// Copyright The Monogon Project Authors.
// SPDX-License-Identifier: Apache-2.0

// This package runs the installer image in a VM provided with an empty block
// device. It then examines the installer console output and the blok device to
// determine whether the installation process completed without issue.
package installer

import (
	"bytes"
	"context"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"syscall"
	"testing"
	"time"

	"github.com/bazelbuild/rules_go/go/runfiles"
	"github.com/diskfs/go-diskfs"
	"github.com/diskfs/go-diskfs/disk"
	"github.com/diskfs/go-diskfs/partition/gpt"

	"source.monogon.dev/metropolis/proto/api"

	mctl "source.monogon.dev/metropolis/cli/metroctl/core"
	"source.monogon.dev/osbase/build/mkimage/osimage"
	"source.monogon.dev/osbase/cmd"
)

var (
	// These are filled by bazel at linking time with the canonical path of
	// their corresponding file. Inside the init function we resolve it
	// with the rules_go runfiles package to the real path.
	xOvmfCodePath  string
	xOvmfVarsPath  string
	xInstallerPath string
	xBundlePath    string
)

func init() {
	var err error
	for _, path := range []*string{
		&xOvmfCodePath, &xOvmfVarsPath,
		&xInstallerPath, &xBundlePath,
	} {
		*path, err = runfiles.Rlocation(*path)
		if err != nil {
			panic(err)
		}
	}
}

// Each variable in this block points to either a test dependency or a side
// effect. These variables are initialized in TestMain using Bazel.
var (
	// installerImage is a filesystem path pointing at the installer image that
	// is generated during the test, and is removed afterwards.
	installerImage string
)

// runQemu starts a new QEMU process, expecting the given output to appear
// in any line printed. It returns true, if the expected string was found,
// and false otherwise.
//
// QEMU is killed shortly after the string is found, or when the context is
// cancelled.
func runQemu(ctx context.Context, args []string, expectedOutput string) (bool, error) {
	defaultArgs := []string{
		"-machine", "q35", "-accel", "kvm", "-nographic", "-nodefaults",
		"-m", "512",
		"-smp", "2",
		"-cpu", "host",
		"-drive", "if=pflash,format=raw,snapshot=on,file=" + xOvmfCodePath,
		"-drive", "if=pflash,format=raw,readonly=on,file=" + xOvmfVarsPath,
		"-serial", "stdio",
		"-no-reboot",
	}
	qemuArgs := append(defaultArgs, args...)
	pf := cmd.TerminateIfFound(expectedOutput, nil)
	return cmd.RunCommand(ctx, "qemu-system-x86_64", qemuArgs, pf)
}

// runQemuWithInstaller runs the Metropolis Installer in a qemu, performing the
// same search-through-std{out,err} as runQemu.
func runQemuWithInstaller(ctx context.Context, args []string, expectedOutput string) (bool, error) {
	args = append(args, "-drive", "if=virtio,format=raw,snapshot=on,cache=unsafe,file="+installerImage)
	return runQemu(ctx, args, expectedOutput)
}

// getStorage creates a sparse file, given a size expressed in mebibytes, and
// returns a path to that file. It may return an error.
func getStorage(size int64) (string, error) {
	nodeStorageDir, err := os.MkdirTemp(os.Getenv("TEST_TMPDIR"), "storage")
	if err != nil {
		return "", err
	}
	nodeStorage := filepath.Join(nodeStorageDir, "stor.img")
	image, err := os.Create(nodeStorage)
	if err != nil {
		return "", fmt.Errorf("couldn't create the block device image at %q: %w", nodeStorage, err)
	}
	if err := syscall.Ftruncate(int(image.Fd()), size*1024*1024); err != nil {
		return "", fmt.Errorf("couldn't resize the block device image at %q: %w", nodeStorage, err)
	}
	image.Close()
	return nodeStorage, nil
}

