import type { Env, RegionInput, InstanceTypeInput, InstanceFamily } from '../types';
import { VaultClient, VaultError } from './vault';
import { RateLimiter } from './base';
import { createLogger } from '../utils/logger';
import { HTTP_STATUS } from '../constants';

/**
 * Linode API error class
 */
export class LinodeError extends Error {
  constructor(
    message: string,
    public statusCode?: number,
    public details?: unknown
  ) {
    super(message);
    this.name = 'LinodeError';
  }
}

/**
 * Linode API response types
 */
interface LinodeRegion {
  id: string;
  label: string;
  country: string;
  capabilities: string[];
  status: string;
}

interface LinodeInstanceType {
  id: string;
  label: string;
  price: {
    hourly: number;
    monthly: number;
  };
  memory: number;
  vcpus: number;
  disk: number;
  transfer: number;
  network_out: number;
  gpus: number;
  class: string;
}

interface LinodeApiResponse<T> {
  data: T[];
  page?: number;
  pages?: number;
  results?: number;
}

/**
 * Linode API Connector
 *
 * Features:
 * - Fetches regions and instance types from Linode API
 * - Rate limiting: 1600 requests/hour
 * - Data normalization for database storage
 * - Comprehensive error handling
 * - Vault integration for credentials
 *
 * @example
 * const vault = new VaultClient(vaultUrl, vaultToken);
 * const connector = new LinodeConnector(vault);
 * const regions = await connector.fetchRegions();
 */
export class LinodeConnector {
  readonly provider = 'linode';
  private readonly baseUrl = 'https://api.linode.com/v4';
  private readonly rateLimiter: RateLimiter;
  private readonly requestTimeout = 10000; // 10 seconds
  private readonly logger: ReturnType<typeof createLogger>;
  private apiToken: string | null = null;

  constructor(private vaultClient: VaultClient, env?: Env) {
    // Rate limit: 1600 requests/hour = ~0.44 requests/second
    // Token bucket: maxTokens=5 (allow burst), refillRate=0.5 (conservative)
    this.rateLimiter = new RateLimiter(5, 0.5);
    this.logger = createLogger('[LinodeConnector]', env);
    this.logger.info('Initialized');
  }

  /**
   * Initialize connector by fetching credentials from Vault
   * Must be called before making API requests
   */
  async initialize(): Promise<void> {
    this.logger.info('Fetching credentials from Vault');

    try {
      const credentials = await this.vaultClient.getCredentials(this.provider);
      this.apiToken = credentials.api_token || null;
      this.logger.info('Credentials loaded successfully');
    } catch (error) {
      if (error instanceof VaultError) {
        throw new LinodeError(
          `Failed to load Linode credentials: ${error.message}`,
          error.statusCode
        );
      }
      throw error;
    }
  }

  /**
   * Fetch all regions from Linode API
   *
   * @returns Array of raw Linode region data
   * @throws LinodeError on API failures
   */
  async fetchRegions(): Promise<LinodeRegion[]> {
    this.logger.info('Fetching regions');

    const response = await this.makeRequest<LinodeApiResponse<LinodeRegion>>(
      '/regions'
    );

    this.logger.info('Regions fetched', { count: response.data.length });
    return response.data;
  }

  /**
   * Fetch all instance types from Linode API
   *
   * @returns Array of raw Linode instance type data
   * @throws LinodeError on API failures
   */
  async fetchInstanceTypes(): Promise<LinodeInstanceType[]> {
    this.logger.info('Fetching instance types');

    const response = await this.makeRequest<LinodeApiResponse<LinodeInstanceType>>(
      '/linode/types'
    );

    this.logger.info('Instance types fetched', { count: response.data.length });
    return response.data;
  }

  /**
   * Normalize Linode region data for database storage
   *
   * @param raw - Raw Linode region data
   * @param providerId - Database provider ID
   * @returns Normalized region data ready for insertion
   */
  normalizeRegion(raw: LinodeRegion, providerId: number): RegionInput {
    return {
      provider_id: providerId,
      region_code: raw.id,
      region_name: raw.label,
      country_code: raw.country.toLowerCase(),
      latitude: null, // Linode doesn't provide coordinates
      longitude: null,
      available: raw.status === 'ok' ? 1 : 0,
    };
  }

