/*global Buffer require exports console setTimeout */

var net = require("net"),
    util = require("./lib/util").util,
    Queue = require("./lib/queue").Queue,
    to_array = require("./lib/to_array"),
    events = require("events"),
    parsers = [], commands,
    default_port = 6379,
    default_host = "127.0.0.1";

// can set this to true to enable for all connections
exports.debug_mode = false;

// hiredis might not be installed
try {
    require("./lib/parser/hiredis");
    parsers.push(require("./lib/parser/hiredis"));
} catch (err) {
    if (exports.debug_mode) {
        console.log("hiredis parser not installed.");
    }
}

parsers.push(require("./lib/parser/javascript"));

function RedisClient(stream, options) {
    this.stream = stream;
    this.options = options || {};

    this.connected = false;
    this.ready = false;
    this.connections = 0;
    this.attempts = 1;
    this.command_queue = new Queue(); // holds sent commands to de-pipeline them
    this.offline_queue = new Queue(); // holds commands issued but not able to be sent
    this.commands_sent = 0;
    this.retry_delay = 250; // inital reconnection delay
    this.current_retry_delay = this.retry_delay;
    this.retry_backoff = 1.7; // each retry waits current delay * retry_backoff
    this.subscriptions = false;
    this.monitoring = false;
    this.closing = false;
    this.server_info = {};
    this.auth_pass = null;

    var parser_module, self = this;

    if (self.options.parser) {
        if (! parsers.some(function (parser) {
            if (parser.name === self.options.parser) {
                parser_module = parser;
                if (exports.debug_mode) {
                    console.log("Using parser module: " + parser_module.name);
                }
                return true;
            }
        })) {
            throw new Error("Couldn't find named parser " + self.options.parser + " on this system");
        }
    } else {
        if (exports.debug_mode) {
            console.log("Using default parser module: " + parsers[0].name);
        }
        parser_module = parsers[0];
    }

    parser_module.debug_mode = exports.debug_mode;
    this.reply_parser = new parser_module.Parser({
        return_buffers: self.options.return_buffers || false
    });

    // "reply error" is an error sent back by Redis
    this.reply_parser.on("reply error", function (reply) {
        self.return_error(new Error(reply));
    });
    this.reply_parser.on("reply", function (reply) {
        self.return_reply(reply);
    });
    // "error" is bad.  Somehow the parser got confused.  It'll try to reset and continue.
    this.reply_parser.on("error", function (err) {
        self.emit("error", new Error("Redis reply parser error: " + err.stack));
    });

    this.stream.on("connect", function () {
        self.on_connect();
    });

    this.stream.on("data", function (buffer_from_socket) {
        self.on_data(buffer_from_socket);
    });

    this.stream.on("error", function (msg) {
        if (this.closing) {
            return;
        }

        var message = "Redis connection to " + self.host + ":" + self.port + " failed - " + msg.message;

        if (exports.debug_mode) {
            console.warn(message);
        }
        self.offline_queue.forEach(function (args) {
            if (typeof args[2] === "function") {
                args[2](message);
            }
        });
        self.offline_queue = new Queue();

        self.command_queue.forEach(function (args) {
            if (typeof args[2] === "function") {
                args[2](message);
            }
        });
        self.command_queue = new Queue();

        self.connected = false;
        self.ready = false;

        self.emit("error", new Error(message));
        // "error" events get turned into exceptions if they aren't listened for.  If the user handled this error
        // then we should try to reconnect.
        self.connection_gone("error");
    });

    this.stream.on("close", function () {
        self.connection_gone("close");
    });

    this.stream.on("end", function () {
        self.connection_gone("end");
    });

    this.stream.on("drain", function () {
        self.emit("drain");
    });

    events.EventEmitter.call(this);
}
util.inherits(RedisClient, events.EventEmitter);
exports.RedisClient = RedisClient;

