#!/usr/bin/env perl

use 5.006;
use strict;
use warnings;

use File::Spec;

sub shell ($@);
sub env ($$);
sub cd ($);
sub auto_complete ($);
sub usage ($);

my (@make_cmds, @make_install_cmds);

my $root_dir = `pwd`;
chomp $root_dir;

my $OS = $^O;

my $ngx_dir;

for my $opt (@ARGV) {
    if ($opt =~ /^--platform=(.*)/) {
        $OS = $1;
        undef $opt;
    }
}

my ($platform, $on_solaris);

if ($OS =~ /solaris|sunos/i) {
    $platform = 'solaris';
    $on_solaris = $platform;

} elsif ($OS eq 'linux') {
    $platform = $OS;

} elsif ($OS eq 'MSWin32') {
    die "MS Windows not supported. Abort.\n";

} elsif ($OS =~ /^(?:MacOS|darwin|rhapsody)$/) {
    $platform = 'macosx';

} elsif ($OS eq 'freebsd') {
    $platform = $OS;

} elsif ($OS =~ /^(?:openbsd|netbsd)$/) {
    $platform = 'bsd';

} else {
    $platform = 'posix';
}

my @modules = (
    [ndk => 'ngx_devel_kit'],
    [http_iconv => 'iconv-nginx-module', 'disabled'],
    [http_echo => 'echo-nginx-module'],
    [http_xss => 'xss-nginx-module'],
    [http_set_misc => 'set-misc-nginx-module'],
    [http_form_input => 'form-input-nginx-module'],
    [http_encrypted_session => 'encrypted-session-nginx-module'],
    [http_drizzle => 'drizzle-nginx-module', 'disabled'],
    [http_postgres => 'ngx_postgres', 'disabled'],
    [http_lua => 'ngx_lua'],
    [http_headers_more => 'headers-more-nginx-module'],
    [http_srcache => 'srcache-nginx-module'],
    [http_array_var => 'array-var-nginx-module'],
    [http_memc => 'memc-nginx-module'],
    [http_redis2 => 'redis2-nginx-module'],
    [http_upstream_keepalive => 'upstream-keepalive-nginx-module'],
    [http_auth_request => 'auth-request-nginx-module'],
    [http_rds_json => 'rds-json-nginx-module'],
);

my $without_resty_mods_regex;
{
    my $s = '^--without-('
        . join('|',
            map { $_->[0] }
                grep { @$_ == 2 && $_->[0] =~ /^http_/ }
                @modules
          )
        . ')_module$';

    #warn "without regex: $s";

    $without_resty_mods_regex = qr/$s/;
}

my $with_resty_mods_regex;
{
    my $s = '^--with-('
        . join('|',
            map { $_->[0] }
                grep { @$_ == 3 && $_->[0] =~ /^http_/ }
                @modules
          )
        . ')_module$';

    #warn "with regex: $s";

    $with_resty_mods_regex = qr/$s/;
}

my $prefix = '/usr/local/openresty';
my %resty_opts;
my $dry_run;
my @ngx_rpaths;
my $cc;

my (@ngx_opts, @ngx_cc_opts, @ngx_ld_opts);

for my $opt (@ARGV) {
    next unless defined $opt;

    if ($opt =~ /^--with-cc=(.+)/) {
        $cc = $1;
        push @ngx_opts, $opt;
        next;
    }

    if ($opt eq '--dry-run') {
        $dry_run = 1;
        next;
    }

    if ($opt =~ /^--with-make=(.*)/) {
        $resty_opts{make} = $1;
        next;
    }

    if ($opt =~ /^--prefix=(.*)/) {
        $prefix = $1;

    } elsif ($opt eq '--without-lua51') {
        $resty_opts{no_lua} = 1;

    } elsif ($opt eq '--without-lua_cjson') {
        $resty_opts{no_lua_cjson} = 1;

    } elsif ($opt eq '--with-debug') {
        $resty_opts{debug} = 1;

    } elsif ($opt eq '--help') {
        usage 0;

    } elsif ($opt =~ /^--with-cc-opt=(.*)/) {
        push @ngx_cc_opts, $1;

    } elsif ($opt =~ /^--with-ld-opt=(.*)/) {
        push @ngx_ld_opts, $1;

    } elsif ($opt =~ $without_resty_mods_regex) {
        #die "no_$1\n";
        $resty_opts{"no_$1"} = 1;