// qemuDriveParam returns QEMU parameters required to run it with a
// raw-format image at path.
func qemuDriveParam(path string) []string {
	return []string{"-drive", "if=virtio,format=raw,snapshot=off,cache=unsafe,file=" + path}
}

// checkEspContents verifies the presence of the EFI payload inside of image's
// first partition. It returns nil on success.
func checkEspContents(image *disk.Disk) error {
	// Get the ESP.
	fs, err := image.GetFilesystem(1)
	if err != nil {
		return fmt.Errorf("couldn't read the installer ESP: %w", err)
	}
	// Make sure the EFI payload exists by attempting to open it.
	efiPayload, err := fs.OpenFile(osimage.EFIPayloadPath, os.O_RDONLY)
	if err != nil {
		return fmt.Errorf("couldn't open the installer's EFI Payload at %q: %w", osimage.EFIPayloadPath, err)
	}
	efiPayload.Close()
	return nil
}

func TestMain(m *testing.M) {
	installerImage = filepath.Join(os.Getenv("TEST_TMPDIR"), "installer.img")

	installer, err := os.ReadFile(xInstallerPath)
	if err != nil {
		log.Fatal(err)
	}

	bundle, err := os.ReadFile(xBundlePath)
	if err != nil {
		log.Fatal(err)
	}

	iargs := mctl.MakeInstallerImageArgs{
		Installer:  bytes.NewReader(installer),
		TargetPath: installerImage,
		NodeParams: &api.NodeParameters{},
		Bundle:     bytes.NewReader(bundle),
	}
	if err := mctl.MakeInstallerImage(iargs); err != nil {
		log.Fatalf("Couldn't create the installer image at %q: %v", installerImage, err)
	}
	// With common dependencies set up, run the tests.
	code := m.Run()
	// Clean up.
	os.Remove(installerImage)
	os.Exit(code)
}

func TestInstallerImage(t *testing.T) {
	// This test examines the installer image, making sure that the GPT and the
	// ESP contents are in order.
	image, err := diskfs.OpenWithMode(installerImage, diskfs.ReadOnly)
	if err != nil {
		t.Errorf("Couldn't open the installer image at %q: %s", installerImage, err.Error())
	}
	// Verify that GPT exists.
	ti, err := image.GetPartitionTable()
	if err != nil {
		t.Fatalf("Couldn't read the installer image partition table: %s", err)
	}
	if ti.Type() != "gpt" {
		t.Error("Couldn't verify that the installer image contains a GPT.")
	}
	// Check that the first partition is likely to be a valid ESP.
	pi := ti.GetPartitions()
	esp := (pi[0]).(*gpt.Partition)
	if esp.Start == 0 || esp.End == 0 {
		t.Error("The installer's ESP GPT entry looks off.")
	}
	// Verify that the image contains only one partition.
	second := (pi[1]).(*gpt.Partition)
	if second.Name != "" || second.Start != 0 || second.End != 0 {
		t.Error("It appears the installer image contains more than one partition.")
	}
	// Verify the ESP contents.
	if err := checkEspContents(image); err != nil {
		t.Error(err.Error())
	}
}

func TestNoBlockDevices(t *testing.T) {
	ctx, ctxC := context.WithCancel(context.Background())
	defer ctxC()

	// No block devices are passed to QEMU aside from the install medium. Expect
	// the installer to fail at the device probe stage rather than attempting to
	// use the medium as the target device.
	expectedOutput := "couldn't find a suitable block device"
	result, err := runQemuWithInstaller(ctx, nil, expectedOutput)
	if err != nil {
		t.Error(err.Error())
	}
	if !result {
		t.Errorf("QEMU didn't produce the expected output %q", expectedOutput)
	}
}

func TestBlockDeviceTooSmall(t *testing.T) {
	ctx, ctxC := context.WithCancel(context.Background())
	defer ctxC()

	// Prepare the block device the installer will install to. This time the
	// target device is too small to host a Metropolis installation.
	imagePath, err := getStorage(64)
	defer os.Remove(imagePath)
	if err != nil {
		t.Error(err.Error())
	}

