// =============================================================================
// DATABASE OPERATIONS FOR THREAT SCORING (TypeScript)
// =============================================================================

import { Level } from 'level';
// @ts-ignore - level-ttl doesn't have TypeScript definitions
import ttl from 'level-ttl';
import { rootDir } from '../../index.js';
import { join } from 'path';
import { Readable } from 'stream';
import * as fs from 'fs';
import { DB_TTL_CONFIG } from './constants.js';

// Import types from the main threat scoring module
// Local type definitions for database operations
type ThreatFeatures = Record<string, any>;
type AssessmentData = Record<string, any>;
type SanitizedFeatures = Record<string, any>;

// =============================================================================
// TYPE DEFINITIONS
// =============================================================================

interface DatabaseOperation {
  readonly type: 'put' | 'del';
  readonly key: string;
  readonly value?: unknown;
}

interface ThreatAssessment {
  readonly score: number;
  readonly action: 'allow' | 'challenge' | 'block';
  readonly features: Record<string, unknown>;
  readonly scoreComponents: Record<string, number>;
  readonly confidence: number;
  readonly timestamp: number;
}

interface BehaviorData {
  readonly lastScore: number;
  readonly lastSeen: number;
  readonly features: Record<string, unknown>;
  readonly requestCount: number;
}

interface ReputationData {
  score: number;
  incidents: number;
  blacklisted: boolean;
  tags: string[];
  notes?: string;
  firstSeen?: number;
  lastUpdate: number;
  source: 'static_migration' | 'dynamic' | 'manual';
  migrated?: boolean;
}

interface RequestHistoryEntry {
  readonly timestamp: number;
  readonly method?: string;
  readonly path?: string;
  readonly userAgent?: string;
  readonly score?: number;
}

interface MigrationRecord {
  readonly completed: number;
  readonly count: number;
}

interface StaticReputationEntry {
  readonly score?: number;
  readonly incidents?: number;
  readonly blacklisted?: boolean;
  readonly tags?: readonly string[];
  readonly notes?: string;
}

interface LevelDatabase {
  put(key: string, value: unknown): Promise<void>;
  get(key: string): Promise<unknown>;
  del(key: string): Promise<void>;
  batch(operations: readonly DatabaseOperation[]): Promise<void>;
  createReadStream(options?: DatabaseStreamOptions): AsyncIterable<DatabaseEntry>;
  iterator(options?: DatabaseStreamOptions): AsyncIterable<[string, unknown]>;
}

interface DatabaseStreamOptions {
  readonly gte?: string;
  readonly lte?: string;
  readonly limit?: number;
  readonly reverse?: boolean;
}

interface DatabaseEntry {
  readonly key: string;
  readonly value: unknown;
}

type SanitizeFeaturesFunction = (features: Record<string, unknown> | ThreatFeatures) => SanitizedFeatures;

// =============================================================================
// DATABASE INITIALIZATION
// =============================================================================

// Database paths
const threatDBPath = join(rootDir, 'db', 'threats');
const behaviorDBPath = join(rootDir, 'db', 'behavior');

// Ensure database directories exist
fs.mkdirSync(threatDBPath, { recursive: true });
fs.mkdirSync(behaviorDBPath, { recursive: true });

// Add read stream support for LevelDB
function addReadStreamSupport(dbInstance: any): LevelDatabase {
  if (!dbInstance.createReadStream) {
    dbInstance.createReadStream = (opts?: DatabaseStreamOptions): AsyncIterable<DatabaseEntry> => 
      Readable.from((async function* () {
        for await (const [key, value] of dbInstance.iterator(opts)) {
          yield { key, value };
        }
      })());
  }
  return dbInstance as LevelDatabase;
}

// Initialize databases with proper TTL and stream support
const rawThreatDB = addReadStreamSupport(new Level(threatDBPath, { valueEncoding: 'json' }));
export const threatDB: LevelDatabase = addReadStreamSupport(
  ttl(rawThreatDB, { defaultTTL: DB_TTL_CONFIG.THREAT_DB_TTL })
);

const rawBehaviorDB = addReadStreamSupport(new Level(behaviorDBPath, { valueEncoding: 'json' }));
export const behaviorDB: LevelDatabase = addReadStreamSupport(
  ttl(rawBehaviorDB, { defaultTTL: DB_TTL_CONFIG.BEHAVIOR_DB_TTL })
);