  /**
   * Normalize Linode instance type data for database storage
   *
   * @param raw - Raw Linode instance type data
   * @param providerId - Database provider ID
   * @returns Normalized instance type data ready for insertion
   */
  normalizeInstance(raw: LinodeInstanceType, providerId: number): InstanceTypeInput {
    return {
      provider_id: providerId,
      instance_id: raw.id,
      instance_name: raw.label,
      vcpu: raw.vcpus,
      memory_mb: raw.memory, // Already in MB
      storage_gb: Math.round(raw.disk / 1024), // Convert MB to GB
      transfer_tb: raw.transfer / 1000, // Convert GB to TB
      network_speed_gbps: raw.network_out / 1000, // Convert Mbps to Gbps
      gpu_count: raw.gpus,
      gpu_type: raw.gpus > 0 ? 'nvidia' : null, // Linode uses NVIDIA GPUs
      instance_family: this.mapInstanceFamily(raw.class),
      metadata: JSON.stringify({
        class: raw.class,
        hourly_price: raw.price.hourly,
        monthly_price: raw.price.monthly,
      }),
    };
  }

  /**
   * Map Linode instance class to standard instance family
   *
   * @param linodeClass - Linode instance class
   * @returns Standard instance family type
   */
  private mapInstanceFamily(linodeClass: string): InstanceFamily {
    const classLower = linodeClass.toLowerCase();

    if (classLower === 'nanode' || classLower === 'standard') {
      return 'general';
    }
    if (classLower === 'highmem') {
      return 'memory';
    }
    if (classLower === 'dedicated') {
      return 'compute';
    }
    if (classLower === 'gpu') {
      return 'gpu';
    }

    // Default to general for unknown classes
    this.logger.warn('Unknown instance class, defaulting to general', { class: linodeClass });
    return 'general';
  }

  /**
   * Make authenticated request to Linode API with rate limiting
   *
   * @param endpoint - API endpoint (e.g., '/regions')
   * @returns Parsed API response
   * @throws LinodeError on API failures
   */
  private async makeRequest<T>(endpoint: string): Promise<T> {
    if (!this.apiToken) {
      throw new LinodeError(
        'Connector not initialized. Call initialize() first.',
        HTTP_STATUS.INTERNAL_ERROR
      );
    }

    // Apply rate limiting
    await this.rateLimiter.waitForToken();

    const url = `${this.baseUrl}${endpoint}`;
    this.logger.debug('Making request', { endpoint });

    try {
      const controller = new AbortController();
      const timeoutId = setTimeout(() => controller.abort(), this.requestTimeout);

      const response = await fetch(url, {
        method: 'GET',
        headers: {
          'Authorization': `Bearer ${this.apiToken}`,
          'Content-Type': 'application/json',
        },
        signal: controller.signal,
      });

      clearTimeout(timeoutId);

      // Handle HTTP errors
      if (!response.ok) {
        await this.handleHttpError(response);
      }

      const data = await response.json() as T;
      return data;

    } catch (error) {
      // Handle timeout
      if (error instanceof Error && error.name === 'AbortError') {
        this.logger.error('Request timeout', { endpoint, timeout_ms: this.requestTimeout });
        throw new LinodeError(
          `Request to Linode API timed out after ${this.requestTimeout}ms`,
          504
        );
      }

      // Re-throw LinodeError
      if (error instanceof LinodeError) {
        throw error;
      }

      // Handle unexpected errors
      this.logger.error('Unexpected error', { endpoint, error: error instanceof Error ? error.message : String(error) });
      throw new LinodeError(
        `Failed to fetch from Linode API: ${error instanceof Error ? error.message : 'Unknown error'}`,
        HTTP_STATUS.INTERNAL_ERROR,
        error
      );
    }
  }

  /**
   * Handle HTTP error responses from Linode API
   * This method always throws a LinodeError
   */
  private async handleHttpError(response: Response): Promise<never> {
    const statusCode = response.status;
    let errorMessage: string;
    let errorDetails: unknown;

    try {
      const errorData = await response.json() as { errors?: Array<{ reason?: string }> };
      errorMessage = errorData.errors?.[0]?.reason || response.statusText;
      errorDetails = errorData;
    } catch {
      errorMessage = response.statusText;
      errorDetails = null;
    }

    this.logger.error('HTTP error', { statusCode, errorMessage });

    if (statusCode === 401) {
      throw new LinodeError(
        'Linode authentication failed: Invalid or expired API token',
        401,
        errorDetails
      );
    }

    if (statusCode === 403) {
      throw new LinodeError(
        'Linode authorization failed: Insufficient permissions',
        403,
        errorDetails
      );
    }

    if (statusCode === HTTP_STATUS.TOO_MANY_REQUESTS) {
      throw new LinodeError(
        'Linode rate limit exceeded: Too many requests',
        HTTP_STATUS.TOO_MANY_REQUESTS,
        errorDetails
      );
    }

    if (statusCode >= 500 && statusCode < 600) {
      throw new LinodeError(
        `Linode server error: ${errorMessage}`,
        statusCode,
        errorDetails
      );
    }

    throw new LinodeError(
      `Linode API request failed: ${errorMessage}`,
      statusCode,
      errorDetails
    );
  }
}