#!/usr/bin/perl -T

# IceVault - An external password manager for firefox
# Copyright © 2015 Guilhem Moulin <guilhem@fripost.org>
#
# This program 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, either version 3 of the License, or (at
# your option) any later version.
#
# This program 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 program.  If not, see <http://www.gnu.org/licenses/>.

use strict;
use warnings;

our $VERSION = '0.1';
use Getopt::Long qw/:config posix_default no_ignore_case gnu_compat
                            bundling auto_version/;
use Encode qw/decode_utf8 encode_utf8/;
use I18N::Langinfo ();
use List::Util qw/all any first min none/;


# Clean up PATH, and set TMPDIR to a ramdisk's mountpoint if possible
$ENV{PATH} = join ':', qw{/usr/local/bin /usr/bin /bin};
$ENV{TMPDIR} //= first { -d } qw{/dev/shm /run/shm /var/run/shm /tmp};
delete @ENV{qw/IFS CDPATH ENV BASH_ENV/};

my $LANGINFO = I18N::Langinfo::langinfo(I18N::Langinfo::CODESET());
my $LOCALE = Encode::find_encoding $LANGINFO;
my %CONFIG;
my $SOCKET;


#######################################################################
# Utilities

# myprintf [FILEHANDLE,] FORMAT, LIST
# Like printf, but allows locale-dependent markup.
sub myprintf($@) {
    my $fh = ref $_[0] eq 'GLOB' ? shift : \*STDOUT;
    my $format = shift;
    chomp $format;
    $LANGINFO =~ /^utf-?8$/aai ? $format =~ s/C<%s>/\N{U+2018}%s\N{U+2019}/g
                               : $format =~ s/C<%s>/'%s'/g;
    $format =~ s/I<%s>/%s/g;
    $format =~ s/B<%s>/%s/g;
    die "Illegal markup '$1' in message:\n", $format if $format =~ /([A-Z])<%s>/;
    printf $fh map {$LOCALE->encode($_)} ($format."\n", @_);
}

# error FORMAT, LIST
sub error($@) {
    myprintf \*STDERR, shift, @_;
    exit 1;
}

# warning FORMAT, LIST
sub warning($@) {
    myprintf \*STDERR, shift, @_;
}

# Print usage and exit.
sub usage($) {
    my $rv = shift;
    my $fh = $rv ? \*STDERR : \*STDOUT;
    print $fh "Usage: $0 [OPTIONS] [fill] scheme://hostname/identity\n"
             ."  or: $0 [OPTIONS] insert [identity]\n"
             ."  or: $0 [OPTIONS] dump scheme://hostname/identity\n"
             ."  or: $0 [OPTIONS] clip scheme://hostname/identity\n"
             ."  or: $0 [OPTIONS] edit scheme://hostname/identity\n"
             ."  or: $0 [OPTIONS] ls [scheme://[hostname/[identity]]]\n"
             . "Consult the manual page for more information.\n";
    exit $rv;
}

# grepIdx BLOCK LIST
# Evaluates the BLOCK for each element of LIST (locally setting $_ to
# each element) and returns the list value consisting of the index of
# those elements for which the expression evaluated to true.
sub grepIdx(&@) {
    my ($code, @list) = @_;
    my @ret;
    for (my $i = 0; $i <= $#list; $i++) {
        local $_ = $list[$i];
        push @ret, $i if $code->();
    }
    return @ret;
}

# firstIdx BLOCK LIST
# Evaluates the BLOCK for each element of LIST (locally setting $_ to
# each element) and returns the first index of those elements for which
# the expression evaluated to true.  Or undef if the expression never
# evaluates to true.
sub firstIdx(&@) {
    my ($code, @list) = @_;
    for (my $i = 0; $i <= $#list; $i++) {
        local $_ = $list[$i];
        return $i if $code->();
    }
    return;
}

sub groupByName(@) {
    my @fields = @_;
    my %indices;
    for (my $i = 0; $i <= $#fields; $i++) {
        push @{$indices{$fields[$i]->{name}}}, $i;
    }
    return %indices;
}

sub delete($$) {
    my ($x, $l) = @_;
    @$l = grep { $_ ne $x } @$l;
}


#######################################################################

# Load the given configuration file
sub loadConfig($) {
    my $configFile = shift;
    error "Configuration file C<%s> doesn't exist", $configFile unless -f $configFile;
    open my $CONFIG, '<', $configFile or error "Can't open C<%s>: %s", $configFile, $!;
    while (<$CONFIG>) {
        chomp;
        s/#.*//;         # ignore comments
        next if /^\s*$/; # ignore empty and blank lines
        /^([-\@\w.]+)(?:\s*=\s*)(\p{print}+)/ or error "Can't parse config line: C<%s>", $_;
        $CONFIG{$1} //= $2;
    }
    close $CONFIG;
}

