyncStatus.FAILED
        );
        this.lastSyncSubject.next(new Date());

        if (response.status === 'success') {
          this.removePendingSync(session.id);
        }
      }),
      catchError(error => {
        console.error('❌ Session sync failed:', error);
        this.syncStatusSubject.next(SyncStatus.FAILED);
        return this.handleHttpError(error);
      })
    );
  }

  public syncSessionAnalytics(sessionId: string, analytics: SessionAnalytics, improvements: string[]): Observable<AnalyticsResponse> {
    const request: AnalyticsRequest = {
      sessionId,
      analytics,
      improvements
    };

    const endpoint = `${this.apiConfig.baseUrl}/webhook/analytics`;

    return this.http.post<AnalyticsResponse>(endpoint, request, {
      headers: this.getN8nApiHeaders()
    }).pipe(
      retry(this.apiConfig.retryAttempts),
      catchError(this.handleHttpError.bind(this))
    );
  }

  // Bulk Synchronization Methods
  public syncAllPendingData(): Observable<void> {
    if (!this.isAuthenticated() || this.pendingSyncs.size === 0) {
      return of(void 0);
    }

    this.syncStatusSubject.next(SyncStatus.IN_PROGRESS);

    const syncObservables: Observable<any>[] = [];

    this.pendingSyncs.forEach(syncData => {
      if (syncData.dataSnapshot.sessionSummary) {
        // Reconstruct session from snapshot
        const session: InterviewSession = {
          id: syncData.sessionId,
          cvProfileId: syncData.dataSnapshot.cvProfile.id,
          questionBankId: '', // Will be filled from session summary
          startTime: new Date(),
          endTime: undefined,
          duration: 0,
          detectedQuestions: [],
          providedAnswers: [],
          questionsAnswered: [],
          manualComments: [],
          speechHints: [],
          analytics: syncData.dataSnapshot.analytics,
          status: 'completed' as any
        };

        syncObservables.push(this.syncInterviewSession(session));
      }
    });

    if (syncObservables.length === 0) {
      this.syncStatusSubject.next(SyncStatus.SUCCESS);
      return of(void 0);
    }

    return new Observable(observer => {
      Promise.all(syncObservables.map(obs => obs.toPromise()))
        .then(() => {
          this.syncStatusSubject.next(SyncStatus.SUCCESS);
          observer.next();
          observer.complete();
        })
        .catch(error => {
          this.syncStatusSubject.next(SyncStatus.FAILED);
          observer.error(error);
        });
    });
  }

  // Data Mapping Methods (N8nDataMapper implementation)
  public mapCVProfileToRequest(profile: CVProfile): CVAnalysisRequest {
    return {
      cvProfileId: profile.id,
      personalInfo: profile.personalInfo,
      experience: profile.experience,
      education: profile.education,
      skills: profile.skills,
      certifications: profile.certifications,
      parsedText: profile.extractedText || ''
    };
  }

  public mapResponseToQuestionBank(response: QuestionBankResponse): QuestionBank {
    // Convert the response questions to our internal format
    const mappedQuestions = response.questions.map(q => ({
      ...q,
      category: q.category as any, // Type assertion for enum conversion
      difficulty: q.difficulty as any, // Type assertion for enum conversion
    }));

    return {
      id: response.questionBankId,
      cvProfileId: response.cvProfileId,
      generatedDate: new Date(response.generatedDate),
      lastUsed: new Date(),
      questions: mappedQuestions,
      accuracy: 0.9, // Default accuracy
      metadata: {
        ...response.metadata,
        categoriesDistribution: response.metadata.categoriesDistribution || {}
      }
    };
  }

  public mapSessionToSyncRequest(session: InterviewSession): SessionSyncRequest {
    return {
      sessionId: session.id,
      cvProfileId: session.cvProfileId,
      startTime: session.startTime.toISOString(),
      endTime: session.endTime?.toISOString(),
      detectedQuestions: session.detectedQuestions,
      providedAnswers: session.providedAnswers,
      manualComments: session.manualComments,
      analytics: session.analytics
    };
  }

  public mapSyncResponseToSession(response: SessionSyncResponse, session: InterviewSession): InterviewSession {
    return {
      ...session,
      // Update questions based on server response
      detectedQuestions: session.detectedQuestions.map(dq => {
        const updatedQuestion = response.updatedQuestions.find(uq => uq.id === dq.questionBankMatch);
        if (updatedQuestion) {
          return {
            ...dq,
            confidence: Math.max(dq.confidence, updatedQuestion.confidence)
          };
        }
        return dq;
      })
    };
  }

