/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * Base classes in node-js for storm Bolt and Spout.
 * Implements the storm multilang protocol for nodejs.
 */


var fs = require('fs');

function Storm() {
    this.messagePart = "";
    this.taskIdsCallbacks = [];
    this.isFirstMessage = true;
    this.separator = '\nend\n';
}

Storm.prototype.sendMsgToParent = function(msg) {
    var str = JSON.stringify(msg);
    process.stdout.write(str + this.separator);
}

Storm.prototype.sync = function() {
    this.sendMsgToParent({"command":"sync"});
}

Storm.prototype.sendPid = function(heartbeatdir) {
    var pid = process.pid;
    fs.closeSync(fs.openSync(heartbeatdir + "/" + pid, "w"));
    this.sendMsgToParent({"pid": pid})
}

Storm.prototype.log = function(msg) {
    this.sendMsgToParent({"command": "log", "msg": msg});
}

Storm.prototype.initSetupInfo = function(setupInfo) {
    var self = this;
    var callback = function() {
        self.sendPid(setupInfo['pidDir']);
    }
    this.initialize(setupInfo['conf'], setupInfo['context'], callback);
}

Storm.prototype.startReadingInput = function() {
    var self = this;
    process.stdin.on('readable', function() {
        var chunk = process.stdin.read();
        var messages = self.handleNewChunk(chunk);
        messages.forEach(function(message) {
            self.handleNewMessage(message);
        })

    });
}

/**
 * receives a new string chunk and returns a list of new messages with the separator removed
 * stores state in this.messagePart
 * @param chunk
 */
Storm.prototype.handleNewChunk = function(chunk) {
    //invariant: this.messagePart has no separator otherwise we would have parsed it already
    var messages = [];
    if (chunk && chunk.length !== 0) {
        //"{}".split("\nend\n")           ==> ['{}']
        //"\nend\n".split("\nend\n")      ==> [''  , '']
        //"{}\nend\n".split("\nend\n")    ==> ['{}', '']
        //"\nend\n{}".split("\nend\n")    ==> [''  , '{}']
        // "{}\nend\n{}".split("\nend\n") ==> ['{}', '{}' ]
        this.messagePart = this.messagePart + chunk;
        var newMessageParts = this.messagePart.split(this.separator);
        while (newMessageParts.length > 0) {
            var potentialMessage = newMessageParts.shift();
            var anotherMessageAhead = newMessageParts.length > 0;
            if  (!anotherMessageAhead) {
                this.messagePart = potentialMessage;
            }
            else if (potentialMessage.length > 0) {
                messages.push(potentialMessage);
            }
        }
    }
    return messages;
}

Storm.prototype.isTaskIds = function(msg) {
    return (msg instanceof Array);
}

Storm.prototype.handleNewMessage = function(msg) {
    var parsedMsg = JSON.parse(msg);

    if (this.isFirstMessage) {
        this.initSetupInfo(parsedMsg);
        this.isFirstMessage = false;
    } else if (this.isTaskIds(parsedMsg)) {
        this.handleNewTaskId(parsedMsg);
    } else {
        this.handleNewCommand(parsedMsg);
    }
}

Storm.prototype.handleNewTaskId = function(taskIds) {
    //When new list of task ids arrives, the callback that was passed with the corresponding emit should be called.
    //Storm assures that the task ids will be sent in the same order as their corresponding emits so it we can simply
    //take the first callback in the list and be sure it is the right one.

    var callback = this.taskIdsCallbacks.shift();
    if (callback) {
        callback(taskIds);
    } else {
        throw new Error('Something went wrong, we off the split of task id callbacks');
    }
}


/**
 *
 * @param messageDetails json with the emit details.
 *
 * For bolt, the json must contain the required fields:
 * - tuple - the value to emit
 * - anchorTupleId - the value of the anchor tuple (the input tuple that lead to this emit). Used to track the source
 * tuple and return ack when all components successfully finished to process it.
 * and may contain the optional fields:
 * - stream (if empty - emit to default stream)
 *
 * For spout, the json must contain the required fields:
 * - tuple - the value to emit
 *
 * and may contain the optional fields:
 * - id - pass id for reliable emit (and receive ack/fail later).
 * - stream - if empty - emit to default stream.
 *
 * @param onTaskIds function than will be called with list of task ids the message was emitted to (when received).
 */
Storm.prototype.emit = function(messageDetails, onTaskIds) {
    //Every emit triggers a response - list of task ids to which the tuple was emitted. The task ids are accessible
    //through the callback (will be called when the response arrives). The callback is stored in a list until the
    //corresponding task id list arrives.
    if (messageDetails.task) {
        throw new Error('Illegal input - task. To emit to specific task use emit direct!');
    }

    if (!onTaskIds) {
        throw new Error('You must pass a onTaskIds callback when using emit!')
    }

    this.taskIdsCallbacks.push(onTaskIds);
    this.__emit(messageDetails);;
}


/**
 * Emit message to specific task.
 * @param messageDetails json with the emit details.
 *
 * For bolt, the json must contain the required fields:
 * - tuple - the value to emit
 * - anchorTupleId - the value of the anchor tuple (the input tuple that lead to this emit). Used to track the source
 * tuple and return ack when all components successfully finished to process it.
 * - task - indicate the task to send the tuple to.
 * and may contain the optional fields:
 * - stream (if empty - emit to default stream)
 *
 * For spout, the json must contain the required fields:
 * - tuple - the value to emit
 * - task - indicate the task to send the tuple to.
 * and may contain the optional fields:
 * - id - pass id for reliable emit (and receive ack/fail later).
 * - stream - if empty - emit to default stream.
 *
 * @param onTaskIds function than will be called with list of task ids the message was emitted to (when received).
 */
Storm.prototype.emitDirect = function(commandDetails) {
    if (!commandDetails.task) {
        throw new Error("Emit direct must receive task id!")
    }
    this.__emit(commandDetails);
}

