#!/usr/bin/perl -w

#
# apt-file - APT package searching utility -- command-line interface
#
# (c) 2001 Sebastien J. Gross <seb@debian.org>
#
# This package is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 dated June, 1991.
#
# This package is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this package; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA 02110-1301 USA.

use strict;
use warnings;

use constant {
    RETURN_CODE_SUCCESS => 0,
    RETURN_CODE_NO_RESULTS => 1,
    RETURN_CODE_GENERIC_ERROR => 2,
    RETURN_CODE_CACHE_IS_EMPTY => 3,
    RETURN_CODE_CACHE_NO_MATCHING_INDICES => 4,

    CONFIG_SEARCH_INDEX_NAMES => 'apt-file::Index-Names',
    CONFIG_SEARCH_FILTER_ORIGINS => 'apt-file::Search-Filter::Origin',
    CONFIG_SEARCH_FILTER_SUITES => 'apt-file::Search-Filter::Suite',
    CONFIG_SEARCH_PARSER_DESC_HEADER => 'apt-file::Parser::Check-For-Description-Header',
};

use Getopt::Long qw/:config gnu_getopt no_ignore_case/;
use File::Basename;
use AptPkg::Config '$_config';
use List::Util qw/any none uniq/;
use Time::HiRes qw(gettimeofday tv_interval);

my ($Conf, @apt_options);
my $time_baseline = [gettimeofday()];
my $time_since_last = $time_baseline;

sub warning {
    my ($msg) = @_;
    print STDERR "W: $msg\n";
    return;
}

sub error($) {
    my ($msg) = @_;
    print STDERR "E: $msg\n";
    exit RETURN_CODE_GENERIC_ERROR;
}

sub stop_with_msg {
    my ($msg, $return_code) = @_;
    print STDERR "E: $msg\n";
    if (not defined($return_code)) {
        print STDERR "INTERNAL ERROR: Missing correct return code\n";
        $return_code //= 255;
    }
    exit $return_code;
}

{
    my $do_progress;
    my $clear_length = 0;
    sub tty_human_status {
        my ($msg) = @_;
        if (not defined($do_progress)) {
            $do_progress = 0;
            if (-t STDOUT and ($Conf->{verbose} // 0) == 0) {
                $do_progress = 1;
            }
        }
        return if not $do_progress;
        print "\r" . (' ' x $clear_length) . "\r";
        print $msg;
        $clear_length = length($msg);
    }
}

sub debug {
    my ($level, $msg) = @_;
    return if not defined $Conf->{verbose} or $level > $Conf->{verbose};
    my $now = [gettimeofday()];
    my $diff_baseline = tv_interval($time_baseline, $now);
    my $diff_last = tv_interval($time_since_last, $now);
    $time_since_last = $now;
    print STDERR sprintf("D: <%.3fs> [%.3fs] ($$) %s\n", $diff_baseline, $diff_last, $msg);
}

sub debug_line($) {
    return if !defined $Conf->{verbose};
    print STDERR shift;
}

sub reverse_hash($) {
    my $hash = shift;
    my $ret;
    foreach my $key ( keys %$hash ) {
        foreach ( @{ $hash->{$key} } ) {
            push @{ $ret->{$_} }, $key;
        }
    }
    return $ret;
}

sub fetch_files ($) {
    my @cmd = ('apt', @apt_options, 'update');
    $cmd[0] = 'apt-get' if not -t STDOUT;
    debug(1, "Running @cmd");
    exec(@cmd);
}

sub print_winners ($$) {
    my ( $db, $matchfname ) = @_;
    my $filtered_db;

    if ($matchfname) {
        # Everything is a match
        $filtered_db = $db;
    } else {
        tty_human_status('Filtering matches ...');
        # $db is a hash from package name to array of file names.  It
        # is a superset of the matching cases, so first we filter this
        # by the real pattern.
        $filtered_db = {};
        foreach my $key ( keys %$db ) {
            if ( $key =~ /$Conf->{pattern}/ ) {
                $filtered_db->{$key} = $db->{$key};
            }
        }
    }

    tty_human_status('');

    if (not $filtered_db or not %{$filtered_db}) {
        debug(1, 'No matches');
        exit RETURN_CODE_NO_RESULTS;
    }

