# encoding: utf-8

if RUBY_PLATFORM != "java"
    require 'rubygems' ; # pour (c)ruby
    puts "execution of require 'rubygems' done (because not java platform)"
end

# This require works either with ruby or with jruby-1.2 (which contains a dummy ffi gem)
# require 'rubygems'
require 'ffi'
require 'pp'

module Glpk

    extend FFI::Library

    # one should load the libglpk.so or like file in your lib path
    # To way to make this
    #
    # 1 - The best way: work on osx leopard, but not yet on every linux
    #     version
    #
    # ffi_lib "glpk"
    #
    # 2 - Other way is to load the file directly, but you need to know were
    #     it is located. FFI should provide an easier way to make this
    #     One suppose the env variable contains the path to the glpk library
    #
    if %x(uname -a) =~ /Darwin/
        libsuffix=".dylib"
    else
        libsuffix=".so"
    end
    # # glpk_lib_file=ENV["GLPK_LIB"] + "/libglpk" + libsuffix
    # # pp glpk_lib_file
    ffi_lib ENV["GLPK_LIB"] + "/libglpk" + libsuffix


    # constants (see glpk.h)
    # stead replace_in_selection:
    #   rs -l {#define\s+(\w+)\s+(\d+)\s*(?:/\*(.+)\*/)?} {\1 = \2  # \3}
    GLP_MIN = 1 # minimization
    GLP_MAX = 2 # maximization

    # kind of structural variable:
    GLP_CV = 1 #  continuous variable
    GLP_IV = 2 #  integer variable
    GLP_BV = 3 #  binary variable

    # type of auxiliary/structural variable:
    GLP_FR = 1 #  free variable
    GLP_LO = 2 #  variable with lower bound
    GLP_UP = 3 #  variable with upper bound
    GLP_DB = 4 #  double-bounded variable
    GLP_FX = 5 #  fixed variable


    # 16/0/2015 (diam) the binded function is called `glp_create_prob_` so that
    # the ffi-glpk user function can be called `glp_create_prob`
    #
    # attach_function :glp_create_prob, [], :pointer   # __OLD__
    # attach_function :glp_delete_prob, [:pointer], :void
    #
    attach_function :glp_create_prob_, :glp_create_prob, [], :pointer
    attach_function :glp_delete_prob_, :glp_delete_prob, [:pointer], :void

    attach_function :glp_set_prob_name, [:pointer, :string], :pointer
    attach_function :glp_get_prob_name, [:pointer], :string

    attach_function :glp_set_obj_dir, [:pointer, :int], :int
    attach_function :glp_get_obj_dir, [:pointer], :int
    attach_function :glp_set_obj_coef,[:pointer, :int, :double], :void
    attach_function :glp_get_obj_coef, [:pointer, :int], :double
    attach_function :glp_get_obj_val, [:pointer], :double
    attach_function :glp_mip_obj_val, [:pointer], :double

    attach_function :glp_add_rows,
                    [:pointer, :int], :int
    attach_function :glp_set_row_name,
                    [:pointer, :int, :string], :int
    attach_function :glp_set_row_bnds,
                    [:pointer, :int, :int, :double, :double], :int

    attach_function :glp_add_cols,
                    [:pointer, :int], :int
    attach_function :glp_set_col_name,
                    [:pointer, :int, :string], :void
    attach_function :glp_set_col_bnds,
                    [:pointer,:int,:int,:double,:double],:void
    attach_function :glp_set_col_kind,
                    [:pointer, :int, :int], :void
    attach_function :glp_get_col_prim,
                    [:pointer, :int], :double
    attach_function :glp_mip_col_val,
                    [:pointer, :int], :double

    attach_function :glp_load_matrix,
                    [:pointer, :int, :pointer, :pointer, :pointer], :void

    attach_function :glp_simplex, [:pointer, :int], :void;

    attach_function :glp_intopt, [:pointer, :int], :void;

    # bug diam 16/02/2015: new problem "constructor" to cleanup attributes
    def glp_create_prob
        @ia_vector = Array.new
        @ja_vector = Array.new
        @ar_vector = Array.new
        glp_create_prob_
    end

    # bug diam 16/02/2015: new problem "constructor" to cleanup attributes
    def glp_delete_prob glpk_pb
        glp_delete_prob_ glpk_pb
        @ia_vector = nil
        @ja_vector = nil
        @ar_vector = nil
    end


    # could become a method of a higher level shell over this Glpk module
    #
    def glp_set_aij_coef(idx_cst, idx_var, coef)
        @ia_vector = Array.new unless @ia_vector
        @ja_vector = Array.new unless @ja_vector
        @ar_vector = Array.new unless @ar_vector
        @ia_vector << idx_cst
        @ja_vector << idx_var
        @ar_vector << coef
    end

    def glp_load_matrix2 lp
        glp_load_matrix(lp, @ar_vector.length - 1,
                            to_array_of_int32(@ia_vector),
                            to_array_of_int32(@ja_vector),
                            to_array_of_double(@ar_vector));
    end

    def to_array_of_int32 tab
        tab_p = FFI::MemoryPointer.new(:int, tab.length)
        tab_p.put_array_of_int32(0, tab)
        return tab_p
    end

    def to_array_of_double tab
        tab_p = FFI::MemoryPointer.new(:double, tab.length)
        tab_p.put_array_of_double(0, tab)
        return tab_p
    end
end
#./