RedisClient.prototype.on_connect = function () {
    if (exports.debug_mode) {
        console.log("Stream connected " + this.host + ":" + this.port + " fd " + this.stream.fd);
    }
    var self = this;

    this.connected = true;
    this.ready = false;
    this.attempts = 0;
    this.connections += 1;
    this.command_queue = new Queue();
    this.emitted_end = false;
    this.retry_timer = null;
    this.current_retry_delay = this.retry_time;
    this.stream.setNoDelay();
    this.stream.setTimeout(0);

    if (this.auth_pass) {
        if (exports.debug_mode) {
            console.log("Sending auth to " + this.host + ":" + this.port + " fd " + this.stream.fd);
        }
        self.send_anyway = true;
        self.send_command("auth", this.auth_pass, function (err, res) {
            if (err) {
                return self.emit("error", "Auth error: " + err);
            }
            if (res.toString() !== "OK") {
                return self.emit("error", "Auth failed: " + res.toString());
            }
            if (exports.debug_mode) {
                console.log("Auth succeeded " + self.host + ":" + self.port + " fd " + self.stream.fd);
            }
            if (self.auth_callback) {
                self.auth_callback(err, res);
                self.auth_callback = null;
            }
        });
        self.send_anyway = false;
    }

    this.emit("connect");

    if (this.options.no_ready_check) {
        this.ready = true;
        this.send_offline_queue();
    } else {
        this.ready_check();
    }
};

RedisClient.prototype.ready_check = function () {
    var self = this;

    function send_info_cmd() {
        if (exports.debug_mode) {
            console.log("checking server ready state...");
        }

        self.send_anyway = true;  // secret flag to send_command to send something even if not "ready"
        self.info(function (err, res) {
            if (err) {
                return self.emit("error", "Ready check failed: " + err);
            }

            var lines = res.toString().split("\r\n"), obj = {}, retry_time;

            lines.forEach(function (line) {
                var parts = line.split(':');
                if (parts[1]) {
                    obj[parts[0]] = parts[1];
                }
            });

            obj.versions = [];
            obj.redis_version.split('.').forEach(function (num) {
                obj.versions.push(+num);
            });

            // expose info key/vals to users
            self.server_info = obj;

            if (!obj.loading || (obj.loading && obj.loading === "0")) {
                if (exports.debug_mode) {
                    console.log("Redis server ready.");
                }
                self.ready = true;

                self.send_offline_queue();
                self.emit("ready");
            } else {
                retry_time = obj.loading_eta_seconds * 1000;
                if (retry_time > 1000) {
                    retry_time = 1000;
                }
                if (exports.debug_mode) {
                    console.log("Redis server still loading, trying again in " + retry_time);
                }
                setTimeout(send_info_cmd, retry_time);
            }
        });
        self.send_anyway = false;
    }

    send_info_cmd();
};

RedisClient.prototype.send_offline_queue = function () {
    var command_obj;
    while (this.offline_queue.length > 0) {
        command_obj = this.offline_queue.shift();
        if (exports.debug_mode) {
            console.log("Sending offline command: " + command_obj.command);
        }
        this.send_command(command_obj.command, command_obj.args, command_obj.callback);
    }
    this.offline_queue = new Queue();
    // Even though items were shifted off, Queue backing store still uses memory until next add
};

RedisClient.prototype.connection_gone = function (why) {
    var self = this;

    // If a retry is already in progress, just let that happen
    if (this.retry_timer) {
        return;
    }

    // Note that this may trigger another "close" or "end" event
    this.stream.destroy();

    if (exports.debug_mode) {
        console.warn("Redis connection is gone from " + why + " event.");
    }
    this.connected = false;
    this.ready = false;
    this.subscriptions = false;
    this.monitoring = false;

    // since we are collapsing end and close, users don't expect to be called twice
    if (! this.emitted_end) {
        this.emit("end");
        this.emitted_end = true;
    }

    this.command_queue.forEach(function (args) {
        if (typeof args[2] === "function") {
            args[2]("Server connection closed");
        }
    });
    this.command_queue = new Queue();