    # Now print the winners
    if ( !defined $Conf->{package_only} ) {
        foreach my $key ( sort keys %$filtered_db ) {
            foreach ( uniq sort @{ $filtered_db->{$key} } ) {
                print "$key: $_\n";
            }
        }
    }
    else {
        print map {"$_\n"} ( sort keys %$filtered_db );
    }
    exit 0;
}

sub start_pipe_to_cmd {
    my ($sub_proc_write_end, @cmd) = @_;
    my ($read_end, $our_write_end, $pid);
    my $parser_pid = $$;
    pipe($read_end, $our_write_end)
        or error("pipe failed: $!");
    $pid = fork()
        // error("fork failed: $!");
    if (not $pid) {
        open(STDIN, '>&', $read_end);
        open(STDOUT, '>&', $sub_proc_write_end)
            or error("fdup stdout failed: $!");
        close($our_write_end)
            or error("close write end of pipe: $!");
        debug(1, "Starting " . join(' ', @cmd));
        exec {$cmd[0]} @cmd
            or error('exec ' . join(' ', @cmd) . " failed: $!");
    }
    close($read_end)
        or error("close write end of pipe: $!");
    close($sub_proc_write_end)
        or error("close unneeded write end of pipe: $!");
    return ($our_write_end, $pid);
}

sub open_data_pipeline {
    my ($file_list) = @_;
    my ($read_end, $write_end, $pid);
    my $remove_header = $_config->get_bool(CONFIG_SEARCH_PARSER_DESC_HEADER, 0);
    pipe($read_end, $write_end)
        or error("pipe failed: $!");
    $pid = fork()
        // error("fork failed: $!");
    if (not $pid) {
        my ($to_cat, $dead_pid, $failed_cmd, $cat_pid, $sed_pid, %pid_table);
        my $sub_proc_error = 0;
        my $grep_pattern = $Conf->{grep_pattern} // '.';
        my @cat_cmd = (
            'xargs',
            '-0r',
            '/usr/lib/apt/apt-helper',
            @apt_options,
            'cat-file'
        );
        my @sed_cmd = (
            'sed',
            '/^This file maps each file available/,/^FILE *LOCATION$/d'
        );
        close($read_end)
            or error("Close read end of pipeline: $!");
        if ($grep_pattern ne '.' and not $Conf->{is_regexp}) {
            my ($grep_pid);
            my @grep_cmd = ('grep', '-F');
            push(@grep_cmd, '-i') if $Conf->{ignore_case};
            if ($Conf->{from_file}) {
                 push(@grep_cmd, '-f', $Conf->{zgrep_tmpfile});
            } else {
                my $gp = $grep_pattern;
                $gp =~ s{^/}{};
                push(@grep_cmd, '--', $gp);
            }

            delete $ENV{$_} foreach qw{GREP_OPTIONS GREP_COLOR
                                       POSIXLY_CORRECT GREP_COLORS};
            ($write_end, $grep_pid) = start_pipe_to_cmd($write_end, @grep_cmd);
            $pid_table{$grep_pid} = {
                'ignore-exit' => 1,
                'cmd' => \@grep_cmd,
            };
        }
        if ($remove_header) {
            debug(1, 'Using sed to remove header');
            ($write_end, $sed_pid) = start_pipe_to_cmd($write_end, @sed_cmd);
            $pid_table{$sed_pid} = {
                'cmd' => \@sed_cmd,
            };
        } else {
            debug(1, 'Assuming there is no header in Contents to skip');
        }
        ($to_cat, $cat_pid) = start_pipe_to_cmd($write_end, @cat_cmd);
        $pid_table{$cat_pid} = {
            'cmd' => \@cat_cmd,
        };
        debug(1, 'Starting to pass files');
        for my $file (uniq(@{$file_list})) {
            debug(1, "Passing $file");
            printf {$to_cat} "%s\0", $file;
        }
        debug(1, 'Closing input to cat');
        close($to_cat)
            or error("close write end of xargs pipe: $!");
        debug(1, 'Input closed, reaping completed children');
        # We load POSIX here as it take ~0.010s and the children will
        # be vastly longer, so we can "hide" the load time here.
        require POSIX;
        do {
            $dead_pid = waitpid(-1, 0);
            if ($dead_pid > 0) {
                my $pid_info = $pid_table{$dead_pid};
                my $is_issue = $?;
                if ($pid_info->{'ignore-exit'}) {
                    # Only "killed by signal" counts in this case
                    $is_issue = $? & 0x7F;
                }
                if ($is_issue and not $sub_proc_error) {
                    $sub_proc_error = $?;
                    $failed_cmd = join(' ', @{$pid_info->{'cmd'}});
                }
            }
        } while ($dead_pid > 0);
        debug(1, 'Reaped children complete');
        if (my $sig = ($sub_proc_error & 0x7f)) {
            warn("Command ${failed_cmd} was killed by signal ${sig}");
            POSIX::_exit($sig);
        }
        if ($sub_proc_error) {
            my $retval = ($sub_proc_error >> 8) & 0xff;
            warn("Command ${failed_cmd} exited with code ${retval}");
            POSIX::_exit($retval);
        }
        POSIX::_exit(0);
    }
    close($write_end)
        or error("close write end of pipe: $!");
    return $read_end;
}