  // Queue Management Methods
  private queueSyncForLater(session: InterviewSession): Observable<SessionSyncResponse> {
    const syncData: N8nSyncData = {
      id: DataSanitizer.generateUUID(),
      sessionId: session.id,
      lastSyncTime: new Date(),
      syncStatus: SyncStatus.PENDING,
      dataSnapshot: {
        cvProfile: {} as CVProfile, // Would need to get from service
        questionBank: {} as QuestionBank, // Would need to get from service
        sessionSummary: this.createSessionSummary(session),
        analytics: session.analytics
      }
    };

    this.pendingSyncs.set(session.id, syncData);
    this.syncQueue.push(session.id);

    // Return a pending response
    return of({
      syncId: syncData.id,
      status: 'partial',
      updatedQuestions: [],
      recommendations: ['Sync queued for when connection is available'],
      errors: []
    });
  }

  private createSessionSummary(session: InterviewSession): SessionSummary {
    const duration = session.endTime && session.startTime ?
      (session.endTime.getTime() - session.startTime.getTime()) / (1000 * 60) : 0;

    return {
      sessionId: session.id,
      duration,
      questionsAnswered: session.providedAnswers.length,
      successRate: session.analytics.accuracyRate,
      improvements: [],
      newQuestions: []
    };
  }

  private removePendingSync(sessionId: string): void {
    this.pendingSyncs.delete(sessionId);
    const index = this.syncQueue.indexOf(sessionId);
    if (index > -1) {
      this.syncQueue.splice(index, 1);
    }
  }

  private startSyncQueueProcessor(): void {
    // Process sync queue when online
    this.isOnline$.subscribe(isOnline => {
      if (isOnline && this.syncQueue.length > 0 && this.isAuthenticated()) {
        this.processSyncQueue();
      }
    });
  }

  private processSyncQueue(): void {
    if (this.syncQueue.length === 0) return;

    const sessionId = this.syncQueue.shift();
    if (!sessionId) return;

    const syncData = this.pendingSyncs.get(sessionId);
    if (!syncData) return;

    // Process this sync item
    setTimeout(() => {
      if (this.isAuthenticated() && this.isOnlineSubject.value) {
        // Try to sync this item
        // This would need the actual session data
        console.log('Processing queued sync for session:', sessionId);
      }
    }, 1000);
  }

  // Utility Methods
  private isAuthenticated(): boolean {
    const token = this.authTokenSubject.value;
    return !!(token && token.expiresAt > new Date());
  }

  private getAuthHeaders(): HttpHeaders {
    const token = this.authTokenSubject.value;
    return new HttpHeaders({
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${token?.token || ''}`
    });
  }

  private getN8nApiHeaders(): HttpHeaders {
    return new HttpHeaders({
      'Content-Type': 'application/json',
      'X-N8N-API-KEY': environment.n8n.apiKey,
      'Accept': 'application/json'
    });
  }

  private handleHttpError(error: HttpErrorResponse): Observable<never> {
    let errorMessage = 'An error occurred';

    if (error.error instanceof ErrorEvent) {
      // Client-side error
      errorMessage = `Error: ${error.error.message}`;
    } else {
      // Server-side error
      switch (error.status) {
        case 401:
          errorMessage = 'Authentication failed';
          this.clearAuthToken();
          break;
        case 403:
          errorMessage = 'Access forbidden';
          break;
        case 404:
          errorMessage = 'Service not found';
          break;
        case 500:
          errorMessage = 'Server error';
          break;
        case 503:
          errorMessage = 'Service unavailable';
          break;
        default:
          errorMessage = `Error ${error.status}: ${error.message}`;
      }
    }

    console.error('N8n API Error:', errorMessage, error);
    return throwError(errorMessage);
  }

  private setupNetworkStatusMonitoring(): void {
    window.addEventListener('online', () => {
      this.isOnlineSubject.next(true);
      console.log('Network connection restored');
    });

    window.addEventListener('offline', () => {
      this.isOnlineSubject.next(false);
      console.log('Network connection lost');
    });
  }

  private initializeAuthToken(): void {
    const storedToken = this.getStoredAuthToken();
    if (storedToken && storedToken.expiresAt > new Date()) {
      this.authTokenSubject.next(storedToken);
      this.apiConfig.authToken = storedToken.token;
    }
  }

