#--
# Copyright (c) 2005-2010, John Mettraux, jmettraux@gmail.com
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
#
# Made in Japan.
#++

#require 'redis'
  # now letting the end-user doing this require

require 'rufus-json'
require 'ruote/storage/base'
require 'ruote/redis/version'


module Ruote
module Redis

  #
  # A Redis storage for ruote.
  #
  # The constructor accepts two arguments, the first one is a Redis instance
  # ( see http://github.com/ezmobius/redis-rb ), the second one is the classic
  # ruote engine options ( see
  # http://ruote.rubyforge.org/configuration.html#engine )
  #
  #   require 'redis' # gem install redis
  #   require 'ruote' # gem install ruote
  #   require 'ruote-redis' # gem install ruote-redis
  #
  #   engine = Ruote::Engine.new(
  #     Ruote::Worker.new(
  #       Ruote::Redis::RedisStorage.new(
  #         ::Redis.new(:db => 14, :thread_safe => true), {})))
  #
  #
  # == em-redis
  #
  # Not tried, but I guess, that substituting an instance of em-redis for
  # the redis instance passed to the constructor might work.
  # http://github.com/madsimian/em-redis
  #
  # If you try and it works, feedback is welcome
  # http://groups.google.com/group/openwferu-users
  #
  class RedisStorage

    include Ruote::StorageBase

    attr_reader :redis

    def initialize (redis, options={})

      @redis = redis
      @options = options

      def @redis.keys_to_a (opt)
        r = keys(opt)
        r.is_a?(Array) ? r : r.split(' ')
      end

      put_configuration
    end

    def reserve (doc)

      @redis.del(key_for(doc))
    end

    def put_msg (action, options)

      doc = prepare_msg_doc(action, options)

      @redis.set(key_for(doc), to_json(doc))

      nil
    end

    def put_schedule (flavour, owner_fei, s, msg)

      if doc = prepare_schedule_doc(flavour, owner_fei, s, msg)
        @redis.set(key_for(doc), to_json(doc))
        return doc['_id']
      end

      nil
    end

    def delete_schedule (schedule_id)

      @redis.del(key_for('schedules', schedule_id))
    end

    def put (doc, opts={})

      rev = doc['_rev'].to_i
      key = key_for(doc)

      current_rev = @redis.get(key).to_i

      return true if current_rev == 0 && rev > 0
      return do_get(doc, current_rev) if rev != current_rev

      nrev = rev + 1

      # the setnx here is crucial in multiple workers env...

      r = @redis.setnx(
        key_rev_for(doc, nrev),
        to_json(doc.merge('_rev' => nrev), opts))

      return get(doc['type'], doc['_id']) if r == false

      @redis.set(key, nrev)
      @redis.del(key_rev_for(doc, rev)) if rev > 0

      doc['_rev'] = nrev if opts[:update_rev]

      nil
    end

    def get (type, key)

      do_get(type, key, @redis.get(key_for(type, key)))
    end

    def delete (doc)

      raise ArgumentError.new(
        "can't delete doc without _rev") unless doc['_rev']

      r = put(doc, :delete => true)

      return r if r != nil

      @redis.keys_to_a("#{key_for(doc)}*").sort.each { |k|
        Thread.pass # lingering a bit...
        @redis.del(k)
      }
        # deleting the key_rev last and making 1 'keys' call preliminarily

      nil
    end

    def get_many (type, key=nil, opts={})

      keys = "#{type}/*"

      ids = if type == 'msgs' || type == 'schedules'

        @redis.keys_to_a(keys)

      else

        @redis.keys_to_a(keys).inject({}) { |h, k|

          if m = k.match(/^[^\/]+\/([^\/]+)\/(\d+)$/)

            if ( ! key) || m[1].match(key)

              o = h[m[1]]
              n = [ m[2].to_i, k ]
              h[m[1]] = [ m[2].to_i, k ] if ( ! o) || o.first < n.first
            end
          end

          h
        }.values.collect { |i| i[1] }
      end

      if l = opts[:limit]
        ids = ids[0, l]
      end

      ids.inject([]) do |a, i|
        v = @redis.get(i)
        a << Rufus::Json.decode(v) if v
        a
      end
    end

    def ids (type)

      @redis.keys_to_a("#{type}/*").inject([]) { |a, k|

        if m = k.match(/^[^\/]+\/([^\/]+)$/)
          a << m[1]
        end

        a
      }.sort
    end

    def purge!

      @redis.keys_to_a('*').each { |k| @redis.del(k) }
    end

    #def dump (type)
    #  @dbs[type].dump
    #end

    def shutdown
    end

    # Mainly used by ruote's test/unit/ut_17_storage.rb
    #
    def add_type (type)
    end

    # Nukes a db type and reputs it (losing all the documents that were in it).
    #
    def purge_type! (type)

      @redis.keys_to_a("#{type}/*").each { |k| @redis.del(k) }
    end

    protected

    #   key_for(doc)
    #   key_for(type, key)
    #
    def key_for (*args)

      a = args.first

      (a.is_a?(Hash) ? [ a['type'], a['_id'] ] : args[0, 2]).join('/')
    end

    #   key_rev_for(doc)
    #   key_rev_for(doc, rev)
    #   key_rev_for(type, key, rev)
    #
    def key_rev_for (*args)

      as = nil
      a = args.first

      if a.is_a?(Hash)
        as = [ a['type'], a['_id'], a['_rev'] ] if a.is_a?(Hash)
        as[2] = args[1] if args[1]
      else
        as = args[0, 3]
      end

      as.join('/')
    end

    def do_get (*args)

      d = @redis.get(key_rev_for(*args))

      d ? Rufus::Json.decode(d) : nil
    end

    def to_json (doc, opts={})

      doc = if opts[:delete]
        nil
      else
        doc.merge('put_at' => Ruote.now_to_utc_s)
      end

      Rufus::Json.encode(doc)
    end

    # Don't put configuration if it's already in
    #
    # (avoid storages from trashing configuration...)
    #
    def put_configuration

      return if get('configurations', 'engine')

      put({ '_id' => 'engine', 'type' => 'configurations' }.merge(@options))
    end
  end
end
end