// =============================================================================
// DATABASE OPERATIONS
// =============================================================================

/**
 * Stores a threat assessment in the database with automatic TTL
 * @param clientIP - The IP address being assessed
 * @param assessment - The threat assessment data
 */
export async function storeAssessment(clientIP: string, assessment: ThreatAssessment | AssessmentData): Promise<void> {
  try {
    // Input validation
    if (!clientIP || typeof clientIP !== 'string') {
      throw new Error('Invalid client IP provided');
    }
    
    if (!assessment || typeof assessment !== 'object') {
      throw new Error('Invalid assessment data provided');
    }

    const key = `assessment:${clientIP}:${Date.now()}`;
    
    // Store assessment with TTL to prevent unbounded growth
    await threatDB.put(key, assessment);
  } catch (err) {
    const error = err as Error;
    // CRITICAL: Database errors should not crash the threat scorer
    // Log the error but continue processing - the system can function without
    // storing assessments, though learning capabilities will be reduced
    console.error('Failed to store threat assessment:', error.message);
  }
}

/**
 * Updates behavioral models based on observed client behavior
 * @param clientIP - The IP address to update
 * @param features - Extracted threat features
 * @param score - Calculated threat score
 * @param sanitizeFeatures - Function to sanitize features for storage
 */
export async function updateBehavioralModels(
  clientIP: string,
  features: Record<string, unknown> | ThreatFeatures,
  score: number,
  sanitizeFeatures: SanitizeFeaturesFunction
): Promise<void> {
  try {
    // Input validation
    if (!clientIP || typeof clientIP !== 'string') {
      throw new Error('Invalid client IP provided');
    }
    
    if (typeof score !== 'number' || score < 0 || score > 100) {
      throw new Error('Invalid threat score provided');
    }

    // Batch database operations for better performance
    const operations: DatabaseOperation[] = [];

    // Update IP behavior history
    const behaviorKey = `behavior:${clientIP}`;
    const existingBehavior = await getBehaviorData(clientIP);
    
    const behaviorData: BehaviorData = {
      lastScore: score,
      lastSeen: Date.now(),
      features: sanitizeFeatures(features) as unknown as Record<string, unknown>,
      requestCount: (existingBehavior?.requestCount || 0) + 1
    };

    operations.push({
      type: 'put',
      key: behaviorKey,
      value: behaviorData
    });

    // Update reputation based on observed behavior (automatic reputation management)
    await updateIPReputation(clientIP, score, features as ThreatFeatures, operations);

    // Execute batch operation if we have operations to perform
    if (operations.length > 0) {
      await behaviorDB.batch(operations);
    }
  } catch (err) {
    const error = err as Error;
    // Log but don't throw - behavioral model updates shouldn't crash the system
    console.error('Failed to update behavioral models:', error.message);
  }
}

/**
 * Automatic IP reputation management based on observed behavior
 * @param clientIP - The IP address to update
 * @param score - Current threat score
 * @param features - Threat features detected
 * @param operations - Array to append database operations to
 */
export async function updateIPReputation(
  clientIP: string,
  score: number,
  features: ThreatFeatures,
  operations: DatabaseOperation[]
): Promise<void> {
  try {
    const currentRep: ReputationData = await getReputationData(clientIP) || {
      score: 0,
      incidents: 0,
      blacklisted: false,
      tags: [],
      firstSeen: Date.now(),
      lastUpdate: Date.now(),
      source: 'dynamic'
    };

    let reputationChanged = false;
    const now = Date.now();