# Connect to the given socket and assign the IO::Socket object to
# $SOCKET.  If  the socket path is relative, prepend the default Firefox
# profile (or the first profile found if there is no default profile).
# Returns "scheme://hostname:port" (the ":port" part is optional)
sub connect($) {
    my $sockname = shift;

    if ($sockname !~ /^\//) { # relative path
        my $ffdir = "$ENV{HOME}/.mozilla/firefox";
        opendir my $dh, $ffdir or error "Can't open directory C<%s>: %s", $ffdir, $!;
        my $profile;
        while (readdir $dh) {
            next if $_ eq '.' or $_ eq '..';
            next unless -d "$ffdir/$_";
            if (/\.default$/) { # default profile takes precedence
                $profile = $_;
                last;
            }
            $profile //= $_;
        }
        closedir $dh;
        error "No Firefox profile found under C<%s>", $ffdir unless defined $profile;
        $sockname = "$ffdir/$profile/$sockname";
        myprintf \*STDERR, "Using socket C<%s>", $sockname if $CONFIG{debug};
    }

    require 'IO/Socket/UNIX.pm';
    $SOCKET = IO::Socket::UNIX->new( Type => IO::Socket::UNIX::SOCK_STREAM(), Peer => $sockname )
        or error "Can't connect to socket C<%s>: %s", $sockname, $!;

    # get the URI greeting; don't perform domain validation (it's done
    # by the browser), but ensure that it doesn't contain non-graphical
    # chars, : or /
    require 'JSON.pm';
    my $uri = getResponse();
    $uri =~ s/\A([A-Za-z0-9-]+:\/\/[^\P{Graph}:\/]+(?::\d+)?)(?:\/.*)?\z/$1/
        or error "Invalid URI C<%s>", $uri;

    my $scheme = $uri =~ s/:\/\/.*//r;
    warning "Warning: Insecure (%s://) connection! Form values can be stolen", $scheme
        unless $scheme eq 'https';

    return lc $uri;
}

# Read a response line on the socket, and return the decoded scalar or
# object.
sub getResponse() {
    my $buf = $SOCKET->getline;
    chomp $buf;
    myprintf \*STDERR, "S: %s", decode_utf8 $buf if $CONFIG{debug};
    my ($code, $msg) = split / /, $buf, 2;
    # allow $msg to be decoded to a string
    $msg = JSON->new->utf8->allow_nonref->decode($msg) if defined $msg;
    if ($code eq 'OK') {
        return $msg;
    }
    elsif ($code eq 'BYE') {
        # terminates the connection
        $SOCKET->close;
        undef $SOCKET;
    }
    elsif ($code eq 'ERROR') {
        error "Server said: C<%s>", 'ERROR ' . decode_utf8 $msg;
    }
    else {
        error "Unexpected response from server: C<%s>", decode_utf8 $msg;
    }
}

# Send the given UTF8 string (with a linefeed appended) on to the
# socket, flush the handle, then return the server response.
sub sendCommand(@) {
    my $command = join(' ',@_);
    myprintf \*STDERR, "C: %s", Encode::decode_utf8 $command if $CONFIG{debug};
    $command .= "\n";
    for (my $offset = 0; $offset < length $command;) {
        $offset += $SOCKET->syswrite($command, length($command) - $offset, $offset);
    }
    $SOCKET->flush;
    getResponse();
}

# Get all identities with the given $prefix.  If there are multiple
# matches and $all is false, limit the output to one depth more than the
# longuest common prefix.
sub complete($;$) {
    my $prefix = shift // '';
    my $all = shift;
    require 'File/Glob.pm';

    my $pat = $CONFIG{store};
    my ($s, $h, $i); # extract URI components from the prefix
    if ($prefix =~ /\A([A-Za-z0-9-]+):\/\/([^\P{Graph}:\/]+(?::\d+)?)\/([^\P{Print}\/]*)\z/) {
        ($s, $h, $i) = ($1, $2, $3);
    } elsif ($prefix =~ /\A([A-Za-z0-9-]+):\/\/([^\P{Graph}\/]*)\z/) {
        ($s, $h, $i) = ($1, $2, undef);
    } elsif ($prefix =~ /\A([A-Za-z0-9-]*)(:\/?)?\z/) {
        ($s, $h, $i) = ($1, (defined $2 ? '' : undef), undef);
    } else {
        exit;
    }

    # construct a glob pattern with these URI components
    my ($gs, $gh, $gi) = ($s, $h, $i);
    s/([\\\[\]\{\}\*\?\~])/\\$1/g foreach grep defined, ($gs, $gh, $gi); # escape meta chars

    # add trailing wildcards
    $gs .= '*' if defined $gs and !defined $gh;
    $gh .= '*' if defined $gh and !defined $gi;
    $gi .= '*' if defined $gi;

    my $glob = $pat;
    $glob =~ s/([\\\[\]\{\}\*\?\~])/\\$1/g;
    $glob =~ s{\%(.)}{ $1 eq '%' ? '%' :
                       $1 eq 's' ? $gs // '*' :
                       $1 eq 'h' ? $gh // '*' :
                       $1 eq 'i' ? $gi // '*' :
                       die "Invalid placeholder %$1" }ge;

