//go:build linux && rootrunner

package host

import (
	"context"
	"encoding/json"
	"errors"
	"net"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/carlosframework/platform/internal/rootstate"
	"golang.org/x/sys/unix"
)

const unitMigrationRebootDir = "/var/lib/carlos-e52-migration"
const migrationRebootUnit = "plan14-e52-migration.service"
const migrationRebootSocket = "/run/carlos/plan14-e52.sock"

func migrationRebootMaterial(t *testing.T) claimUnitMaterializer {
	t.Helper()
	store, err := rootstate.Open(filepath.Join(unitMigrationRebootDir, "state"), true, false)
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { store.Close() })
	files := claimUnitFiles{dir: "/etc/systemd/system"}
	k := claimPredecessorKernel{ctl: rebootPredecessorCtl, group: claimPredecessorGroup, boot: claimUnitBoot}
	return claimUnitMaterializer{state: store, read: files.read, create: files.create, replace: files.replace, predecessor: k.capture, stopPredecessor: k.stop,
		socketCapture: captureProductionClaimUnitSocket, socketPark: parkProductionClaimUnitSocket, idle: func(string) error { return nil }}
}

func TestRootRebootClaimUnitMigrationPhase1(t *testing.T) {
	for _, dir := range []string{unitMigrationRebootDir, "/run/carlos", "/run/carlos-control"} {
		if err := os.Mkdir(dir, 0755); err != nil {
			t.Fatal(err)
		}
	}
	binary, err := os.Executable()
	if err != nil {
		t.Fatal(err)
	}
	body, err := os.ReadFile(binary)
	if err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(unitMigrationRebootDir, "payload"), body, 0755); err != nil {
		t.Fatal(err)
	}
	legacy := []byte("[Service]\nType=simple\nEnvironment=PLAN14_TENANT_SOCKET=" + migrationRebootSocket + "\nExecStart=" + unitMigrationRebootDir + "/payload plan14-tenant\n")
	path := "/etc/systemd/system/" + migrationRebootUnit
	f, err := os.OpenFile(path, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0644)
	if err != nil {
		t.Fatal(err)
	}
	_, err = f.Write(legacy)
	if err = errors.Join(err, f.Close()); err != nil {
		t.Fatal(err)
	}
	if out, err := rebootPredecessorCtl(t.Context(), "daemon-reload"); err != nil {
		t.Fatal(out, err)
	}
	if out, err := rebootPredecessorCtl(t.Context(), "start", migrationRebootUnit); err != nil {
		t.Fatal(out, err)
	}
	for until := time.Now().Add(5 * time.Second); ; {
		conn, err := net.DialTimeout("unix", migrationRebootSocket, time.Second)
		if err == nil {
			conn.Close()
			break
		}
		if time.Now().After(until) {
			t.Fatal(err)
		}
		time.Sleep(20 * time.Millisecond)
	}
	_, in, s := plan14UnitBindingFixture(t, migrationRebootUnit, "", migrationRebootSocket)
	s.Program, s.PredecessorDigest = strings.Repeat("a", 64), claimUnitDigest(legacy)
	b := claimUnitBinding{Schema: 1, Owner: unitBindingOwner(in), Shape: s}
	m := migrationRebootMaterial(t)
	m.stopPredecessor = func(context.Context, claimUnitPredecessor) error { return os.ErrClosed }
	if err := m.install(t.Context(), b); !errors.Is(err, os.ErrClosed) {
		t.Fatal("migration intent boundary", err)
	}
	r, err := m.load(b.Owner.Host)
	if err != nil || r.Migration == nil || r.Migration.Socket.Boot == "" || r.Identity != (rootstate.FileIdentity{}) {
		t.Fatal("lost durable migration", r, err)
	}
	raw, _ := json.Marshal(b)
	if err := os.WriteFile(filepath.Join(unitMigrationRebootDir, "binding.json"), raw, 0600); err != nil {
		t.Fatal(err)
	}
	old := claimEdgeMaskOwner
	defer func() { claimEdgeMaskOwner = old }()
	claimEdgeMaskOwner = filepath.Join(unitMigrationRebootDir, "edge-mask")
	if _, err := createClaimEdgeMask(t.Context(), r.Migration.Socket.Boot); err != nil {
		t.Fatal(err)
	}
	t.Logf("migration saved boot=%s device=%d mount=%d socket=%d:%d", r.Migration.Definition.Boot, r.Migration.Definition.Device, r.Migration.Definition.Mount, r.Migration.Socket.Device, r.Migration.Socket.Inode)
}

