From 5e9409d925fe81f6c9c4eed767febf6b59738742 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 14 May 2017 21:49:45 +0100
Subject: [PATCH] git-debrebase: wip import handling etc.

---
 git-debrebase | 67 +++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 51 insertions(+), 16 deletions(-)

diff --git a/git-debrebase b/git-debrebase
index d6bd8a51..3048793a 100755
--- a/git-debrebase
+++ b/git-debrebase
@@ -332,6 +332,14 @@ sub walk {
     my $rewrite_from_here = sub {
 	push @processed, { SpecialMethod => 'StartRewrite' };
     };
+    my $bomb = sub { # usage: return $bomb->();
+	    print $report " Unprocessable" if $report;
+	    $prprdelim->();
+	    if ($nogenerate) {
+		return (undef,undef);
+	    }
+	    die "commit $cur: Cannot cope with this commit";
+    };
 
     my $cur = $input;
     my $basis;
@@ -340,6 +348,14 @@ sub walk {
     my $prprdelim = sub { print $report $prdelim if $report; $prdelim=""; };
 
     for (;;) {
+	if (!defined $cur) {
+	    if ($report) {
+		print $report $predelim, "Origin";
+		$prdelim = "\n";
+	    }
+	    $basis = undef;
+	    last;
+	}
 	$cl = classify $cur;
 	my $ty = $cl->{Type};
 	my $st = $cl->{SubType};
@@ -349,7 +365,7 @@ sub walk {
 	}
 	$found{$ty. ( defined($st) ? "-$st" : '' )}++;
 	push @processed, $cl;
-	my $p0 = $cl->{Parents}[0]{CommitId};
+	my $p0 = @[ $cl->{Parents} }==1 ? $cl->{Parents}[0]{CommitId} : undef;
 	if ($ty eq 'AddPatches') {
 	    $cur = $p0;
 	    $rewrite_from_here->();
@@ -381,8 +397,7 @@ sub walk {
 	} elsif ($ty eq 'BreakwaterUpstreamMerge') {
 	    $basis = $cur;
 	    last;
-	} elsif ($ty eq 'DgitImportUnpatched' &&
-		 @pseudomerges == 1) {
+	} elsif ($ty eq 'DgitImportUnpatched') {
 	    # This import has a tree which is just like a breakwater
 	    # tree, but it has the wrong history.  Its ought to have
 	    # the previous breakwater (which dgit ought to have
@@ -397,6 +412,10 @@ sub walk {
 	    printf $report " Differs=%#x", $differs if $report;
 	    if ($differs & D_UPS) {
 		printf $report " D_UPS" if $report;
+		# This will also trigger if a non-dgit git-based NMU
+		# deleted .gitignore (which is a thing that some of
+		# the existing git tools do if the user doesn't
+		# somehow tell them not to).  Ah well.
 		push @deb_cl, {
                     %$cl,
                     SpecialMethod => 'DgitImportUpstreamUpdate',
@@ -407,21 +426,37 @@ sub walk {
 		%$cl,
 		SpecialMethod => 'DgitImportDebianUpdate',
                 $xmsg->("convert dgit import: upstream changes")
-	    };
-	    $prprdelim->();
-	    $basis = walk
-		$pseudomerges[0]{Overwritten},
-		$nogenerate, $report,
-		1, $depth+1;
+            };
+	    my $pm = $pseudomerges[-1];
+	    if (defined $pm) {
+		# To an extent, this is heurstic.  Imports don't have
+		# a useful history of the debian/ branch.  We assume
+		# that the first pseudomerge after an import has a
+		# useful history or debian/, and ignore the histories
+		# from later pseudomerge.  Often the first pseudomerge
+		# will be the dgit import of the upload to the actual
+		# suite intended by the non-dgit NMUer, and later
+		# pseudomerges may represent in-archive copies.
+		my $ovwr = $pm->{Overwritten};
+		printf $report " PM=%s \@Ovewritten:%d", $pm, (scalar @$ovwr)
+		    if $report;
+		if (@$ovwr != 1) {
+		    return $bomb->();
+		}
+		$basis = walk
+		    $ovwr->[0]{CommitId},
+		    $nogenerate, $report,
+		    1, $depth+1;
+	    } else {
+		# Everything is from this import.
+		printf $report " NoPM" if $report;
+		
+		xxx set basis to undef or something to mean make origin
+	    }
 	    $rewrite_from_here->();
 	    last;
-	} else {
-	    print $report " Unprocessable" if $report;
-	    $prprdelim->();
-	    if ($nogenerate) {
-		return (undef,undef);
-	    }
-	    die "commit $cur: Cannot cope with this commit";
+        } else {
+	    return $bomb->();
 	}
     }
     $prprdelim->();
-- 
2.30.2