# --
# 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'

# A BSON seralizer/deserializer in pure Ruby.
class BSON_RUBY

  include Mongo

  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
  TIMESTAMP = 17
  NUMBER_LONG = 18
  MAXKEY = 127

  def initialize
    @buf = ByteBuffer.new
  end

  if RUBY_VERSION >= '1.9'
    def self.to_utf8(str)
      str.encode("utf-8")
    end
  else
    def self.to_utf8(str)
      begin
      str.unpack("U*")
      rescue => ex
        raise InvalidStringEncoding, "String not valid utf-8: #{str}"
      end
      str
    end
  end

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

  def self.serialize_key(buf, key)
    raise InvalidDocument, "Key names / regex patterns must not contain the NULL byte" if key.include? "\x00"
    self.serialize_cstr(buf, key)
  end

  def to_a
    @buf.to_a
  end

  def to_s
    @buf.to_s
  end

  # Serializes an object.
  # Implemented to ensure an API compatible with BSON extension.
  def self.serialize(obj, check_keys=false)
    new.serialize(obj, check_keys)
  end

  def self.deserialize(buf=nil)
    new.deserialize(buf)
  end

  def serialize(obj, check_keys=false)
    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.
    if obj.has_key? '_id'
      serialize_key_value('_id', obj['_id'], check_keys)
    elsif obj.has_key? :_id
      serialize_key_value('_id', obj[:_id], check_keys)
    end

    obj.each {|k, v| serialize_key_value(k, v, check_keys) unless k == '_id' || k == :_id }

    serialize_eoo_element(@buf)
    if @buf.size > 4 * 1024 * 1024
      raise InvalidDocument, "Document is too large (#{@buf.size}). BSON documents are limited to 4MB (#{4 * 1024 * 1024})."
    end
    @buf.put_int(@buf.size, 0)
    self
  end

  # Returns the array stored in the buffer.
  # Implemented to ensure an API compatible with BSON extension.
  def unpack(arg)
    @buf.to_a
  end

  def serialize_key_value(k, v, check_keys)
    k = k.to_s
    if check_keys
      if k[0] == ?$
        raise InvalidName.new("key #{k} must not start with '$'")
      end
      if k.include? ?.
        raise InvalidName.new("key #{k} must not contain '.'")
      end
    end
    type = bson_type(v)
    case type
    when STRING, 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, check_keys)
    when OID
      serialize_oid_element(@buf, k, v)
    when ARRAY
      serialize_array_element(@buf, k, v, check_keys)
    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_null_element(@buf, k)
    when CODE_W_SCOPE
      serialize_code_w_scope(@buf, k, v)
    when MAXKEY
      serialize_max_key_element(@buf, k)
    when MINKEY
      serialize_min_key_element(@buf, k)
    else
      raise "unhandled type #{type}"
    end
  end

  def deserialize(buf=nil)
    # If buf is nil, use @buf, assumed to contain already-serialized BSON.
    # This is only true during testing.
    if buf.is_a? String
      @buf = ByteBuffer.new(buf) if buf
    else
      @buf = ByteBuffer.new(buf.to_a) if buf
    end
    @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 NUMBER_LONG
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_number_long_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)
      when REGEX
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_regex_data(@buf)
      when OBJECT
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_object_data(@buf)
      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] = nil
      when REF
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_dbref_data(@buf)
      when BINARY
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_binary_data(@buf)
      when CODE_W_SCOPE
        key = deserialize_cstr(@buf)
        doc[key] = deserialize_code_w_scope_data(@buf)
      when TIMESTAMP
        key = deserialize_cstr(@buf)
        doc[key] = [deserialize_number_int_data(@buf),
                    deserialize_number_int_data(@buf)]
      when MAXKEY
        key = deserialize_cstr(@buf)
        doc[key] = MaxKey.new
      when MINKEY, 255 # This is currently easier than unpack the type byte as an unsigned char.
        key = deserialize_cstr(@buf)
        doc[key] = MinKey.new
      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)
    unsigned = buf.get_long()
    # see note for deserialize_number_long_data below
    milliseconds = unsigned >= 2 ** 64 / 2 ? unsigned - 2**64 : unsigned
    Time.at(milliseconds.to_f / 1000.0).utc # 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)
    # sometimes ruby makes me angry... why would the same code pack as signed
    # but unpack as unsigned
    unsigned = buf.get_int
    unsigned >= 2**32 / 2 ? unsigned - 2**32 : unsigned
  end

