# -*- encoding: binary -*-

# \MogileFS file manipulation client.
#
#   Create a new instance that will communicate with these trackers:
#   hosts = %w[192.168.1.69:6001 192.168.1.70:6001]
#   mg = MogileFS::MogileFS.new(:domain => 'test', :hosts => hosts)
#
#   # Stores "A bunch of text to store" into 'some_key' with a class of 'text'.
#   mg.store_content('some_key', 'text', "A bunch of text to store")
#
#   # Retrieve data from 'some_key' as a string
#   data = mg.get_file_data('some_key')
#
#   # Store the contents of 'image.jpeg' into the key 'my_image' with a
#   # class of 'image'.
#   mg.store_file('my_image', 'image', 'image.jpeg')
#
#   # Store the contents of 'image.jpeg' into the key 'my_image' with a
#   # class of 'image' using an open IO object.
#   File.open('image.jpeg') { |fp| mg.store_file('my_image', 'image', fp) }
#
#   # Retrieve the contents of 'my_image' into '/path/to/huge_file'
#   # without slurping the entire contents into memory:
#   mg.get_file_data('my_image', '/path/to/huge_file')
#
#   # Remove the key 'my_image' and 'some_key'.
#   mg.delete('my_image')
#   mg.delete('some_key')
#
class MogileFS::MogileFS < MogileFS::Client
  include MogileFS::Bigfile

  # The domain of keys for this MogileFS client.
  attr_accessor :domain

  # The timeout for get_file_data (per-read() system call).
  # Defaults to five seconds.
  attr_accessor :get_file_data_timeout

  # The maximum allowed time for creating a new_file.  Defaults to 1 hour.
  attr_accessor :new_file_max_time

  # Creates a new MogileFS::MogileFS instance.  +args+ must include a key
  # :domain specifying the domain of this client.
  #
  # Optional parameters for +args+:
  #
  # [:get_file_data_timeout => Numeric]
  #
  #   See get_file_data_timeout
  #
  # [:new_file_max_time => Numeric]
  #
  #   See new_file_max_time
  #
  # [:fail_timeout => Numeric]
  #
  #   Delay before retrying a failed tracker backends.
  #   Defaults to 5 seconds.
  #
  # [:timeout => Numeric]
  #
  #   Timeout for tracker backend responses.
  #   Defaults to 3 seconds.
  #
  def initialize(args = {})
    @domain = args[:domain]

    @get_file_data_timeout = args[:get_file_data_timeout] || 5
    @new_file_max_time = args[:new_file_max_time] || 3600.0

    raise ArgumentError, "you must specify a domain" unless @domain

    if @backend = args[:db_backend]
      @readonly = true
    else
      super
    end
  end

  # Enumerates keys, limited by optional +prefix+
  def each_key(prefix = "", &block)
    after = nil
    begin
      keys, after = list_keys(prefix, after, 1000, &block)
    end while keys && keys[0]
    nil
  end

  # Retrieves the contents of +key+.  If +dst+ is specified, +dst+
  # should be an IO-like object capable of receiving the +write+ method
  # or a path name.  +copy_length+ may be specified to limit the number of
  # bytes to retrieve, and +src_offset+ can be specified to specified the
  # start position of the copy.
  def get_file_data(key, dst = nil, copy_length = nil, src_offset = nil)
    paths = get_paths(key)
    sock = MogileFS::HTTPReader.first(paths, @get_file_data_timeout,
                                      copy_length, src_offset)
    if dst
      sock.stream_to(dst)
    elsif block_given?
      yield(sock)
    else
      sock.to_s
    end
    ensure
      sock.close if sock && ! sock.closed?
  end

  # Get the paths (URLs as strings) for +key+.  If +args+ is specified,
  # it may contain:
  # - :noverify -> boolean, whether or not the tracker checks (default: true)
  # - :pathcount -> a positive integer of URLs to retrieve (default: 2)
  # - :zone -> "alt" or nil (default: nil)
  #
  # :noverify defaults to true because this client library is capable of
  # verifying paths for readability itself.  It is also faster and more
  # reliable to verify paths on the client.
  def get_paths(key, *args)
    opts = {
      :domain => @domain,
      :key => key,
      :noverify => args[0],
      :zone => args[1],
    }
    if Hash === args[0]
      args = args[0]
      opts[:noverify] = args[:noverify]
      opts[:zone] = args[:zone]
      pathcount = args[:pathcount] and opts[:pathcount] = pathcount.to_i
    end

    opts[:noverify] = false == opts[:noverify] ? 0 : 1
    @backend.respond_to?(:_get_paths) and return @backend._get_paths(opts)
    res = @backend.get_paths(opts)
    (1..res['paths'].to_i).map { |i| res["path#{i}"] }
  end

  # Returns +true+ if +key+ exists, +false+ if not
  def exist?(key)
    args = { :key => key, :domain => @domain , :ruby_no_raise => true}
    case rv = @backend.get_paths(args)
    when Hash
      true
    when MogileFS::Backend::UnknownKeyError
      false
    else
      raise rv
    end
  end