    // Automatic reputation scoring based on behavior
    if (score >= 90) {
      // Critical threat - significant reputation penalty
      currentRep.score = Math.min(100, currentRep.score + 25);
      currentRep.incidents += 1;
      currentRep.tags = Array.from(new Set([...currentRep.tags, 'critical_threat']));
      reputationChanged = true;
    } else if (score >= 75) {
      // High threat - moderate reputation penalty  
      currentRep.score = Math.min(100, currentRep.score + 15);
      currentRep.incidents += 1;
      currentRep.tags = Array.from(new Set([...currentRep.tags, 'high_threat']));
      reputationChanged = true;
    } else if (score >= 50) {
      // Medium threat - small reputation penalty
      currentRep.score = Math.min(100, currentRep.score + 5);
      currentRep.tags = Array.from(new Set([...currentRep.tags, 'medium_threat']));
      reputationChanged = true;
    } else if (score <= 10) {
      // Very low threat - slowly improve reputation for good behavior
      currentRep.score = Math.max(0, currentRep.score - 1);
      if (currentRep.score === 0) {
        currentRep.tags = currentRep.tags.filter(tag => !tag.includes('threat'));
      }
      reputationChanged = true;
    }

    // Add specific behavior tags for detailed tracking
    if (features.userAgent?.isAttackTool) {
      currentRep.tags = Array.from(new Set([...currentRep.tags, 'attack_tool']));
      currentRep.score = Math.min(100, currentRep.score + 20);
      reputationChanged = true;
    }

    if (features.pattern?.patternAnomalies?.includes('enumeration_detected')) {
      currentRep.tags = Array.from(new Set([...currentRep.tags, 'enumeration']));
      currentRep.score = Math.min(100, currentRep.score + 10);
      reputationChanged = true;
    }

    if (features.pattern?.patternAnomalies?.includes('bruteforce_detected')) {
      currentRep.tags = Array.from(new Set([...currentRep.tags, 'bruteforce']));
      currentRep.score = Math.min(100, currentRep.score + 15);
      reputationChanged = true;
    }

    if (features.velocity?.impossibleTravel) {
      currentRep.tags = Array.from(new Set([...currentRep.tags, 'impossible_travel']));
      currentRep.score = Math.min(100, currentRep.score + 12);
      reputationChanged = true;
    }

    // Automatic blacklisting for consistently bad actors
    if (currentRep.score >= 80 && currentRep.incidents >= 5) {
      currentRep.blacklisted = true;
      currentRep.tags = Array.from(new Set([...currentRep.tags, 'auto_blacklisted']));
      reputationChanged = true;
      console.log(`Threat scorer: Auto-blacklisted ${clientIP} (score: ${currentRep.score}, incidents: ${currentRep.incidents})`);
    }

    // Automatic reputation decay over time (good IPs recover slowly)
    const daysSinceLastUpdate = (now - currentRep.lastUpdate) / (1000 * 60 * 60 * 24);
    if (daysSinceLastUpdate > 7 && currentRep.score > 0) {
      // Decay reputation by 1 point per week for inactive IPs
      const decayAmount = Math.floor(daysSinceLastUpdate / 7);
      currentRep.score = Math.max(0, currentRep.score - decayAmount);
      if (currentRep.score < 50) {
        currentRep.blacklisted = false; // Unblacklist if score drops
      }
      reputationChanged = true;
    }

    // Only update database if reputation actually changed
    if (reputationChanged) {
      currentRep.lastUpdate = now;
      operations.push({
        type: 'put',
        key: `reputation:${clientIP}`,
        value: currentRep
      });
      
      console.log(`Threat scorer: Updated reputation for ${clientIP}: score=${currentRep.score}, incidents=${currentRep.incidents}, tags=[${currentRep.tags.join(', ')}]`);
    }
  } catch (err) {
    const error = err as Error;
    console.error('Failed to update IP reputation:', error.message);
  }
}

// =============================================================================
// HELPER METHODS
// =============================================================================

/**
 * Retrieves behavioral data for a specific IP address
 * @param clientIP - The IP address to look up
 * @returns Behavioral data or null if not found
 */
export async function getBehaviorData(clientIP: string): Promise<BehaviorData | null> {
  try {
    if (!clientIP || typeof clientIP !== 'string') {
      return null;
    }
    
    const data = await behaviorDB.get(`behavior:${clientIP}`);
    return data as BehaviorData;
  } catch (err) {
    return null; // Key doesn't exist or database error
  }
}