  def deserialize_number_long_data(buf)
    # same note as above applies here...
    unsigned = buf.get_long
    unsigned >= 2 ** 64 / 2 ? unsigned - 2**64 : unsigned
  end

  def deserialize_object_data(buf)
    size = buf.get_int
    buf.position -= 4
    object = BSON.new().deserialize(buf.get(size))
    if object.has_key? "$ref"
      DBRef.new(object["$ref"], object["$id"])
    else
      object
    end
  end

  def deserialize_array_data(buf)
    h = deserialize_object_data(buf)
    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]
    if str.respond_to? "pack"
      str = str.pack("C*")
    end
    if RUBY_VERSION >= '1.9'
      str.force_encoding("utf-8")
    end
    str
  end

  def deserialize_code_w_scope_data(buf)
    buf.get_int
    len = buf.get_int
    code = buf.get(len)[0..-2]
    if code.respond_to? "pack"
      code = code.pack("C*")
    end
    if RUBY_VERSION >= '1.9'
      code.force_encoding("utf-8")
    end

    scope_size = buf.get_int
    buf.position -= 4
    scope = BSON.new().deserialize(buf.get(scope_size))

    Code.new(code, scope)
  end

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

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

  def serialize_dbref_element(buf, key, val)
    oh = OrderedHash.new
    oh['$ref'] = val.namespace
    oh['$id'] = val.object_id
    serialize_object_element(buf, key, oh, false)
  end

  def serialize_binary_element(buf, key, val)
    buf.put(BINARY)
    self.class.serialize_key(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_boolean_element(buf, key, val)
    buf.put(BOOLEAN)
    self.class.serialize_key(buf, key)
    buf.put(val ? 1 : 0)
  end

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

  def serialize_number_element(buf, key, val, type)
    if type == NUMBER
      buf.put(type)
      self.class.serialize_key(buf, key)
      buf.put_double(val)
    else
      if val > 2**64 / 2 - 1 or val < -2**64 / 2
        raise RangeError.new("MongoDB can only handle 8-byte ints")
      end
      if val > 2**32 / 2 - 1 or val < -2**32 / 2
        buf.put(NUMBER_LONG)
        self.class.serialize_key(buf, key)
        buf.put_long(val)
      else
        buf.put(type)
        self.class.serialize_key(buf, key)
        buf.put_int(val)
      end
    end
  end

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

  def serialize_array_element(buf, key, val, check_keys)
    # 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, check_keys, ARRAY)
  end

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

    str = val.source
    # We use serialize_key here since regex patterns aren't prefixed with
    # length (can't contain the NULL byte).
    self.class.serialize_key(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_max_key_element(buf, key)
    buf.put(MAXKEY)
    self.class.serialize_key(buf, key)
  end

  def serialize_min_key_element(buf, key)
    buf.put(MINKEY)
    self.class.serialize_key(buf, key)
  end

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

    buf.put_array(val.to_a)
  end

  def serialize_string_element(buf, key, val, type)
    buf.put(type)
    self.class.serialize_key(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 serialize_code_w_scope(buf, key, val)
    buf.put(CODE_W_SCOPE)
    self.class.serialize_key(buf, key)

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

    buf.put_int(val.length + 1)
    self.class.serialize_cstr(buf, val)
    buf.put_array(BSON.new.serialize(val.scope).to_a)

    end_pos = buf.position
    buf.put_int(end_pos - len_pos, len_pos)
    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)
    case o
    when nil
      NULL
    when Integer
      NUMBER_INT
    when Float
      NUMBER
    when ByteBuffer
      BINARY
    when Code
      CODE_W_SCOPE
    when String
      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 MaxKey
      MAXKEY
    when MinKey
      MINKEY
    when Numeric
      raise InvalidDocument, "The Numeric type #{o.class} cannot be encoded as BSON; only Fixum, Bignum, and Float are supported."
    when Date, DateTime
      raise InvalidDocument, "#{o.class} is not currently supported; " +
        "use a UTC Time instance instead."
    else
      if defined?(ActiveSupport::TimeWithZone) && o.is_a?(ActiveSupport::TimeWithZone)
        raise InvalidDocument, "ActiveSupport::TimeWithZone is not currently supported; " +
                               "use a UTC Time instance instead."
      else
        raise InvalidDocument, "#{o.class} isn't supported as a BSON type."
      end
    end
  end

end