// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package mypackagebeingfuzzed

import (
	"io/fs"
	"io/ioutil"
	"os"
	"path/filepath"
	"runtime/pprof"
	"testing"
)

func TestFuzzCorpus(t *testing.T) {
	dir := os.Getenv("FUZZ_CORPUS_DIR")
	if dir == "" {
		t.Logf("No fuzzing corpus directory set")
		return
	}
	filename := ""
	defer func() {
		if r := recover(); r != nil {
			t.Error("Fuzz panicked in "+filename, r)
		}
	}()
	profname := os.Getenv("FUZZ_PROFILE_NAME")
	if profname != "" {
		f, err := os.Create(profname + ".cpu.prof")
		if err != nil {
			t.Logf("error creating profile file %s\n", err)
		} else {
			_ = pprof.StartCPUProfile(f)
		}
	}
	_, err := ioutil.ReadDir(dir)
	if err != nil {
		t.Logf("Not fuzzing corpus directory %s", err)
		return
	}
	// recurse for regressions subdirectory
	err = filepath.Walk(dir, func(fname string, info fs.FileInfo, err error) error {
		if info.IsDir() {
			return nil
		}
		data, err := ioutil.ReadFile(fname)
		if err != nil {
			t.Error("Failed to read corpus file", err)
			return err
		}
		filename = fname
		FuzzFunction(data)
		return nil
	})
	if err != nil {
		t.Error("Failed to run corpus", err)
	}
	if profname != "" {
		pprof.StopCPUProfile()
		f, err := os.Create(profname + ".heap.prof")
		if err != nil {
			t.Logf("error creating heap profile file %s\n", err)
		}
		if err = pprof.WriteHeapProfile(f); err != nil {
			t.Logf("error writing heap profile file %s\n", err)
		}
		f.Close()
	}
}