    // If this is a requested shutdown, then don't retry
    if (this.closing) {
        this.retry_timer = null;
        return;
    }

    this.current_retry_delay = this.retry_delay * this.retry_backoff;

    if (exports.debug_mode) {
        console.log("Retry connection in " + this.current_retry_delay + " ms");
    }
    this.attempts += 1;
    this.emit("reconnecting", {
        delay: this.current_retry_delay,
        attempt: this.attempts
    });
    this.retry_timer = setTimeout(function () {
        if (exports.debug_mode) {
            console.log("Retrying connection...");
        }
        self.stream.connect(self.port, self.host);
        self.retry_timer = null;
    }, this.current_retry_delay);
};

RedisClient.prototype.on_data = function (data) {
    if (exports.debug_mode) {
        console.log("net read " + this.host + ":" + this.port + " fd " + this.stream.fd + ": " + data.toString());
    }

    try {
        this.reply_parser.execute(data);
    } catch (err) {
        // This is an unexpected parser problem, an exception that came from the parser code itself.
        // Parser should emit "error" events if it notices things are out of whack.
        // Callbacks that throw exceptions will land in return_reply(), below.
        // TODO - it might be nice to have a different "error" event for different types of errors
        this.emit("error", err);
    }
};

RedisClient.prototype.return_error = function (err) {
    var command_obj = this.command_queue.shift();

    if (this.subscriptions === false && this.command_queue.length === 0) {
        this.emit("idle");
        this.command_queue = new Queue();
    }

    if (command_obj && typeof command_obj.callback === "function") {
        try {
            command_obj.callback(err);
        } catch (callback_err) {
            // if a callback throws an exception, re-throw it on a new stack so the parser can keep going
            process.nextTick(function () {
                throw callback_err;
            });
        }
    } else {
        console.log("node_redis: no callback to send error: " + err.message);
        // this will probably not make it anywhere useful, but we might as well throw
        process.nextTick(function () {
            throw err;
        });
    }
};

RedisClient.prototype.return_reply = function (reply) {
    var command_obj = this.command_queue.shift(),
        obj, i, len, key, val, type, timestamp, args;

    if (this.subscriptions === false && this.command_queue.length === 0) {
        this.emit("idle");
        this.command_queue = new Queue();
    }

    if (command_obj && !command_obj.sub_command) {
        if (typeof command_obj.callback === "function") {
            // HGETALL special case replies with keyed Buffers
            if (reply && 'hgetall' === command_obj.command.toLowerCase()) {
                obj = {};
                for (i = 0, len = reply.length; i < len; i += 2) {
                    key = reply[i].toString();
                    val = reply[i + 1];
                    obj[key] = val;
                }
                reply = obj;
            }

            try {
                command_obj.callback(null, reply);
            } catch (err) {
                // if a callback throws an exception, re-throw it on a new stack so the parser can keep going
                process.nextTick(function () {
                    throw err;
                });
            }
        } else if (exports.debug_mode) {
            console.log("no callback for reply: " + (reply && reply.toString && reply.toString()));
        }
    } else if (this.subscriptions || (command_obj && command_obj.sub_command)) {
        if (Array.isArray(reply)) {
            type = reply[0].toString();

            if (type === "message") {
                this.emit("message", reply[1].toString(), reply[2]); // channel, message
            } else if (type === "pmessage") {
                this.emit("pmessage", reply[1].toString(), reply[2].toString(), reply[3]); // pattern, channel, message
            } else if (type === "subscribe" || type === "unsubscribe" || type === "psubscribe" || type === "punsubscribe") {
                if (reply[2] === 0) {
                    this.subscriptions = false;
                    if (this.debug_mode) {
                        console.log("All subscriptions removed, exiting pub/sub mode");
                    }
                }
                this.emit(type, reply[1].toString(), reply[2]); // channel, count
            } else {
                throw new Error("subscriptions are active but got unknown reply type " + type);
            }
        } else if (! this.closing) {
            throw new Error("subscriptions are active but got an invalid reply: " + reply);
        }
    } else if (this.monitoring) {
        len = reply.indexOf(" ");
        timestamp = reply.slice(0, len);
        args = reply.slice(len + 1).match(/"[^"]+"/g).map(function (elem) {
            return elem.replace(/"/g, "");
        });
        this.emit("monitor", timestamp, args);
    } else {
        throw new Error("node_redis command queue state error. If you can reproduce this, please report it.");
    }
};