    # construct regexp to extract the URI compontents of the matching URIs
    my ($ps, $ph, $pi) = ($s, $h, $i);
    $ps = defined $h ? qr/(?<s>\Q$s\E)/ : (defined $s and $s ne '') ? qr/(?<s>\Q$s\E[A-Za-z0-9-]*)/ : qr/(?<s>[A-Za-z0-9-]+)/;
    $ph = defined $i ? qr/(?<h>\Q$h\E)/ : (defined $h and $h ne '') ? qr/(?<h>\Q$h\E[^\P{Graph}\/]*)/ : qr/(?<h>[^\P{Graph}\/]+)/;
    $pi = (defined $i and $i ne '') ? qr/(?<i>\Q$i\E[^\P{Print}\/]*)/ : qr/(?<i>[^\P{Print}\/]+)/;

    $pat =~ s/(\%.)([^\%]*)\z/$1.quotemeta($2)/e;
    $pat =~ s{(.*?)\%(.)}{$2 eq '%' ? '%' :
                          $2 eq 's' ? quotemeta($1).$ps :
                          $2 eq 'h' ? quotemeta($1).$ph :
                          $2 eq 'i' ? quotemeta($1).$pi :
                          die "Invalid placeholder %$1"}ge;
    $pat = qr/\A$pat\z/;

    myprintf \*STDERR, "Using glob pattern C<%s>", $glob if $CONFIG{debug};
    myprintf \*STDERR, "Using regexp C<%s>", "$pat"      if $CONFIG{debug};

    my @matches;
    foreach my $filename (File::Glob::bsd_glob($glob)) {
        $LOCALE->decode($filename) =~ $pat or die "$filename doesn't match $pat";
        push @matches, "$+{s}://$+{h}/$+{i}";
    }
    return @matches if $all or $#matches < 1;

    # find the longest common prefix to determine the depth level of completion
    $matches[0] =~ /\A([A-Za-z0-9-]+):\/\/([^\P{Graph}:\/]+(?::\d+)?)\// or die;
    ($s, $h) = ($1, $2);

    if (all { /\A\Q$s\E:\/\/\Q$h\E\// } @matches) { # common host: list all ids
    } elsif (all { /\A\Q$s\E:\/\// } @matches) { # common scheme: list only hosts
        s#/[^\P{Print}\/]+\z#/# foreach @matches;
    } else { # no common scheme: list only schemes
        s#://[^\P{Graph}\/]+/[^\P{Print}\/]+\z#://# foreach @matches;
    }

    my %matches = map {( $_ => 1 )} @matches;
    return sort keys %matches;
}

# Redact passwords, unless $CONFIG{'show-passwords'} is set.
sub safeValue($;$) {
    my $field = shift;
    my $value = shift // $field->{value};
    return ($field->{type} eq 'password' and !$CONFIG{'show-passwords'}) ?
           ('x' x length $value) : $value;
}

# Send a FILL command with the given form index and field values.
sub fill($$@) {
    my $idx = shift;
    my $form = shift;
    my @fill = @_;

    return if none {defined} @fill; # noop
    for (my $i = 0; $i <= $#fill; $i++) {
        myprintf "Filling field C<%s>, value C<%s>",
                 $form->{fields}->[$i]->{name},
                 safeValue($form->{fields}->[$i], $fill[$i])
            if defined $fill[$i];
    }

    sendCommand('FILL', $idx, JSON::encode_json(\@fill));
}

# Parse a scheme://hostname(:port)?/identity, and return the associated
# file.
sub getIdentityFile($) {
    my $id = shift;
    $id =~ /\A([A-Za-z0-9-]+):\/\/([^\P{Graph}:\/]+(?::\d+)?)\/([^\P{Print}\/]+)\z/
        or error "Invalid identity C<%s>", $id;
    my ($s, $h, $i) = ($1, $2, $3);

    my $filename = $CONFIG{store};
    $filename =~ s{\%(.)}{ $1 eq '%' ? '%' :
                           $1 eq 's' ? $s :
                           $1 eq 'h' ? $h :
                           $1 eq 'i' ? $i :
                           die "Invalid placeholder %$1" }ge;
    return $filename;
}

# Decrypt the given identity file and return the YAML-parsed form.
open my $NULL, '<', '/dev/null';
sub loadIdentityFile($;$) {
    my ($filename, $fh) = @_;
    myprintf \*STDERR, "Decrypting identity file C<%s>", $filename if $CONFIG{debug};

    require 'IPC/Open2.pm';
    my $pid = IPC::Open2::open2( (defined wantarray ? $fh : ">&".$fh->fileno)
                               , "<&".fileno($NULL)
                               , $CONFIG{gpg}, qw/-o - --decrypt --/, $filename)
                or error "Can't fork: %s", $!;
    my $str = do { local $/ = undef; <$fh> } if defined wantarray;
    waitpid $pid, 0;
    error "C<%s> exited with value %d", $CONFIG{gpg}, ($? >> 8) if $? and $? != -1;
    close $fh;

    return unless defined wantarray;