    } elsif ($opt eq '--without-ngx_devel_kit_module') {
        $resty_opts{no_ndk} = 1;

    } elsif ($opt =~ $with_resty_mods_regex) {
        $resty_opts{"$1"} = 1;

    } elsif ($opt eq '--with-luajit') {
        $resty_opts{luajit} = 1;

    } elsif ($opt =~ /^--with-libdrizzle=(.*)/) {
        $resty_opts{libdrizzle} = $1;

    } elsif ($opt =~ /^--with-libpq=(.*)/) {
        $resty_opts{libpq} = $1;
        if ($resty_opts{pg_config}) {
            die "--with-libpq is not allowed when ",
                "--with-pg_config is already specified.\n";
        }

    } elsif ($opt =~ /^--with-pg_config=(.*)/) {
        $resty_opts{pg_config} = $1;
        if ($resty_opts{libpq}) {
            die "--with-pg_config is not allowed when ",
                "--with-libpq is already specified.\n";
        }

    } elsif ($opt eq '--with-no-pool-patch') {
        $resty_opts{no_pool} = 1;

    } elsif ($opt eq '--with-http_ssl_module') {
        $resty_opts{http_ssl} = 1;
        push @ngx_opts, $opt;

    } elsif ($opt eq '--without-http_ssl_module') {
        $resty_opts{no_http_ssl} = 1;

    } elsif ($opt =~ /^--\w.*/) {
        push @ngx_opts, $opt;

    } else {
        die "Invalid option $opt\n";
    }
}

print "platform: $platform ($OS)\n";

my $ngx_prefix = "$prefix/nginx";

my $postamble = '';

my $resty_opts = build_resty_opts(\%resty_opts);

if (@ngx_rpaths) {
    unshift @ngx_ld_opts, "-Wl,-rpath," . join(":", @ngx_rpaths);
}

my $ld_opts = '';
if (@ngx_ld_opts) {
    $ld_opts = " \\\n  --with-ld-opt='@ngx_ld_opts'";
}

my $cmd = "./configure --prefix=$ngx_prefix"
    . $resty_opts
    . $ld_opts
    . (@ngx_opts ? " \\\n  @ngx_opts" : "");
    ;

shell $cmd, $dry_run;

push @make_cmds, "cd $root_dir/build/$ngx_dir && "
    . "\$(MAKE)";

push @make_install_cmds, "cd $root_dir/build/$ngx_dir && "
    . "\$(MAKE) install DESTDIR=\$(DESTDIR)";

cd '../..'; # to the root
#die "pwd: " .. `pwd`;

gen_makefile();

if ($postamble) {
    print $postamble;
}

sub env ($$) {
    my ($name, $val) = @_;
    print "export $name='$val'\n";
    $ENV{$name} = $val;
}

sub shell ($@) {
    my ($cmd, $dry_run) = @_;

    print "$cmd\n";

    unless ($dry_run) {
        system($cmd) == 0 or
            die "failed to run command: $cmd\n";
    }
}

sub auto_complete ($) {
    my $name = shift;
    my @dirs = glob "$name-[0-9]*" or
        die "No source directory found for $name\n";

    if (@dirs > 1) {
        die "More than one hits for $name: @dirs\n";
    }

    return $dirs[0];
}

sub cd ($) {
    my $dir = shift;
    print("cd $dir\n");
    chdir $dir or die "failed to cd $dir: $!\n";
}

sub build_resty_opts {
    my $opts = shift;

    my $make;

    if ($opts->{make}) {
        $make = $opts->{make};
        if (! can_run($make)) {
            die "make utility $make cannot be run.\n";
        }

    } else {
        if (can_run("gmake")) {
            $make = 'gmake';

        } else {
            # no gmake found

            if ($platform =~ /bsd/i && $opts->{luajit}) {
                die "you need to install gmake to build LuaJIT.\n";
            }

            if (can_run("make")) {
                $make = "make";

            } else {
                die "No gmake nor make found in PATH.\n";
            }
        }
    }

