// Copyright 2019 The Bazel Authors. All rights reserved.
//
// 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 strip_test

import (
	"bytes"
	"errors"
	"fmt"
	"os/exec"
	"strings"
	"testing"

	"github.com/bazelbuild/rules_go/go/tools/bazel_testing"
)

func TestMain(m *testing.M) {
	bazel_testing.TestMain(m, bazel_testing.Args{
		Main: `
-- BUILD.bazel --
load("@io_bazel_rules_go//go:def.bzl", "go_binary")

go_binary(
    name = "strip",
    srcs = ["strip.go"],
)
-- strip.go --
package main

import (
	"debug/elf"
	"debug/macho"
	"debug/pe"
	"errors"
	"flag"
	"fmt"
	"io"
	"os"
	"regexp"
	"runtime"
	"runtime/debug"
	"strings"
)

var wantStrip = flag.Bool("wantstrip", false, "")

func main() {
	flag.Parse()
	stackTrace, err := panicAndRecover()
	if err != nil {
		panic(err)
	}
	gotStackTrace := strings.Split(stackTrace, "\n")
	if len(gotStackTrace) != len(wantStackTrace) {
		panic(fmt.Sprintf("got %d lines of stack trace, want %d", len(gotStackTrace), len(wantStackTrace)))
	}
	for i := range gotStackTrace {
		expectedLine := regexp.MustCompile(wantStackTrace[i])
		if !expectedLine.MatchString(gotStackTrace[i]) {
			panic(fmt.Sprintf("got unexpected stack trace line %q at index %d", gotStackTrace[i], i))
		}
	}
	stripped, err := isStripped()
	if err != nil {
		panic(err)
	}
	if stripped != *wantStrip {
		panic(fmt.Sprintf("got stripped=%t, want stripped=%t", stripped, *wantStrip))
	}
}

func panicAndRecover() (stackTrace string, err error) {
	defer func() {
		if r := recover(); r != nil {
			stackTrace = string(debug.Stack())
		}
	}()
	panic("test")
	return "", errors.New("should not reach here")
}

func isStripped() (bool, error) {
	ownLocation, err := os.Executable()
	if err != nil {
		return false, err
	}
	ownBinary, err := os.Open(ownLocation)
	if err != nil {
		return false, err
	}
	defer ownBinary.Close()
	switch runtime.GOOS {
	case "darwin":
		return isStrippedMachO(ownBinary)
	case "linux":
		return isStrippedElf(ownBinary)
	case "windows":
		return isStrippedPE(ownBinary)
	default:
		return false, fmt.Errorf("unsupported OS: %s", runtime.GOOS)
	}
}

func isStrippedMachO(f io.ReaderAt) (bool, error) {
	macho, err := macho.NewFile(f)
	if err != nil {
		return false, err
	}
	gotDwarf := macho.Segment("__DWARF") != nil
	gotDebugInfo := macho.Section("__zdebug_info") != nil
	if gotDwarf != gotDebugInfo {
		return false, fmt.Errorf("inconsistent stripping: gotDwarf=%v, gotDebugInfo=%v", gotDwarf, gotDebugInfo)
	}
	return !gotDwarf, nil
}

func isStrippedElf(f io.ReaderAt) (bool, error) {
	elf, err := elf.NewFile(f)
	if err != nil {
		return false, err
	}
	var gotSymtab bool
	for _, section := range elf.Sections {
		if section.Name == ".symtab" {
			gotSymtab = true
			break
		}
	}
	return !gotSymtab, nil
}


func isStrippedPE(f io.ReaderAt) (bool, error) {
	pe, err := pe.NewFile(f)
	if err != nil {
		return false, err
	}
	symtab := pe.Section(".symtab")
	if symtab == nil {
		return false, fmt.Errorf("no .symtab section")
	}
	emptySymtab := (symtab.VirtualSize <= 4) && (symtab.Size <= 512)
	return emptySymtab, nil
}


