module FFI::Library

def self.extended(mod)
  raise RuntimeError.new("must only be extended by module") unless mod.kind_of?(::Module)
end

def attach_function(name, func, args, returns = nil, options = nil)
  mname, a2, a3, a4, a5 = name, func, args, returns, options
  cname, arg_types, ret_type, opts = (a4 && (a2.is_a?(String) || a2.is_a?(Symbol))) ? [ a2, a3, a4, a5 ] : [ mname.to_s, a2, a3, a4 ]
  # Convert :foo to the native type
  arg_types = arg_types.map { |e| find_type(e) }
  options = {
    :convention => ffi_convention,
    :type_map => defined?(@ffi_typedefs) ? @ffi_typedefs : nil,
    :blocking => defined?(@blocking) && @blocking,
    :enums => defined?(@ffi_enums) ? @ffi_enums : nil,
  }
  @blocking = false
  options.merge!(opts) if opts && opts.is_a?(Hash)
  # Try to locate the function in any of the libraries
  invokers = []
  ffi_libraries.each do |lib|
    if invokers.empty?
      begin
        function = nil
        function_names(cname, arg_types).find do |fname|
          function = lib.find_function(fname)
        end
        raise LoadError unless function
        invokers << if arg_types[-1] == FFI::NativeType::VARARGS
          VariadicInvoker.new(function, arg_types, find_type(ret_type), options)
        else
          Function.new(find_type(ret_type), arg_types, function, options)
        end
      rescue LoadError
      end
    end
  end
  invoker = invokers.compact.shift
  raise FFI::NotFoundError.new(cname.to_s, ffi_libraries.map { |lib| lib.name }) unless invoker
  invoker.attach(self, mname.to_s)
  invoker
end

def attach_variable(mname, a1, a2 = nil)
  cname, type = a2 ? [ a1, a2 ] : [ mname.to_s, a1 ]
  mname = mname.to_sym
  address = nil
  ffi_libraries.each do |lib|
    begin
      address = lib.find_variable(cname.to_s)
      break unless address.nil?
    rescue LoadError
    end
  end
  raise FFI::NotFoundError.new(cname, ffi_libraries) if address.nil? || address.null?
  if type.is_a?(Class) && type < FFI::Struct
    # If it is a global struct, just attach directly to the pointer
    s = s = type.new(address) # Assigning twice to suppress unused variable warning
    self.module_eval <<-code, __FILE__, __LINE__
      @ffi_gsvars = {} unless defined?(@ffi_gsvars)
      @ffi_gsvars[#{mname.inspect}] = s
      def self.#{mname}
        @ffi_gsvars[#{mname.inspect}]
      end
    code
  else
    sc = Class.new(FFI::Struct)
    sc.layout :gvar, find_type(type)
    s = sc.new(address)
    #
    # Attach to this module as mname/mname=
    #
    self.module_eval <<-code, __FILE__, __LINE__
      @ffi_gvars = {} unless defined?(@ffi_gvars)
      @ffi_gvars[#{mname.inspect}] = s
      def self.#{mname}
        @ffi_gvars[#{mname.inspect}][:gvar]
      end
      def self.#{mname}=(value)
        @ffi_gvars[#{mname.inspect}][:gvar] = value
      end
    code
  end
  address
end

def attached_functions
  @ffi_functions || {}
end

def attached_variables
  (
    (@ffi_gsvars || {}).map do |name, gvar|
      [name, gvar.class]
    end +
    (@ffi_gvars || {}).map do |name, gvar|
      [name, gvar.layout[:gvar].type]
    end
  ).to_h
end