RedisClient.prototype.send_command = function () {
    var command, callback, arg, args, this_args, command_obj, i, il,
        elem_count, stream = this.stream, buffer_args, command_str = "";

    this_args = to_array(arguments);

    if (this_args.length === 0) {
        throw new Error("send_command: not enough arguments");
    }

    if (typeof this_args[0] !== "string") {
        throw new Error("First argument of send_command must be the command name");
    }
    command = this_args[0].toLowerCase();

    if (this_args[1] && Array.isArray(this_args[1])) {
        args = this_args[1];
        if (typeof this_args[2] === "function") {
            callback = this_args[2];
        }
    } else {
        if (typeof this_args[this_args.length - 1] === "function") {
            callback = this_args[this_args.length - 1];
            args = this_args.slice(1, this_args.length - 1);
        } else {
            args = this_args.slice(1, this_args.length);
        }
    }

    if (args.length === 2 && Array.isArray(args[1])) {
        args = [args[0]].concat(args[1]);
    }

    command_obj = {
        command: command,
        args: args,
        callback: callback,
        sub_command: false
    };

    if (!this.ready && !this.send_anyway) {
        if (exports.debug_mode) {
            console.log("Queueing " + command + " for next server connection.");
        }
        this.offline_queue.push(command_obj);
        return;
    }

    if (command === "subscribe" || command === "psubscribe" || command === "unsubscribe" || command === "punsubscribe") {
        if (this.subscriptions === false && exports.debug_mode) {
            console.log("Entering pub/sub mode from " + command);
        }
        command_obj.sub_command = true;
        this.subscriptions = true;
    } else if (command === "monitor") {
        this.monitoring = true;
    } else if (command === "quit") {
        this.closing = true;
    } else if (this.subscriptions === true) {
        throw new Error("Connection in pub/sub mode, only pub/sub commands may be used");
    }
    this.command_queue.push(command_obj);
    this.commands_sent += 1;

    elem_count = 1;
    buffer_args = false;

    elem_count += args.length;
    // Probably should just scan this like a normal person. This is clever, but might be slow.
    buffer_args = args.some(function (arg) {
        return arg instanceof Buffer;
    });

    // Always use "Multi bulk commands", but if passed any Buffer args, then do multiple writes, one for each arg
    // This means that using Buffers in commands is going to be slower, so use Strings if you don't already have a Buffer.
    // Also, why am I putting user documentation in the library source code?

    command_str = "*" + elem_count + "\r\n$" + command.length + "\r\n" + command + "\r\n";

    if (! stream.writable && exports.debug_mode) {
        console.log("send command: stream is not writeable, should get a close event next tick.");
        return;
    }

    if (! buffer_args) { // Build up a string and send entire command in one write
        for (i = 0, il = args.length, arg; i < il; i += 1) {
            arg = args[i];
            if (typeof arg !== "string") {
                arg = String(arg);
            }
            command_str += "$" + Buffer.byteLength(arg) + "\r\n" + arg + "\r\n";
        }
        if (exports.debug_mode) {
            console.log("send " + this.host + ":" + this.port + " fd " + this.stream.fd + ": " + command_str);
        }
        stream.write(command_str);
    } else {
        if (exports.debug_mode) {
            console.log("send command: " + command_str);
            console.log("send command has Buffer arguments");
        }
        stream.write(command_str);