    # the cleartext's charset is always UTF8
    require 'YAML/Tiny.pm'; # XXX use Tiny::YAML instead?
    return YAML::Tiny::Load(decode_utf8 $str) if defined wantarray;
}

# Dump and encrypt a form into the given filename.
sub saveIdentityFile($$) {
    my ($form, $filename) = @_;
    myprintf \*STDERR, "Saving identity file C<%s>", $filename if $CONFIG{debug};

    require 'File/Copy.pm';
    require 'File/Path.pm';
    require 'File/Temp.pm';
    require 'IPC/Open2.pm';
    require 'YAML/Tiny.pm' if ref $form; # XXX use Tiny::YAML instead?

    # don't encrypt directly into the destination file so we don't
    # end up with a messed up file if something goes wrong
    my $outfh = File::Temp->new(SUFFIX => '.gpg', UNLINK => 0, TMPDIR => 1);
    my $pid = IPC::Open2::open2( ">&".$outfh->fileno
                               , (ref $form ? my $infh : "<&".fileno($NULL))
                               , $CONFIG{gpg}, qw/-o - --no-encrypt-to --recipient/, $CONFIG{keyid}
                               , '--encrypt', '--', (ref $form ? () : $form)
                               )
                or error "Can't fork: %s", $!;

    if (ref $form) {
        $form->{fields} = [ grep defined, @{$form->{fields}} ]; # remove undefined fields
        print $infh encode_utf8(YAML::Tiny::Dump($form)); # dump the form as UTF8
        close $infh;
    }
    waitpid $pid, 0;
    error "C<%s> exited with value %d", $CONFIG{gpg}, ($? >> 8) if $? and $? != -1;
    $outfh->close;

    my $parent_dir = $filename =~ s/\/[^\/]+$//r;
    File::Path::make_path($parent_dir) unless -d $parent_dir; # create parent directories recursively
    File::Copy::move($outfh->filename, $filename) or error "Can't move C<%s>: %s", $outfh->filename, $!;

    # TODO: git add $filename; git commit
}

# Get the visible form list from the server, and croak if it's empty.
sub getForms() {
    my $forms = sendCommand 'GETFORMS';
    error "No (visible) form found" unless @$forms;
    return @$forms;
}

# Guess which form is to be filled: take the first form with a password
# field if there are any, otherwise the first non-empty form.  If the
# first argument is defined, only consider forms with a matching base
# URI.
sub findForm($@) {
    my $myform = shift;
    my @forms = @_;

    if (defined $myform) {
        # ignore forms with non-matching action
        @forms = map { $_->{action} =~ /\A\Q$myform->{baseURI}\E(?:\/.*)?\z/ ? $_ : undef } @forms;
        my @formIdx = grepIdx { defined $_ } @forms;
        error "No form found with action matching known base URI C<%s>", $myform->{baseURI}
            unless @formIdx;
        return $formIdx[0] if $#formIdx == 0; # single match
    }

    my $idx = firstIdx { defined $_ and any {$_->{type} eq 'password'} @{$_->{fields}} } @forms;
    $idx  //= firstIdx { defined $_ and any {$_->{value} ne ''} @{$_->{fields}} } @forms;
    error 'Dunno which form to '. (defined $myform ? 'fill' : 'import') unless defined $idx;
    return $idx;
}

# For a page with two or three passwords, try to guess from their value
# which are the old and new/confirm fields.  Returns a list of indices
# (old, new, confirm).
sub guessPasswordPage(@) {
    my ($pw0, $pw1, $pw2) = @_;
    my ($idx0, $idx1, $idx2);

    if (!defined $pw2) {
        if ($pw0->{value} eq $pw1->{value}) {
            ($idx0, $idx1, $idx2) = (undef, 0, 1)
        }
    }
    else {
        if ($pw1->{value} eq $pw2->{value}) { 
            ($idx0, $idx1, $idx2) = (0, 1, 2);
        }
        elsif ($pw0->{value} eq $pw1->{value}) { 
            ($idx0, $idx1, $idx2) = (2, 0, 1);
        }
        elsif ($pw0->{value} eq $pw2->{value}) {
            ($idx0, $idx1, $idx2) = (1, 0, 2);
        }
    }
    return ($idx0, $idx1, $idx2);
}

# Generate a (single) random password for the given fields, with the
# maximum possible length.
sub pwgen(@) {
    my @fields = @_;
    return unless @fields;
    my $pwgen = $CONFIG{pwgen};

