import Redis from 'ioredis';

const REDIS_HOST = process.env.REDIS_HOST || 'localhost';
const REDIS_PORT = parseInt(process.env.REDIS_PORT || '6379', 10);
const REDIS_PASSWORD = process.env.REDIS_PASSWORD || undefined;
const REDIS_DB = parseInt(process.env.REDIS_DB || '0', 10);

export const INDEX_NAME = 'hasher';

// Create Redis client with connection pooling
export const redisClient = new Redis({
  host: REDIS_HOST,
  port: REDIS_PORT,
  password: REDIS_PASSWORD,
  db: REDIS_DB,
  retryStrategy: (times) => {
    const delay = Math.min(times * 50, 2000);
    return delay;
  },
  maxRetriesPerRequest: 3,
  enableReadyCheck: true,
  lazyConnect: false,
});

// Handle connection errors
redisClient.on('error', (err) => {
  console.error('Redis Client Error:', err);
});

redisClient.on('connect', () => {
  console.log('Redis connected successfully');
});

/**
 * Redis Keys Structure:
 * 
 * 1. Hash documents: hash:plaintext:{plaintext} = JSON string
 *    - Stores all hash data for a plaintext
 * 
 * 2. Hash indexes: hash:index:{algorithm}:{hash} = plaintext
 *    - Allows reverse lookup from hash to plaintext
 *    - One key per algorithm (md5, sha1, sha256, sha512)
 * 
 * 3. Statistics: hash:stats = Hash {count, size}
 *    - count: total number of unique plaintexts
 *    - size: approximate total size in bytes
 */

export interface HashDocument {
  plaintext: string;
  md5: string;
  sha1: string;
  sha256: string;
  sha512: string;
  created_at: string;
}

/**
 * Store a hash document in Redis
 */
export async function storeHashDocument(doc: HashDocument): Promise<void> {
  const pipeline = redisClient.pipeline();
  
  // Store main document
  const key = `hash:plaintext:${doc.plaintext}`;
  pipeline.set(key, JSON.stringify(doc));
  
  // Create indexes for each hash type
  pipeline.set(`hash:index:md5:${doc.md5}`, doc.plaintext);
  pipeline.set(`hash:index:sha1:${doc.sha1}`, doc.plaintext);
  pipeline.set(`hash:index:sha256:${doc.sha256}`, doc.plaintext);
  pipeline.set(`hash:index:sha512:${doc.sha512}`, doc.plaintext);
  
  // Update statistics
  pipeline.hincrby('hash:stats', 'count', 1);
  pipeline.hincrby('hash:stats', 'size', JSON.stringify(doc).length);
  
  await pipeline.exec();
}

/**
 * Find a hash document by plaintext
 */
export async function findByPlaintext(plaintext: string): Promise<HashDocument | null> {
  const key = `hash:plaintext:${plaintext}`;
  const data = await redisClient.get(key);
  
  if (!data) return null;
  
  return JSON.parse(data) as HashDocument;
}

/**
 * Find a hash document by any hash value
 */
export async function findByHash(algorithm: string, hash: string): Promise<HashDocument | null> {
  const indexKey = `hash:index:${algorithm}:${hash}`;
  const plaintext = await redisClient.get(indexKey);
  
  if (!plaintext) return null;
  
  return findByPlaintext(plaintext);
}

/**
 * Check if plaintext or any of its hashes exist
 */
export async function checkExistence(plaintext: string, hashes: {
  md5: string;
  sha1: string;
  sha256: string;
  sha512: string;
}): Promise<boolean> {
  const pipeline = redisClient.pipeline();
  
  pipeline.exists(`hash:plaintext:${plaintext}`);
  pipeline.exists(`hash:index:md5:${hashes.md5}`);
  pipeline.exists(`hash:index:sha1:${hashes.sha1}`);
  pipeline.exists(`hash:index:sha256:${hashes.sha256}`);
  pipeline.exists(`hash:index:sha512:${hashes.sha512}`);
  
  const results = await pipeline.exec();
  
  if (!results) return false;
  
  // Check if any key exists
  return results.some(([err, value]) => !err && value === 1);
}

/**
 * Get index statistics
 */
export async function getStats(): Promise<{ count: number; size: number }> {
  const stats = await redisClient.hgetall('hash:stats');
  
  return {
    count: parseInt(stats.count || '0', 10),
    size: parseInt(stats.size || '0', 10)
  };
}

/**
 * Initialize Redis (compatibility function, Redis doesn't need explicit initialization)
 */
export async function initializeRedis(): Promise<void> {
  // Check connection
  await redisClient.ping();
  console.log('Redis initialized successfully');
}

/**
 * Get Redis info for health check
 */
export async function getRedisInfo(): Promise<{
  connected: boolean;
  version: string;
  usedMemory: number;
  dbSize: number;
}> {
  const info = await redisClient.info('server');
  const memory = await redisClient.info('memory');
  const dbSize = await redisClient.dbsize();
  
  // Parse Redis info string
  const parseInfo = (infoStr: string, key: string): string => {
    const match = infoStr.match(new RegExp(`${key}:(.+)`));
    return match ? match[1].trim() : 'unknown';
  };
  
  return {
    connected: redisClient.status === 'ready',
    version: parseInfo(info, 'redis_version'),
    usedMemory: parseInt(parseInfo(memory, 'used_memory'), 10) || 0,
    dbSize
  };
}

export { REDIS_HOST, REDIS_PORT };