  # Get the URIs for +key+ (paths) as URI::HTTP objects
  def get_uris(key, *args)
    get_paths(key, *args).map! { |path| URI.parse(path) }
  end

  # Creates a new file +key+ in the domain of this object.
  #
  # +bytes+ is the expected size of the file if known in advance
  #
  # It operates like File.open(..., "w") and may take an optional
  # block, yielding an IO-like object with support for the methods
  # documented in MogileFS::NewFile::Writer.
  #
  # This atomically replaces existing data stored as +key+
  # when the block exits or when the returned object is closed.
  #
  # +args+ may contain the following options:
  #
  # [:content_length => Integer]
  #
  #   This has the same effect as the (deprecated) +bytes+ parameter.
  #
  # [ :largefile => :stream, :content_range or :tempfile ]
  #
  #   See MogileFS::NewFile for more information on this
  #
  # [ :class => String]
  #
  #   The MogileFS storage class of the object.
  #
  # [:content_md5 => String, Proc, or :trailer]
  #
  #   This can either be a Base64-encoded String, a Proc object, or
  #   the :trailer symbol.  If given a String, it will be used as the
  #   Content-MD5 HTTP header.  If given the :trailer symbol, this library
  #   will automatically generate an Content-MD5 HTTP trailer.  If given
  #   a Proc object, this Proc object should give a Base64-encoded string
  #   which can be used as the Content-MD5 HTTP trailer when called at the
  #   end of the request.
  #
  #   Keep in mind most HTTP servers do not support HTTP trailers, so
  #   passing a String is usually the safest way to use this.
  #
  def new_file(key, args = nil, bytes = nil) # :yields: file
    raise MogileFS::ReadOnlyError if readonly?
    opts = { :key => key, :multi_dest => 1 }
    case args
    when Hash
      opts[:domain] = args[:domain]
      klass = args[:class] and "default" != klass and opts[:class] = klass
    when String
      opts[:class] = args if "default" != args
    end
    opts[:domain] ||= @domain
    res = @backend.create_open(opts)

    dests = if dev_count = res['dev_count'] # multi_dest succeeded
      (1..dev_count.to_i).map { |i| [res["devid_#{i}"], res["path_#{i}"]] }
    else # single destination returned
      # 0x0040:  d0e4 4f4b 2064 6576 6964 3d31 2666 6964  ..OK.devid=1&fid
      # 0x0050:  3d33 2670 6174 683d 6874 7470 3a2f 2f31  =3&path=http://1
      # 0x0060:  3932 2e31 3638 2e31 2e37 323a 3735 3030  92.168.1.72:7500
      # 0x0070:  2f64 6576 312f 302f 3030 302f 3030 302f  /dev1/0/000/000/
      # 0x0080:  3030 3030 3030 3030 3033 2e66 6964 0d0a  0000000003.fid..

      [[res['devid'], res['path']]]
    end

    opts.merge!(args) if Hash === args
    opts[:backend] = @backend
    opts[:fid] = res['fid']
    opts[:content_length] ||= bytes if bytes
    opts[:new_file_max_time] ||= @new_file_max_time
    opts[:start_time] = Time.now

    case (dests[0][1] rescue nil)
    when %r{\Ahttp://}
      http_file = MogileFS::NewFile.new(dests, opts)
      if block_given?
        yield http_file
        return http_file.commit # calls create_close
      else
        return http_file
      end
    when nil, ''
      raise MogileFS::EmptyPathError,
            "Empty path for mogile upload res=#{res.inspect}"
    else
      raise MogileFS::UnsupportedPathError,
            "paths '#{dests.inspect}' returned by backend is not supported"
    end
  end

  # Copies the contents of +file+ into +key+ in class +klass+.  +file+ can be
  # either a path name (String or Pathname object) or an IO-like object that
  # responds to #read or #readpartial.  Returns size of +file+ stored.
  # This atomically replaces existing data stored as +key+
  def store_file(key, klass, file, opts = nil)
    raise MogileFS::ReadOnlyError if readonly?
    (opts ||= {})[:class] = klass if String === klass

    new_file(key, opts) { |mfp| mfp.big_io = file }
  end

  # Stores +content+ into +key+ in class +klass+, where +content+ is a String
  # This atomically replaces existing data stored as +key+
  def store_content(key, klass, content, opts = nil)
    raise MogileFS::ReadOnlyError if readonly?
    (opts ||= {})[:class] = klass if String === klass

    new_file(key, opts) do |mfp|
      if content.is_a?(MogileFS::Util::StoreContent)
        mfp.streaming_io = content
      else
        mfp << content
      end
    end
  end

  # Removes +key+.
  def delete(key)
    raise MogileFS::ReadOnlyError if readonly?

    @backend.delete :domain => @domain, :key => key
    true
  end

  # Updates +key+ to +newclass+
  def updateclass(key, newclass)
    raise MogileFS::ReadOnlyError if readonly?

    @backend.updateclass(:domain => @domain, :key => key, :class => newclass)
    true
  end