    $postamble .= <<"_END_";
Type the following commands to build and install:
    $make
    $make install
_END_

    if ($opts->{no_ndk}) {
        for my $name (qw(lua set_misc iconv lz_session form_input array_var)) {
            if (! $opts->{"no_http_$name"}) {
                warn "WARNING: ngx_http_${name}_module is automatically disabled ",
                    "because ngx_devel_kit_module is disabled.\n";
                $opts->{"no_http_$name"} = 1;
            }
        }
    }

    if (! $opts->{luajit} && ! $opts->{no_http_lua} && ! $opts->{no_lua}) {
        $opts->{lua} = 1;
    }

    if ($opts->{no_http_ssl} && $opts->{http_ssl}) {
        die "--with-http_ssl_module conflicts with --without-http_ssl_module.\n";
    }

    if (! $opts->{no_http_ssl} && ! $opts->{http_ssl}) {
        $opts->{http_ssl} = 1;
        push @ngx_opts, '--with-http_ssl_module';
    }

    if (! $opts->{http_drizzle} && $opts->{libdrizzle}) {
        die "The http_drizzle_module is not enabled while --with-libdrizzle is specified.\n";
    }

    if (! $opts->{http_postgres} && $opts->{libpq}) {
        die "The http_postgres_module is not enabled while --with-libpq is specified.\n";
    }

    if (! $opts->{http_postgres} && $opts->{pg_config}) {
        die "The http_postgres_module is not enabled while --with-pg_config is specified.\n";
    }

    if ($platform eq 'linux' && $opts->{luajit} && ! can_run("ldconfig")) {
        die "you need to have ldconfig in your PATH env when enabling luajit.\n";
    }

    my $opts_line = '';

    if ($opts->{debug}) {
        unshift @ngx_cc_opts, '-O0';
        $opts_line .= " \\\n  --with-debug";

    } else {
        #unshift @ngx_cc_opts, '-O2';
    }

    if (@ngx_cc_opts) {
        $opts_line .= " \\\n  --with-cc-opt='@ngx_cc_opts'";
    }

    if (-d 'build') {
        system("rm -rf build");
    }

    if (-f 'build') {
        die "build/ directory already exists\n";
    }

    shell "cp -rp bundle/ build/";

    cd 'build';

    # build 3rd-party C libraries if required

    if ($opts->{no_pool}) {
        if (! can_run("patch")) {
            die "no \"patch\" utility found in your PATH environment.\n";
        }

        shell "patch -p0 < nginx-no_pool.patch";
    }

    if (my $drizzle_prefix = $opts->{libdrizzle}) {
        my $drizzle_lib = "$drizzle_prefix/lib";
        env LIBDRIZZLE_LIB => $drizzle_lib;
        env LIBDRIZZLE_INC => "$drizzle_prefix/include/libdrizzle-1.0";
        push @ngx_rpaths, $drizzle_lib;
    }

    if (my $pg_prefix = $opts->{libpq}) {
        my $pg_lib = "$pg_prefix/lib";
        env LIBPQ_LIB => $pg_lib;
        env LIBPQ_INC => "$pg_prefix/include";
        push @ngx_rpaths, $pg_lib;
    }

    if (my $pg_config = $opts->{pg_config}) {
        if (!can_run($pg_config)) {
            die "pg_config is not runnable.\n";
        }

        my $cmd = "$pg_config --libdir";
        my $pg_lib = `$cmd`;
        chomp $pg_lib;
        if (!defined $pg_lib) {
            die "Failed to run command $cmd\n";
        }

        $cmd = "$pg_config --includedir";
        my $pg_inc = `$cmd`;
        chomp $pg_inc;
        if (!defined $pg_inc) {
            die "Failed to run command $cmd\n";
        }

        env LIBPQ_LIB => $pg_lib;
        env LIBPQ_INC => $pg_inc;
        push @ngx_rpaths, $pg_lib;
    }

    if ($opts->{luajit}) {
        my $luajit_src = auto_complete 'LuaJIT';
        my $luajit_prefix = "$prefix/luajit";
        my $luajit_root = File::Spec->rel2abs("luajit-root");

        if (-d $luajit_root) {
            shell "rm -rf $luajit_root";
        }

        mkdir $luajit_root or
            die "create create directory luajit-root: $!\n";

        cd $luajit_src;

        my $extra_opts = ' TARGET_STRIP=@:';

        if ($opts->{debug}) {
            $extra_opts = ' CCDEBUG=-g Q=';
        }

        if ($platform =~ /bsd/i) {
            $extra_opts .= ' CFLAGS=-I..';
        }

        if ($on_solaris) {
            $extra_opts .= " INSTALL_X='$root_dir/build/install -m 0755' " .
                    "INSTALL_F='$root_dir/build/install -m 0644'";
        }

        if (defined $cc) {
            $extra_opts .= " CC=$cc";
        }

        shell "${make}$extra_opts PREFIX=$luajit_prefix", $dry_run;

