// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package testenv provides information about what functionality
// is available in different testing environments run by the Go team.
//
// It is an internal package because these details are specific
// to the Go team's test setup (on build.golang.org) and not
// fundamental to tests in general.
package testenv

import (
	"bytes"
	"errors"
	"flag"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"testing"
	"time"
)

const KnownEnv = `
	AR
	CC
	CGO_CFLAGS
	CGO_CFLAGS_ALLOW
	CGO_CFLAGS_DISALLOW
	CGO_CPPFLAGS
	CGO_CPPFLAGS_ALLOW
	CGO_CPPFLAGS_DISALLOW
	CGO_CXXFLAGS
	CGO_CXXFLAGS_ALLOW
	CGO_CXXFLAGS_DISALLOW
	CGO_ENABLED
	CGO_FFLAGS
	CGO_FFLAGS_ALLOW
	CGO_FFLAGS_DISALLOW
	CGO_LDFLAGS
	CGO_LDFLAGS_ALLOW
	CGO_LDFLAGS_DISALLOW
	CXX
	FC
	GCCGO
	GO111MODULE
	GO386
	GOAMD64
	GOARCH
	GOARM
	GOBIN
	GOCACHE
	GOENV
	GOEXE
	GOEXPERIMENT
	GOFLAGS
	GOGCCFLAGS
	GOHOSTARCH
	GOHOSTOS
	GOINSECURE
	GOMIPS
	GOMIPS64
	GOMODCACHE
	GONOPROXY
	GONOSUMDB
	GOOS
	GOPATH
	GOPPC64
	GOPRIVATE
	GOPROXY
	GOROOT
	GOSUMDB
	GOTMPDIR
	GOTOOLDIR
	GOVCS
	GOWASM
	GOWORK
	GO_EXTLINK_ENABLED
	PKG_CONFIG
`

// Builder reports the name of the builder running this test
// (for example, "linux-amd64" or "windows-386-gce").
// If the test is not running on the build infrastructure,
// Builder returns the empty string.
func Builder() string {
	return os.Getenv("GO_BUILDER_NAME")
}

// HasGoBuild reports whether the current system can build programs with ``go build''
// and then run them with os.StartProcess or exec.Command.
func HasGoBuild() bool {
	if os.Getenv("GO_GCFLAGS") != "" {
		// It's too much work to require every caller of the go command
		// to pass along "-gcflags="+os.Getenv("GO_GCFLAGS").
		// For now, if $GO_GCFLAGS is set, report that we simply can't
		// run go build.
		return false
	}
	switch runtime.GOOS {
	case "android", "js", "ios":
		return false
	}
	return true
}

// MustHaveGoBuild checks that the current system can build programs with ``go build''
// and then run them with os.StartProcess or exec.Command.
// If not, MustHaveGoBuild calls t.Skip with an explanation.
func MustHaveGoBuild(t testing.TB) {
	if os.Getenv("GO_GCFLAGS") != "" {
		t.Skipf("skipping test: 'go build' not compatible with setting $GO_GCFLAGS")
	}
	if !HasGoBuild() {
		t.Skipf("skipping test: 'go build' not available on %s/%s", runtime.GOOS, runtime.GOARCH)
	}
}

// HasGoRun reports whether the current system can run programs with ``go run.''
func HasGoRun() bool {
	// For now, having go run and having go build are the same.
	return HasGoBuild()
}

// MustHaveGoRun checks that the current system can run programs with ``go run.''
// If not, MustHaveGoRun calls t.Skip with an explanation.
func MustHaveGoRun(t testing.TB) {
	if !HasGoRun() {
		t.Skipf("skipping test: 'go run' not available on %s/%s", runtime.GOOS, runtime.GOARCH)
	}
}

// GoToolPath reports the path to the Go tool.
// It is a convenience wrapper around GoTool.
// If the tool is unavailable GoToolPath calls t.Skip.
// If the tool should be available and isn't, GoToolPath calls t.Fatal.
func GoToolPath(t testing.TB) string {
	MustHaveGoBuild(t)
	path, err := GoTool()
	if err != nil {
		t.Fatal(err)
	}
	// Add all environment variables that affect the Go command to test metadata.
	// Cached test results will be invalidate when these variables change.
	// See golang.org/issue/32285.
	for _, envVar := range strings.Fields(KnownEnv) {
		os.Getenv(envVar)
	}
	return path
}