/**
 * Initialize storm component according to the configuration received.
 * @param conf configuration object accrding to storm protocol.
 * @param context context object according to storm protocol.
 * @param done callback. Call this method when finished initializing.
 */
Storm.prototype.initialize = function(conf, context, done) {
    done();
}

Storm.prototype.run = function() {
    process.stdout.setEncoding('utf8');
    process.stdin.setEncoding('utf8');
    this.startReadingInput();
}

function Tuple(id, component, stream, task, values) {
    this.id = id;
    this.component = component;
    this.stream = stream;
    this.task = task;
    this.values = values;
}

/**
 * Base class for storm bolt.
 * To create a bolt implement 'process' method.
 * You may also implement initialize method to
 */
function BasicBolt() {
    Storm.call(this);
    this.anchorTuple = null;
};

BasicBolt.prototype = Object.create(Storm.prototype);
BasicBolt.prototype.constructor = BasicBolt;

/**
 * Emit message.
 * @param commandDetails json with the required fields:
 * - tuple - the value to emit
 * - anchorTupleId - the value of the anchor tuple (the input tuple that lead to this emit). Used to track the source
 * tuple and return ack when all components successfully finished to process it.
 * and the optional fields:
 * - stream (if empty - emit to default stream)
 * - task (pass only to emit to specific task)
 */
BasicBolt.prototype.__emit = function(commandDetails) {
    var self = this;

    var message = {
        command: "emit",
        tuple: commandDetails.tuple,
        stream: commandDetails.stream,
        task: commandDetails.task,
        anchors: [commandDetails.anchorTupleId]
    };

    this.sendMsgToParent(message);
}

BasicBolt.prototype.handleNewCommand = function(command) {
    var self = this;
    var tup = new Tuple(command["id"], command["comp"], command["stream"], command["task"], command["tuple"]);

    if (tup.task === -1 && tup.stream === "__heartbeat") {
        self.sync();
        return;
    }

    var callback = function(err) {
        if (err) {
            self.fail(tup, err);
            return;
        }
        self.ack(tup);
    }
    this.process(tup, callback);
}

/**
 * Implement this method when creating a bolt. This is the main method that provides the logic of the bolt (what
 * should it do?).
 * @param tuple the input of the bolt - what to process.
 * @param done call this method when done processing.
 */
BasicBolt.prototype.process = function(tuple, done) {};

BasicBolt.prototype.ack = function(tup) {
    this.sendMsgToParent({"command": "ack", "id": tup.id});
}

BasicBolt.prototype.fail = function(tup, err) {
    this.sendMsgToParent({"command": "fail", "id": tup.id});
}


/**
 * Base class for storm spout.
 * To create a spout implement the following methods: nextTuple, ack and fail (nextTuple - mandatory, ack and fail
 * can stay empty).
 * You may also implement initialize method.
 *
 */
function Spout() {
    Storm.call(this);
};

Spout.prototype = Object.create(Storm.prototype);

Spout.prototype.constructor = Spout;

/**
 * This method will be called when an ack is received for preciously sent tuple. One may implement it.
 * @param id The id of the tuple.
 * @param done Call this method when finished and ready to receive more tuples.
 */
Spout.prototype.ack = function(id, done) {};

/**
 * This method will be called when an fail is received for preciously sent tuple. One may implement it (for example -
 * log the failure or send the tuple again).
 * @param id The id of the tuple.
 * @param done Call this method when finished and ready to receive more tuples.
 */
Spout.prototype.fail = function(id, done) {};

/**
 * Method the indicates its time to emit the next tuple.
 * @param done call this method when done sending the output.
 */
Spout.prototype.nextTuple = function(done) {};

Spout.prototype.handleNewCommand = function(command) {
    var self = this;
    var callback = function() {
        self.sync();
    }

    if (command["command"] === "next") {
        this.nextTuple(callback);
    }

    if (command["command"] === "ack") {
        this.ack(command["id"], callback);
    }

    if (command["command"] === "fail") {
        this.fail(command["id"], callback);
    }
}

/**
 * @param commandDetails json with the required fields:
 * - tuple - the value to emit.
 * and the optional fields:
 * - id - pass id for reliable emit (and receive ack/fail later).
 * - stream - if empty - emit to default stream.
 * - task - pass only to emit to specific task.
 */
Spout.prototype.__emit = function(commandDetails) {
    var message = {
        command: "emit",
        tuple: commandDetails.tuple,
        id: commandDetails.id,
        stream: commandDetails.stream,
        task: commandDetails.task
    };

    this.sendMsgToParent(message);
}

module.exports.BasicBolt = BasicBolt;
module.exports.Spout = Spout;