        shell "${make} install$extra_opts PREFIX=$luajit_prefix DESTDIR=$luajit_root", $dry_run;

        push @make_cmds, "cd $root_dir/build/$luajit_src && "
            . "\$(MAKE)$extra_opts PREFIX=$luajit_prefix";

        push @make_install_cmds, "cd $root_dir/build/$luajit_src && "
            . "\$(MAKE) install$extra_opts PREFIX=$luajit_prefix DESTDIR=\$(DESTDIR)";

        env LUAJIT_LIB => "$luajit_root$luajit_prefix/lib";
        env LUAJIT_INC => "$luajit_root$luajit_prefix/include/luajit-2.0";

        push @ngx_rpaths, "$luajit_prefix/lib";

        cd '..';

    } elsif ($opts->{lua}) {
        # build stdandard lua

        my $lua_src = auto_complete 'lua';

        if (!defined $lua_src) {
            die "No lua5 found";
        }

        my $lua_prefix = "$prefix/lua";
        my $lua_root = File::Spec->rel2abs("lua-root");

        if (-d $lua_root) {
            shell "rm -rf $lua_root";
        }

        mkdir $lua_root or
            die "create create directory lua-root: $!\n";

        cd $lua_src;

        my $extra_opts = '';
        if (defined $cc) {
            $extra_opts .= " CC=$cc";
        }

        shell "${make}$extra_opts $platform", $dry_run;
        shell "${make} install$extra_opts INSTALL_TOP=$lua_root$lua_prefix", $dry_run;

        env LUA_LIB => "$lua_root$lua_prefix/lib";
        env LUA_INC => "$lua_root$lua_prefix/include";

        push @make_cmds, "cd $root_dir/build/$lua_src && \$(MAKE)$extra_opts $platform";

        push @make_install_cmds, "cd $root_dir/build/$lua_src && "
            . "\$(MAKE) install$extra_opts INSTALL_TOP=\$(DESTDIR)$lua_prefix";

        cd '..';

    }

    if ($opts->{lua} || $opts->{luajit}) {
        # build lua modules

        my $lualib_prefix = "$prefix/lualib";

        my $ngx_lua_dir = auto_complete 'ngx_lua';

        open my $in, ">>$ngx_lua_dir/config" or
            die "Cannot open $ngx_lua_dir/config for appending: $!\n";

        print $in <<"_EOC_";

CFLAGS=\$"\$CFLAGS -DLUA_DEFAULT_PATH='\\"$lualib_prefix/?.lua\\"'"
CFLAGS=\$"\$CFLAGS -DLUA_DEFAULT_CPATH='\\"$lualib_prefix/?.so\\"'"
_EOC_

        close $in;

        unless ($opts->{no_lua_cjson}) {
            my $dir = auto_complete 'lua-cjson';


            if (!defined $dir) {
                die "No lua-cjson found";
            }

            my $install;
            if ($on_solaris) {
                $install = "$root_dir/build/install";
            } else {
                $install = "install";
            }

            my $lua_inc = $ENV{LUA_INC};

            my $extra_opts = " DESTDIR=\$(DESTDIR) LUA_INCLUDE_DIR=$lua_inc " .
                "LUA_LIB_DIR=$lualib_prefix";

            push @make_cmds, "cd $root_dir/build/$dir && ".
                "\$(MAKE)$extra_opts";

            push @make_install_cmds, "cd $root_dir/build/$dir && " .
                "\$(MAKE) install$extra_opts";
        }
    }

    # prepare nginx configure line

    $ngx_dir = auto_complete "nginx";

    cd $ngx_dir;

    for my $mod (@modules) {
        my ($name, $prefix, $attr) = @$mod;

        if ($attr && $attr eq 'disabled') {
            next if not $opts->{"$name"};

        } else {
            next if $opts->{"no_$name"};
        }

        my $dir = auto_complete "../$prefix";

        $opts_line .= " \\\n  --add-module=$dir";
    }

    return $opts_line;
}

sub usage ($) {
    my $retval = shift;
    my $msg = <<'_EOC_';
  --help                             this message

  --prefix=PATH                      set the installation prefix

  --with-debug                       enable the debugging logging and also enable -O0 -g for gcc.
                                     this not only affects nginx, but also other components.

  --with-no-pool-patch               enable the no-pool patch for debugging memory issues.

