[PATCH] gitweb: Add "next" link to commitdiff view

[Jakub Narebski <jnareb@gmail.com>]

Add a kind of "next" view in the bottom part of navigation bar for
"commitdiff" view.

For commitdiff between two commits:
  (from: _commit_)
For commitdiff for one single parent commit:
  (parent: _commit_)
For commitdiff for one merge commit
  (merge: _commit_ _commit_ ...)
For commitdiff for root (parentless) commit
  (initial)
where _link_ denotes hyperlink. SHA1 is shortened to 7 characters on
display, everything is perhaps unnecessary esc_html on display.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---

Junio (and others), is it what you wanted? The idea was to change
"commitdiff" view only in minimal way, and preserve similarity
to "commit" format. 

SHA1 ids are printed in monospace (fixed width) font. BTW. should
we put '...' after shortened SHA1? Should those '...' be included
in link?


 gitweb/gitweb.perl |   49 +++++++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index c9e57f0..4241d5c 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -3280,6 +3280,51 @@ sub git_commitdiff {
 	if (!%co) {
 		die_error(undef, "Unknown commit object");
 	}
+
+	# we need to prepare $formats_nav before any parameter munging
+	my $formats_nav;
+	if ($format eq 'html') {
+		$formats_nav =
+			$cgi->a({-href => href(action=>"commitdiff_plain",
+			                       hash=>$hash, hash_parent=>$hash_parent)},
+			        "raw");
+
+		if (defined $hash_parent) {
+			# commitdiff with two commits given
+			my $hash_parent_short = $hash_parent;
+			if ($hash_parent =~ m/^[0-9a-fA-F]{40}$/) {
+				$hash_parent_short = substr($hash_parent, 0, 7);
+			}
+			$formats_nav .=
+				' (from: ' .
+				$cgi->a({-href => href(action=>"commitdiff",
+				                       hash=>$hash_parent)},
+				        esc_html($hash_parent_short)) .
+				')';
+		} elsif (!$co{'parent'}) {
+			# --root commitdiff
+			$formats_nav .= ' (initial)';
+		} elsif (scalar @{$co{'parents'}} == 1) {
+			# single parent commit
+			$formats_nav .=
+				' (parent: ' .
+				$cgi->a({-href => href(action=>"commitdiff",
+				                       hash=>$co{'parent'})},
+				        esc_html(substr($co{'parent'}, 0, 7))) .
+				')';
+		} else {
+			# merge commit
+			$formats_nav .=
+				' (merge: ' .
+				join(' ', map {
+					$cgi->a({-href => href(action=>"commitdiff",
+					                       hash=>$_)},
+					        esc_html(substr($_, 0, 7)));
+				} @{$co{'parents'}} ) .
+				')';
+		}
+	}
+
 	if (!defined $hash_parent) {
 		$hash_parent = $co{'parent'} || '--root';
 	}
@@ -3317,10 +3362,6 @@ sub git_commitdiff {
 	if ($format eq 'html') {
 		my $refs = git_get_references();
 		my $ref = format_ref_marker($refs, $co{'id'});
-		my $formats_nav =
-			$cgi->a({-href => href(action=>"commitdiff_plain",
-			                       hash=>$hash, hash_parent=>$hash_parent)},
-			        "raw");
 
 		git_header_html(undef, $expires);
 		git_print_page_nav('commitdiff','', $hash,$co{'tree'},$hash, $formats_nav);
-- 
1.4.2.1