module ICU
  class Error < StandardError
  end

  class BufferOverflowError < StandardError
  end

  module Lib
    extend FFI::Library

    VERSIONS = {
      "42" => "_4_2",
      "44" => "_44"
    }

    # FIXME: this is incredibly ugly, figure out some better way
    def self.find_icu
      suffix = ''

      # let the user tell us where the lib is
      if ENV['FFI_ICU_LIB']
        libs = ENV['FFI_ICU_LIB'].split(",")
        ffi_lib *libs

        if ENV['FFI_ICU_VERSION_SUFFIX']
          return ENV['FFI_ICU_VERSION_SUFFIX']
        elsif num = libs.first[/\d+$/]
          return num.split(//).join("_")
        else
          return suffix
        end
      end

      # ok, try to find it
      case ICU.platform
      when :osx
        ffi_lib "icucore"
      when :linux
        versions = VERSIONS.keys
        libs = ffi_lib versions.map { |v| "libicui18n.so.#{v}"},
                       versions.map { |v| "libicutu.so.#{v}"}

        VERSIONS.find do |so_version, func_version|
          if libs.first.name =~ /#{so_version}$/
            suffix = func_version
          end
        end
      else
        raise "no idea how to load ICU on #{ICU.platform}, patches appreciated!"
      end

      suffix
    end

    def self.check_error
      ptr = FFI::MemoryPointer.new(:int)
      ret = yield(ptr)
      error_code = ptr.read_int

      if error_code > 0
        name = Lib.u_errorName error_code
        if name == "U_BUFFER_OVERFLOW_ERROR"
          raise BufferOverflowError
        else
          raise Error, name
        end
      elsif error_code < 0
        warn "ffi-icu: #{Lib.u_errorName error_code}"
      end

      ret
    end

    def self.enum_ptr_to_array(enum_ptr)
      length = check_error do |status|
        uenum_count(enum_ptr, status)
      end

      len = FFI::MemoryPointer.new(:int)

      (0...length).map do |idx|
        check_error { |st| uenum_next(enum_ptr, len, st) }
      end
    end

    def self.not_available(func_name)
      self.class.send :define_method, func_name do |*args|
        raise Error, "#{func_name} not available on platform #{ICU.platform.inspect}"
      end
    end


    suffix = find_icu()

    attach_function :u_errorName, "u_errorName#{suffix}", [:int], :string
    attach_function :uenum_count, "uenum_count#{suffix}", [:pointer, :pointer], :int
    attach_function :uenum_close, "uenum_close#{suffix}",  [:pointer], :void
    attach_function :uenum_next, "uenum_next#{suffix}",  [:pointer, :pointer, :pointer], :string
    attach_function :u_charsToUChars, "u_charsToUChars#{suffix}", [:string, :pointer, :int32_t], :void
    attach_function :u_UCharsToChars, "u_UCharsToChars#{suffix}", [:pointer, :string, :int32_t], :void

    # CharDet
    #
    # http://icu-project.org/apiref/icu4c/ucsdet_8h.html
    #

    attach_function :ucsdet_open, "ucsdet_open#{suffix}",  [:pointer], :pointer
    attach_function :ucsdet_close, "ucsdet_close#{suffix}",  [:pointer], :void
    attach_function :ucsdet_setText, "ucsdet_setText#{suffix}",  [:pointer, :string, :int32_t, :pointer], :void
    attach_function :ucsdet_setDeclaredEncoding, "ucsdet_setDeclaredEncoding#{suffix}",  [:pointer, :string, :int32_t, :pointer], :void
    attach_function :ucsdet_detect, "ucsdet_detect#{suffix}",  [:pointer, :pointer], :pointer
    attach_function :ucsdet_detectAll, "ucsdet_detectAll#{suffix}",  [:pointer, :pointer, :pointer], :pointer
    attach_function :ucsdet_getName, "ucsdet_getName#{suffix}",  [:pointer, :pointer], :string
    attach_function :ucsdet_getConfidence, "ucsdet_getConfidence#{suffix}",  [:pointer, :pointer], :int32_t
    attach_function :ucsdet_getLanguage, "ucsdet_getLanguage#{suffix}",  [:pointer, :pointer], :string
    attach_function :ucsdet_getAllDetectableCharsets, "ucsdet_getAllDetectableCharsets#{suffix}",  [:pointer, :pointer], :pointer
    attach_function :ucsdet_isInputFilterEnabled, "ucsdet_isInputFilterEnabled#{suffix}",  [:pointer], :bool
    attach_function :ucsdet_enableInputFilter, "ucsdet_enableInputFilter#{suffix}",  [:pointer, :bool], :bool