_EOC_

    my $opt_max_len = length "  --without-ngx_devel_kit_module     ";

    #warn "opt max len: $opt_max_len";

    my $with_resty_opts = '';

    for my $mod (@modules) {
        my $name = $mod->[0];
        if ($name =~ /^http_/) {
            if (@$mod == 2) {
                my $opt = "  --without-${name}_module";
                $msg .= $opt;

                my $n = $opt_max_len - length $opt;

                if ($n > 0) {
                    $msg .= " " x $n;

                } else {
                    $msg .= "\n" . (" " x $opt_max_len);
                }

                $msg .= "disable ngx_${name}_module\n";

            } else {
                my $opt = "  --with-${name}_module";
                $with_resty_opts .= $opt;

                my $n = $opt_max_len - length $opt;

                if ($n > 0) {
                    $with_resty_opts .= " " x $n;

                } else {
                    $with_resty_opts .= "\n" . (" " x $opt_max_len);
                }

                $with_resty_opts .= "enable ngx_${name}_module\n";
            }
        }
    }

    $msg .= <<'_EOC_';
  --without-ngx_devel_kit_module     disable ngx_devel_kit_module
  --without-http_ssl_module          disable ngx_http_ssl_module

_EOC_

    $msg .= $with_resty_opts;

    $msg .= <<'_EOC_';

  --without-lua51                    disable the bundled Lua 5.1 interpreter
  --with-luajit                      enable LuaJIT 2.0
  --with-libdrizzle=DIR              specify the libdrizzle 1.0 (or drizzle) installation prefix
  --with-libpq=DIR                   specify the libpq (or postgresql) installation prefix
  --with-pg_config=PATH              specify the path of the pg_config utility

Options directly inherited from nginx

  --sbin-path=PATH                   set path to the nginx binary file
  --conf-path=PATH                   set path to the nginx.conf file
  --error-log-path=PATH              set path to the error log
  --pid-path=PATH                    set path to nginx.pid file
  --lock-path=PATH                   set path to nginx.lock file

  --user=USER                        set non-privilege user
                                     for the worker processes
  --group=GROUP                      set non-privilege group
                                     for the worker processes

  --builddir=DIR                     set the build directory

  --with-rtsig_module                enable rtsig module
  --with-select_module               enable select module
  --without-select_module            disable select module
  --with-poll_module                 enable poll module
  --without-poll_module              disable poll module

  --with-file-aio                    enable file aio support
  --with-ipv6                        enable ipv6 support

  --with-http_realip_module          enable ngx_http_realip_module
  --with-http_addition_module        enable ngx_http_addition_module
  --with-http_xslt_module            enable ngx_http_xslt_module
  --with-http_image_filter_module    enable ngx_http_image_filter_module
  --with-http_geoip_module           enable ngx_http_geoip_module
  --with-http_sub_module             enable ngx_http_sub_module
  --with-http_dav_module             enable ngx_http_dav_module
  --with-http_flv_module             enable ngx_http_flv_module
  --with-http_gzip_static_module     enable ngx_http_gzip_static_module
  --with-http_random_index_module    enable ngx_http_random_index_module
  --with-http_secure_link_module     enable ngx_http_secure_link_module
  --with-http_degradation_module     enable ngx_http_degradation_module
  --with-http_stub_status_module     enable ngx_http_stub_status_module

  --without-http_charset_module      disable ngx_http_charset_module
  --without-http_gzip_module         disable ngx_http_gzip_module
  --without-http_ssi_module          disable ngx_http_ssi_module
  --without-http_userid_module       disable ngx_http_userid_module
  --without-http_access_module       disable ngx_http_access_module
  --without-http_auth_basic_module   disable ngx_http_auth_basic_module
  --without-http_autoindex_module    disable ngx_http_autoindex_module
  --without-http_geo_module          disable ngx_http_geo_module
  --without-http_map_module          disable ngx_http_map_module
  --without-http_split_clients_module disable ngx_http_split_clients_module
  --without-http_referer_module      disable ngx_http_referer_module
  --without-http_rewrite_module      disable ngx_http_rewrite_module
  --without-http_proxy_module        disable ngx_http_proxy_module
  --without-http_fastcgi_module      disable ngx_http_fastcgi_module
  --without-http_uwsgi_module        disable ngx_http_uwsgi_module
  --without-http_scgi_module         disable ngx_http_scgi_module
  --without-http_memcached_module    disable ngx_http_memcached_module
  --without-http_limit_zone_module   disable ngx_http_limit_zone_module
  --without-http_limit_req_module    disable ngx_http_limit_req_module
  --without-http_empty_gif_module    disable ngx_http_empty_gif_module
  --without-http_browser_module      disable ngx_http_browser_module
  --without-http_upstream_ip_hash_module
                                     disable ngx_http_upstream_ip_hash_module

