1#!/bin/sh
2
3USAGE="[-a] [-r] [-m] [-t] [-n] [-b <newname>] <name>"
4LONG_USAGE="git-resurrect attempts to find traces of a branch tip
5called <name>, and tries to resurrect it.  Currently, the reflog is
6searched for checkout messages, and with -r also merge messages.  With
7-m and -t, the history of all refs is scanned for Merge <name> into
8other/Merge <other> into <name> (respectively) commit subjects, which
9is rather slow but allows you to resurrect other people's topic
10branches."
11
12OPTIONS_KEEPDASHDASH=
13OPTIONS_STUCKLONG=
14OPTIONS_SPEC="\
15git resurrect $USAGE
16--
17b,branch=            save branch as <newname> instead of <name>
18a,all                same as -l -r -m -t
19k,keep-going         full rev-list scan (instead of first match)
20l,reflog             scan reflog for checkouts (enabled by default)
21r,reflog-merges      scan for merges recorded in reflog
22m,merges             scan for merges into other branches (slow)
23t,merge-targets      scan for merges of other branches into <name>
24n,dry-run            don't recreate the branch"
25
26. git-sh-setup
27
28search_reflog () {
29	sed -ne 's~^\([^ ]*\) .*	checkout: moving from '"$1"' .*~\1~p' \
30		< "$GIT_DIR"/logs/HEAD
31}
32
33search_reflog_merges () {
34	git rev-parse $(
35		sed -ne 's~^[^ ]* \([^ ]*\) .*	merge '"$1"':.*~\1^2~p' \
36			< "$GIT_DIR"/logs/HEAD
37	)
38}
39
40oid_pattern=$(git hash-object --stdin </dev/null | sed -e 's/./[0-9a-f]/g')
41
42search_merges () {
43	git rev-list --all --grep="Merge branch '$1'" \
44		--pretty=tformat:"%P %s" |
45	sed -ne "/^$oid_pattern \($oid_pattern\) Merge .*/ {s//\1/p;$early_exit}"
46}
47
48search_merge_targets () {
49	git rev-list --all --grep="Merge branch '[^']*' into $branch\$" \
50		--pretty=tformat:"%H %s" --all |
51	sed -ne "/^\($oid_pattern\) Merge .*/ {s//\1/p;$early_exit} "
52}
53
54dry_run=
55early_exit=q
56scan_reflog=t
57scan_reflog_merges=
58scan_merges=
59scan_merge_targets=
60new_name=
61
62while test "$#" != 0; do
63	case "$1" in
64	    -b|--branch)
65		shift
66		new_name="$1"
67		;;
68	    -n|--dry-run)
69		dry_run=t
70		;;
71	    --no-dry-run)
72		dry_run=
73		;;
74	    -k|--keep-going)
75		early_exit=
76		;;
77	    --no-keep-going)
78		early_exit=q
79		;;
80	    -m|--merges)
81		scan_merges=t
82		;;
83	    --no-merges)
84		scan_merges=
85		;;
86	    -l|--reflog)
87		scan_reflog=t
88		;;
89	    --no-reflog)
90		scan_reflog=
91		;;
92	    -r|--reflog_merges)
93		scan_reflog_merges=t
94		;;
95	    --no-reflog_merges)
96		scan_reflog_merges=
97		;;
98	    -t|--merge-targets)
99		scan_merge_targets=t
100		;;
101	    --no-merge-targets)
102		scan_merge_targets=
103		;;
104	    -a|--all)
105		scan_reflog=t
106		scan_reflog_merges=t
107		scan_merges=t
108		scan_merge_targets=t
109		;;
110	    --)
111		shift
112		break
113		;;
114	    *)
115		usage
116		;;
117	esac
118	shift
119done
120
121test "$#" = 1 || usage
122
123all_strategies="$scan_reflog$scan_reflog_merges$scan_merges$scan_merge_targets"
124if test -z "$all_strategies"; then
125	die "must enable at least one of -lrmt"
126fi
127
128branch="$1"
129test -z "$new_name" && new_name="$branch"
130
131if test ! -z "$scan_reflog"; then
132	if test -r "$GIT_DIR"/logs/HEAD; then
133		candidates="$(search_reflog $branch)"
134	else
135		die 'reflog scanning requested, but' \
136			'$GIT_DIR/logs/HEAD not readable'
137	fi
138fi
139if test ! -z "$scan_reflog_merges"; then
140	if test -r "$GIT_DIR"/logs/HEAD; then
141		candidates="$candidates $(search_reflog_merges $branch)"
142	else
143		die 'reflog scanning requested, but' \
144			'$GIT_DIR/logs/HEAD not readable'
145	fi
146fi
147if test ! -z "$scan_merges"; then
148	candidates="$candidates $(search_merges $branch)"
149fi
150if test ! -z "$scan_merge_targets"; then
151	candidates="$candidates $(search_merge_targets $branch)"
152fi
153
154candidates="$(git rev-parse $candidates | sort -u)"
155
156if test -z "$candidates"; then
157	hint=
158	test "z$all_strategies" != "ztttt" \
159		&& hint=" (maybe try again with -a)"
160	die "no candidates for $branch found$hint"
161fi
162
163echo "** Candidates for $branch **"
164for cmt in $candidates; do
165	git --no-pager log --pretty=tformat:"%ct:%h [%cr] %s" --abbrev-commit -1 $cmt
166done \
167| sort -n | cut -d: -f2-
168
169newest="$(git rev-list -1 $candidates)"
170if test ! -z "$dry_run"; then
171	printf "** Most recent: "
172	git --no-pager log -1 --pretty=tformat:"%h %s" $newest
173elif ! git rev-parse --verify --quiet $new_name >/dev/null; then
174	printf "** Restoring $new_name to "
175	git --no-pager log -1 --pretty=tformat:"%h %s" $newest
176	git branch $new_name $newest
177else
178	printf "Most recent: "
179	git --no-pager log -1 --pretty=tformat:"%h %s" $newest
180	echo "** $new_name already exists, doing nothing"
181fi
182