    # see how long the password is allowed to be
    my $l = $CONFIG{'max-password-length'};
    $l = min (map { my $x = $1 if defined $_->{maxLength} and $_->{maxLength} =~ /^(\d+)$/;
                    (defined $x and $x > 0 and $x < $l) ?  $x : $l } @fields);
    $pwgen =~ s/%d/$l/g;
    myprintf "Generating $l-char long random value for field".($#fields > 0 ? '(s) ' : ' ')
             .join(',', map {'C<%s>'} @fields),
            map {$_->{name}} @fields;

    my @pw = `$pwgen`;
    error "Can't exec C<%s>: %s", $pwgen, $! unless @pw;
    chomp $pw[$#pw]; # remove the last \n, but keep the others
    $_->{value} = join ('', @pw) foreach @fields;
}

# Prompt a question with an optional defaut response.
sub prompt($;$) {
    my ($prompt, $default) = @_;
    $prompt .= " [$default]" if defined $default;
    print $LOCALE->encode($prompt), " ";

    my $r = <STDIN>;
    die "\n" unless defined $r;
    chomp $r;
    return ($r eq '' and defined $default) ? $default : $LOCALE->decode($r);
}

# Prompt a Yes/No question.
sub promptYN($;$) {
    my $prompt = shift;
    my $default = shift // 0;

    while (1) {
        print $LOCALE->encode($prompt), " [", ($default ? 'Y/n' : 'y/N'), "] ";
        my $r = <STDIN>;
        die "\n" unless defined $r;
        chomp $r;

        if (lc $r eq 'y' or lc $r eq 'yes' or ($r eq '' and $default)) {
            return 1
        }
        elsif (lc $r eq 'n' or lc $r eq 'no' or ($r eq '' and !$default)) {
            return 0
        }
        myprintf \*STDERR, "Answer: C<%s> or C<%s>", 'y', 'n';
    }
}

# Get the SHA-256 digest of the given file.
sub sha256_file($) {
    my $filename = shift;
    
    require 'Digest.pm';
    my $sha256 = Digest->new('SHA-256');
    open my $fh, '<', $filename or error "Can't open C<%s>: %s", $filename, $!;
    $sha256->addfile($fh);
    close $fh;
    return $sha256->digest;
}


#######################################################################

GetOptions(\%CONFIG, qw/debug show-passwords|p socket|s=s help|? zero|0/) or usage(1);
usage(0) if $CONFIG{help};

# Load configuration
my $XDG_CONFIG_HOME = $ENV{XDG_CONFIG_HOME} // "$ENV{HOME}/.config";
my $XDG_DATA_HOME   = $ENV{XDG_DATA_HOME}   // "$ENV{HOME}/.data";
loadConfig "$XDG_CONFIG_HOME/icevault";

# Default options
$CONFIG{gpg} //= 'gpg';
$CONFIG{socket} //= 'S.IceVault';
$CONFIG{store} //= "$XDG_DATA_HOME/icevault/%s/%h/%i.gpg";
$CONFIG{pwgen} //= 'pwgen -s -cyn %d';
$CONFIG{'max-password-length'} //= 32;
$CONFIG{keyid} // error "Missing keyid in configuration file";
error "C<%s> is not a 64-bits key ID or fingerprint", $CONFIG{keyid}
    unless $CONFIG{keyid} =~ /^(?:(?:0x)?\p{AHex}{16}|\p{AHex}{40})$/;

usage(1) unless @ARGV;
@ARGV = map { $LOCALE->decode($_) } @ARGV;
my $command = $ARGV[0] =~ /\A[A-Za-z0-9-]+:\/\//aa ? 'fill' : shift;

# Process the commands
if ($command eq '_complete') {
    # used internaly for auto-completion
    usage(1) unless $#ARGV == 0;
    my $delim = $CONFIG{zero} ? "\0" : "\n";
    print $LOCALE->encode($_), $delim foreach complete(shift @ARGV);
    exit;
}

elsif ($command eq '_geturi') {
    # used internaly for auto-completion
    usage(1) if @ARGV;
    print $LOCALE->encode( &connect($CONFIG{socket}) ), "\n";
    sendCommand 'QUIT';
    exit;
}
elsif ($command eq 'insert') {
    usage(1) unless $#ARGV < 1;
    my $uri = &connect($CONFIG{socket});
    myprintf "Importing HTML form from URI C<%s>", $uri;

    my @forms = getForms();
    my $formIdx = findForm undef, @forms;
    my $form = $forms[$formIdx];
    my @fill = map {undef} (0 .. $#{$form->{fields}});