  # Sleeps +duration+, only used for testing
  def sleep(duration) # :nodoc:
    @backend.sleep :duration => duration
  end

  # Renames a key +from+ to key +to+.
  def rename(from, to)
    raise MogileFS::ReadOnlyError if readonly?

    @backend.rename :domain => @domain, :from_key => from, :to_key => to
    nil
  end

  # Returns the size of +key+.
  def size(key)
    @backend.respond_to?(:_size) and return @backend._size(domain, key)
    begin
      file_info(key)["length"].to_i
    rescue MogileFS::Backend::UnknownCommandError
      paths_size(get_paths(key))
    end
  end

  def paths_size(paths) # :nodoc:
    require "mogilefs/paths_size"
    MogileFS::PathsSize.call(paths)
  end

  # Lists keys starting with +prefix+ following +after+ up to +limit+.  If
  # +after+ is nil the list starts at the beginning.
  def list_keys(prefix = "", after = nil, limit = 1000, &block)
    @backend.respond_to?(:_list_keys) and
      return @backend._list_keys(domain, prefix, after, limit, &block)

    res = @backend.list_keys(:domain => domain, :prefix => prefix,
                             :after => after, :limit => limit,
                             :ruby_no_raise => true)
    MogileFS::Backend::NoneMatchError === res and return
    raise res if MogileFS::Error === res

    keys = (1..res['key_count'].to_i).map { |i| res["key_#{i}"] }
    if block
      if 1 == block.arity
        keys.each { |key| block.call(key) }
      else
        list_keys_verbose(keys, block)
      end
    end

    [ keys, res['next_after'] ]
  end

  def list_keys_verbose(keys, block) # :nodoc:
    # emulate the MogileFS::Mysql interface, slowly...
    ordered = keys.dup
    ready = {}
    on_file_info = lambda do |info|
      Hash === info or raise info
      file_info_cleanup(info)

      # deal with trackers with multiple queryworkers responding out-of-order
      ready[info["key"]] = info
      while info = ready.delete(ordered[0])
        block.call(ordered.shift, info["length"], info["devcount"])
      end
    end
    opts = { :domain => @domain }
    begin
      keys.each do |key|
        opts[:key] = key
        @backend.pipeline_dispatch(:file_info, opts, &on_file_info)
      end
      @backend.pipeline_wait
    rescue MogileFS::Backend::UnknownCommandError # MogileFS < 2.45
      @backend.shutdown # reset the socket
      args = { :pathcount => 0x7fffffff }
      keys.each do |key|
        paths = get_paths(key, args)
        block.call(key, paths_size(paths), paths.size)
      end
    rescue MogileFS::PipelineError, SystemCallError,
           MogileFS::RequestTruncatedError,
           MogileFS::UnreadableSocketError,
           MogileFS::InvalidResponseError, # truncated response
           MogileFS::Timeout
      @backend.shutdown
      keys = ordered - ready.keys
      retry
    rescue
      @backend.shutdown
      raise
    end
  end

  # Return metadata about a file as a hash.
  # Returns the domain, class, length, devcount, etc. as keys.
  # Optionally, device ids (not paths) can be returned as
  # well if :devices is specified and +true+.
  #
  # This should only be used for informational purposes, and not usually
  # for dynamically serving files.
  #
  #   mg.file_info("bar")
  #
  # Returns:
  #
  #   {
  #     "domain" => "foo",
  #     "key" => "bar",
  #     "class" => "default",
  #     "devcount" => 2,
  #     "length => 666
  #   }
  def file_info(key, args = nil)
    opts = { :domain => @domain, :key => key }
    args and devices = args[:devices] and opts[:devices] = devices ? 1 : 0
    file_info_cleanup(@backend.file_info(opts))
  end

  def file_info_cleanup(rv) # :nodoc:
    %w(fid length devcount).each { |f| rv[f] = rv[f].to_i }
    devids = rv["devids"] and
      rv["devids"] = devids.split(/,/).map! { |x| x.to_i }
    rv
  end

  # Given an Integer +fid+ or String +key+ and domain, thorougly search
  # the database for all occurences of a particular fid.
  #
  # Use this sparingly, this command hits the master database numerous
  # times and is very expensive.  This is not for production use, only
  # troubleshooting and debugging.
  #
  # Searches for fid=666:
  #
  #   client.file_debug(666)
  #
  # Search for key=foo using the default domain for this object:
  #
  #   client.file_debug("foo")
  #
  # Search for key=foo in domain="bar":
  #
  #   client.file_debug(:key => "foo", :domain => "bar")
  #
  def file_debug(args)
    case args
    when Integer then args = { "fid" => args }
    when String then args = { "key" => args }
    end
    opts = { :domain => args[:domain] || @domain }.merge!(args)

    rv = @backend.file_debug(opts)
    rv.each do |k,v|
      case k
      when /_(?:classid|devcount|dmid|fid|length|
            nexttry|fromdevid|failcount|flags|devid|type)\z/x
        rv[k] = v.to_i
      when /devids\z/
        rv[k] = v.split(/,/).map! { |x| x.to_i }
      end
    end
  end
end