sub do_grep($$) {
    my ( $data, $pattern ) = @_;
    my ( $pkgs, $fname, @cmd, $ret);
    debug(1, "regexp: ${pattern}");
    $| = 1;
    my $regexp = eval { $Conf->{ignore_case} ? qr/${pattern}/i : qr/${pattern}/ };
    error($@) if $@;
    my $matches = 0;
    my $quick_regexp = escape_parens($regexp);
    my $fd = open_data_pipeline($data);
    my $stream_results = $Conf->{streaming};
    tty_human_status('') if $stream_results;
    debug(1, "Pipeline open, waiting for input");
    while (<$fd>) {

        # faster, non-capturing search first
        next if !/$quick_regexp/o;

        next if !( ( $fname, $pkgs ) = /$regexp/o );

        debug_line ".";

        if ($stream_results) {
            stream_results("/$fname", map { basename($_) } split(m/,/, $pkgs));
        } else {
            # Put leading slash on file name
            push(@{ $ret->{"/$fname"} },
                 # ... and extract the package name
                 map { basename($_) } split(m/,/, $pkgs)
            );
            if (++$matches % 10 == 0) {
                tty_human_status("Searching, found $matches results so far ...");
            }
        }
    }
    close($fd);
    debug_line "\n";
    waitpid(-1, 0);
    if ($?) {
        error("A subprocess exited uncleanly (raw: $?)");
    }
    debug(1, 'Read all input');
    return if $stream_results;
    return reverse_hash($ret);
}

sub stream_results {
    my ($filename, @pkgs) = @_;
    if ($Conf->{package_only}) {
        print map { "$_\n" } @pkgs;
    } else {
        for my $pkg (@pkgs) {
            print "$pkg: $filename\n";
        }
    }
    return;
}

sub escape_parens {
    my $pattern = shift;

    # turn any capturing ( ... ) into non capturing (?: ... )
    $pattern =~ s{ (?<! \\ )    # not preceded by a \ 
                        \(      # (
                   (?!  \? )    # not followed by a ?
                 }{(?:}gx;
    return $pattern;
}

sub fix_regexp {
    my $pattern = shift;
    
    # If pattern starts with /, we need to match both ^pattern-without-slash
    # (which is put in $pattern) and ^.*pattern (put in $pattern2).
    # Later, they will be or'ed together.
    my $pattern2;
    if ( $pattern !~ s{(\$|\\[zZ])$}{} ) {
        # Not anchored at the end:
        $pattern = $pattern . '\S*';
    }

    if ( $pattern =~ s{^(\^|\\A)/?}{} ) {
        # If pattern is anchored at the start, we're just not prefixing it
        # with .* after having removed ^ and /
    }
    else {
        if ( $pattern =~ m{^/} ) {

            # same logic as below, but the "/" is not escaped here
            $pattern2 = '.*?' . $pattern;
            $pattern  = substr( $pattern, 1 );
        }
        else {
            $pattern = '.*?' . $pattern;
        }
    }

