# Copyright (C) 2019-2020 all contributors
# License: AGPL-3.0+
#
# used by PublicInbox::View
# This adds CSS spans for diff highlighting.
# It also generates links for ViewVCS + SolverGit to show
# (or reconstruct) blobs.
package PublicInbox::ViewDiff;
use 5.010_001;
use strict;
use warnings;
use base qw(Exporter);
our @EXPORT_OK = qw(flush_diff);
use URI::Escape qw(uri_escape_utf8);
use PublicInbox::Hval qw(ascii_html to_attr);
use PublicInbox::Git qw(git_unquote);
sub UNSAFE () { "^A-Za-z0-9\-\._~/" }
my $OID_NULL = '0{7,40}';
my $OID_BLOB = '[a-f0-9]{7,40}';
# cf. git diff.c :: get_compact_summary
my $DIFFSTAT_COMMENT = qr/\((?:new|gone|(?:(?:new|mode) [\+\-][lx]))\)/;
# link to line numbers in blobs
sub diff_hunk ($$$$) {
my ($dst, $dctx, $ca, $cb) = @_;
my ($oid_a, $oid_b, $spfx) = @$dctx{qw(oid_a oid_b spfx)};
if (defined($spfx) && defined($oid_a) && defined($oid_b)) {
my ($n) = ($ca =~ /^-([0-9]+)/);
$n = defined($n) ? do { ++$n; "#n$n" } : '';
$$dst .= qq(@@ {Q}$n">$ca);
($n) = ($cb =~ /^\+([0-9]+)/);
$n = defined($n) ? do { ++$n; "#n$n" } : '';
$$dst .= qq( {Q}$n">$cb @@);
} else {
$$dst .= "@@ $ca $cb @@";
}
}
sub oid ($$$) {
my ($dctx, $spfx, $oid) = @_;
defined($spfx) ? qq({Q}">$oid) : $oid;
}
# returns true if diffstat anchor written, false otherwise
sub anchor0 ($$$$) {
my ($dst, $ctx, $fn, $rest) = @_;
my $orig = $fn;
# normal git diffstat output is impossible to parse reliably
# without --numstat, and that isn't the default for format-patch.
# So only do best-effort handling of renames for common cases;
# which works well in practice. If projects put "=>", or trailing
# spaces in filenames, oh well :P
$fn =~ s/(?: *$DIFFSTAT_COMMENT)? *\z//so;
$fn =~ s/{(?:.+) => (.+)}/$1/ or $fn =~ s/.* => (.+)/$1/;
$fn = git_unquote($fn);
# long filenames will require us to walk backwards in anchor1
if ($fn =~ s!\A\.\.\./?!!) {
$ctx->{-long_path}->{$fn} = qr/\Q$fn\E\z/s;
}
if (my $attr = to_attr($ctx->{-apfx}.$fn)) {
$ctx->{-anchors}->{$attr} = 1;
my $spaces = ($orig =~ s/( +)\z//) ? $1 : '';
$$dst .= " " .
ascii_html($orig) . '' . $spaces .
$ctx->{-linkify}->to_html($rest);
return 1;
}
undef;
}
# returns "diff --git" anchor destination, undef otherwise
sub anchor1 ($$) {
my ($ctx, $pb) = @_;
my $attr = to_attr($ctx->{-apfx}.$pb) or return;
my $ok = delete $ctx->{-anchors}->{$attr};
# unlikely, check the end of all long path names we captured:
unless ($ok) {
my $lp = $ctx->{-long_path} or return;
foreach my $fn (keys %$lp) {
$pb =~ $lp->{$fn} or next;
delete $lp->{$fn};
$attr = to_attr($ctx->{-apfx}.$fn) or return;
$ok = delete $ctx->{-anchors}->{$attr} or return;
last;
}
}
$ok ? "diff --git" : undef
}
sub diff_header ($$$$) {
my ($dst, $x, $ctx, $top) = @_;
my (undef, undef, $pa, $pb) = splice(@$top, 0, 4); # ignore oid_{a,b}
my $spfx = $ctx->{-spfx};
my $dctx = { spfx => $spfx };
if ($pa eq $pb && $pb ne '/dev/null') {
$pa = $pb = (split('/', git_unquote($pb), 2))[1];
$dctx->{Q} = "?b=".uri_escape_utf8($pb, UNSAFE);
} else {
my @q;
if ($pb ne '/dev/null') {