    if (defined $form->{action}) {
        $form->{baseURI} = delete $form->{action};
        # perform minimal validation on the action URI (ensure that it
        # doesn't contain non-graphical chars, " or /)
        $form->{baseURI} =~ s/\A([A-Za-z0-9-]+:\/\/[^\P{Graph}:\/]+(?::\d+)?)(?:\/.*)?\z/$1/
            or error "Invalid form action: C<%s>", $form->{baseURI};
        my $scheme = $uri =~ s/:\/\/.*//r;
        warning "Warning! Form action scheme C<%s> doesn't match the URI's", $scheme
            unless $uri =~ /\A\Q$scheme\E:\/\//;
    }

    my $id = shift;
    unless (defined $id) {
        # no identity was provided from command line: try to use the
        # last non-empty text field before the first password, and
        # fallback to the first non-empty text field altogether
        my $pwIdx = firstIdx { $_->{type} eq 'password' } @{$form->{fields}};
        my $idx = first { $form->{fields}->[$_]->{value} ne '' and
                          ($form->{fields}->[$_]->{type} eq 'text' or $form->{fields}->[$_]->{type} eq 'email')
                        } ($pwIdx-1 .. 0)
            if defined $pwIdx;
        $idx //= firstIdx { $_->{value} ne '' and ($_->{type} eq 'text' or $_->{type} eq 'email') } @{$form->{fields}};
        $id = $form->{fields}->[$idx]->{value} if defined $idx;
        while (1) {
            # ask for confirmation
            my $r = prompt 'Identity name?', $id;
            if ($r !~ /\A[^\P{Print}\/]+\z/) {
                myprintf \*STDERR, "Invalid identity: C<%s>", $r;
            }
            elsif (-e getIdentityFile "$uri/$r") {
                myprintf \*STDERR, "Identity C<%s> already exists", "$uri/$r";
            }
            else {
                $id = $r;
                last;
            }
        }
    }

    my $filename = getIdentityFile "$uri/$id";
    error "Identity C<%s> already exists", "$uri/$id" if -e $filename;

    my @passIdx = grepIdx { $_->{type} eq 'password' } @{$form->{fields}};
    my @dontsave;
    if ($#passIdx == 0) { # single password in the form
        if ($form->{fields}->[$passIdx[0]]->{value} eq '') {
            warning "Warning! Empty password for field C<%s>", $form->{fields}->[$passIdx[0]]->{name};
            exit 1 unless promptYN "Continue?";
        }
    }
    elsif ($#passIdx < 3) { # 2 or 3 passwords in the form
        my ($idx0, $idx1, $idx2) = map {defined $_ ? $passIdx[$_] : undef}
                                       guessPasswordPage(@{$form->{fields}}[@passIdx]);
        my ($pw0, $pw1, $pw2) = map {defined $_ ? $form->{fields}->[$_] : undef}
                                    ($idx0, $idx1, $idx2);

        if (defined $idx1 and defined $idx2) {
            # it can also be a password changing page when !defined
            # $pw0, but it doesn't matter here as all values are the
            # same
            print STDERR "Assuming a ".(defined $pw0 ? 'password changing' : 'signup')." page\n";
            if ($pw1->{value} eq '') { # generate a password for the two fields
                pwgen ($pw1, $pw2);
                $fill[$_] = $form->{fields}->[$_]->{value} foreach ($idx1, $idx2);
            }

            if (defined $pw0) {
                # keep only the first field, but use the second field's value
                $pw0->{value} = $pw1->{value};
                push @dontsave, $idx1, $idx2;
            } else {
                # keep only the first field
                push @dontsave, $idx2;
            }

        }
    }
    elsif ($#passIdx >= 3) {
        print STDERR "Assuming all ".scalar(@passIdx)." passwords are independent\n";
        foreach my $i (@passIdx) {
            next unless $form->{fields}->[$i]->{value} eq '';
            pwgen $form->{fields}->[$i];
            $fill[$i] = $form->{fields}->[$i]->{value};
        }
    }

    fill $formIdx, $form, @fill;
    sendCommand 'QUIT';

    undef @{$form->{fields}}[@dontsave] if @dontsave; # remove the field we don't want to save
    myprintf "Saving identity C<%s>", "$uri/$id";
    saveIdentityFile $form, $filename;
}

elsif ($command eq 'fill') {
    usage(1) unless $#ARGV == 0;
    my $id = shift;
    my $filename = getIdentityFile $id;
    error "No such identity C<%s>", $id unless -f $filename;

    my $uri = &connect($CONFIG{socket});
    error "Possible phishing attempt! (URI C<%s> doesn't match identity.) Aborting.", $uri
        unless $id =~ /\A\Q$uri\E(?:\/.*)\z/;

    # get the list of forms and load the known form from disk
    my @forms = getForms();
    my $myform = loadIdentityFile $filename;
    my $formIdx = findForm $myform, @forms;
    my $form = $forms[$formIdx];
    my @fill = map {undef} (0 .. $#{$form->{fields}});

