tig: add subcommand to browse an umpf and its context interactively

The 'tig' subcommand makes it possible to browse an umpf interactively
in tig(1) while showing the local and remote state of all topic
branches. This can give a broader overview how the topic branches have
developed before building another umpf.

For simplicity sake, also limit the range of the topics to the history
leading up from the umpf-base.

Signed-off-by: Roland Hieber <rhi@pengutronix.de>

bash_completion

@@ -38,7 +38,7 @@ _umpf_completion()
 	"")
 		COMPREPLY=( $( compgen -W "${completion_cmds[*]} help" -- $cur ) )
 		;;
-	diff|show|tag|build)
+	diff|show|tag|tig|build)
 		local -a refs
 		refs=( $( compgen -W "$( git for-each-ref --format='%(refname:short)' refs/tags refs/heads refs/remotes)" -- $cur ) )
 		if [ ${#refs[@]} -eq 0 ]; then

umpf

@@ -199,6 +199,8 @@ usage() {
 	  diff <commit-ish>          show patches not in any topic branch (not
 	                             upstream) and patches missing locally
 	  show <commit-ish>          show an useries file from an umpf
+	  tig [umpf]                 browse an umpf interactively, showing state of
+	                             local, remote and remote-tracking topic branches
 
 	  tag <commit-ish>           generate a utag from an umerge
 	  format-patch <utag>        generate a useries file and patch stack
@@ -1862,6 +1864,56 @@ do_show() {
 	cleanup
 }
 
+### namespace: tig ###
+
+tig_topic() {
+	local reply
+	find_branch_rev "${content}"
+	if [ -n "${reply}" ]; then
+		echo "${reply}" >> "${STATE}/refs"
+	fi
+
+	# possibly-existing local topic branch
+	if ${GIT} rev-parse --verify -q "${content}" >/dev/null 2>&1; then
+		echo "${content}" >> "${STATE}/refs"
+	fi
+
+	# possibly-existing remote-tracking topic branch
+	# (might be different from the remote chosen above)
+	if ${GIT} rev-parse --verify -q "${content}@{u}" >/dev/null 2>&1; then
+		echo "${content}@{u}" >> "${STATE}/refs"
+	fi
+}
+
+tig_release() {
+	echo "${content}" >> "${STATE}/refs"
+}
+
+tig_hashinfo() {
+	echo "${content}" >> "${STATE}/refs"
+}
+
+### command: tig ###
+
+do_tig () {
+	local refs base ranges
+
+	prepare_persistent tig "${@}"
+	parse_series tig "${STATE}/series"
+
+	mapfile -t refs < "${STATE}/refs"
+	base="$(<"${STATE}/base-name")"
+	ranges=
+
+	# cut off each ref at base
+	for ref in "${refs[@]}"; do
+		ranges="${ranges} ${base}^..${ref}"
+	done
+
+	tig ${ranges}
+	cleanup
+}
+
 ### command: init ###
 
 do_init() {