def bitmask(*args)
  generic_enum(FFI::Bitmask, *args)
end

def callback(*args)
  raise ArgumentError, "wrong number of arguments" if args.length < 2 || args.length > 3
  name, params, ret = if args.length == 3
    args
  else
    [ nil, args[0], args[1] ]
  end
  native_params = params.map { |e| find_type(e) }
  raise ArgumentError, "callbacks cannot have variadic parameters" if native_params.include?(FFI::Type::VARARGS)
  options = Hash.new
  options[:convention] = ffi_convention
  options[:enums] = @ffi_enums if defined?(@ffi_enums)
  ret_type = find_type(ret)
  if ret_type == Type::STRING
    raise TypeError, ":string is not allowed as return type of callbacks"
  end
  cb = FFI::CallbackInfo.new(ret_type, native_params, options)
  # Add to the symbol -> type map (unless there was no name)
  unless name.nil?
    typedef cb, name
  end
  cb
end

def enum(*args)
  generic_enum(FFI::Enum, *args)
end

def enum_type(name)
  @ffi_enums.find(name) if defined?(@ffi_enums)
end

def enum_value(symbol)
  @ffi_enums.__map_symbol(symbol)
end

def ffi_convention(convention = nil)
  @ffi_convention ||= :default
  @ffi_convention = convention if convention
  @ffi_convention
end

def ffi_lib(*names)
  raise LoadError.new("library names list must not be empty") if names.empty?
  lib_flags = defined?(@ffi_lib_flags) && @ffi_lib_flags
  @ffi_libs = names.map do |name|
    FFI::DynamicLibrary.send(:load_library, name, lib_flags)
  end
end

def ffi_lib_flags(*flags)
  @ffi_lib_flags = flags.inject(0) { |result, f| result | FlagsMap[f] }
end

def ffi_libraries
  raise LoadError.new("no library specified") if !defined?(@ffi_libs) || @ffi_libs.empty?
  @ffi_libs
end

def find_type(t)
  if t.kind_of?(Type)
    t
  elsif defined?(@ffi_typedefs) && @ffi_typedefs.has_key?(t)
    @ffi_typedefs[t]
  elsif t.is_a?(Class) && t < Struct
    Type::POINTER
  elsif t.is_a?(DataConverter)
    # Add a typedef so next time the converter is used, it hits the cache
    typedef Type::Mapped.new(t), t
  end || FFI.find_type(t)
end

def freeze
  instance_variables.each do |name|
    var = instance_variable_get(name)
    FFI.make_shareable(var)
  end
  nil
end

def function_names(name, arg_types)
  result = [name.to_s]
  if ffi_convention == :stdcall
    # Get the size of each parameter
    size = arg_types.inject(0) do |mem, arg|
      size = arg.size
      # The size must be a multiple of 4
      size += (4 - size) % 4
      mem + size
    end
    result << "_#{name.to_s}@#{size}" # win32
    result << "#{name.to_s}@#{size}" # win64
  end
  result
end

def generic_enum(klass, *args)
  native_type = args.first.kind_of?(FFI::Type) ? args.shift : nil
  name, values = if args[0].kind_of?(Symbol) && args[1].kind_of?(Array)
    [ args[0], args[1] ]
  elsif args[0].kind_of?(Array)
    [ nil, args[0] ]
  else
    [ nil, args ]
  end
  @ffi_enums = FFI::Enums.new unless defined?(@ffi_enums)
  @ffi_enums << (e = native_type ? klass.new(native_type, values, name) : klass.new(values, name))
  # If called with a name, add a typedef alias
  typedef(e, name) if name
  e
end

def typedef(old, add, info=nil)
  @ffi_typedefs = Hash.new unless defined?(@ffi_typedefs)
  @ffi_typedefs[add] = if old.kind_of?(FFI::Type)
    old
  elsif @ffi_typedefs.has_key?(old)
    @ffi_typedefs[old]
  elsif old.is_a?(DataConverter)
    FFI::Type::Mapped.new(old)
  elsif old == :enum
    if add.kind_of?(Array)
      self.enum(add)
    else
      self.enum(info, add)
    end
  else
    FFI.find_type(old)
  end
end