# --
# Copyright (C) 2008-2009 10gen Inc.
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License, version 3, as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License
# for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# ++

require 'base64'
require 'mongo/util/byte_buffer'
require 'mongo/util/ordered_hash'
require 'mongo/types/binary'
require 'mongo/types/dbref'
require 'mongo/types/objectid'
require 'mongo/types/regexp_of_holding'
require 'mongo/types/undefined'

# A BSON seralizer/deserializer.
class BSON

  include XGen::Mongo::Driver

  MINKEY = -1
  EOO = 0
  NUMBER = 1
  STRING = 2
  OBJECT = 3
  ARRAY = 4
  BINARY = 5
  UNDEFINED = 6
  OID = 7
  BOOLEAN = 8
  DATE = 9
  NULL = 10
  REGEX = 11
  REF = 12
  CODE = 13
  SYMBOL = 14
  CODE_W_SCOPE = 15
  NUMBER_INT = 16
  MAXKEY = 127

  if RUBY_VERSION >= '1.9'
    def self.to_utf8(str)
      str.encode("utf-8")
    end
  else
    def self.to_utf8(str)
      str                       # TODO Ruby 1.8 punt for now
    end
  end

  def self.serialize_cstr(buf, val)
    buf.put_array(to_utf8(val.to_s).unpack("C*") + [0])
  end

  def initialize(db=nil)
    # db is only needed during deserialization when the data contains a DBRef
    @db = db
    @buf = ByteBuffer.new
  end

  def to_a
    @buf.to_a
  end

  begin
    require 'mongo/ext/cbson'
    def serialize(obj)
      @buf = ByteBuffer.new(CBson.serialize(obj))
    end
  rescue LoadError
    def serialize(obj)
      raise "Document is null" unless obj

      @buf.rewind
      # put in a placeholder for the total size
      @buf.put_int(0)

      # Write key/value pairs. Always write _id first if it exists.
      oid = obj['_id'] || obj[:_id]
      serialize_key_value('_id', oid) if oid
      obj.each {|k, v| serialize_key_value(k, v) unless k == '_id' || k == :_id }

      serialize_eoo_element(@buf)
      @buf.put_int(@buf.size, 0)
      self
    end
  end

  def serialize_key_value(k, v)
      type = bson_type(v, k)
      case type
      when STRING, CODE, SYMBOL
        serialize_string_element(@buf, k, v, type)
      when NUMBER, NUMBER_INT
        serialize_number_element(@buf, k, v, type)
      when OBJECT
        serialize_object_element(@buf, k, v)
      when OID
        serialize_oid_element(@buf, k, v)
      when ARRAY
        serialize_array_element(@buf, k, v)
      when REGEX
        serialize_regex_element(@buf, k, v)
      when BOOLEAN
        serialize_boolean_element(@buf, k, v)
      when DATE
        serialize_date_element(@buf, k, v)
      when NULL
        serialize_null_element(@buf, k)
      when REF
        serialize_dbref_element(@buf, k, v)
      when BINARY
        serialize_binary_element(@buf, k, v)
      when UNDEFINED
        serialize_undefined_element(@buf, k)
      when CODE_W_SCOPE
        # TODO CODE_W_SCOPE unimplemented; may be removed
        raise "unimplemented type #{type}"
      else
        raise "unhandled type #{type}"
      end
  end

