require 'redis'

begin
  require 'yajl'
rescue
  require 'json'
end

$LOAD_PATH << './lib'

require 'kthxbye/config'
require 'kthxbye/helper'
require 'kthxbye/job'
require 'kthxbye/worker'
require 'kthxbye/failure'

require 'kthxbye/version'

require 'kthxbye/exceptions'

# Kthxbye is a light-weight, distributed delayed-job processor. It is meant
# to take the load of long running processes off of your web-server any place 
# it in the capable hands of a backend processor. It is unique in that it 
# provides results delievery post-processing so that your front-end can actually
# have its results back. 
#
# Most delayed job processors out there are meant for running processes that we
# don't need to get a result from. For example mass-mailings or image processing.
# However I've found many a case in which I need the result of a long process but
# my web server is bogging down watiting for a response.
#
# And this is where Kthxbye shines.
#
# Okay, you say, enough glowing, let's see this thinger work. Simple enough.
#
# On your front-end (e.g. a Rails app) initialization process, run
#   Kthxbye::Config.setup(:redis_server => "localhost", :redis_port => 9876)
#
# Then somewhere accessable to both your app and your workers (maybe a separate
# job class file in you /lib dir) create your job class with a class method
# perform:
#   class MyJob
#     def self.perform(param1, param2)
#       puts "I'm here with data!"
#       # perform stuff with data
#       result = param1 + param2
#       return result
#     end
#   end
# 
# Then all that's left is to queue up the job at the appropriate time:
#   Kthxbye.enqueue("job-queue", MyJob, 6, 4)
# 
# Your job is now queued for processing! To work this job, its even simpler.
#   require 'whatever/file/my_job/class/is/in'
#   worker = Kthxbye::Worker.new("job-queue")
#   worker.run
#
# Let the processing commence!
module Kthxbye
  include Helper
  extend self

  # This is not necessary to call. Any of the methods that use redis
  # Will make an inital call to connect to redis.
  # Useful if you want to connect to an existing redis instance. Othewise, if 
  # called without params, it simply connects a new instance of redis.
  def connect( redis_instance=nil )
    @redis = ( redis_instance || Redis.new( :host => Config.options[:redis_server], :port => Config.options[:redis_port] ) )
  end

  # Returns the Redis instance for direct calls to the Redis db
  def redis
    return @redis if @redis
    Config.setup
    self.connect
    self.redis
  end

  # Returns a hash of all existing Redis keys.
  def keys
    redis.keys("*")
  end

  # Queues jobs. Takes at minimum two paramters
  #   1) A string representing a queue
  #   2) The class of the job being queued.
  #
  # You can optionally pass in additional params to the perform method within
  # the class. You will need to match the number of args in the perform method
  # when you queue the job. Otherwise this will throw an exception.
  def enqueue(queue, klass, *args)
    Job.create(queue, klass, *args)    
  end

  # Takes a string that represents a job queue.
  # Returns the size of the given queue.
  def size(queue)
    redis.llen("queue:#{queue}").to_i
  end

  # This method is used mostly internally to pop the next job off of the given
  # queue. It takes in a string representing a queue and will return a 
  # Kthxbye::Job object if a job exists on the queue. This is destructive on
  # the queue as it will REMOVE the next job off queue and return the job object.
  def salvage(q)
    id = redis.lpop( "queue:#{q}" ) 
    if id 
      payload = decode( redis.hget( "data-store:#{q}", id ) )
      return Job.new(id, q, payload)
    else
      log "No jobs found in #{q}"
      return nil
    end
  end

  # This is a generic queue peek method. It isn't used directly but is the basis
  # for the "ghost" methods "data_peek" and "result_peek". This method takes in
  # a string representing a redis hash store (only two in kthxbye: "data-store"
  # and "result-store"), a string representing a queue, and optionally a job id.
  # If a job id is given, it will return the data for that job only. Otherwise
  # it returns all the data for all jobs/results.
  def peek(store, queue, id=nil)
    if id
      decode( redis.hget( "#{store}-store:#{queue}", id ) )
    else
      all = redis.hgetall( "#{store}-store:#{queue}" )
      results = {}
      all.each {|k,v| results[k] = decode( v ) }
      return results
    end
  end

  def method_missing(name, *args) #:nodoc:
    method_name = name.id2name
    if method_name =~ /^(data|result)_peek$/
      Kthxbye.send(:peek, $1, *args)
    else
      super
    end

  end

  # Returns all the queues Kthxbye knows about
  def queues
    redis.smembers( :queues ).sort
  end

  # This method takes a string and registers it as a queue in our "known queues" 
  # list
  def register_queue(queue)
    redis.sadd(:queues, queue) unless redis.sismember(:queues, queue)
  end

  # Removes the queue from the active queue listing, does not delete queue.
  # This will lead to phantom queues. use delete_queue for complete removal 
  # of queue.
  def unregister_queue(queue)
    redis.srem(:queues, queue)
  end

  # Completely removes queue: Unregisters it then deletes it should return true 
  # in all cases (including if we try to delete a non-existent queue).
  def delete_queue(queue)
    unregister_queue(queue)
    redis.del( "queue:#{queue}" ) || true 
  end

  # Returns all workers registered with Kthxbye by the Kthxbye::Worker class.
  # Special note: Workers are only registered once you call #run on the worker.
  # You may also run #register_worker on the worker to manually register it, but
  # this also occurs once the worker is run so there is no need to run this 
  # manually.
  def workers
    workers = redis.smembers( :workers )
    workers.map {|x| Worker.find( x ) }
  end

  # Returns all of the workers that are currently working a job.
  # Also returns the job id and started time of the worker as a hash as follows:
  #
  #   [worker_id, {:job_id, :started}]
  def working
    workers = redis.smembers( :working ) 
    data = []
    workers.each do |w_id|
      data << [w_id, decode( redis.get("worker:#{w_id}") )]
    end
    return data
  end

  # Returns either the job results for a specific job (if id specified).
  # If a job is not specified, it returns all the job results for the given
  # queue.
  def job_results(queue, id=nil)
    if id
      decode( redis.hget( "result-store:#{queue}", id ) )
    else
      Array( redis.hgetall( "result-store:#{queue}" ) )
    end
  end

  # Returns a pretty inspect message about this instance of Kthxbye.
  def inspect
    {
      :version => Version,
      :keys => keys.size,
      :workers => workers.size,
      :working => working.size,
      :queues => queues.size,
      :failed => Failure.count,
      :pending => queues.inject(0) {|m,o| m + size(o)}
    }
  end
end