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(mname, a3, a4, a5=nil)
  cname, arg_types, ret_type = a5 ? [ a3, a4, a5 ] : [ mname.to_s, a3, a4 ]
  # Convert :foo to the native type
  arg_types.map! { |e| find_type(e) }
  has_callback = arg_types.any? {|t| t.kind_of?(FFI::CallbackInfo)}
  options = Hash.new
  options[:convention] = defined?(@ffi_convention) ? @ffi_convention : :default
  options[:type_map] = @ffi_typedefs if defined?(@ffi_typedefs)
  options[:enums] = @ffi_enums if defined?(@ffi_enums)
  # Try to locate the function in any of the libraries
  invokers = []
  ffi_libraries.each do |lib|
    begin
      invokers << FFI.create_invoker(lib, cname.to_s, arg_types, find_type(ret_type), options)
    rescue LoadError => ex
    end if invokers.empty?
  end
  invoker = invokers.compact.shift
  raise FFI::NotFoundError.new(cname.to_s, ffi_libraries.map { |lib| lib.name }) unless invoker
  # Setup the parameter list for the module function as (a1, a2)
  arity = arg_types.length
  params = (1..arity).map {|i| "a#{i}" }.join(",")
  # Always use rest args for functions with callback parameters
  if has_callback || invoker.kind_of?(FFI::VariadicInvoker)
    params = "*args, &block"
  end
  call = arity <= 3 && !has_callback && !invoker.kind_of?(FFI::VariadicInvoker)? "call#{arity}" : "call"
  #
  # Attach the invoker to this module as 'mname'.
  #
  if !has_callback && !invoker.kind_of?(FFI::VariadicInvoker)
    invoker.attach(self, mname.to_s)
  else
    self.module_eval <<-code
      @@#{mname} = invoker
      def self.#{mname}(#{params})
        @@#{mname}.#{call}(#{params})
      end
      def #{mname}(#{params})
        @@#{mname}.#{call}(#{params})
      end
    code
  end
  invoker
end

def attach_variable(mname, a1, a2 = nil)
  cname, type = a2 ? [ a1, a2 ] : [ mname.to_s, a1 ]
  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 = type.new(address)
    self.module_eval <<-code, __FILE__, __LINE__
      @@ffi_gvar_#{mname} = s
      def self.#{mname}
        @@ffi_gvar_#{mname}
      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_gvar_#{mname} = s
      def self.#{mname}
        @@ffi_gvar_#{mname}[:gvar]
      end
      def self.#{mname}=(value)
        @@ffi_gvar_#{mname}[:gvar] = value
      end
    code
  end
  address
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
  options = Hash.new
  options[:convention] = defined?(@ffi_convention) ? @ffi_convention : :default
  options[:enums] = @ffi_enums if defined?(@ffi_enums)
  cb = FFI::CallbackInfo.new(find_type(ret), params.map { |e| find_type(e) }, options)
  # Add to the symbol -> type map (unless there was no name)
  unless name.nil?
    @ffi_callbacks = Hash.new unless defined?(@ffi_callbacks)
    @ffi_callbacks[name] = cb
  end
  cb
end

def enum(*args)
  #
  # enum can be called as:
  # enum :zero, :one, :two  # unnamed enum
  # enum [ :zero, :one, :two ] # equivalent to above
  # enum :foo, [ :zero, :one, :two ] create an enum named :foo
  #
  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 = FFI::Enum.new(values, name))
  # If called as enum :foo, [ :zero, :one, :two ], add a typedef alias
  typedef(e, name) if name
  e
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)
  @ffi_convention = convention
end

def ffi_lib(*names)
  ffi_libs = names.map do |name|
    if name == FFI::CURRENT_PROCESS
      FFI::DynamicLibrary.open(nil, FFI::DynamicLibrary::RTLD_LAZY | FFI::DynamicLibrary::RTLD_GLOBAL)
    else
      libnames = (name.is_a?(::Array) ? name : [ name ]).map { |n| [ n, FFI.map_library_name(n) ].uniq }.flatten.compact
      lib = nil
      errors = {}
      libnames.each do |libname|
        begin
          lib = FFI::DynamicLibrary.open(libname, FFI::DynamicLibrary::RTLD_LAZY | FFI::DynamicLibrary::RTLD_GLOBAL)
          break if lib
        rescue Exception => ex
          errors[libname] = ex
        end
      end
      if lib.nil?
        raise LoadError.new(errors.values.join('. '))
      end
      # return the found lib
      lib
    end
  end
  @ffi_libs = ffi_libs
end

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

def find_type(name)
  code = if defined?(@ffi_typedefs) && @ffi_typedefs.has_key?(name)
    @ffi_typedefs[name]
  elsif defined?(@ffi_callbacks) && @ffi_callbacks.has_key?(name)
    @ffi_callbacks[name]
  elsif name.is_a?(Class) && name < FFI::Struct
    FFI::NativeType::POINTER
  elsif name.kind_of?(FFI::Type)
    name
  end
  if code.nil? || code.kind_of?(Symbol)
    FFI.find_type(name)
  else
    code
  end
end

def typedef(current, add, info=nil)
  @ffi_typedefs = Hash.new unless defined?(@ffi_typedefs)
  code = if current.kind_of?(FFI::Type)
    current
  elsif current == :enum
    if add.kind_of?(Array)
      self.enum(add)
    else
      self.enum(info, add)
    end
  else
    @ffi_typedefs[current] || FFI.find_type(current)
  end
  @ffi_typedefs[add] = code
end