  def deserialize(buf=nil, parent=nil)
    # If buf is nil, use @buf, assumed to contain already-serialized BSON.
    # This is only true during testing.
    @buf = ByteBuffer.new(buf.to_a) if buf
    @buf.rewind
    @buf.get_int                # eat message size
    doc = OrderedHash.new
    while @buf.more?
      type = @buf.get
      case type
      when STRING, CODE
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_string_data(@buf)
      when SYMBOL
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_string_data(@buf).intern
      when NUMBER
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_number_data(@buf)
      when NUMBER_INT
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_number_int_data(@buf)
      when OID
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_oid_data(@buf)
      when ARRAY
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_array_data(@buf, doc)
      when REGEX
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_regex_data(@buf)
      when OBJECT
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_object_data(@buf, doc)
      when BOOLEAN
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_boolean_data(@buf)
      when DATE
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_date_data(@buf)
      when NULL
        key = deserialize_cstr(@buf)
        doc[key] = nil
      when UNDEFINED
        key = deserialize_cstr(@buf)
        doc[key] = Undefined.new
      when REF
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_dbref_data(@buf, key, parent)
      when BINARY
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_binary_data(@buf)
      when CODE_W_SCOPE
        # TODO CODE_W_SCOPE unimplemented; may be removed
        raise "unimplemented type #{type}"
      when EOO
        break
      else
        raise "Unknown type #{type}, key = #{key}"
      end
    end
    @buf.rewind
    doc
  end

  # For debugging.
  def hex_dump
    str = ''
    @buf.to_a.each_with_index { |b,i|
      if (i % 8) == 0
        str << "\n" if i > 0
        str << '%4d:  ' % i
      else
        str << ' '
      end
      str << '%02X' % b
    }
    str
  end

  def deserialize_date_data(buf)
    millisecs = buf.get_long()
    Time.at(millisecs.to_f / 1000.0) # at() takes fractional seconds
  end

  def deserialize_boolean_data(buf)
    buf.get == 1
  end

  def deserialize_number_data(buf)
    buf.get_double
  end

  def deserialize_number_int_data(buf)
    buf.get_int
  end

  def deserialize_object_data(buf, parent)
    size = buf.get_int
    buf.position -= 4
    BSON.new(@db).deserialize(buf.get(size), parent)
  end

  def deserialize_array_data(buf, parent)
    h = deserialize_object_data(buf, parent)
    a = []
    h.each { |k, v| a[k.to_i] = v }
    a
  end

  def deserialize_regex_data(buf)
    str = deserialize_cstr(buf)
    options_str = deserialize_cstr(buf)
    options = 0
    options |= Regexp::IGNORECASE if options_str.include?('i')
    options |= Regexp::MULTILINE if options_str.include?('m')
    options |= Regexp::EXTENDED if options_str.include?('x')
    options_str.gsub!(/[imx]/, '') # Now remove the three we understand
    RegexpOfHolding.new(str, options, options_str)
  end

  def deserialize_string_data(buf)
    len = buf.get_int
    bytes = buf.get(len)
    str = bytes[0..-2].pack("C*")
    if RUBY_VERSION >= '1.9'
      str.force_encoding("utf-8")
    end
    str
  end

  def deserialize_oid_data(buf)
    ObjectID.new(buf.get(12))
  end

  def deserialize_dbref_data(buf, key, parent)
    ns = deserialize_string_data(buf)
    oid = deserialize_oid_data(buf)
    DBRef.new(parent, key, @db, ns, oid)
  end

  def deserialize_binary_data(buf)
    len = buf.get_int
    type = buf.get
    len = buf.get_int if type == Binary::SUBTYPE_BYTES
    Binary.new(buf.get(len), type)
  end

  def serialize_eoo_element(buf)
    buf.put(EOO)
  end

  def serialize_null_element(buf, key)
    buf.put(NULL)
    self.class.serialize_cstr(buf, key)
  end

  def serialize_dbref_element(buf, key, val)
    serialize_string_element(buf, key, val.namespace, REF)
    buf.put_array(val.object_id.to_a)
  end

  def serialize_binary_element(buf, key, val)
    buf.put(BINARY)
    self.class.serialize_cstr(buf, key)

