with Ada.Text_IO; use Ada.Text_IO;
-- !! will disappear in favour of Ada.Exceptions

with Multi_precision_integers.IO;

package body Multi_precision_integers.Check is

  package IOi renames Multi_precision_integers.IO;

  -- Don't be afraid by the bug reporting tools,
  -- they are unlikely to pop out of a programme ;-)

  Bug_file: Ada.Text_IO.File_type;
  Bug_file_name: constant String:= "mupreint.bug";

  -- The flaw detection (DEBUG mode) could suffer from
  -- a chicken-and-egg problem: e.g. "*" works, but the "/"
  -- to verify it doesn't !

  Multiply_flawed_div1_has_rest       : exception;
  Multiply_flawed_div1_wrong_quotient : exception;
  Multiply_flawed_div2_has_rest       : exception;
  Multiply_flawed_div2_wrong_quotient : exception;

  Div_Rem_flawed : exception;

  procedure Open_Bug_Report is
  begin
    Create( Bug_file, out_file, Bug_file_name );
    Put_Line( Bug_file, "Bug in Multi_precision_integers");
  end Open_Bug_Report;

  procedure Close_Bug_Report is
  begin
    Close( Bug_file );
    -- These console messages can provoke a silent quit in GUI apps,
    -- so we put them after closing the report.
    Put_Line( "Bug in Multi_precision_integers !");
    Put_Line( "For details, read file: " & Bug_file_name);
  end Close_Bug_Report;

  procedure Test( m: multi_int; test_last: Boolean:= True ) is
    last_nz: index_int:= 0;
    Negative_block,
    Last_index_has_zero,
    Field_last_outside_range, Field_last_is_negative: exception;
  begin
    if m.zero then return; end if; -- 0, nothing to test
    if m.last_used > m.n then raise Field_last_outside_range; end if;
    if m.last_used <   0 then raise Field_last_is_negative; end if;
    for i in 0 .. m.last_used loop
      if m.blk(i) < 0 then
        raise Negative_block;
      end if;
      if m.blk(i) /= 0 then
        last_nz:= i;
      end if;
    end loop;
    if test_last and then 0 < last_nz and then last_nz < m.last_used then
      raise Last_index_has_zero;
    end if;
  end Test;

  procedure Check_Multiplication(i1,i2,i3: in multi_int) is
    jeu: constant:= 5; -- 0 suffit
    q1: Multi_int( i2.last_used + jeu );
    r1: Multi_int( i1.last_used + i2.last_used + jeu );
    q2: Multi_int( jeu );
    r2: Multi_int( i2.last_used + jeu );

    procedure Bug_Report is
    begin
      Open_Bug_Report;
      Put_Line( Bug_file, "Multiply_and_verify");
      Put( Bug_file, "i1 ="); IOi.Put_in_blocks(Bug_file, i1); New_Line(Bug_file);
      Put( Bug_file, "i2 ="); IOi.Put_in_blocks(Bug_file, i2); New_Line(Bug_file);
      Put( Bug_file, "i3 ="); IOi.Put_in_blocks(Bug_file, i3); New_Line(Bug_file);
    end Bug_Report;

  begin
    Test(i1);
    Test(i2);

    if not (i1.zero or i2.zero) then
      -- Now we divide i3 by i1, q1 should be = i2
      Div_Rem_internal_both_export(i3,i1, q1,r1);
      if not r1.zero then
        Bug_Report;
        Close_Bug_Report;
        raise Multiply_flawed_div1_has_rest;
      end if;
      if not Equal( q1, i2 ) then
        Bug_Report;
        Put( Bug_file, "q1 ="); IOi.Put_in_blocks(Bug_file, q1); New_Line(Bug_file);
        Close_Bug_Report;
        raise Multiply_flawed_div1_wrong_quotient;
      end if;
      -- Now we divide q1 by i2, should be = 1
      Div_Rem_internal_both_export(q1,i2, q2,r2);
      if not r2.zero then
        Bug_Report;
        Close_Bug_Report;
        raise Multiply_flawed_div2_has_rest;
      end if;
      if not Equal( q2, Multi(1) ) then
        Bug_Report;
        Put( Bug_file, "q2 ="); IOi.Put_in_blocks(Bug_file, q1); New_Line(Bug_file);
        Close_Bug_Report;
        raise Multiply_flawed_div2_wrong_quotient;
      end if;
    end if;

  end Check_Multiplication;

  procedure Check_Div_Rem(i1,i2,q,r: in multi_int) is

    procedure Bug_Report is
    begin
      Open_Bug_Report;
      Put_Line( Bug_file, "Div_Rem_and_verify");
      Put( Bug_file, "i1 ="); IOi.Put_in_blocks(Bug_file, i1); New_Line(Bug_file);
      Put( Bug_file, "i2 ="); IOi.Put_in_blocks(Bug_file, i2); New_Line(Bug_file);
      Put( Bug_file, "q  ="); IOi.Put_in_blocks(Bug_file, q); New_Line(Bug_file);
      Put( Bug_file, "r  ="); IOi.Put_in_blocks(Bug_file, r); New_Line(Bug_file);
    end Bug_Report;

  begin
    Test(i1);
    Test(i2);

    if not Equal( i1, i2*q + r ) then
      Bug_Report;
      Close_Bug_Report;
      raise Div_Rem_flawed;
    end if;

    Test(q);
    Test(r);
  end Check_Div_Rem;

end Multi_precision_integers.Check;