// GoTool reports the path to the Go tool.
func GoTool() (string, error) {
	if !HasGoBuild() {
		return "", errors.New("platform cannot run go tool")
	}
	var exeSuffix string
	if runtime.GOOS == "windows" {
		exeSuffix = ".exe"
	}
	path := filepath.Join(runtime.GOROOT(), "bin", "go"+exeSuffix)
	if _, err := os.Stat(path); err == nil {
		return path, nil
	}
	goBin, err := exec.LookPath("go" + exeSuffix)
	if err != nil {
		return "", errors.New("cannot find go tool: " + err.Error())
	}
	return goBin, nil
}

// HasExec reports whether the current system can start new processes
// using os.StartProcess or (more commonly) exec.Command.
func HasExec() bool {
	switch runtime.GOOS {
	case "js", "ios":
		return false
	}
	return true
}

// HasSrc reports whether the entire source tree is available under GOROOT.
func HasSrc() bool {
	switch runtime.GOOS {
	case "ios":
		return false
	}
	return true
}

// MustHaveExec checks that the current system can start new processes
// using os.StartProcess or (more commonly) exec.Command.
// If not, MustHaveExec calls t.Skip with an explanation.
func MustHaveExec(t testing.TB) {
	if !HasExec() {
		t.Skipf("skipping test: cannot exec subprocess on %s/%s", runtime.GOOS, runtime.GOARCH)
	}
}

var execPaths sync.Map // path -> error

// MustHaveExecPath checks that the current system can start the named executable
// using os.StartProcess or (more commonly) exec.Command.
// If not, MustHaveExecPath calls t.Skip with an explanation.
func MustHaveExecPath(t testing.TB, path string) {
	MustHaveExec(t)

	err, found := execPaths.Load(path)
	if !found {
		_, err = exec.LookPath(path)
		err, _ = execPaths.LoadOrStore(path, err)
	}
	if err != nil {
		t.Skipf("skipping test: %s: %s", path, err)
	}
}

// HasExternalNetwork reports whether the current system can use
// external (non-localhost) networks.
func HasExternalNetwork() bool {
	return !testing.Short() && runtime.GOOS != "js"
}

// MustHaveExternalNetwork checks that the current system can use
// external (non-localhost) networks.
// If not, MustHaveExternalNetwork calls t.Skip with an explanation.
func MustHaveExternalNetwork(t testing.TB) {
	if runtime.GOOS == "js" {
		t.Skipf("skipping test: no external network on %s", runtime.GOOS)
	}
	if testing.Short() {
		t.Skipf("skipping test: no external network in -short mode")
	}
}

var haveCGO bool

// HasCGO reports whether the current system can use cgo.
func HasCGO() bool {
	return haveCGO
}

// MustHaveCGO calls t.Skip if cgo is not available.
func MustHaveCGO(t testing.TB) {
	if !haveCGO {
		t.Skipf("skipping test: no cgo")
	}
}

// CanInternalLink reports whether the current system can link programs with
// internal linking.
// (This is the opposite of cmd/internal/sys.MustLinkExternal. Keep them in sync.)
func CanInternalLink() bool {
	switch runtime.GOOS {
	case "android":
		if runtime.GOARCH != "arm64" {
			return false
		}
	case "ios":
		if runtime.GOARCH == "arm64" {
			return false
		}
	}
	return true
}

// MustInternalLink checks that the current system can link programs with internal
// linking.
// If not, MustInternalLink calls t.Skip with an explanation.
func MustInternalLink(t testing.TB) {
	if !CanInternalLink() {
		t.Skipf("skipping test: internal linking on %s/%s is not supported", runtime.GOOS, runtime.GOARCH)
	}
}

// HasSymlink reports whether the current system can use os.Symlink.
func HasSymlink() bool {
	ok, _ := hasSymlink()
	return ok
}

// MustHaveSymlink reports whether the current system can use os.Symlink.
// If not, MustHaveSymlink calls t.Skip with an explanation.
func MustHaveSymlink(t testing.TB) {
	ok, reason := hasSymlink()
	if !ok {
		t.Skipf("skipping test: cannot make symlinks on %s/%s%s", runtime.GOOS, runtime.GOARCH, reason)
	}
}

