#
# Copyright (C) 2008, 2009 Wayne Meissner
# Copyright (C) 2008 Luc Heinrich <luc@honk-honk.com>
# Copyright (c) 2007, 2008 Evan Phoenix
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
#   list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above copyright notice
#   this list of conditions and the following disclaimer in the documentation
#   and/or other materials provided with the distribution.
# * Neither the name of the Evan Phoenix nor the names of its contributors
#   may be used to endorse or promote products derived from this software
#   without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

module FFI
  CURRENT_PROCESS = USE_THIS_PROCESS_AS_LIBRARY = Object.new

  module Library
    CURRENT_PROCESS = FFI::CURRENT_PROCESS
    LIBC = FFI::Platform::LIBC

    def self.extended(mod)
      raise RuntimeError.new("must only be extended by module") unless mod.kind_of?(Module)
    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_LOCAL)
        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_LOCAL)
              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_convention(convention)
      @ffi_convention = convention
    end


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

    ##
    # Attach C function +name+ to this module.
    #
    # If you want to provide an alternate name for the module function, supply
    # it after the +name+, otherwise the C function name will be used.#
    #
    # After the +name+, the C function argument types are provided as an Array.
    #
    # The C function return type is provided last.

    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 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

    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 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
  end
end