# Shared groundwork for the t05xx scripts, sourced after setup.sh from inside
# the trash directory. It locates the shipped extensions and the unit checks
# beside this file, lists the standalone Lua interpreters the checks can run
# under, and offers a probe that asks the Lua inside the cgit binary itself
# whether a module is available to it, since that interpreter can differ from
# every standalone one on the path. LUA_PATH, LUA_CPATH and their versioned
# forms come through from the environment on purpose, as they are how a
# system points Lua at its modules, so the probes find what the system has.
# A fallback that needs a module gone runs through without_lua_modules.

EXTENSIONS_DIRECTORY=$(cd "$TEST_OUTPUT_DIRECTORY/../custom/extensions" && pwd)
EXT_TEST_DIRECTORY=$(cd "$TEST_OUTPUT_DIRECTORY/extensions" && pwd)

# Prints the version an interpreter reports, LuaJIT by its own name rather
# than the 5.1 it is compatible with, or the name it was given when it does
# not run.
lua_version() {
	"$1" -e 'io.write(jit and jit.version or _VERSION)' 2>/dev/null ||
		printf '%s' "$1"
}

# The interpreters on the path whose version the extensions claim, 5.1 to
# 5.5 with LuaJIT counting as 5.1, so no script is failed on a version it
# never claimed to run on. Systems spell a versioned name in one of three
# ways, and a plain lua is usually one of those again, so each version runs
# once, under the first name found for it.
interpreters=
ext_lua_versions=
for ext_lua_bin in luajit lua5.1 lua51 lua-5.1 lua5.2 lua52 lua-5.2 \
	lua5.3 lua53 lua-5.3 lua5.4 lua54 lua-5.4 lua5.5 lua55 lua-5.5 lua
do
	command -v "$ext_lua_bin" >/dev/null 2>&1 || continue
	ext_lua_version=$(lua_version "$ext_lua_bin")
	case "$ext_lua_version" in
	"Lua 5."[1-5]|"LuaJIT 2."*)
		;;
	*)
		continue
		;;
	esac
	case "$ext_lua_versions" in
	*"|$ext_lua_version|"*)
		continue
		;;
	esac
	ext_lua_versions="$ext_lua_versions|$ext_lua_version|"
	interpreters="$interpreters $ext_lua_bin"
done

# A script registers its unit checks for each of ${interpreters:-lua} under
# the STANDALONE_LUA prerequisite, so with none found they still show in
# the count, as skipped, rather than vanishing from it.
test -z "$interpreters" || test_set_prereq STANDALONE_LUA

# Leaves in lua_prereq the name of a prerequisite that holds when the
# interpreter given first can load every module named after it, so a check
# needing a module shows as skipped under an interpreter that lacks it.
lua_module_prereq() {
	lua_prereq=$(printf '%s' "$*" | tr -c 'A-Za-z0-9' '_' | tr 'a-z' 'A-Z')
	lua_prereq_bin=$1
	shift
	lua_prereq_code=
	for lua_prereq_module
	do
		lua_prereq_code="$lua_prereq_code require('$lua_prereq_module')"
	done
	if "$lua_prereq_bin" -e "$lua_prereq_code" >/dev/null 2>&1
	then
		test_set_prereq "$lua_prereq"
	fi
}

# Runs the command given with every Lua search path pointed at an empty
# directory, so no Lua it starts, cgit's own included, finds a module that
# is not built in. A fallback for a missing module then runs on any machine.
without_lua_modules() {
	mkdir -p "$TRASH_DIRECTORY/no-lua-modules" &&
	(
		for lua_variable in LUA_PATH LUA_PATH_5_2 LUA_PATH_5_3 \
			LUA_PATH_5_4 LUA_PATH_5_5
		do
			eval "$lua_variable=\$TRASH_DIRECTORY/no-lua-modules/?.lua"
			export $lua_variable
		done
		for lua_variable in LUA_CPATH LUA_CPATH_5_2 LUA_CPATH_5_3 \
			LUA_CPATH_5_4 LUA_CPATH_5_5
		do
			eval "$lua_variable=\$TRASH_DIRECTORY/no-lua-modules/?.so"
			export $lua_variable
		done
		"$@"
	)
}

# Asks whether cgit's own Lua can require every module named, by pointing a
# throwaway commit-filter at the given repository and reading its answer off
# the rendered commit page. Filters need a page to run on, which is why a
# repository has to be handed in. A probe that crashes or answers neither
# way stops the run, since reading it as a missing module would switch the
# tests to the wrong expectations.
cgit_lua_probe() {
	test "$CGIT_HAS_LUA" -eq 1 || return 1
	cgit_lua_probe_gitdir=$1
	shift
	{
		echo "function filter_open(...) end"
		echo "function filter_write(str) end"
		echo "function filter_close()"
		echo "local ok = true"
		for cgit_lua_probe_module in "$@"
		do
			echo "if not pcall(require, '$cgit_lua_probe_module') then"
			echo "ok = false"
			echo "end"
		done
		echo "if ok then html('LUA_PROBE_YES') else html('LUA_PROBE_NO') end"
		echo "return 0"
		echo "end"
	} >lua-probe.lua
	cat >lua-probe-cgitrc <<EOF
virtual-root=/
cache-size=0
repo.url=lua-probe
repo.path=$cgit_lua_probe_gitdir
repo.commit-filter=lua:$PWD/lua-probe.lua
EOF
	CGIT_CONFIG="$PWD/lua-probe-cgitrc" QUERY_STRING="url=lua-probe/commit/" \
		cgit >lua-probe.out 2>lua-probe.err ||
		BAIL_OUT "cgit failed while probing its Lua for $*"
	if grep LUA_PROBE_YES lua-probe.out >/dev/null
	then
		return 0
	elif grep LUA_PROBE_NO lua-probe.out >/dev/null
	then
		return 1
	fi
	BAIL_OUT "probing cgit's Lua for $* gave no answer"
}