func TestRootRebootClaimUnitMigrationPhase2(t *testing.T) {
	t.Cleanup(func() {
		rebootPredecessorCtl(context.Background(), "stop", migrationRebootUnit)
		os.Remove("/etc/systemd/system/" + migrationRebootUnit)
		os.Remove("/run/systemd/system/carlos-edge.service")
		rebootPredecessorCtl(context.Background(), "daemon-reload")
		for _, dir := range []string{unitMigrationRebootDir, "/run/carlos", "/run/carlos-control"} {
			os.RemoveAll(dir)
		}
	})
	for _, dir := range []string{"/run/carlos", "/run/carlos-control"} {
		if err := os.Mkdir(dir, 0755); err != nil {
			t.Fatal(err)
		}
	}
	var b claimUnitBinding
	raw, err := os.ReadFile(filepath.Join(unitMigrationRebootDir, "binding.json"))
	if err != nil || json.Unmarshal(raw, &b) != nil {
		t.Fatal(err)
	}
	m := migrationRebootMaterial(t)
	r, err := m.load(b.Owner.Host)
	if err != nil {
		t.Fatal(err)
	}
	boot, err := claimUnitBoot()
	if err != nil || boot == r.Migration.Definition.Boot {
		t.Fatal("actual reboot required", err)
	}
	oldMaskOwner := claimEdgeMaskOwner
	defer func() { claimEdgeMaskOwner = oldMaskOwner }()
	claimEdgeMaskOwner = filepath.Join(unitMigrationRebootDir, "edge-mask")
	if err := os.Symlink("/dev/null", "/run/systemd/system/carlos-edge.service"); err != nil {
		t.Fatal(err)
	}
	if out, err := rebootPredecessorCtl(t.Context(), "daemon-reload"); err != nil {
		t.Fatal(out, err)
	}
	if err := recoverLegacyClaimEdgeMask(t.Context()); err != nil {
		t.Fatal(err)
	}
	if target, err := os.Readlink("/run/systemd/system/carlos-edge.service"); err != nil || target != "/dev/null" {
		t.Fatal("old boot removed replacement mask", err)
	}
	if _, err := os.Lstat(claimEdgeMaskOwner); !os.IsNotExist(err) {
		t.Fatal("old mask record retained", err)
	}
	path := "/etc/systemd/system/" + migrationRebootUnit
	if err := unix.Mount(path, path, "", unix.MS_BIND, ""); err != nil {
		t.Fatal(err)
	}
	refused := m.install(t.Context(), b)
	if err := unix.Unmount(path, 0); err != nil {
		t.Fatal(err)
	}
	if refused == nil {
		t.Fatal("substituted definition mount accepted")
	}
	listener, err := net.ListenUnix("unix", &net.UnixAddr{Name: migrationRebootSocket, Net: "unix"})
	if err != nil {
		t.Fatal(err)
	}
	if err = m.install(t.Context(), b); err == nil {
		t.Fatal("post-boot replacement socket removed")
	}
	if _, err := os.Lstat(migrationRebootSocket); err != nil {
		t.Fatal("replacement socket lost", err)
	}
	listener.Close()
	if err := m.install(t.Context(), b); err != nil {
		t.Fatal("resume migration after reboot", err)
	}
	if err := m.verify(b); err != nil {
		t.Fatal(err)
	}
	if err := projectClaimBoundSocket(b.Shape); err != nil {
		t.Fatal(err)
	}
	if target, err := os.Readlink(migrationRebootSocket); err != nil || target != claimSocketTarget(b.Shape) {
		t.Fatal("socket projection", target, err)
	}
	if out, err := exec.Command("systemctl", "daemon-reload").CombinedOutput(); err != nil {
		t.Fatal(string(out), err)
	}
	if _, err := rebootPredecessorCtl(t.Context(), "start", migrationRebootUnit); err == nil {
		time.Sleep(100 * time.Millisecond)
		pid, _ := rebootPredecessorCtl(t.Context(), "show", "-p", "MainPID", "--value", migrationRebootUnit)
		if pid != "0" {
			t.Fatal("migration started without reservation", pid)
		}
	}
}