    $pattern  = escape_parens($pattern);
    $pattern2 = escape_parens($pattern2) if defined $pattern2;

    return ($pattern, $pattern2);
}

sub grep_file($) {
    my $data    = shift;
    my $pattern = $Conf->{pattern};

    tty_human_status("Searching through filenames ...");
    # If pattern starts with /, we need to match both ^pattern-without-slash
    # (which is put in $pattern) and ^.*pattern (put in $pattern2).
    # Later, they will be or'ed together.
    my $pattern2;

    if ( $Conf->{is_regexp} ) {
        if (!$Conf->{from_file}) {
            ($pattern, $pattern2) = fix_regexp($pattern);
        }
    }
    elsif ( substr( $pattern, 0, 2 ) eq '\/' ) {
        if ( $Conf->{fixed_strings} ) {

            # remove leading /
            $pattern = substr( $pattern, 2 );
        }
        else {

            # If pattern starts with /, match both ^pattern-without-slash
            # and ^.*pattern.
            $pattern2 = '.*?' . $pattern;
            $pattern  = substr( $pattern, 2 );
        }
    }
    else {
        $pattern = '.*?' . $pattern unless $Conf->{fixed_strings};
    }

    if ( ! defined $Conf->{fixed_strings} && ! defined $Conf->{is_regexp} ) {
        $pattern  .= '(?:.*[^\s])?';
        $pattern2 .= '(?:.*[^\s])?' if defined $pattern2;
    }

    $pattern = "$pattern|$pattern2" if defined $pattern2;
    $pattern = '^(' . $pattern . ')\s+(\S+)\s*$';

    my $ret = do_grep $data, $pattern;
    print_winners $ret, 1;
}

sub grep_package($) {
    my $data = shift;

    my $pkgpat = $Conf->{pattern};
    tty_human_status("Searching for contents of the packages ...");

    if ( $Conf->{is_regexp} ) {
        if ( $pkgpat !~ s{^(\^|\\A)}{} ) {
            $pkgpat = '\S*' . $pkgpat;
        }

        if ( $pkgpat !~ s{(\$|\\[zZ])$}{} ) {
            $pkgpat = $pkgpat . '\S*';
        }
        $pkgpat = escape_parens($pkgpat);
    }
    elsif ($Conf->{fixed_strings}) {
        $pkgpat = $Conf->{pattern};
    }
    else {
        $pkgpat = '\S*' . $Conf->{pattern};
    }

    # File name may contain spaces, so match template is
    # ($fname, $pkgs) = (line =~ '^\s*(.*?)\s+(\S+)\s*$')
    my $pattern = join "",
        (
        '^\s*(.*?)\s+', '((?:\S*[,/])?', $pkgpat,
        defined $Conf->{fixed_strings} || defined $Conf->{regexp} ?
            '(?:,\S*|)' : '\S*', ')\s*$',
        );
    my $ret = do_grep $data, $pattern;
    print_winners $ret, 0;
}

sub list_indices {
    my $iter = AptPkg::Config::Iter->new($_config);

    my @indices;
    my @headers = (
        {
            header => 'Index Name (-I)',
            key => 'name'
        },
        {
            header => 'DefaultEnabled (Apt config)',
            key => 'default-enabled',
        },
        {
            header => 'Index Status',
            key => 'cache-lookup',
        },
    );
    my @len = map { length($_->{header}) } @headers;
    my ($results, $entries, %files_by_index);

    tty_human_status('Computing index status ...');

    ($results, $entries) = lookup_indices(['ALL'], [], [], []);

    if ($results == RETURN_CODE_SUCCESS) {
        for my $entry (@{$entries}) {
            $files_by_index{$entry->{'index'}}++;
        }
    }

