viewdiff: support renames and long paths in diffstat anchors

This is best-effort, but works well-enough in practice for
projects which use shell-friendly filenames as well as the
long path names for some Linux kernel selftests.

1 files changed, 47 insertions, 15 deletions

diff --git a/lib/PublicInbox/ViewDiff.pm b/lib/PublicInbox/ViewDiff.pm
index fbdc5b95..c818203b 100644
--- a/lib/PublicInbox/ViewDiff.pm
+++ b/lib/PublicInbox/ViewDiff.pm
@@ -77,10 +77,28 @@ sub to_state ($$$) {
 
 sub anchor0 ($$$$$) {
         my ($dst, $ctx, $linkify, $fn, $rest) = @_;
+
+        my $orig = $fn;
+
+        # normal git diffstat output is impossible to parse reliably
+        # without --numstat, and that isn't the default for format-patch.
+        # So only do best-effort handling of renames for common cases;
+        # which works well in practice. If projects put "=>", or trailing
+        # spaces in filenames, oh well :P
+        $fn =~ s/ +\z//s;
+        $fn =~ s/{(?:.+) => (.+)}/$1/ or $fn =~ s/.* => (.+)/$1/;
+        $fn = git_unquote($fn);
+
+        # long filenames will require us to walk backwards in anchor1
+        if ($fn =~ s!\A\.\.\./?!!) {
+                my $lp = $ctx->{-long_path} ||= {};
+                $lp->{$fn} = qr/\Q$fn\E\z/s;
+        }
+
         if (my $attr = to_attr($ctx->{-apfx}.$fn)) {
                 $ctx->{-anchors}->{$attr} = 1;
                 $$dst .= " <a\nid=i$attr\nhref=#$attr>" .
-                        ascii_html($fn) . '</a>'.
+                        ascii_html($orig) . '</a>'.
                         to_html($linkify, $rest);
                 return 1;
         }
@@ -92,7 +110,21 @@ sub anchor1 ($$$$$) {
         my $attr = to_attr($ctx->{-apfx}.$pb) or return;
         my $line = to_html($linkify, $s);
 
-        if (delete $ctx->{-anchors}->{$attr} && $line =~ s/^diff //) {
+        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;
+                }
+        }
+        if ($ok && $line =~ s/^diff //) {
                 $$dst .= "<a\nhref=#i$attr\nid=$attr>diff</a> ".$line;
                 return 1;
         }
@@ -113,7 +145,7 @@ sub flush_diff ($$$) {
                 } elsif ($s =~ /^ /) {
                         # works for common cases, but not weird/long filenames
                         if ($state == DSTATE_STAT &&
-                                        $s =~ /^ (\S+)(\s+\|.*\z)/s) {
+                                        $s =~ /^ (.+)( +\| .*\z)/s) {
                                 anchor0($dst, $ctx, $linkify, $1, $2) and next;
                         } elsif ($state2class[$state]) {
                                 to_state($dst, $state, DSTATE_CTX);
@@ -124,20 +156,20 @@ sub flush_diff ($$$) {
                                 to_state($dst, $state, DSTATE_INIT);
                         $$dst .= $s;
                 } elsif ($s =~ m!^diff --git ($PATH_A) ($PATH_B)$!) {
+                        my ($pa, $pb) = ($1, $2);
                         if ($state != DSTATE_HEAD) {
-                                my ($pa, $pb) = ($1, $2);
                                 to_state($dst, $state, DSTATE_HEAD);
-                                $pa = (split('/', git_unquote($pa), 2))[1];
-                                $pb = (split('/', git_unquote($pb), 2))[1];
-                                $dctx = {
-                                        Q => "?b=".uri_escape_utf8($pb, UNSAFE),
-                                };
-                                if ($pa ne $pb) {
-                                        $dctx->{Q} .= '&amp;a='.
-                                                uri_escape_utf8($pa, UNSAFE);
-                                }
-                                anchor1($dst, $ctx, $linkify, $pb, $s) and next;
                         }
+                        $pa = (split('/', git_unquote($pa), 2))[1];
+                        $pb = (split('/', git_unquote($pb), 2))[1];
+                        $dctx = {
+                                Q => "?b=".uri_escape_utf8($pb, UNSAFE),
+                        };
+                        if ($pa ne $pb) {
+                                $dctx->{Q} .= '&amp;a='.
+                                        uri_escape_utf8($pa, UNSAFE);
+                        }
+                        anchor1($dst, $ctx, $linkify, $pb, $s) and next;
                         $$dst .= to_html($linkify, $s);
                 } elsif ($s =~ s/^(index $OID_NULL\.\.)($OID_BLOB)\b//o) {
                         $$dst .= $1 . oid($dctx, $spfx, $2);
@@ -160,7 +192,7 @@ sub flush_diff ($$$) {
                         $$dst .= to_html($linkify, $s);
                 } elsif ($s =~ m!^--- $PATH_A! ||
                          $s =~ m!^\+{3} $PATH_B!)  {
-                        # color only (no oid link)
+                        # color only (no oid link) if missing dctx->{oid_*}
                         $state <= DSTATE_STAT and
                                 to_state($dst, $state, DSTATE_HEAD);
                         $$dst .= to_html($linkify, $s);