var redis = require('redis');
var winston = require('winston');

// For storing in redis or KeyDB (Redis API compatible)
// options[type] = redis
// options[host] - The host to connect to (default localhost)
// options[port] - The port to connect to (default 6379)
// options[db] - The db to use (default 0)
// options[password] - The password to use (if any)
// options[expire] - The time to live for each key set (default never)
// options[connectionTimeout] - Connection timeout in ms (default 5000)

var RedisDocumentStore = function(options, client) {
  this.expire = options.expire;
  if (client) {
    winston.info('using predefined redis client');
    RedisDocumentStore.client = client;
    
    // Check if we need to promisify the client (for redis-url 0.1.0)
    if (!RedisDocumentStore.client.connect && !RedisDocumentStore.isLegacyClient) {
      winston.info('using legacy redis client from redis-url');
      RedisDocumentStore.isLegacyClient = true;
    }
  } else if (!RedisDocumentStore.client) {
    winston.info('configuring redis/keydb client');
    RedisDocumentStore.connect(options);
  }
};

// Create a connection according to config
RedisDocumentStore.connect = async function(options) {
  var host = options.host || '127.0.0.1';
  var port = options.port || 6379;
  var index = options.db || 0;
  var connectionTimeout = options.connectionTimeout || 5000;
  
  const redisOptions = {
    socket: {
      host: host,
      port: port,
      connectTimeout: connectionTimeout
    },
    database: index
  };
  
  // Add password if provided
  if (options.password) {
    redisOptions.password = options.password;
  }
  
  // Add URL if provided (overrides other options)
  if (options.url) {
    delete redisOptions.socket;
    delete redisOptions.database;
    redisOptions.url = options.url;
  }
  
  try {
    RedisDocumentStore.client = redis.createClient(redisOptions);
    
    // Set up error handling
    RedisDocumentStore.client.on('error', (err) => {
      winston.error('Redis/KeyDB error', { error: err });
    });
    
    // Connect the client
    await RedisDocumentStore.client.connect();
    
    winston.info('connected to redis/keydb on ' + host + ':' + port + '/' + index);
  }
  catch (err) {
    winston.error('error connecting to redis/keydb', { error: err });
    process.exit(1);
  }
};

// Save file in a key
RedisDocumentStore.prototype.set = async function(key, data, callback, skipExpire) {
  var _this = this;
  
  try {
    // Handle legacy client (redis-url 0.1.0)
    if (RedisDocumentStore.isLegacyClient) {
      RedisDocumentStore.client.set(key, data, function(err) {
        if (err) {
          winston.error('error setting key', { error: err });
          callback(false);
          return;
        }
        
        if (!skipExpire) {
          _this.setExpiration(key);
        }
        callback(true);
      });
      return;
    }
    
    // Modern redis 4.x client
    await RedisDocumentStore.client.set(key, data);
    
    if (!skipExpire) {
      _this.setExpiration(key);
    }
    callback(true);
  }
  catch (err) {
    winston.error('error setting key', { error: err });
    callback(false);
  }
};

// Expire a key in expire time if set
RedisDocumentStore.prototype.setExpiration = async function(key) {
  if (this.expire) {
    try {
      if (RedisDocumentStore.isLegacyClient) {
        RedisDocumentStore.client.expire(key, this.expire, function(err) {
          if (err) {
            winston.error('failed to set expiry on key: ' + key, { error: err });
          }
        });
        return;
      }
      
      await RedisDocumentStore.client.expire(key, this.expire);
    }
    catch (err) {
      winston.error('failed to set expiry on key: ' + key, { error: err });
    }
  }
};

// Get a file from a key
RedisDocumentStore.prototype.get = async function(key, callback, skipExpire) {
  var _this = this;
  
  try {
    // Handle legacy client (redis-url 0.1.0)
    if (RedisDocumentStore.isLegacyClient) {
      RedisDocumentStore.client.get(key, function(err, reply) {
        if (err) {
          winston.error('error getting key', { error: err });
          callback(false);
          return;
        }
        
        if (reply && !skipExpire) {
          _this.setExpiration(key);
        }
        callback(reply);
      });
      return;
    }
    
    // Modern redis 4.x client
    const reply = await RedisDocumentStore.client.get(key);
    
    if (reply && !skipExpire) {
      _this.setExpiration(key);
    }
    callback(reply);
  }
  catch (err) {
    winston.error('error getting key', { error: err });
    callback(false);
  }
};

module.exports = RedisDocumentStore;