    while (defined(my $key = $iter->next)) {
        my ($type, $index_name) = @_;
        my $cache_status = 'Ok';
        next if $key !~ m/^Acquire::IndexTargets::(deb|deb-src)::Contents-([^:  \t]+)$/;
        ($type, $index_name) = ($1, $2);
        my $index =  {
            'name' => $index_name,
            'type' => $type,
            'key' => $key,
            'default-enabled' => ($_config->{"${key}::DefaultEnabled"} // '<unset>'),
            'fallback-of' => $_config->{"${key}::Fallback-Of"},
        };
        # Hide fallback-of entries.
        next if $index->{'fallback-of'};
        if (exists($files_by_index{$index_name})) {
            $cache_status = 'Ok';
        } elsif ($results == RETURN_CODE_SUCCESS
                 || $results == RETURN_CODE_CACHE_IS_EMPTY
                 || $results == RETURN_CODE_CACHE_NO_MATCHING_INDICES) {
            my $code = $results;
            if ($code == RETURN_CODE_SUCCESS) {
                $code = RETURN_CODE_CACHE_NO_MATCHING_INDICES;
            }
            $cache_status = "Empty (code: $code)";
        } else {
            $cache_status = "Error (code: $results)";
        }
        $index->{'cache-lookup'} = $cache_status;
        for my $i (0..$#headers) {
            my $header = $headers[$i];
            my $value = $index->{$header->{'key'}};
            $len[$i] = length($value) if length($value) > $len[$i];
        }
        push(@indices, $index);
    }

    debug(1, 'All information collected; creating table');
    my $row_delimit = sprintf("+-%s-+", join('-+-', map { '-' x $len[$_] } (0..$#headers)));

    tty_human_status('');

    printf("%s\n", $row_delimit);
    printf("| %s |\n", join(' | ', map { sprintf("%-*s", $len[$_], $headers[$_]{'header'}) }
                        (0..$#headers)));
    printf("%s\n", $row_delimit);
    for my $index (@indices) {
        my $name = $index->{'name'};
        my $type = $index->{'type'};
        my $key = $index->{'key'};
        my $enabled = $_config->{"${key}::DefaultEnabled"} // '<unset>';
        printf("| %s |\n", join(' | ', map {
            sprintf("%-*s", $len[$_], $index->{$headers[$_]{'key'}})
        } (0..$#headers)));
    }
    printf("%s\n", $row_delimit);
    debug(1, 'Finished writing table');

}

sub print_help {
    my $err_code = shift || 0;

    print <<"EOF";

apt-file [options] action [pattern]
apt-file [options] -f action <file>
apt-file [options] -D action <debfile>

Pattern options:
================

    --fixed-string     -F               Do not expand pattern
    --from-deb         -D               Use file list of .deb package(s) as
                                        patterns; implies -F
    --from-file        -f               Read patterns from file(s), one per line
                                        (use '-' for stdin)
    --ignore-case      -i               Ignore case distinctions
    --regexp           -x               pattern is a regular expression
    --substring-match                   pattern is a substring (no glob/regex)


Search filter options:
======================

    --architecture     -a  <arch>       Use specific architecture [L]
    --index-names      -I  <names>      Only search indices listed in <names> [L]
    --filter-suites        <suites>     Only search indices for the listed <suites> [L]
                                        (E.g. "unstable")
    --filter-origins       <origins>    Only search indices from <origins> [L]
                                        (E.g. "Debian")

Other options:
==============

    --config           -c <file>        Parse the given APT config file [R]
    --option           -o <A::B>=<V>    Set the APT config option A::B to "V" [R]
    --package-only     -l               Only display packages name
    --stream-results                    Emit results immediately (without deduplication)
    --verbose          -v               run in verbose mode [R]
    --help             -h               Show this help.
                       --               End of options (necessary if pattern
                                        starts with a '-')

[L]: Takes a comma-separated list of values.
[R]: The option can be used repeatedly

Action:
    list|show          <pattern>        List files in packages
    list-indices                        List indices configured in APT.
    search|find        <pattern>        Search files in packages
    update                              Fetch Contents files from apt-sources.
EOF
    exit $err_code;
}

