#!/bin/bash

POLYGLOT=1--[===[

set -o pipefail

if [[ "$#" == "0" ]]; then

	echo "Lua mutation testing tool"

	echo

	echo "Usage:"

	echo "    $BASH_SOURCE MODULE_NAME SPEC_FILE"

	echo

	echo "Requires 'lua', 'ltokenp' and 'busted' in PATH"

	exit 1;

fi

MOD_NAME="$1"

MOD_FILE="$(lua "$BASH_SOURCE" resolve "$MOD_NAME")"

if [[ "$MOD_FILE" == "" || ! -f "$MOD_FILE" ]]; then

	echo "EE: Failed to locate module '$MOD_NAME' ($MOD_FILE)";

	exit 1;

fi

SPEC_FILE="$2"

if [[ "$SPEC_FILE" == "" ]]; then

	SPEC_FILE="spec/${MOD_NAME/./_}_spec.lua"

fi

if [[ "$SPEC_FILE" == "" || ! -f "$SPEC_FILE" ]]; then

	echo "EE: Failed to find test spec file ($SPEC_FILE)"

	exit 1;

fi

if ! busted --helper=loader "$SPEC_FILE"; then

	echo "EE: Tests fail on original source. Fix it"\!;

	exit 1;

fi

export MUTANT_N=0

LIVING_MUTANTS=0

FILE_PREFIX="${MOD_FILE%.*}.mutant-"

FILE_SUFFIX=".${MOD_FILE##*.}"

gen_mutant () {

	echo "Generating mutant $2 to $3..."

	ltokenp -s "$BASH_SOURCE" "$1" > "$3"

	return "$?"

}

# $1 = MOD_NAME, $2 = MUTANT_N, $3 = SPEC_FILE

test_mutant () {

	(

		ulimit -m 131072 # 128MB

		ulimit -t 16     # 16s

		ulimit -f 32768  # 128MB (?)

		exec busted --helper="$BASH_SOURCE" -Xhelper mutate="$1":"$2" "$3"

	) >/dev/null

	return "$?";

}

MUTANT_FILE="${FILE_PREFIX}${MUTANT_N}${FILE_SUFFIX}"

gen_mutant "$MOD_FILE" "$MUTANT_N" "$MUTANT_FILE"

while [[ "$?" == "0" ]]; do

	if ! test_mutant "$MOD_NAME" "$MUTANT_N" "$SPEC_FILE"; then

		echo "Tests successfully killed mutant $MUTANT_N";

		rm "$MUTANT_FILE";

	else

		echo "Mutant $MUTANT_N lives on"\!

		LIVING_MUTANTS=$((LIVING_MUTANTS+1))

	fi

	MUTANT_N=$((MUTANT_N+1))

	MUTANT_FILE="${FILE_PREFIX}${MUTANT_N}${FILE_SUFFIX}"

	gen_mutant "$MOD_FILE" "$MUTANT_N" "$MUTANT_FILE"

done

if [[ "$?" != "2" ]]; then

	echo "Failed: $?"

	exit "$?";

fi

MUTANT_SCORE="$(lua -e "print(('%0.2f'):format((1-($LIVING_MUTANTS/$MUTANT_N))*100))")"

if test -f mutant-scores.txt; then

	echo "$MOD_NAME $MUTANT_SCORE" >> mutant-scores.txt

fi

echo "$MOD_NAME: All $MUTANT_N mutants generated, $LIVING_MUTANTS survived (score: $MUTANT_SCORE%)"

rm "$MUTANT_FILE"; # Last file is always unmodified

exit 0;

]===]

-- busted helper that runs mutations

if arg then

	if arg[1] == "resolve" then

		local filename = package.searchpath(assert(arg[2], "no module name given"), package.path);

		if filename then

			print(filename);

		end

		os.exit(filename and 0 or 1);

	end

	local mutants = {};

	for i = 1, #arg do

		local opt = arg[i];

		print("LOAD", i, opt)

		local module_name, mutant_n = opt:match("^mutate=([^:]+):(%d+)");

		if module_name then

			mutants[module_name] = tonumber(mutant_n);

		end

	end

	local orig_lua_searcher = package.searchers[2];

	local function mutant_searcher(module_name)

		local mutant_n = mutants[module_name];

		if not mutant_n then

			return orig_lua_searcher(module_name);

		end

		local base_file, err = package.searchpath(module_name, package.path);

		if not base_file then

			return base_file, err;

		end

		local mutant_file = base_file:gsub("%.lua$", (".mutant-%d.lua"):format(mutant_n));

		return loadfile(mutant_file), mutant_file;

	end

	if next(mutants) then

		table.insert(package.searchers, 1, mutant_searcher);

	end

end

-- filter for ltokenp to mutate scripts

do

	local last_output = {};

	local function emit(...)

		last_output = {...};

		io.write(...)

		io.write(" ")

		return true;

	end

	local did_mutate = false;

	local count = -1;

	local threshold = tonumber(os.getenv("MUTANT_N")) or 0;

	local function should_mutate()

		count = count + 1;

		return count == threshold;

	end

	local function mutate(name, value)

		if name == "if" then

			-- Bypass conditionals

			if should_mutate() then

				return emit("if true or");

			elseif should_mutate() then

				return emit("if false and");

			end

		elseif name == "<integer>" then

			-- Introduce off-by-one errors

			if should_mutate() then

				return emit(("%d"):format(tonumber(value)+1));

			elseif should_mutate() then

				return emit(("%d"):format(tonumber(value)-1));

			end

		elseif name == "and" then

			if should_mutate() then

				return emit("or");

			end

		elseif name == "or" then

			if should_mutate() then

				return emit("and");

			end

		end

	end

	local current_line_n, current_line_input, current_line_output = 0, {}, {};

	function FILTER(line_n,token,name,value)

		if current_line_n ~= line_n then -- Finished a line, moving to the next?

			if did_mutate and did_mutate.line == current_line_n then

				-- The line we finished was mutated. Store the original and modified outputs.

				did_mutate.line_original_src = table.concat(current_line_input, " ");

				did_mutate.line_modified_src = table.concat(current_line_output, " ");

			end

			current_line_input = {};

			current_line_output = {};

		end

		current_line_n = line_n;

		if name == "<file>" then return; end

		if name == "<eof>" then

			if not did_mutate then

				return os.exit(2);

			else

				emit(("\n-- Mutated line %d (changed '%s' to '%s'):\n"):format(did_mutate.line, did_mutate.original, did_mutate.modified))

				emit(  ("--   Original: %s\n"):format(did_mutate.line_original_src))

				emit(  ("--   Modified: %s\n"):format(did_mutate.line_modified_src));

				return;

			end

		end

		if name == "<string>" then

			value = string.format("%q",value);

		end

		if mutate(name, value) then

			did_mutate = {

				original = value;

				modified = table.concat(last_output);

				line = line_n;

			};

		else

			emit(value);

		end

		table.insert(current_line_input, value);

		table.insert(current_line_output, table.concat(last_output));

	end

end