    # map each field name to the list of its indices; this allows
    # multivalued names
    my %fields = groupByName @{$form->{fields}};
    my %myfields = groupByName @{$myform->{fields}};
    my $changed = 0;

    my @mypassIdx = grepIdx { $_->{type} eq 'password' } @{$myform->{fields}};
    my @passIdx = grepIdx { $_->{type} eq 'password' } @{$form->{fields}};
    if ($#mypassIdx == 0 and $#passIdx == 0 and
        $#{$myfields{$myform->{fields}->[$mypassIdx[0]]->{name}}} == 0 and
        $#{$fields{$form->{fields}->[$passIdx[0]]->{name}}} == 0) {
        # there is a single password on both the know form and that we
        # want to fill, and both field names are unique in these forms:
        # assume this is the password to be filled regardless of the
        # name

        my $mypass = $myform->{fields}->[$mypassIdx[0]];
        my $pass = $form->{fields}->[$passIdx[0]];
        delete $myfields{$mypass->{name}}; # don't process these names later
        delete $fields{$pass->{name}};

        if ($mypass->{name} ne $pass->{name}) { # use the new name
            myprintf "Renaming field C<%s> as C<%s>",
                               $mypass->{name}, $pass->{name};
            $mypass->{name} = $pass->{name};
            $changed = 1;
        }

        if ($pass->{value} eq '') { # fill the password with the known value
            $fill[$passIdx[0]] = $mypass->{value};
        }
        elsif ($mypass->{value} ne $pass->{value}) { # update the password
            myprintf "Updating field C<%s> to C<%s> (former value: C<%s>)",
                     $mypass->{name}, safeValue($pass), safeValue($mypass);
            $mypass->{value} = $pass->{value};
            $changed = 1;
        }
    }
    elsif ($#mypassIdx == 0 and $#passIdx > 0 and $#passIdx < 3) {
        # there is a single known password, but two or three fields to
        # fill: probably a password changing page
        my $mypass = $myform->{fields}->[$mypassIdx[0]];
        my ($idx0, $idx1, $idx2) = map {defined $_ ? $passIdx[$_] : undef}
                                       guessPasswordPage(@{$form->{fields}}[@passIdx]);
        my ($pw0, $pw1, $pw2) = map {defined $_ ? $form->{fields}->[$_] : undef}
                                    ($idx0, $idx1, $idx2);

        if (defined $pw1 and defined $pw2) {
            print STDERR "Assuming a password changing page\n";
            if ($pw1->{value} eq '') {
                pwgen ($pw1, $pw2);
                $fill[$_] = $form->{fields}->[$_]->{value} foreach ($idx1, $idx2);
            }

            # fill the first password field with the known value
            $fill[$idx0] = $mypass->{value} if defined $idx0 and $pw0->{value} eq '';

            if ($mypass->{value} ne $pw1->{value}) {
                # update the known password with the new value
                $mypass->{value} = $pw1->{value};
                $changed = 1;
            }

            # don't process these fields later
            &delete($mypassIdx[0], $myfields{$mypass->{name}});
            &delete($_, $fields{$form->{fields}->[$_]->{name}}) foreach grep defined, ($idx0, $idx1, $idx2);
        }
    }

    # walk through each names in both %myfields and %fields, and fill
    # the values in the order they are found
    foreach my $name (keys %myfields) {
        next unless exists $fields{$name};
        while (@{$myfields{$name}} and @{$fields{$name}}) {
            my $myidx = shift @{$myfields{$name}};
            my $idx = shift @{$fields{$name}};
            next unless defined $myidx and defined $idx; # was taken care of before
            if ($form->{fields}->[$idx]->{value} eq '' and $myform->{fields}->[$myidx]->{value} ne '') {
                # fill with the known value
                $fill[$idx] = $myform->{fields}->[$myidx]->{value};
            }
            elsif ($myform->{fields}->[$myidx]->{value} ne $form->{fields}->[$idx]->{value}) {
                # update the known value with that found in the page
                myprintf "Updating field C<%s> to C<%s> (former value: C<%s>)",
                         $myform->{fields}->[$myidx]->{name},
                         safeValue($form->{fields}->[$idx]),
                         safeValue($myform->{fields}->[$myidx]);
                $myform->{fields}->[$myidx]->{value} = $form->{fields}->[$idx]->{value};
                $changed = 1;
            }
        }
    }
    # add the fields that were found in the page, but not in our form
    foreach my $name (keys %fields) {
        my @fieldIdx = grep defined, @{$fields{$name}};
        my $i;
        for ($i = $#fieldIdx; $i >= 0; $i--) {
            last unless $form->{fields}->[$i]->{value} eq '';
        }
        # don't store empty values (unless a later value is non-empty,
        # to preserve the order)
        @fieldIdx = @fieldIdx[(0 .. $i)] if $i >= 0;
        next unless @fieldIdx and $i >= 0;
        myprintf "Adding field C<%s>, value".($#fieldIdx > 0 ? '(s) ' : ' ').
                  join(',', map {'C<%s>'} @fieldIdx),
                 $name, map {safeValue $form->{fields}->[$_]} @fieldIdx;
        push @{$myform->{fields}}, @{$form->{fields}}[@fieldIdx];
        $changed = 1;
    }
    foreach my $name (keys %myfields) {
        my @fieldIdx = grep defined, @{$myfields{$name}};
        next unless @fieldIdx;
        myprintf "Deleting field C<%s>, value".($#fieldIdx > 0 ? '(s) ' : ' ').
                  join(',', map {'C<%s>'} @fieldIdx),
                 $name, map {safeValue $myform->{fields}->[$_]} @fieldIdx;
        undef $myform->{fields}->[$_] foreach @fieldIdx;
        $changed = 1;
    }