sub get_options() {
    my %options = (
        "architecture|a=s"  => \$Conf->{arch},
        "index-names|I=s"   => sub { $_config->set(CONFIG_SEARCH_INDEX_NAMES, $_[1]) },
        "verbose|v+"        => \$Conf->{verbose},
        "ignore-case|i"     => \$Conf->{ignore_case},
        "regexp|x"          => \$Conf->{is_regexp},
        "substring-match"   => \$Conf->{substring_match},
        "package-only|l"    => \$Conf->{package_only},
        "fixed-string|F"    => \$Conf->{fixed_strings},
        "from-file|f"       => \$Conf->{from_file},
        "from-deb|D"        => \$Conf->{from_deb},
        'stream-results'    => \$Conf->{streaming},
        'filter-suites=s'   => sub { _set_option('in-suites', CONFIG_SEARCH_FILTER_SUITES, $_[1]); },
        'filter-origins=s'  => sub { _set_option('from-origin', CONFIG_SEARCH_FILTER_ORIGINS, $_[1]); },
        'config-file|c=s@'  => \&_parse_apt_config_file,
        'option|o=s@'       => \&_parse_apt_option,
        "help|h"            => \$Conf->{help},
    );
    Getopt::Long::Configure("bundling");
    GetOptions(%options) || print_help(RETURN_CODE_GENERIC_ERROR);
}

sub _set_option {
    my ($option_name, $apt_option_name, $value) = @_;
    $_config->set($apt_option_name, $value);
    debug(1, "Set ${apt_option_name} to ${value} (due to --${option_name})");
}

sub _parse_apt_config_file {
    my (undef, $conf_file) = @_;
    if ( -d $conf_file) {
        print STDERR <<EOF;
You passed a directory to -c but apt-file (now) expects a file.

The "-c" option is now short for "--config-file" and parses an APT
config file.  It /used/ to be the option for specifying a custom
"cache-dir", but support for these were retired in apt-file 3.

If you need the cache-dir feature, please create an APT config file
that makes APT use the desired cache dir directory.  (The man page has
an example to get you started.)

EOF
        error("Please pass an APT config file after -c/--config-file");
    }
    debug(1, "Parsed $conf_file (due to --config-file)");

    $_config->read_file($conf_file)
        or error("Cannot parse ${conf_file}");
    push(@apt_options, '-c', $conf_file);
    return;
}

sub _parse_apt_option {
    my (undef, $option_str) = @_;
    my ($opt_name, $opt_value) = split(m/=/, $option_str, 2);
    if (not defined($opt_value)) {
        if ($opt_name =~ m/ /) {
            my ($n, $v) = split(m/ /, $opt_name);
            warning("Did you perhaps intend to use -o \"${n}=${v}\"?");
        }
        error("Missing value for ${opt_name}: Expected -o \"Foo::Bar=value\"");
    }
    $_config->set($opt_name, $opt_value);
    debug(1, "Parsed set ${opt_name} to ${opt_value} (due to --option)");
    push(@apt_options, '-o', $option_str);
    return;
}

sub main {
    my ($action, $is_search, @arch_res, @index_names, @origins, @suites);
    $_config->init;
    if (@ARGV and ($ARGV[0] eq '-v' or $ARGV[0] eq '--verbose')) {
        # To enable debug for the apt-file.conf
        shift(@ARGV);
        $Conf->{verbose} = 1;
    }
    if (my $apt_file_conf = $_config->get_file('Dir::Etc::apt-file-main')) {
        debug(1, "Dir::Etc::apt-file-main is set to $apt_file_conf");
        if ( -l $apt_file_conf or -e $apt_file_conf) {
            debug(1, "Reading ${apt_file_conf}");
            $_config->read_file($apt_file_conf)
                or error("Cannot parse ${apt_file_conf}");
            push(@apt_options, '-c', $apt_file_conf);
        } else {
            debug(1, "The file ${apt_file_conf} does not exist");
        }
    } else {
        debug(1, "Dir::Etc::apt-file-main was not set");
    }
    get_options();
    @arch_res = split(m/\s*,\s*/,
                      $Conf->{arch} || $_config->{'APT::Architecture'});
    @suites = split(m/\s*,\s*/, $_config->get(CONFIG_SEARCH_FILTER_SUITES) // '');
    @origins = split(m/\s*,\s*/, $_config->get(CONFIG_SEARCH_FILTER_ORIGINS) // '');
    if (none { $_ eq 'all' } @arch_res) {
        # Automatically support that arch:all contents move to a
        # separate file"
        push(@arch_res, 'all');
    }
    @suites = () if (any { $_ eq '*' } @suites);
    @origins = () if (any { $_ eq '*' } @origins);
    @index_names = split(m/\s*,\s*/,
                         $_config->get(CONFIG_SEARCH_INDEX_NAMES, 'deb'));
    if (@index_names > 1 and any { $_ eq 'ALL' } @index_names) {
        @index_names = ('ALL');
    }