        for (i = 0, il = args.length, arg; i < il; i += 1) {
            arg = args[i];
            if (!(arg instanceof Buffer || arg instanceof String)) {
                arg = String(arg);
            }

            if (arg instanceof Buffer) {
                if (arg.length === 0) {
                    if (exports.debug_mode) {
                        console.log("Using empty string for 0 length buffer");
                    }
                    stream.write("$0\r\n\r\n");
                } else {
                    stream.write("$" + arg.length + "\r\n");
                    stream.write(arg);
                    stream.write("\r\n");
                }
            } else {
                stream.write("$" + Buffer.byteLength(arg) + "\r\n" + arg + "\r\n");
            }
        }
    }
};

RedisClient.prototype.end = function () {
    this.stream._events = {};
    this.connected = false;
    this.ready = false;
    return this.stream.end();
};


function Multi(client, args) {
    this.client = client;
    this.queue = [["MULTI"]];
    if (Array.isArray(args)) {
        this.queue = this.queue.concat(args);
    }
}

// take 2 arrays and return the union of their elements
function set_union(seta, setb) {
    var obj = {};
    
    seta.forEach(function (val) {
        obj[val] = true;
    });
    setb.forEach(function (val) {
        obj[val] = true;
    });
    return Object.keys(obj);
}

// This static list of commands is updated from time to time.  ./lib/commands.js can be updated with generate_commands.js
commands = set_union(["get", "set", "setnx", "setex", "append", "strlen", "del", "exists", "setbit", "getbit", "setrange", "getrange", "substr",
    "incr", "decr", "mget", "rpush", "lpush", "rpushx", "lpushx", "linsert", "rpop", "lpop", "brpop", "brpoplpush", "blpop", "llen", "lindex",
    "lset", "lrange", "ltrim", "lrem", "rpoplpush", "sadd", "srem", "smove", "sismember", "scard", "spop", "srandmember", "sinter", "sinterstore",
    "sunion", "sunionstore", "sdiff", "sdiffstore", "smembers", "zadd", "zincrby", "zrem", "zremrangebyscore", "zremrangebyrank", "zunionstore",
    "zinterstore", "zrange", "zrangebyscore", "zrevrangebyscore", "zcount", "zrevrange", "zcard", "zscore", "zrank", "zrevrank", "hset", "hsetnx",
    "hget", "hmset", "hmget", "hincrby", "hdel", "hlen", "hkeys", "hvals", "hgetall", "hexists", "incrby", "decrby", "getset", "mset", "msetnx",
    "randomkey", "select", "move", "rename", "renamenx", "expire", "expireat", "keys", "dbsize", "auth", "ping", "echo", "save", "bgsave",
    "bgrewriteaof", "shutdown", "lastsave", "type", "multi", "exec", "discard", "sync", "flushdb", "flushall", "sort", "info", "monitor", "ttl",
    "persist", "slaveof", "debug", "config", "subscribe", "unsubscribe", "psubscribe", "punsubscribe", "publish", "watch", "unwatch", "cluster",
    "restore", "migrate", "dump", "object", "client", "eval", "evalsha"], require("./lib/commands"));

commands.forEach(function (command) {
    RedisClient.prototype[command] = function () {
        var args = to_array(arguments);
        args.unshift(command); // put command at the beginning
        this.send_command.apply(this, args);
    };
    RedisClient.prototype[command.toUpperCase()] = RedisClient.prototype[command];

    Multi.prototype[command] = function () {
        var args = to_array(arguments);
        args.unshift(command);
        this.queue.push(args);
        return this;
    };
    Multi.prototype[command.toUpperCase()] = Multi.prototype[command];
});

// Stash auth for connect and reconnect.  Send immediately if already connected.
RedisClient.prototype.auth = function () {
    var args = to_array(arguments);
    this.auth_pass = args[0];
    this.auth_callback = args[1];
    if (exports.debug_mode) {
        console.log("Saving auth as " + this.auth_pass);
    }

    if (this.connected) {
        args.unshift("auth");
        this.send_command.apply(this, args);
    }
};
RedisClient.prototype.AUTH = RedisClient.prototype.auth;

