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
40_x40="[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]"
41_x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
42
43search_merges () {
44        git rev-list --all --grep="Merge branch '$1'" \
45                --pretty=tformat:"%P %s" |
46        sed -ne "/^$_x40 \($_x40\) Merge .*/ {s//\1/p;$early_exit}"
47}
48
49search_merge_targets () {
50	git rev-list --all --grep="Merge branch '[^']*' into $branch\$" \
51		--pretty=tformat:"%H %s" --all |
52	sed -ne "/^\($_x40\) Merge .*/ {s//\1/p;$early_exit} "
53}
54
55dry_run=
56early_exit=q
57scan_reflog=t
58scan_reflog_merges=
59scan_merges=
60scan_merge_targets=
61new_name=
62
63while test "$#" != 0; do
64	case "$1" in
65	    -b|--branch)
66		shift
67		new_name="$1"
68		;;
69	    -n|--dry-run)
70		dry_run=t
71		;;
72	    --no-dry-run)
73		dry_run=
74		;;
75	    -k|--keep-going)
76		early_exit=
77		;;
78	    --no-keep-going)
79		early_exit=q
80		;;
81	    -m|--merges)
82		scan_merges=t
83		;;
84	    --no-merges)
85		scan_merges=
86		;;
87	    -l|--reflog)
88		scan_reflog=t
89		;;
90	    --no-reflog)
91		scan_reflog=
92		;;
93	    -r|--reflog_merges)
94		scan_reflog_merges=t
95		;;
96	    --no-reflog_merges)
97		scan_reflog_merges=
98		;;
99	    -t|--merge-targets)
100		scan_merge_targets=t
101		;;
102	    --no-merge-targets)
103		scan_merge_targets=
104		;;
105	    -a|--all)
106		scan_reflog=t
107		scan_reflog_merges=t
108		scan_merges=t
109		scan_merge_targets=t
110		;;
111	    --)
112		shift
113		break
114		;;
115	    *)
116		usage
117		;;
118	esac
119	shift
120done
121
122test "$#" = 1 || usage
123
124all_strategies="$scan_reflog$scan_reflog_merges$scan_merges$scan_merge_targets"
125if test -z "$all_strategies"; then
126	die "must enable at least one of -lrmt"
127fi
128
129branch="$1"
130test -z "$new_name" && new_name="$branch"
131
132if test ! -z "$scan_reflog"; then
133	if test -r "$GIT_DIR"/logs/HEAD; then
134		candidates="$(search_reflog $branch)"
135	else
136		die 'reflog scanning requested, but' \
137			'$GIT_DIR/logs/HEAD not readable'
138	fi
139fi
140if test ! -z "$scan_reflog_merges"; then
141	if test -r "$GIT_DIR"/logs/HEAD; then
142		candidates="$candidates $(search_reflog_merges $branch)"
143	else
144		die 'reflog scanning requested, but' \
145			'$GIT_DIR/logs/HEAD not readable'
146	fi
147fi
148if test ! -z "$scan_merges"; then
149	candidates="$candidates $(search_merges $branch)"
150fi
151if test ! -z "$scan_merge_targets"; then
152	candidates="$candidates $(search_merge_targets $branch)"
153fi
154
155candidates="$(git rev-parse $candidates | sort -u)"
156
157if test -z "$candidates"; then
158	hint=
159	test "z$all_strategies" != "ztttt" \
160		&& hint=" (maybe try again with -a)"
161	die "no candidates for $branch found$hint"
162fi
163
164echo "** Candidates for $branch **"
165for cmt in $candidates; do
166	git --no-pager log --pretty=tformat:"%ct:%h [%cr] %s" --abbrev-commit -1 $cmt
167done \
168| sort -n | cut -d: -f2-
169
170newest="$(git rev-list -1 $candidates)"
171if test ! -z "$dry_run"; then
172	printf "** Most recent: "
173	git --no-pager log -1 --pretty=tformat:"%h %s" $newest
174elif ! git rev-parse --verify --quiet $new_name >/dev/null; then
175	printf "** Restoring $new_name to "
176	git --no-pager log -1 --pretty=tformat:"%h %s" $newest
177	git branch $new_name $newest
178else
179	printf "Most recent: "
180	git --no-pager log -1 --pretty=tformat:"%h %s" $newest
181	echo "** $new_name already exists, doing nothing"
182fi
183