class FDB::TransactionRead

def self.finalize(ptr)
  proc do
    #puts "Destroying transaction #{ptr}"
    FDBC.fdb_transaction_destroy(ptr)
  end
end

def each
  bsel = @bsel
  esel = @esel
  limit = @limit
  iteration = 1 # the first read was fired off when the RangeEnum was initialized
  future = @future
  done = false
  while !done
    if future
      kvs, count, more = future.wait
      index = 0
      future = nil
      return if count.zero?
    end
    result = kvs[index]
    index += 1
    if index == count
      if more.zero? || limit == count
        done = true
      else
        iteration += 1
        if limit.nonzero?
          limit -= count
        end
        if @reverse.nonzero?
          esel = KeySelector.first_greater_or_equal(kvs.last.key)
        else
          bsel = KeySelector.first_greater_than(kvs.last.key)
        end
        future = @get_range.call(bsel, esel, limit, @mode, iteration, @reverse)
      end
    end
    yield result
  end
end

def get(key)
  key = FDB.key_to_bytes(key)
  Value.new(FDBC.fdb_transaction_get(@tpointer, key, key.bytesize, @is_snapshot))
end

def get_key(keysel)
  key = FDB.key_to_bytes(keysel.key)
  Key.new(FDBC.fdb_transaction_get_key(@tpointer, key, key.bytesize, keysel.or_equal, keysel.offset, @is_snapshot))
end

def get_range(bkeysel, ekeysel, options={}, &block)
  defaults = { :limit => 0, :reverse => false, :streaming_mode => :iterator }
  options = defaults.merge options
  bsel = to_selector bkeysel
  esel = to_selector ekeysel
  if options[:streaming_mode].kind_of? Symbol
    streaming_mode = @@StreamingMode[options[:streaming_mode].to_s.upcase]
    raise ArgumentError, "#{options[:streaming_mode]} is not a valid streaming mode" if !streaming_mode
    streaming_mode = streaming_mode[0]
  else
    streaming_mode = options[:streaming_mode]
  end
  r = @@RangeEnum.new(lambda {|bsel, esel, limit, streaming_mode, iteration, reverse|
                        begin_key = FDB.key_to_bytes(bsel.key)
                        end_key = FDB.key_to_bytes(esel.key)
                        FDB::FutureKeyValueArray.new(FDBC.fdb_transaction_get_range(@tpointer, begin_key, begin_key.bytesize, bsel.or_equal, bsel.offset, end_key, end_key.bytesize, esel.or_equal, esel.offset, limit, 0, streaming_mode, iteration, @is_snapshot, reverse))
                      }, bsel, esel, options[:limit], options[:reverse] ? 1 : 0, streaming_mode)
  if !block_given?
    r
  else
    r.each &block
  end
end

def get_range_start_with(prefix, options={}, &block)
  prefix = FDB.key_to_bytes(prefix)
  prefix = prefix.dup.force_encoding "BINARY"
  get_range(prefix, FDB.strinc(prefix), options, &block)
end

def get_read_version
  Version.new(FDBC.fdb_transaction_get_read_version @tpointer)
end

def initialize(tpointer, db, is_snapshot)
  @tpointer = tpointer
  @db = db
  @is_snapshot = is_snapshot
  ObjectSpace.define_finalizer(self, self.class.finalize(@tpointer))
end

def initialize(get_range, bsel, esel, limit, reverse, streaming_mode)
  @get_range = get_range
  @bsel = bsel
  @esel = esel
  @limit = limit
  @reverse = reverse
  @mode = streaming_mode
  @future = @get_range.call(@bsel, @esel, @limit, @mode, 1, @reverse)
end

def to_a
  o = self.dup
  o.instance_eval do
    if @mode == @@StreamingMode["ITERATOR"][0]
      if @limit.zero?
        @mode = @@StreamingMode["WANT_ALL"][0]
      else
        @mode = @@StreamingMode["EXACT"][0]
      end
    end
  end
  Enumerable.instance_method(:to_a).bind(o).call
end

def to_selector(key_or_selector)
  if key_or_selector.kind_of? KeySelector
    key_or_selector
  else
    KeySelector.first_greater_or_equal key_or_selector
  end
end

def transact
  yield self
end