    bytes = val.to_a
    num_bytes = bytes.length
    subtype = val.respond_to?(:subtype) ? val.subtype : Binary::SUBTYPE_BYTES
    if subtype == Binary::SUBTYPE_BYTES
      buf.put_int(num_bytes + 4)
      buf.put(subtype)
      buf.put_int(num_bytes)
      buf.put_array(bytes)
    else
      buf.put_int(num_bytes)
      buf.put(subtype)
      buf.put_array(bytes)
    end
  end

  def serialize_undefined_element(buf, key)
    buf.put(UNDEFINED)
    self.class.serialize_cstr(buf, key)
  end

  def serialize_boolean_element(buf, key, val)
    buf.put(BOOLEAN)
    self.class.serialize_cstr(buf, key)
    buf.put(val ? 1 : 0)
  end

  def serialize_date_element(buf, key, val)
    buf.put(DATE)
    self.class.serialize_cstr(buf, key)
    millisecs = (val.to_f * 1000).to_i
    buf.put_long(millisecs)
  end

  def serialize_number_element(buf, key, val, type)
    buf.put(type)
    self.class.serialize_cstr(buf, key)
    if type == NUMBER
      buf.put_double(val)
    else
      buf.put_int(val)
    end
  end

  def serialize_object_element(buf, key, val, opcode=OBJECT)
    buf.put(opcode)
    self.class.serialize_cstr(buf, key)
    buf.put_array(BSON.new.serialize(val).to_a)
  end

  def serialize_array_element(buf, key, val)
    # Turn array into hash with integer indices as keys
    h = OrderedHash.new
    i = 0
    val.each { |v| h[i] = v; i += 1 }
    serialize_object_element(buf, key, h, ARRAY)
  end

  def serialize_regex_element(buf, key, val)
    buf.put(REGEX)
    self.class.serialize_cstr(buf, key)

    str = val.to_s.sub(/.*?:/, '')[0..-2] # Turn "(?xxx:yyy)" into "yyy"
    self.class.serialize_cstr(buf, str)

    options = val.options
    options_str = ''
    options_str << 'i' if ((options & Regexp::IGNORECASE) != 0)
    options_str << 'm' if ((options & Regexp::MULTILINE) != 0)
    options_str << 'x' if ((options & Regexp::EXTENDED) != 0)
    options_str << val.extra_options_str if val.respond_to?(:extra_options_str)
    # Must store option chars in alphabetical order
    self.class.serialize_cstr(buf, options_str.split(//).sort.uniq.join)
  end

  def serialize_oid_element(buf, key, val)
    buf.put(OID)
    self.class.serialize_cstr(buf, key)

    buf.put_array(val.to_a)
  end

  def serialize_string_element(buf, key, val, type)
    buf.put(type)
    self.class.serialize_cstr(buf, key)

    # Make a hole for the length
    len_pos = buf.position
    buf.put_int(0)

    # Save the string
    start_pos = buf.position
    self.class.serialize_cstr(buf, val)
    end_pos = buf.position

    # Put the string size in front
    buf.put_int(end_pos - start_pos, len_pos)

    # Go back to where we were
    buf.position = end_pos
  end

  def deserialize_cstr(buf)
    chars = ""
    while true
      b = buf.get
      break if b == 0
      chars << b.chr
    end
    if RUBY_VERSION >= '1.9'
      chars.force_encoding("utf-8") # Mongo stores UTF-8
    end
    chars
  end

  def bson_type(o, key)
    case o
    when nil
      NULL
    when Integer
      NUMBER_INT
    when Numeric
      NUMBER
    when ByteBuffer
      BINARY
    when String
      # magic awful stuff - the DB requires that a where clause is sent as CODE
      key == "$where" ? CODE : STRING
    when Array
      ARRAY
    when Regexp
      REGEX
    when ObjectID
      OID
    when DBRef
      REF
    when true, false
      BOOLEAN
    when Time
      DATE
    when Hash
      OBJECT
    when Symbol
      SYMBOL
    when Undefined
      UNDEFINED
    else
      raise "Unknown type of object: #{o.class.name}"
    end
  end

end