  private storeAuthToken(token: AutheliaAuthToken): void {
    try {
      localStorage.setItem('n8n_auth_token', JSON.stringify({
        ...token,
        expiresAt: token.expiresAt.toISOString()
      }));
    } catch (error) {
      console.error('Failed to store auth token:', error);
    }
  }

  private getStoredAuthToken(): AutheliaAuthToken | null {
    try {
      const stored = localStorage.getItem('n8n_auth_token');
      if (stored) {
        const parsed = JSON.parse(stored);
        return {
          ...parsed,
          expiresAt: new Date(parsed.expiresAt)
        };
      }
    } catch (error) {
      console.error('Failed to retrieve stored auth token:', error);
    }
    return null;
  }

  private clearAuthToken(): void {
    this.authTokenSubject.next(null);
    this.apiConfig.authToken = '';
    localStorage.removeItem('n8n_auth_token');
  }

  private generateFallbackResponse(cvProfile: CVProfile): CVAnalysisResponse {
    const analysisId = `fallback_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`;
    const questionBankId = `qb_fallback_${Date.now()}`;
    
    console.log('🔄 Generating fallback response for CV analysis');
    
    return {
      status: 'completed',
      analysisId: analysisId,
      questionBankId: questionBankId,
      questionsGenerated: 3,
      candidateName: cvProfile.personalInfo?.fullName || 'Candidate',
      questions: this.generateFallbackQuestions(cvProfile),
      metadata: {
        skillsAnalyzed: cvProfile.skills?.length || 0,
        experienceYears: Math.max(...(cvProfile.skills?.map(s => s.yearsOfExperience || 0) || [0])),
        processingTime: new Date().toISOString(),
        fallbackMode: true,
        message: 'Questions generated locally (N8N workflow not configured)'
      }
    };
  }

  private generateFallbackQuestions(cvProfile: CVProfile): any[] {
    const skills = cvProfile.skills || [];
    const experience = cvProfile.experience || [];
    const technicalSkills = skills.filter(s => s.category === 'technical').map(s => s.name);
    const primarySkill = technicalSkills[0] || skills[0]?.name || 'your main technology';
    
    return [
      {
        id: 1,
        question: `Tell me about your experience with ${primarySkill} and how you've applied it in recent projects.`,
        category: 'technical',
        difficulty: 'medium',
        expectedSkills: technicalSkills.slice(0, 2),
        reasoning: 'Technical assessment based on CV skills',
        generatedAt: new Date().toISOString()
      },
      {
        id: 2,
        question: 'Describe a challenging project you worked on and how you overcame the main obstacles.',
        category: 'behavioral',
        difficulty: 'medium',
        expectedSkills: ['Problem Solving', 'Communication', 'Critical Thinking'],
        reasoning: 'Behavioral assessment of problem-solving abilities',
        generatedAt: new Date().toISOString()
      },
      {
        id: 3,
        question: experience.length > 0 ? 
          `I see you worked at ${experience[0].company}. What was the most valuable thing you learned there?` :
          'What motivates you in your professional career and where do you see yourself in 5 years?',
        category: experience.length > 0 ? 'experience' : 'career',
        difficulty: 'easy',
        expectedSkills: ['Self-awareness', 'Communication', 'Growth Mindset'],
        reasoning: experience.length > 0 ? 'Experience-specific question' : 'Career development assessment',
        generatedAt: new Date().toISOString()
      }
    ];
  }

  // Health Check Methods
  public checkN8nHealth(): Observable<boolean> {
    const healthEndpoint = `${this.apiConfig.baseUrl}/healthz`;

    return this.http.get(healthEndpoint, {
      timeout: 5000
    }).pipe(
      map(() => true),
      catchError(() => of(false))
    );
  }

  public getApiStatus(): Observable<any> {
    if (!this.isAuthenticated()) {
      return of({ authenticated: false, online: this.isOnlineSubject.value });
    }

    const statusEndpoint = `${this.apiConfig.baseUrl}/api/status`;

    return this.http.get(statusEndpoint, {
      headers: this.getAuthHeaders()
    }).pipe(
      map(response => ({
        authenticated: true,
        online: this.isOnlineSubject.value,
        api: response
      })),
      catchError(() => of({
        authenticated: false,
        online: this.isOnlineSubject.value,
        error: 'Failed to get API status'
      }))
    );
  }

  // Cleanup
  public destroy(): void {
    // Clear any ongoing timers or subscriptions
    this.pendingSyncs.clear();
    this.syncQueue.length = 0;
  }
}