    $action = shift(@ARGV) // 'none';

    if ($Conf->{fixed_strings} and $Conf->{is_regexp}) {
        error('Cannot use -F together with -x');
    }
    if ($Conf->{fixed_strings} and $Conf->{substring_match}) {
        error('Cannot use -F together with --substring-match');
    }
    if ($Conf->{is_regexp} and $Conf->{substring_match}) {
        error('Cannot use -x together with --substring-match');
    }

    if ($action =~ m/^(?:search|find|list|show)$/) {
        $is_search = 1;
        if (not defined($Conf->{substring_match}) and
            not $Conf->{fixed_strings} and not $Conf->{is_regexp}) {
            debug(1, 'substring match (default)');
            $Conf->{fixed_strings} = 1
              if $action eq 'list' or $action eq 'show';
        }
    }

    if ($Conf->{from_file} || $Conf->{from_deb}) {
        require Regexp::Assemble;
        my $ra = Regexp::Assemble->new;
        my @list;
        if ($Conf->{from_deb}) {
            $Conf->{from_file} = 1;
            $Conf->{fixed_strings} = 1;
            $Conf->{is_regexp} = 0;

            debug(1, "this is a .deb file, calling dpkg-deb to get contents");
            my @content;
            foreach my $deb (@ARGV) {
                push @content, qx{dpkg-deb -c \Q$deb};
                if ($? != 0) {
                    error("Couldn't get contents from $deb");
                }
            }
            foreach my $line (@content) {
                next if $line =~ m{/$};  # skip dirs
                my @fields = split(/\s+/, $line);
                my $filename = $fields[5];
                $filename =~ s{^\.}{};
                push @list, "$filename\n";
            }
        }
        else {
            # normal text files
            # - assume "STDIN" if no arguments are given.
            push @ARGV, '-' unless @ARGV;
            foreach my $file (@ARGV) {
                if ($file eq '-') {
                    push @list, <STDIN>;
                    next;
                }
                open(my $fh, '<', $file)
                    or error("Cannot open $file: $!");
                push @list, <$fh>;
                close($fh);
            }
        }
        if ($Conf->{is_regexp}) {
            foreach my $line (@list) {
                chomp $line;
                my ($p1, $p2) = fix_regexp($line);
                $ra->add($p1);
                $ra->add($p2) if defined $p2;
            }
        }
        else {
            # create tmpfile for zgrep with patterns that have leading slash removed
            require File::Temp;
            my @zgrep_list = @list;
            map { s{^/}{} } @zgrep_list;
            my $tmpfile = File::Temp->new();
            print $tmpfile @zgrep_list;
            $tmpfile->flush();
            $Conf->{zgrep_tmpfile} = $tmpfile;

            # create actual search pattern
            @list = map {quotemeta} @list;
            $ra->add(@list);
        }
        $Conf->{pattern} = $ra->as_string(indent => 0);
    }
    else {
        $Conf->{pattern} = shift @ARGV;
        if (defined($Conf->{pattern}) and not $Conf->{is_regexp}) {
            my $pattern = $Conf->{pattern};
            $Conf->{grep_pattern} = $pattern;
            $pattern = quotemeta($pattern);
            $Conf->{pattern} = $pattern;
        }
    }
    undef $!;

    my $actions = {
        update => \&fetch_files,
        search => \&grep_file,
        find   => \&grep_file,
        list   => \&grep_package,
        show   => \&grep_package,
        'list-indices' => \&list_indices,
    };

    if ($Conf->{help}) {
        print_help();
    }
    if ($is_search && not defined($Conf->{pattern})) {
        print_help(RETURN_CODE_GENERIC_ERROR);
    }
    my $action_handler = $actions->{$action};
    if (not defined($action_handler)) {
        print_help(RETURN_CODE_GENERIC_ERROR);
    }

    if ($is_search) {
        tty_human_status('Finding relevant cache files to search ...');
        my @contents = contents_file_paths(\@index_names,
                                           \@arch_res,
                                           \@suites,
                                           \@origins,
        );
        $action_handler->(\@contents);
    } else {
        $action_handler->();
    }

