require 'mkmf'

def transact
  old_libs = $libs.dup
  old_defs = $defs.dup
  result = yield
  if !result
    $libs = old_libs
    $defs = old_defs
  end
  result
end

def check_header_library(hdr, libs)
  if !have_header(hdr)
    return nil
  end
  libs.each {|lib|
    if have_library(lib, "initscr")
      return [hdr, lib]
    end
  }
  nil
end

dir_config('curses')
dir_config('ncurses')
dir_config('termcap')

have_library("mytinfo", "tgetent") if /bow/ =~ RUBY_PLATFORM
have_library("tinfo", "tgetent") or have_library("termcap", "tgetent")

header_library = nil
[
  ["ncurses.h", ["ncursesw", "ncurses"]],
  ["ncurses/curses.h", ["ncurses"]],
  ["curses_colr/curses.h", ["cur_colr"]],
  ["curses.h", ["curses"]],
].each {|hdr, libs|
  header_library = transact { check_header_library(hdr, libs) }
  if header_library
    break;
  end
}

if header_library
  header, library = header_library
  puts "header: #{header}"
  puts "library: #{library}"

  curses = [header]
  if header == 'curses_colr/curses.h'
    curses.unshift("varargs.h")
  end

  for f in %w(beep bkgd bkgdset curs_set deleteln doupdate flash
              getbkgd getnstr init isendwin keyname keypad resizeterm
              scrl set setscrreg ungetch
              wattroff wattron wattrset wbkgd wbkgdset wdeleteln wgetnstr
              wresize wscrl wsetscrreg
              def_prog_mode reset_prog_mode timeout wtimeout nodelay
              init_color wcolor_set use_default_colors newpad)
    have_func(f) || (have_macro(f, curses) && $defs.push(format("-DHAVE_%s", f.upcase)))
  end
  flag = "-D_XOPEN_SOURCE_EXTENDED"
  if try_static_assert("sizeof(char*)>sizeof(int)",
                       %w[stdio.h stdlib.h]+curses,
                       flag)
    $defs << flag
  end
  have_var("ESCDELAY", curses)
  have_var("TABSIZE", curses)
  have_var("COLORS", curses)
  have_var("COLOR_PAIRS", curses)

  # SVR4 curses has a (undocumented) variable char *curses_version.
  # ncurses and PDcurses has a function char *curses_version().
  # Note that the original BSD curses doesn't provide version information.

  prolog = cpp_include(curses)
  if checking_for(checking_message('function curses_version', curses)) {
      try_run(<<-"End")
        #{prolog}
        int main(int argc, char *argv[])
        {
            curses_version();
            return EXIT_SUCCESS;
        }
      End
    }
    $defs << '-DHAVE_FUNC_CURSES_VERSION'
  end

  if checking_for(checking_message('variable curses_version', curses)) {
      try_run(<<-"End")
        #{prolog}
        extern char *curses_version;
        int main(int argc, char *argv[])
        {
            int i = 0;
            for (i = 0; i < 100; i++) {
                if (curses_version[i] == 0)
                    return 0 < i ? EXIT_SUCCESS : EXIT_FAILURE;
                if (curses_version[i] & 0x80)
                    return EXIT_FAILURE;
            }
            return EXIT_FAILURE;
        }
      End
    }
    $defs << '-DHAVE_VAR_CURSES_VERSION'
  end

  create_makefile("curses")
end