$pb = (split('/', git_unquote($pb), 2))[1];
push @q, 'b='.uri_escape_utf8($pb, UNSAFE);
}
if ($pa ne '/dev/null') {
$pa = (split('/', git_unquote($pa), 2))[1];
push @q, 'a='.uri_escape_utf8($pa, UNSAFE);
}
$dctx->{Q} = '?'.join('&', @q);
}
# linkify early and all at once, since we know the following
# subst ops on $$x won't need further escaping:
$$x = $ctx->{-linkify}->to_html($$x);
# no need to capture oid_a and oid_b on add/delete,
# we just linkify OIDs directly via s///e in conditional
if (($$x =~ s/^(index $OID_NULL\.\.)($OID_BLOB)\b/
$1 . oid($dctx, $spfx, $2)/emos) ||
($$x =~ s/^index ($OID_BLOB)(\.\.$OID_NULL)\b/
'index ' . oid($dctx, $spfx, $1) . $2/emos)) {
} elsif ($$x =~ /^index ($OID_BLOB)\.\.($OID_BLOB)/mos) {
# modification-only, not add/delete:
# linkify hunk headers later using oid_a and oid_b
@$dctx{qw(oid_a oid_b)} = ($1, $2);
} else {
warn "BUG? <$$x> had no ^index line";
}
$$x =~ s!^diff --git!anchor1($ctx, $pb) // 'diff --git'!emos;
$$dst .= qq();
$$dst .= $$x;
$$dst .= '';
$dctx;
}
sub diff_before_or_after ($$$) {
my ($dst, $ctx, $x) = @_;
my $linkify = $ctx->{-linkify};
for my $y (split(/(^---\r?\n)/sm, $$x)) {
if ($y =~ /\A---\r?\n\z/s) {
$$dst .= "---\n"; # all HTML is "\r\n" => "\n"
} elsif ($y =~ /^ [0-9]+ files? changed, /sm) {
# ok, looks like a diffstat, go line-by-line:
for my $l (split(/^/m, $y)) {
if ($l =~ /^ (.+)( +\| .*\z)/s) {
anchor0($dst, $ctx, $1, $2) and next;
}
$$dst .= $linkify->to_html($l);
}
} else { # commit message, notes, etc
$$dst .= $linkify->to_html($y);
}
}
}
sub flush_diff ($$$) {
my ($dst, $ctx, $cur) = @_;
state $LF = qr!\r?\n!;
state $ANY = qr![^\r\n]!;
state $FN = qr!(?:"?[^/\n]+/[^\r\n]+|/dev/null)!;
my @top = split(/(
(?: # begin header stuff, don't capture filenames, here,
# but instead wait for the --- and +++ lines.
(?:^diff\x20--git\x20$FN\x20$FN$LF)
# old mode || new mode || copy|rename|deleted|...
(?:^[a-z]$ANY+$LF)*
)? # end of optional stuff, everything below is required
^index\x20($OID_BLOB)\.\.($OID_BLOB)$ANY*$LF
^---\x20($FN)$LF
^\+{3}\x20($FN)$LF)/smxo, $$cur);
$$cur = undef;
my $linkify = $ctx->{-linkify};
my $dctx; # {}, keys: Q, oid_a, oid_b
while (defined(my $x = shift @top)) {
if (scalar(@top) >= 4 &&
$top[1] =~ /\A$OID_BLOB\z/os &&
$top[0] =~ /\A$OID_BLOB\z/os) {
$dctx = diff_header($dst, \$x, $ctx, \@top);
} elsif ($dctx) {
my $after = '';
for my $s (split(/((?:(?:^\+[^\n]*\n)+)|
(?:(?:^-[^\n]*\n)+)|
(?:^@@ [^\n]+\n))/xsm, $x)) {
if (!defined($dctx)) {
$after .= $s;
} elsif ($s =~ s/\A@@ (\S+) (\S+) @@//) {
$$dst .= qq();
diff_hunk($dst, $dctx, $1, $2);
$$dst .= $linkify->to_html($s);
$$dst .= '';
} elsif ($s =~ /\A\+/) {
$$dst .= qq();
$$dst .= $linkify->to_html($s);
$$dst .= '';
} elsif ($s =~ /\A-- $/sm) { # email sig starts
$dctx = undef;
$after .= $s;
} elsif ($s =~ /\A-/) {
$$dst .= qq();
$$dst .= $linkify->to_html($s);
$$dst .= '';
} else {
$$dst .= $linkify->to_html($s);
}
}
diff_before_or_after($dst, $ctx, \$after) unless $dctx;
} else {
diff_before_or_after($dst, $ctx, \$x);
}
}
}
1;