}

sub lookup_indices {
    my ($index_names, $arch_res, $suite_ref, $origin_ref) = @_;
    my (@cache_entries, $any_entries);
    my $any_index = 0;
    my $format = join("\x1F",
                      '$(IDENTIFIER)',
                      '$(ARCHITECTURE)',
                      '$(ORIGIN)',
                      '$(SUITE),$(CODENAME)',
                      '$(FILENAME)');
    my @cmd = ('apt-get', @apt_options, 'indextargets',
               '--format', $format);
    my $cmd_debug = join(' ', map {
        my $c = $_;
        $c =~ s/\x1F/\\x1F/g;
        "\"$c\""
    } @cmd);
    my $debug_level = $Conf->{verbose} // 0;
    my $code = RETURN_CODE_SUCCESS;
    $any_index = 1 if @{$index_names} and $index_names->[0] eq 'ALL';
    debug(1, 'Index restriction [name]: ' . join(' ', @{$index_names}));
    debug(1, 'Index restriction [arch]: ' .  join(' ', @{$arch_res}));
    debug(1, 'Index restriction [suite]: ' . join(' ', @{$suite_ref}));
    debug(1, 'Index restriction [origin]: ' . join(' ', @{$origin_ref}));
    debug(1, "Running $cmd_debug");
    open(my $fd, '-|', @cmd)
      or error('Cannot execute apt-get indextargets');
    while (my $line = <$fd>) {
        my ($index_name, $arch, $origin, $suite_names, $filename);
        chomp($line);
        next if $line !~ s/^Contents-//;
        $any_entries = 1;
        ($index_name, $arch, $origin, $suite_names, $filename) = split("\x1F", $line, 5);
        if ($debug_level > 1) {
            my $c = $line;
            $c =~ s/\x1F/\\x1F/g;
            debug(2, "Contents index [line]: $c");
            debug(2, " - index identifier: $index_name");
            debug(2, " - architecture: $arch");
            debug(2, " - origin: $origin");
            debug(2, " - suite/codenames: $suite_names");
            debug(2, " - filename: $filename");
        }
        if ($arch ne '$(ARCHITECTURE)' and @{$arch_res}) {
            next if none { $_ eq $arch } @{$arch_res};
        }
        next if not $any_index and none { $_ eq $index_name } @{$index_names};
        if (@{$suite_ref}) {
            my ($codename, $suite) = split(m/,/, $suite_names);
            next if none { $_ eq $codename or $_ eq $suite } @{$suite_ref};
        }
        next if @{$origin_ref} and none { $_ eq $origin } @{$origin_ref};
        push(@cache_entries, {
            'path'  => $filename,
            'index' => $index_name,
        });
    }
    debug(1, "Finished reading output from $cmd_debug");
    close($fd);
    if (not @cache_entries) {
        if (not $any_entries) {
            $code = RETURN_CODE_CACHE_IS_EMPTY;
        } else {
            $code = RETURN_CODE_CACHE_NO_MATCHING_INDICES;
        }
    }
    return ($code, \@cache_entries);
}

sub contents_file_paths {
    my ($res, $entries) = lookup_indices(@_);
    if ($res != RETURN_CODE_SUCCESS) {
        if ($res == RETURN_CODE_CACHE_IS_EMPTY) {
            stop_with_msg('The cache is empty. You need to run "apt-file update" first.',
                          RETURN_CODE_CACHE_IS_EMPTY);
        }
        if ($res == RETURN_CODE_CACHE_NO_MATCHING_INDICES) {
            stop_with_msg('No Contents in the cache with the given restrictions',
                          RETURN_CODE_CACHE_NO_MATCHING_INDICES);
        }
        stop_with_msg('Unknown / unexpected error returned when looking up indices.',
                      255);
    }
    return map { $_->{'path'} } @{$entries};
}

eval {
    main();
    exit(0);
};
if (my $err = $@) {
    stop_with_msg($err, 255);
}

__END__

# our style is roughly "perltidy -pbp"
# vim:sts=4:sw=4:expandtab