` + embedWantedStackTraces(),
	})
}

func Test(t *testing.T) {
	for _, test := range []struct {
		desc, stripFlag, compilationMode string
		wantStrip                        bool
	}{
		{
			desc:      "run_auto",
			wantStrip: true,
		},
		{
			desc:            "run_fastbuild",
			compilationMode: "fastbuild",
			wantStrip:       true,
		},
		{
			desc:            "run_dbg",
			compilationMode: "dbg",
		},
		{
			desc:            "run_opt",
			compilationMode: "opt",
		},
		{
			desc:      "run_always",
			stripFlag: "always",
			wantStrip: true,
		},
		{
			desc:            "run_always_opt",
			stripFlag:       "always",
			compilationMode: "opt",
			wantStrip:       true,
		},
		{
			desc:      "run_never",
			stripFlag: "never",
		},
		{
			desc:            "run_sometimes_fastbuild",
			stripFlag:       "sometimes",
			compilationMode: "fastbuild",
			wantStrip:       true,
		},
		{
			desc:            "run_sometimes_dbg",
			stripFlag:       "sometimes",
			compilationMode: "dbg",
		},
		{
			desc:            "run_sometimes_opt",
			stripFlag:       "sometimes",
			compilationMode: "opt",
		},
	} {
		t.Run(test.desc, func(t *testing.T) {
			args := []string{"run"}
			if len(test.stripFlag) > 0 {
				args = append(args, "--strip", test.stripFlag)
			}
			if len(test.compilationMode) > 0 {
				args = append(args, "--compilation_mode", test.compilationMode)
			}
			args = append(args, "//:strip", "--", fmt.Sprintf("-wantstrip=%v", test.wantStrip))
			cmd := bazel_testing.BazelCmd(args...)
			stderr := &bytes.Buffer{}
			cmd.Stderr = stderr
			t.Logf("running: bazel %s", strings.Join(args, " "))
			if err := cmd.Run(); err != nil {
				var xerr *exec.ExitError
				if !errors.As(err, &xerr) {
					t.Fatalf("unexpected error: %v", err)
				}
				if xerr.ExitCode() == bazel_testing.BUILD_FAILURE {
					t.Fatalf("unexpected build failure: %v\nstderr:\n%s", err, stderr.Bytes())
					return
				} else if xerr.ExitCode() == bazel_testing.TESTS_FAILED {
					t.Fatalf("error running %s:\n%s", strings.Join(cmd.Args, " "), stderr.Bytes())
				} else {
					t.Fatalf("unexpected error: %v\nstderr:\n%s", err, stderr.Bytes())
				}
			}
		})
	}
}

var wantStackTrace = []string{
	`^goroutine \d+ \[running\]:$`,
	`^runtime/debug\.Stack\(\)$`,
	`^	GOROOT/src/runtime/debug/stack\.go:\d+ \+0x[0-9a-f]+$`,
	`^main\.panicAndRecover\.func1\(\)$`,
	`^	strip\.go:\d+ \+0x[0-9a-f]+$`,
	`^panic\({0x[0-9a-f]+, 0x[0-9a-f]+}\)$`,
	`^	GOROOT/src/runtime/panic\.go:\d+ \+0x[0-9a-f]+$`,
	`^main\.panicAndRecover\(\)$`,
	`^	strip\.go:\d+ \+0x[0-9a-f]+$`,
	`^main\.main\(\)$`,
	`^	strip\.go:\d+ \+0x[0-9a-f]+$`,
	`^$`,
}

func embedWantedStackTraces() string {
	buf := &bytes.Buffer{}
	fmt.Fprintln(buf, "var wantStackTrace = []string{")
	for _, s := range wantStackTrace {
		fmt.Fprintf(buf, "`%s`,\n", s)
	}
	fmt.Fprintln(buf, "}")
	return buf.String()
}