--- /dev/null
+# Copyright (C) all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+# The "lei mail-diff" sub-command, diffs input contents against
+# the first message of input
+package PublicInbox::LeiMailDiff;
+use strict;
+use v5.10.1;
+use parent qw(PublicInbox::IPC PublicInbox::LeiInput);
+use File::Temp 0.19 (); # 0.19 for ->newdir
+use PublicInbox::Spawn qw(spawn which);
+use PublicInbox::MsgIter qw(msg_part_text);
+use File::Path qw(remove_tree);
+use PublicInbox::ContentHash qw(content_digest);
+require PublicInbox::LeiRediff;
+use Data::Dumper ();
+
+sub write_part { # Eml->each_part callback
+ my ($ary, $self) = @_;
+ my ($part, $depth, $idx) = @$ary;
+ if ($idx ne '1' || $self->{lei}->{opt}->{'raw-header'}) {
+ open my $fh, '>', "$self->{curdir}/$idx.hdr" or die "open: $!";
+ print $fh ${$part->{hdr}} or die "print $!";
+ close $fh or die "close $!";
+ }
+ my $ct = $part->content_type || 'text/plain';
+ my ($s, $err) = msg_part_text($part, $ct);
+ my $sfx = defined($s) ? 'txt' : 'bin';
+ open my $fh, '>', "$self->{curdir}/$idx.$sfx" or die "open: $!";
+ print $fh ($s // $part->body) or die "print $!";
+ close $fh or die "close $!";
+}
+
+sub dump_eml ($$$) {
+ my ($self, $dir, $eml) = @_;
+ local $self->{curdir} = $dir;
+ mkdir $dir or die "mkdir($dir): $!";
+ $eml->each_part(\&write_part, $self);
+
+ open my $fh, '>', "$dir/content_digest" or die "open: $!";
+ my $dig = PublicInbox::ContentDigestDbg->new($fh);
+ local $Data::Dumper::Useqq = 1;
+ local $Data::Dumper::Terse = 1;
+ content_digest($eml, $dig);
+ print $fh "\n", $dig->hexdigest, "\n" or die "print $!";
+ close $fh or die "close: $!";
+}
+
+sub prep_a ($$) {
+ my ($self, $eml) = @_;
+ $self->{tmp} = File::Temp->newdir('lei-mail-diff-XXXX', TMPDIR => 1);
+ dump_eml($self, "$self->{tmp}/a", $eml);
+}
+
+sub diff_a ($$) {
+ my ($self, $eml) = @_;
+ ++$self->{nr};
+ my $dir = "$self->{tmp}/N$self->{nr}";
+ dump_eml($self, $dir, $eml);
+ my $cmd = [ qw(git diff --no-index) ];
+ my $lei = $self->{lei};
+ PublicInbox::LeiRediff::_lei_diff_prepare($lei, $cmd);
+ push @$cmd, qw(-- a), "N$self->{nr}";
+ my $rdr = { -C => "$self->{tmp}" };
+ @$rdr{1, 2} = @$lei{1, 2};
+ my $pid = spawn($cmd, $lei->{env}, $rdr);
+ waitpid($pid, 0);
+ $lei->child_error($?) if $?; # for git diff --exit-code
+ File::Path::remove_tree($self->{curdir});
+}
+
+sub input_eml_cb { # used by PublicInbox::LeiInput::input_fh
+ my ($self, $eml) = @_;
+ $self->{tmp} ? diff_a($self, $eml) : prep_a($self, $eml);
+}
+
+sub lei_mail_diff {
+ my ($lei, @argv) = @_;
+ $lei->{opt}->{'in-format'} //= 'eml';
+ my $self = bless {}, __PACKAGE__;
+ $self->prepare_inputs($lei, \@argv) or return;
+ my $isatty = -t $lei->{1};
+ $lei->{opt}->{color} //= $isatty;
+ $lei->start_pager if $isatty;
+ my $ops = {};
+ $lei->{auth}->op_merge($ops, $self) if $lei->{auth};
+ (my $op_c, $ops) = $lei->workers_start($self, 1, $ops);
+ $lei->{wq1} = $self;
+ $lei->{-err_type} = 'non-fatal';
+ net_merge_all_done($self) unless $lei->{auth};
+ $lei->wait_wq_events($op_c, $ops);
+}
+
+no warnings 'once';
+*net_merge_all_done = \&PublicInbox::LeiInput::input_only_net_merge_all_done;
+
+package PublicInbox::ContentDigestDbg;
+use strict;
+use v5.10.1;
+use Data::Dumper;
+
+sub new { bless { dig => Digest::SHA->new(256), fh => $_[1] }, __PACKAGE__ }
+
+sub add {
+ $_[0]->{dig}->add($_[1]);
+ print { $_[0]->{fh} } Dumper($_[1]) or die "print $!";
+}
+
+sub hexdigest { $_[0]->{dig}->hexdigest; }
+
+1;