/**
 * Retrieves reputation data for a specific IP address
 * @param clientIP - The IP address to look up
 * @returns Reputation data or null if not found
 */
export async function getReputationData(clientIP: string): Promise<ReputationData | null> {
  try {
    if (!clientIP || typeof clientIP !== 'string') {
      return null;
    }
    
    const data = await threatDB.get(`reputation:${clientIP}`);
    return data as ReputationData;
  } catch (err) {
    return null; // Key doesn't exist or database error
  }
}

/**
 * Gets request history from database within a specific time window
 * @param ip - The IP address to get history for
 * @param timeWindow - Time window in milliseconds
 * @returns Array of request history entries
 */
export async function getRequestHistory(ip: string, timeWindow: number): Promise<RequestHistoryEntry[]> {
  const history: RequestHistoryEntry[] = [];
  
  // Input validation
  if (!ip || typeof ip !== 'string') {
    return history;
  }
  
  if (typeof timeWindow !== 'number' || timeWindow <= 0) {
    return history;
  }

  const cutoff = Date.now() - timeWindow;

  try {
    // Get from database
    const stream = threatDB.createReadStream({
      gte: `request:${ip}:${cutoff}`,
      lte: `request:${ip}:${Date.now()}`,
      limit: 1000
    });

    for await (const { value } of stream) {
      const entry = value as RequestHistoryEntry;
      if (entry.timestamp && entry.timestamp > cutoff) {
        history.push(entry);
      }
    }
  } catch (err) {
    const error = err as Error;
    console.warn('Failed to get request history:', error.message);
  }

  return history;
}

/**
 * One-time migration of static IP reputation data to database
 * Safely migrates existing JSON reputation data to the new database format
 */
export async function migrateStaticReputationData(): Promise<void> {
  try {
    const ipReputationPath = join(rootDir, 'data', 'ip-reputation.json');
    
    if (!fs.existsSync(ipReputationPath)) {
      return;
    }

    // Check if we've already migrated
    const migrationKey = 'reputation:migration:completed';
    try {
      await threatDB.get(migrationKey);
      return; // Already migrated
    } catch (err) {
      // Not migrated yet, proceed
    }

    console.log('Threat scorer: Migrating static IP reputation data to database...');
    
    const staticDataRaw = fs.readFileSync(ipReputationPath, 'utf8');
    const staticData = JSON.parse(staticDataRaw) as Record<string, StaticReputationEntry>;
    const operations: DatabaseOperation[] = [];

    for (const [ip, repData] of Object.entries(staticData)) {
      // Validate IP format (basic validation)
      if (!ip || typeof ip !== 'string') {
        console.warn(`Skipping invalid IP during migration: ${ip}`);
        continue;
      }

      const migratedData: ReputationData = {
        score: repData.score || 0,
        incidents: repData.incidents || 0,
        blacklisted: repData.blacklisted || false,
        tags: Array.isArray(repData.tags) ? [...repData.tags] : [],
        notes: repData.notes || '',
        lastUpdate: Date.now(),
        source: 'static_migration',
        migrated: true
      };

      operations.push({
        type: 'put',
        key: `reputation:${ip}`,
        value: migratedData
      });
    }

    // Mark migration as complete
    const migrationRecord: MigrationRecord = {
      completed: Date.now(),
      count: operations.length
    };

    operations.push({
      type: 'put',
      key: migrationKey,
      value: migrationRecord
    });

    if (operations.length > 1) {
      await threatDB.batch(operations);
      console.log(`Threat scorer: Migrated ${operations.length - 1} IP reputation records to database`);

      // Optionally archive the static file
      const archivePath = ipReputationPath + '.migrated';
      fs.renameSync(ipReputationPath, archivePath);
      console.log(`Threat scorer: Static IP reputation file archived to ${archivePath}`);
    }
  } catch (err) {
    const error = err as Error;
    console.error('Failed to migrate static IP reputation data:', error.message);
  }
}