#!/usr/bin/perl -w

use File::Temp qw/ :POSIX /;

use Text::Tabs;

use warnings;
use strict;

my $topdir = substr(`pwd`, 0, -1);

if (index($topdir, "/maxima/doc/info") != -1) {
    $topdir =~ s/\/maxima\/doc\/info//;
}
else {
    $topdir = '';
}

my $strip_topdir = $ENV{"STRIP_TOPDIR"} || $topdir;

my $maxima_command = $ENV{"MAXIMA_EXAMPLE_COMMAND"} || "../../maxima-local";

my $line_cnt    = 0;
my $error_cnt   = 0;
my $warning_cnt = 0;

my $example_input_beg = '^@c ===beg===';
my $example_input_end = '^@c ===end===';

#my $example_output_beg = '^@example[ \t]*\n';
my $example_output_end = '^@end[ \t]+example[ \t]*\n';

my $in_example_input  = 0;
my $in_example_output = 0;

my @example_input_buf  = ();
my @example_output_buf = ();
my @example_result_buf = ();

sub rem_codes {
    my $res;

    $res = $_[0];

    $res =~ s/\cB//g;
    $res =~ s/\cE//g;

    $res =~ s/$strip_topdir//g;

    $res =~ s/\{/\@\{/g;
    $res =~ s/\}/\@\}/g;

    $res = expand($res);

    # Escape "@" to "@@", as an unescaped at-sign might be interpreted as the
    # beginning of a command.
    $res =~s/\@/\@\@/g;
    return $res;
}

sub r_trim {
    my $res;
    $res = $_[0];
    $res =~ s/\s+$/\n/;
    return $res;
}

while (<>) {
    $line_cnt++;

    if ($in_example_input) {
        if ($_ =~ $example_input_end) {
            print $_;
            $in_example_input  = 0;
            $in_example_output = 1;
        }
        elsif ($_ =~ /\@c */) {
            print $_;
            push @example_input_buf, r_trim(substr($_,3)) ;
        }
        else {
            $warning_cnt++;
            print STDERR "Warning: line $line_cnt - example input lines must begin with \'\@c \'.\n";
            print $_;
        }
    }
    elsif ($in_example_output) {
        if (/$example_output_end/) {
            my $tempf = tmpnam();

            my $com = "$maxima_command > $tempf << \\EOF\n";
            foreach my $l (@example_input_buf) {
                $com .= $l;
            }
            $com .= "EOF";

            if (system($com)) {
                $error_cnt++;
                print STDERR
                  "Error: line $line_cnt - maxima invocation failed.\n";
                print @example_output_buf;
                print "\@end example\n";
            }
            else {
                if (open(RESULT, $tempf)) {
                    @example_result_buf = <RESULT>;

                    close RESULT;

                    if (!unlink($tempf)) {
                        $error_cnt++;
                        print STDERR "Error: line $line_cnt - can't delete temp file $tempf\n";
                    }

                    print "\@example\n";

                    until ($#example_result_buf == -1 or $example_result_buf[0] =~ /^\cB/) {
                        shift @example_result_buf;
                    }

                    until ($#example_result_buf == -1 or $#example_input_buf == -1) {
                        my @group;

                        until ($#example_result_buf == -1 or $example_result_buf[0] =~ /\cE/) {
                            push @group, rem_codes($example_result_buf[0]);
                            shift @example_result_buf;
                        }

                        if ($#example_input_buf != -1) {
                            push @group, rem_codes(substr(substr($example_result_buf[0], 0, index($example_result_buf[0], "\cE") + 1), 0, -1)) . rem_codes(substr($example_input_buf[0], 0, -1)) . "\n";
                            shift @example_input_buf;
                            if ($example_result_buf[0] =~ /\cE/ and not $example_result_buf[0] =~ /\cE$/) {
                                $example_result_buf[0] = substr($example_result_buf[0], index($example_result_buf[0], "\cE"));
                            }
                            else {
                                shift @example_result_buf;
                            }
                        }

                        until ($#example_input_buf == -1 or $example_input_buf[0] =~ /^[\S]/) {
                            push @group, rem_codes(substr($example_input_buf[0], 0, -1)) . "\n";
                            shift @example_input_buf;
                        }
                        until ($#example_result_buf == -1 or $example_result_buf[0] =~ /^\cB/) {
                            push @group, rem_codes($example_result_buf[0]);
                            shift @example_result_buf;
                        }

                        print "\@group\n" if scalar @group >= 2;
                        print @group;
                        print "\@end group\n" if scalar @group >= 2;
                    }

                    print "\@end example\n";
                }
                else {
                    $error_cnt++;
                    print STDERR "Error: line $line_cnt - can't open temp file $tempf\n";
                    print @example_output_buf;
                    print "\@end example\n";
                }
            }

            close RESULT;

            @example_result_buf = ();
            @example_input_buf  = ();
            @example_output_buf = ();
            $in_example_output  = 0;
        }
        else {
            push @example_output_buf, $_;
        }
    }
    elsif (/$example_input_beg/) {
        print $_;
        $in_example_input = 1;
    }
    else {
        print $_;
    }
}

if ($in_example_input) {
    $error_cnt++;
    print STDERR "Error: line $line_cnt - EOF while end of example input is expected.\n";
}
elsif ($in_example_output) {
    $error_cnt++;
    print STDERR "Error: line $line_cnt - EOF while end of example is expected.\n";
    print @example_output_buf;
}

exit $error_cnt;