  --with-http_perl_module            enable ngx_http_perl_module
  --with-perl_modules_path=PATH      set path to the perl modules
  --with-perl=PATH                   set path to the perl binary

  --http-log-path=PATH               set path to the http access log
  --http-client-body-temp-path=PATH  set path to the http client request body
                                     temporary files
  --http-proxy-temp-path=PATH        set path to the http proxy temporary files
  --http-fastcgi-temp-path=PATH      set path to the http fastcgi temporary
                                     files
  --http-uwsgi-temp-path=PATH        set path to the http uwsgi temporary files
  --http-scgi-temp-path=PATH         set path to the http scgi temporary files

  --without-http                     disable HTTP server
  --without-http-cache               disable HTTP cache

  --with-mail                        enable POP3/IMAP4/SMTP proxy module
  --with-mail_ssl_module             enable ngx_mail_ssl_module
  --without-mail_pop3_module         disable ngx_mail_pop3_module
  --without-mail_imap_module         disable ngx_mail_imap_module
  --without-mail_smtp_module         disable ngx_mail_smtp_module

  --with-google_perftools_module     enable ngx_google_perftools_module
  --with-cpp_test_module             enable ngx_cpp_test_module

  --add-module=PATH                  enable an external module

  --with-cc=PATH                     set path to C compiler
  --with-cpp=PATH                    set path to C preprocessor
  --with-cc-opt=OPTIONS              set additional options for C compiler
  --with-ld-opt=OPTIONS              set additional options for linker
  --with-cpu-opt=CPU                 build for specified CPU, the valid values:
                                     pentium, pentiumpro, pentium3, pentium4,
                                     athlon, opteron, sparc32, sparc64, ppc64

  --with-make=PATH                   specify the default make utility to be used

  --without-pcre                     disable PCRE library usage
  --with-pcre                        force PCRE library usage
  --with-pcre=DIR                    set path to PCRE library sources
  --with-pcre-opt=OPTIONS            set additional options for PCRE building

  --with-md5=DIR                     set path to md5 library sources
  --with-md5-opt=OPTIONS             set additional options for md5 building
  --with-md5-asm                     use md5 assembler sources

  --with-sha1=DIR                    set path to sha1 library sources
  --with-sha1-opt=OPTIONS            set additional options for sha1 building
  --with-sha1-asm                    use sha1 assembler sources

  --with-zlib=DIR                    set path to zlib library sources
  --with-zlib-opt=OPTIONS            set additional options for zlib building
  --with-zlib-asm=CPU                use zlib assembler sources optimized
                                     for specified CPU, the valid values:
                                     pentium, pentiumpro

  --with-libatomic                   force libatomic_ops library usage
  --with-libatomic=DIR               set path to libatomic_ops library sources

  --with-openssl=DIR                 set path to OpenSSL library sources
  --with-openssl-opt=OPTIONS         set additional options for OpenSSL building

  --dry-run                          dry running the configure, for testing only
  --platform=PLATFORM                forcibly specify a platform name, for testing only
_EOC_

    if ($retval == 0) {
        print $msg;
        exit 0;
    }

    warn $msg;
    exit $retval;
}

sub gen_makefile {
    open my $out, ">Makefile" or
        die "Cannot open Makefile for writing: $!\n";

    print $out ".PHONY: all install clean\n\n";

    print $out "all:\n\t" . join("\n\t", @make_cmds) . "\n\n";

    print $out "install:\n\t" . join("\n\t", @make_install_cmds) . "\n\n";

    print $out "clean:\n\trm -rf build\n";

    close $out;
}

# check if we can run some command
sub can_run {
    my ($cmd) = @_;

    #warn "can run: @_\n";
    my $_cmd = $cmd;
    return $_cmd if -x $_cmd;

    return undef if $_cmd =~ m{[\\/]};

    # FIXME: this is a hack; MSWin32 is not supported anyway
    my $path_sep = ':';

    for my $dir ((split /$path_sep/, $ENV{PATH}), '.') {
        next if $dir eq '';
        my $abs = File::Spec->catfile($dir, $_[0]);
        return $abs if -x $abs;
    }

    return undef;
}