    fill $formIdx, $form, @fill;
    sendCommand 'QUIT';

    if ($changed) {
        my $r = promptYN "Save changes?", 0;
        saveIdentityFile ($myform, $filename) if $r;
    }
}

elsif ($command eq 'dump') {
    usage(1) unless $#ARGV == 0;
    my $id = shift;
    my $filename = getIdentityFile $id;
    error "No such identity C<%s>", $id unless -f $filename;

    my $form = loadIdentityFile $filename;
    $_->{value} = safeValue($_) foreach @{$form->{fields}}; # redact the passwords

    my $str = YAML::Tiny::Dump($form);
    print STDOUT (defined $LOCALE ? $LOCALE->encode($str) : $str)
}

elsif ($command eq 'edit') {
    usage(1) unless $#ARGV == 0;
    my $id = shift;
    my $filename = getIdentityFile $id;
    error "No such identity C<%s>", $id unless -f $filename;
    require 'File/Copy.pm';
    require 'File/Temp.pm';

    error "C<%s> is not set", '$EDITOR' unless defined $ENV{EDITOR};
    $ENV{EDITOR} =~ /\A(\p{Print}+)\z/ or error "Insecure C<%s>", "\$EDITOR";
    my $EDITOR = $1; # untaint $EDITOR

    my $fh = File::Temp->new(SUFFIX => '.yaml', UNLINK => 0, TMPDIR => 1);
    END { unlink $fh->filename if defined $fh; } # never leave cleartext lying around
    loadIdentityFile $filename, $fh;

    my $h = sha256_file $fh->filename;
    system $EDITOR, $fh->filename;
    error "C<%s> exited with value %d", $EDITOR, ($? >> 8) if $? and $? != -1;

    if ($h eq sha256_file $fh->filename) {
        print "No modification made\n";
    }
    else {
        myprintf "Saving user changes for identity C<%s>", $id;
        saveIdentityFile( $fh->filename, $filename);
    }
}

elsif ($command eq 'clip') {
    usage(1) unless $#ARGV == 0;
    my $id = shift;
    my $filename = getIdentityFile $id;
    error "No such identity C<%s>", $id unless -f $filename;

    my $form = loadIdentityFile $filename;
    my $pw = first { $_->{type} eq 'password' } @{$form->{fields}};
    error "No password found in C<%s>", $id unless defined $pw;

    my $pid = open my $fh, '|-', qw/xclip -loop 1 -selection clipboard/
        or error "Can't fork: %s", $!;
    print $fh encode_utf8($pw->{value});
    close $fh;
    waitpid $pid, 0;
    error "C<%s> exited with value %d", 'xclip', ($? >> 8) if $? and $? != -1;
    exit 0;
}

elsif ($command eq 'ls') {
    usage(1) if $#ARGV > 0;
    my $prefix = shift @ARGV;
    my @matches = complete $prefix // '', 1;

    if (!defined $prefix) {
        s/:\/\/.*// foreach @matches;
    } elsif ($prefix =~ /\A[A-Za-z0-9-]+:\/\/[^\P{Graph}:\/]+(?::\d+)?\/[^\P{Print}\/]+\z/) {
        @matches = grep /\A\Q$prefix\E\z/, @matches;
    } elsif ($prefix =~ /\A([A-Za-z0-9-]+:\/\/[^\P{Graph}\/]+)\/?\z/) {
        my $x = $1;
        @matches = grep defined, map { !s/\A\Q$x\E\/// ? undef : $_ } @matches;
    } elsif ($prefix =~ /\A([A-Za-z0-9-]+)(:\/{0,2})?\z/) {
        my $x = $1;
        @matches = grep defined, map { !s/\A\Q$x\E:\/\/// ? undef :
                                       !s/\/[^\P{Print}\/]+\z// ? undef : $_ } @matches;
    } else {
        @matches = ();
    }
    error "No such identity C<%s>", $prefix // '' unless @matches;

    my $delim = $CONFIG{zero} ? "\0" : "\n";
    my %matches = map {($_ => 1)} @matches;
    print $LOCALE->encode($_), $delim foreach sort keys %matches;
}

else {
    myprintf "Unknown command: C<%s>", $command;
    usage(1);
}