// HasLink reports whether the current system can use os.Link.
func HasLink() bool {
	// From Android release M (Marshmallow), hard linking files is blocked
	// and an attempt to call link() on a file will return EACCES.
	// - https://code.google.com/p/android-developer-preview/issues/detail?id=3150
	return runtime.GOOS != "plan9" && runtime.GOOS != "android"
}

// MustHaveLink reports whether the current system can use os.Link.
// If not, MustHaveLink calls t.Skip with an explanation.
func MustHaveLink(t testing.TB) {
	if !HasLink() {
		t.Skipf("skipping test: hardlinks are not supported on %s/%s", runtime.GOOS, runtime.GOARCH)
	}
}

var flaky = flag.Bool("flaky", false, "run known-flaky tests too")

func SkipFlaky(t testing.TB, issue int) {
	t.Helper()
	if !*flaky {
		t.Skipf("skipping known flaky test without the -flaky flag; see golang.org/issue/%d", issue)
	}
}

func SkipFlakyNet(t testing.TB) {
	t.Helper()
	if v, _ := strconv.ParseBool(os.Getenv("GO_BUILDER_FLAKY_NET")); v {
		t.Skip("skipping test on builder known to have frequent network failures")
	}
}

// CleanCmdEnv will fill cmd.Env with the environment, excluding certain
// variables that could modify the behavior of the Go tools such as
// GODEBUG and GOTRACEBACK.
func CleanCmdEnv(cmd *exec.Cmd) *exec.Cmd {
	if cmd.Env != nil {
		panic("environment already set")
	}
	for _, env := range os.Environ() {
		// Exclude GODEBUG from the environment to prevent its output
		// from breaking tests that are trying to parse other command output.
		if strings.HasPrefix(env, "GODEBUG=") {
			continue
		}
		// Exclude GOTRACEBACK for the same reason.
		if strings.HasPrefix(env, "GOTRACEBACK=") {
			continue
		}
		cmd.Env = append(cmd.Env, env)
	}
	return cmd
}

// CPUIsSlow reports whether the CPU running the test is suspected to be slow.
func CPUIsSlow() bool {
	switch runtime.GOARCH {
	case "arm", "mips", "mipsle", "mips64", "mips64le":
		return true
	}
	return false
}

// SkipIfShortAndSlow skips t if -short is set and the CPU running the test is
// suspected to be slow.
//
// (This is useful for CPU-intensive tests that otherwise complete quickly.)
func SkipIfShortAndSlow(t testing.TB) {
	if testing.Short() && CPUIsSlow() {
		t.Helper()
		t.Skipf("skipping test in -short mode on %s", runtime.GOARCH)
	}
}

// RunWithTimeout runs cmd and returns its combined output. If the
// subprocess exits with a non-zero status, it will log that status
// and return a non-nil error, but this is not considered fatal.
func RunWithTimeout(t testing.TB, cmd *exec.Cmd) ([]byte, error) {
	args := cmd.Args
	if args == nil {
		args = []string{cmd.Path}
	}

	var b bytes.Buffer
	cmd.Stdout = &b
	cmd.Stderr = &b
	if err := cmd.Start(); err != nil {
		t.Fatalf("starting %s: %v", args, err)
	}

	// If the process doesn't complete within 1 minute,
	// assume it is hanging and kill it to get a stack trace.
	p := cmd.Process
	done := make(chan bool)
	go func() {
		scale := 1
		// This GOARCH/GOOS test is copied from cmd/dist/test.go.
		// TODO(iant): Have cmd/dist update the environment variable.
		if runtime.GOARCH == "arm" || runtime.GOOS == "windows" {
			scale = 2
		}
		if s := os.Getenv("GO_TEST_TIMEOUT_SCALE"); s != "" {
			if sc, err := strconv.Atoi(s); err == nil {
				scale = sc
			}
		}

		select {
		case <-done:
		case <-time.After(time.Duration(scale) * time.Minute):
			p.Signal(Sigquit)
			// If SIGQUIT doesn't do it after a little
			// while, kill the process.
			select {
			case <-done:
			case <-time.After(time.Duration(scale) * 30 * time.Second):
				p.Signal(os.Kill)
			}
		}
	}()

	err := cmd.Wait()
	if err != nil {
		t.Logf("%s exit status: %v", args, err)
	}
	close(done)

	return b.Bytes(), err
}
