// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: BUSL-1.1

//go:build !windows
// +build !windows

package allocdir

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"testing"

	"github.com/hashicorp/nomad/ci"
	"github.com/shoenig/test/must"
	"golang.org/x/sys/unix"
)

var notFoundErr = fmt.Errorf("not found")

func isMount(path string) (int, error) {
	file, err := os.Open("/proc/self/mounts")
	if err != nil {
		return 0, err
	}
	defer file.Close()
	reader := bufio.NewReaderSize(file, 64*1024)
	const max = 100000
	for i := 0; i < max; i++ {
		line, err := reader.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				return 0, notFoundErr
			}
			return 0, err
		}
		parts := strings.SplitN(line, " ", 3)
		if len(parts) != 3 {
			return 0, fmt.Errorf("unexpected line: %q", line)
		}
		if parts[1] == path {
			// Found it! Make sure it's a tmpfs
			if parts[0] != "tmpfs" {
				return 0, fmt.Errorf("unexpected fs: %q", parts[1])
			}
			sizeMatch := regexp.MustCompile(`size=(\d+)k`).FindStringSubmatch(parts[2])
			if len(sizeMatch) == 0 {
				return 0, fmt.Errorf("mount entry did not include size: %q", parts[2])
			}
			size, err := strconv.ParseInt(sizeMatch[1], 10, 64)
			if err != nil {
				return 0, fmt.Errorf("could not parse %q as int: %w", sizeMatch[0], err)
			}
			return int(size) / 1024, nil
		}
	}
	return 0, fmt.Errorf("exceeded max mount entries (%d)", max)
}

// TestLinuxRootSecretDir asserts secret dir creation and removal are
// idempotent.
func TestLinuxRootSecretDir(t *testing.T) {
	ci.Parallel(t)
	if unix.Geteuid() != 0 {
		t.Skip("Must be run as root")
	}

	secretsDir := filepath.Join(t.TempDir(), TaskSecrets)

	// removing a nonexistent secrets dir should NOT error
	if err := removeSecretDir(secretsDir); err != nil {
		t.Fatalf("error removing nonexistent secrets dir %q: %v", secretsDir, err)
	}
	// run twice as it should be idempotent
	if err := removeSecretDir(secretsDir); err != nil {
		t.Fatalf("error removing nonexistent secrets dir %q: %v", secretsDir, err)
	}

	// creating a secrets dir should work
	taskSecretsSize := 2
	if err := createSecretDir(secretsDir, taskSecretsSize); err != nil {
		t.Fatalf("error creating secrets dir %q: %v", secretsDir, err)
	}
	// creating it again should be a noop (NO error)
	if err := createSecretDir(secretsDir, taskSecretsSize); err != nil {
		t.Fatalf("error creating secrets dir %q: %v", secretsDir, err)
	}

	// ensure it exists and is a directory
	fi, err := os.Lstat(secretsDir)
	if err != nil {
		t.Fatalf("error stat'ing secrets dir %q: %v", secretsDir, err)
	}
	if !fi.IsDir() {
		t.Fatalf("secrets dir %q is not a directory and should be", secretsDir)
	}
	size, err := isMount(secretsDir)
	must.NoError(t, err, must.Sprintf("secrets dir %q is not a mount: %v", secretsDir, err))
	must.Eq(t, taskSecretsSize, size)

	// now remove it
	if err := removeSecretDir(secretsDir); err != nil {
		t.Fatalf("error removing secrets dir %q: %v", secretsDir, err)
	}

	// make sure it's gone
	if _, err := isMount(secretsDir); err != notFoundErr {
		t.Fatalf("error ensuring secrets dir %q isn't mounted: %v", secretsDir, err)
	}

	// removing again should be a noop
	if err := removeSecretDir(secretsDir); err != nil {
		t.Fatalf("error removing nonexistent secrets dir %q: %v", secretsDir, err)
	}
}

// TestLinuxUnprivilegedSecretDir asserts secret dir creation and removal are
// idempotent.
func TestLinuxUnprivilegedSecretDir(t *testing.T) {
	ci.Parallel(t)
	if unix.Geteuid() == 0 {
		t.Skip("Must not be run as root")
	}

	secretsDir := filepath.Join(t.TempDir(), TaskSecrets)

	// removing a nonexistent secrets dir should NOT error
	if err := removeSecretDir(secretsDir); err != nil {
		t.Fatalf("error removing nonexistent secrets dir %q: %v", secretsDir, err)
	}
	// run twice as it should be idempotent
	if err := removeSecretDir(secretsDir); err != nil {
		t.Fatalf("error removing nonexistent secrets dir %q: %v", secretsDir, err)
	}

	// creating a secrets dir should work
	if err := createSecretDir(secretsDir, defaultSecretDirTmpfsSize); err != nil {
		t.Fatalf("error creating secrets dir %q: %v", secretsDir, err)
	}
	// creating it again should be a noop (NO error)
	if err := createSecretDir(secretsDir, defaultSecretDirTmpfsSize); err != nil {
		t.Fatalf("error creating secrets dir %q: %v", secretsDir, err)
	}

	// ensure it exists and is a directory
	fi, err := os.Lstat(secretsDir)
	if err != nil {
		t.Fatalf("error stat'ing secrets dir %q: %v", secretsDir, err)
	}
	if !fi.IsDir() {
		t.Fatalf("secrets dir %q is not a directory and should be", secretsDir)
	}
	if _, err := isMount(secretsDir); err != notFoundErr {
		t.Fatalf("error ensuring secrets dir %q isn't mounted: %v", secretsDir, err)
	}

	// now remove it
	if err := removeSecretDir(secretsDir); err != nil {
		t.Fatalf("error removing secrets dir %q: %v", secretsDir, err)
	}

	// make sure it's gone
	if _, err := os.Lstat(secretsDir); err == nil {
		t.Fatalf("expected secrets dir %q to be gone but it was found", secretsDir)
	}

	// removing again should be a noop
	if err := removeSecretDir(secretsDir); err != nil {
		t.Fatalf("error removing nonexistent secrets dir %q: %v", secretsDir, err)
	}
}