	// Run QEMU. Expect the installer to fail with a predefined error string.
	expectedOutput := "couldn't find a suitable block device"
	result, err := runQemuWithInstaller(ctx, qemuDriveParam(imagePath), expectedOutput)
	if err != nil {
		t.Error(err.Error())
	}
	if !result {
		t.Errorf("QEMU didn't produce the expected output %q", expectedOutput)
	}
}

func TestInstall(t *testing.T) {
	ctx, ctxC := context.WithCancel(context.Background())
	defer ctxC()

	// Prepare the block device image the installer will install to.
	// Needs enough storage for two 4096 MiB system partitions, a 384 MiB ESP
	// and a 128 MiB data partition. In addition at the start and end we need
	// 1MiB for GPT headers and alignment.
	storagePath, err := getStorage(4096*2 + 384 + 128 + 2)
	defer os.Remove(storagePath)
	if err != nil {
		t.Error(err.Error())
	}

	// Run QEMU. Expect the installer to succeed.
	expectedOutput := "Installation completed"
	result, err := runQemuWithInstaller(ctx, qemuDriveParam(storagePath), expectedOutput)
	if err != nil {
		t.Error(err.Error())
	}
	if !result {
		t.Errorf("QEMU didn't produce the expected output %q", expectedOutput)
	}

	// Verify the resulting node image. Check whether the node GPT was created.
	storage, err := diskfs.OpenWithMode(storagePath, diskfs.ReadOnly)
	if err != nil {
		t.Errorf("Couldn't open the resulting node image at %q: %s", storagePath, err.Error())
	}
	// Verify that GPT exists.
	ti, err := storage.GetPartitionTable()
	if err != nil {
		t.Fatalf("Couldn't read the installer image partition table: %s", err)
	}
	if ti.Type() != "gpt" {
		t.Error("Couldn't verify that the resulting node image contains a GPT.")
	}
	// Check that the first partition is likely to be a valid ESP.
	pi := ti.GetPartitions()
	esp := (pi[0]).(*gpt.Partition)
	if esp.Name != osimage.ESPLabel || esp.Start == 0 || esp.End == 0 {
		t.Error("The node's ESP GPT entry looks off.")
	}
	// Verify the system partition's GPT entry.
	system := (pi[1]).(*gpt.Partition)
	if system.Name != osimage.SystemALabel || system.Start == 0 || system.End == 0 {
		t.Error("The node's system partition GPT entry looks off.")
	}
	// Verify the system partition's GPT entry.
	systemB := (pi[2]).(*gpt.Partition)
	if systemB.Name != osimage.SystemBLabel || systemB.Start == 0 || systemB.End == 0 {
		t.Error("The node's system partition GPT entry looks off.")
	}
	// Verify the data partition's GPT entry.
	data := (pi[3]).(*gpt.Partition)
	if data.Name != osimage.DataLabel || data.Start == 0 || data.End == 0 {
		t.Errorf("The node's data partition GPT entry looks off: %+v", data)
	}
	// Verify that there are no more partitions.
	fourth := (pi[4]).(*gpt.Partition)
	if fourth.Name != "" || fourth.Start != 0 || fourth.End != 0 {
		t.Error("The resulting node image contains more partitions than expected.")
	}
	// Verify the ESP contents.
	if err := checkEspContents(storage); err != nil {
		t.Error(err.Error())
	}
	storage.File.Close()
	// Run QEMU again. Expect TestOS to launch successfully.
	expectedOutput = "_TESTOS_LAUNCH_SUCCESS_"
	time.Sleep(time.Second)
	result, err = runQemu(ctx, qemuDriveParam(storagePath), expectedOutput)
	if err != nil {
		t.Error(err.Error())
	}
	if !result {
		t.Errorf("QEMU didn't produce the expected output %q", expectedOutput)
	}
}