    # Collation
    #
    # http://icu-project.org/apiref/icu4c/ucol_8h.html
    #

    attach_function :ucol_open, "ucol_open#{suffix}",  [:string, :pointer], :pointer
    attach_function :ucol_close, "ucol_close#{suffix}",  [:pointer], :void
    attach_function :ucol_strcoll, "ucol_strcoll#{suffix}",  [:pointer, :pointer, :int32_t, :pointer, :int32_t], :int
    attach_function :ucol_getKeywords, "ucol_getKeywords#{suffix}",  [:pointer], :pointer
    attach_function :ucol_getKeywordValues, "ucol_getKeywordValues#{suffix}",  [:string, :pointer], :pointer
    attach_function :ucol_getAvailable, "ucol_getAvailable#{suffix}", [:int32_t], :string
    attach_function :ucol_countAvailable, "ucol_countAvailable#{suffix}", [], :int32_t
    attach_function :ucol_getLocale, "ucol_getLocale#{suffix}", [:pointer, :int, :pointer], :string
    attach_function :ucol_greater, "ucol_greater#{suffix}", [:pointer, :pointer, :int32_t, :pointer, :int32_t], :bool
    attach_function :ucol_greaterOrEqual, "ucol_greaterOrEqual#{suffix}", [:pointer, :pointer, :int32_t, :pointer, :int32_t], :bool
    attach_function :ucol_equal, "ucol_equal#{suffix}", [:pointer, :pointer, :int32_t, :pointer, :int32_t], :bool

    # Transliteration
    #
    # http://icu-project.org/apiref/icu4c/utrans_8h.html
    #

    class UParseError < FFI::Struct
      layout :line,         :int32_t,
             :offset,       :int32_t,
             :pre_context,  :pointer,
             :post_context, :pointer


    end

    class UTransPosition < FFI::Struct
      layout :context_start, :int32_t,
             :context_limit, :int32_t,
             :start,         :int32_t,
             :end,           :int32_t

    end

    enum :trans_direction, [:forward, :reverse]

    attach_function :utrans_openIDs, "utrans_openIDs#{suffix}", [:pointer], :pointer
    attach_function :utrans_openU, "utrans_openU#{suffix}", [:pointer, :int32_t, :trans_direction, :pointer, :int32_t, :pointer, :pointer], :pointer
    attach_function :utrans_open, "utrans_open#{suffix}", [:string, :trans_direction, :pointer, :int32_t, :pointer, :pointer], :pointer
    attach_function :utrans_close, "utrans_close#{suffix}", [:pointer], :void
    attach_function :utrans_transUChars, "utrans_transUChars#{suffix}", [:pointer, :pointer, :pointer, :int32_t, :int32_t, :pointer, :pointer], :void

    # Normalization
    #
    # http://icu-project.org/apiref/icu4c/unorm_8h.html
    #

    enum :normalization_mode, [ :none,    1,
                                :nfd,     2,
                                :nfkd,    3,
                                :nfc,     4,
                                :default, 4,
                                :nfkc,    5,
                                :fcd,     6
                              ]

    attach_function :unorm_normalize, "unorm_normalize#{suffix}", [:pointer, :int32_t, :normalization_mode, :int32_t, :pointer, :int32_t, :pointer], :int32_t
  end # Lib
end # ICU