RedisClient.prototype.hmset = function () {
    var args = to_array(arguments), tmp_args;
    if (args.length >= 2 && typeof args[0] === "string" && typeof args[1] === "object") {
        tmp_args = [ "hmset", args[0] ];
        Object.keys(args[1]).map(function (key) {
            tmp_args.push(key);
            tmp_args.push(args[1][key]);
        });
        if (args[2]) {
            tmp_args.push(args[2]);
        }
        args = tmp_args;
    } else {
        args.unshift("hmset");
    }

    this.send_command.apply(this, args);
};
RedisClient.prototype.HMSET = RedisClient.prototype.hmset;

Multi.prototype.hmset = function () {
    var args = to_array(arguments), tmp_args;
    if (args.length >= 2 && typeof args[0] === "string" && typeof args[1] === "object") {
        tmp_args = [ "hmset", args[0] ];
        Object.keys(args[1]).map(function (key) {
            tmp_args.push(key);
            tmp_args.push(args[1][key]);
        });
        if (args[2]) {
            tmp_args.push(args[2]);
        }
        args = tmp_args;
    } else {
        args.unshift("hmset");
    }

    this.queue.push(args);
    return this;
};
Multi.prototype.HMSET = Multi.prototype.hmset;

Multi.prototype.exec = function (callback) {
    var self = this;

    // drain queue, callback will catch "QUEUED" or error
    // Can't use a for loop here, as we need closure around the index.
    this.queue.forEach(function (args, index) {
        var command = args[0], obj;
        if (typeof args[args.length - 1] === "function") {
            args = args.slice(1, -1);
        } else {
            args = args.slice(1);
        }
        if (args.length === 1 && Array.isArray(args[0])) {
            args = args[0];
        }
        if (command === 'hmset' && typeof args[1] === 'object') {
            obj = args.pop();
            Object.keys(obj).forEach(function (key) {
                args.push(key);
                args.push(obj[key]);
            });
        }
        this.client.send_command(command, args, function (err, reply) {
            if (err) {
                var cur = self.queue[index];
                if (typeof cur[cur.length - 1] === "function") {
                    cur[cur.length - 1](err);
                } else {
                    throw new Error(err);
                }
                self.queue.splice(index, 1);
            }
        });
    }, this);

    this.client.send_command("EXEC", function (err, replies) {
        if (err) {
            if (callback) {
                callback(new Error(err));
                return;
            } else {
                throw new Error(err);
            }
        }

        var i, il, j, jl, reply, args, obj, key, val;

        if (replies) {
            for (i = 1, il = self.queue.length; i < il; i += 1) {
                reply = replies[i - 1];
                args = self.queue[i];

                // Convert HGETALL reply to object
                if (reply && args[0].toLowerCase() === "hgetall") {
                    obj = {};
                    for (j = 0, jl = reply.length; j < jl; j += 2) {
                        key = reply[j].toString();
                        val = reply[j + 1];
                        obj[key] = val;
                    }
                    replies[i - 1] = reply = obj;
                }

                if (typeof args[args.length - 1] === "function") {
                    args[args.length - 1](null, reply);
                }
            }
        }

        if (callback) {
            callback(null, replies);
        }
    });
};

RedisClient.prototype.multi = function (args) {
    return new Multi(this, args);
};
RedisClient.prototype.MULTI = function (args) {
    return new Multi(this, args);
};

exports.createClient = function (port_arg, host_arg, options) {
    var port = port_arg || default_port,
        host = host_arg || default_host,
        redis_client, net_client;

    net_client = net.createConnection(port, host);

    redis_client = new RedisClient(net_client, options);

    redis_client.port = port;
    redis_client.host = host;

    return redis_client;
};

exports.print = function (err, reply) {
    if (err) {
        console.log("Error: " + err);
    } else {
        console.log("Reply: " + reply);
    }
};