《互联网产品的服务端架构·产品、流量与基础能力》4.3 注销、导出与数据留存

// file: internal/profile/deletion.go
// tier: L1
// verify: go test ./internal/profile/

package profile

import (
	"fmt"
	"sort"
	"time"
)

// State 是注销流程的状态。注销不是布尔值，不能一次调用删干净。
type State string

const (
	StatePending State = "pending"
	StateDeleted State = "deleted"
	StatePurged  State = "purged"
)

// Deletion 记录一次注销请求。BackupUntil 是备份的最晚保留时间，
// 在此之前不能清除备份副本。
type Deletion struct {
	State       State
	RequestedAt time.Time
	BackupUntil time.Time
}

// Advance 把注销推进到下一个状态。pending 只能到 deleted；
// deleted 在备份到期后才能到 purged；purged 和未知状态都报错。
func Advance(d Deletion, now time.Time) (Deletion, error) {
	switch d.State {
	case StatePending:
		if d.RequestedAt.IsZero() {
			return d, fmt.Errorf("profile: deletion has no request time")
		}
		d.State = StateDeleted
		return d, nil
	case StateDeleted:
		if d.RequestedAt.IsZero() {
			return d, fmt.Errorf("profile: deletion has no request time")
		}
		if now.Before(d.BackupUntil) {
			return d, fmt.Errorf("profile: backup retained until %s", d.BackupUntil.Format(time.RFC3339))
		}
		d.State = StatePurged
		return d, nil
	case StatePurged:
		return d, fmt.Errorf("profile: deletion already purged")
	default:
		return d, fmt.Errorf("profile: unknown deletion state %q", d.State)
	}
}

// Exportable 返回可交付给用户的数据字段名，按名称排序。
// 公开和敏感字段属于用户本人；内部风控、运营备注不进入导出。
func Exportable(fields []Field) []string {
	names := make([]string, 0, len(fields))
	for _, f := range fields {
		switch f.Class {
		case ClassPublic, ClassSensitive:
			names = append(names, f.Name)
		}
	}
	sort.Strings(names)
	return names
}

// file: internal/profile/deletion_test.go
// tier: L1
// verify: go test ./internal/profile/

package profile

import (
	"reflect"
	"strings"
	"testing"
	"time"
)

func at(day int) time.Time {
	return time.Date(2026, 11, day, 9, 0, 0, 0, time.UTC)
}

func TestAdvanceFollowsStateMachine(t *testing.T) {
	d := Deletion{State: StatePending, RequestedAt: at(1), BackupUntil: at(30)}

	deleted, err := Advance(d, at(2))
	if err != nil {
		t.Fatal(err)
	}
	if deleted.State != StateDeleted {
		t.Fatalf("state = %s, want deleted", deleted.State)
	}
	if !deleted.RequestedAt.Equal(d.RequestedAt) || !deleted.BackupUntil.Equal(d.BackupUntil) {
		t.Fatalf("timestamps changed: %+v", deleted)
	}

	purged, err := Advance(deleted, at(30))
	if err != nil {
		t.Fatal(err)
	}
	if purged.State != StatePurged {
		t.Fatalf("state = %s, want purged", purged.State)
	}
}

func TestAdvanceWaitsForBackupWindow(t *testing.T) {
	d := Deletion{State: StateDeleted, RequestedAt: at(1), BackupUntil: at(30)}

	got, err := Advance(d, at(29))
	if err == nil {
		t.Fatal("want error before backup expiry")
	}
	if got.State != StateDeleted {
		t.Fatalf("state = %s, want unchanged deleted", got.State)
	}
	if !strings.Contains(err.Error(), "backup retained") {
		t.Fatalf("error = %v, want backup message", err)
	}
}

func TestAdvanceRejectsInvalidTransitions(t *testing.T) {
	if _, err := Advance(Deletion{State: StatePurged}, at(1)); err == nil {
		t.Fatal("want error for purged state")
	}
	if _, err := Advance(Deletion{State: State("archived"), RequestedAt: at(1)}, at(2)); err == nil {
		t.Fatal("want error for unknown state")
	}
	if _, err := Advance(Deletion{State: StatePending}, at(2)); err == nil {
		t.Fatal("want error for missing request time")
	}
	if _, err := Advance(Deletion{State: StateDeleted, BackupUntil: at(30)}, at(31)); err == nil {
		t.Fatal("want error for missing request time")
	}
}

func TestExportableSkipsInternalFields(t *testing.T) {
	fields := []Field{
		{Name: "phone", Class: ClassSensitive},
		{Name: "nickname", Class: ClassPublic},
		{Name: "risk_score", Class: ClassInternal},
		{Name: "avatar", Class: ClassPublic},
	}
	got := Exportable(fields)
	want := []string{"avatar", "nickname", "phone"}
	if !reflect.DeepEqual(got, want) {
		t.Fatalf("exportable = %v, want %v", got, want)
	}

	empty := Exportable(nil)
	if empty == nil || len(empty) != 0 {
		t.Fatalf("nil input = %#v, want non-nil empty slice", empty)
	}
}

cd .local/checks/webapp-lab && go test ./internal/profile/ -run 'TestAdvance|TestExportable' -count=1 -v

=== RUN   TestAdvanceFollowsStateMachine
--- PASS: TestAdvanceFollowsStateMachine (0.00s)
=== RUN   TestAdvanceWaitsForBackupWindow
--- PASS: TestAdvanceWaitsForBackupWindow (0.00s)
=== RUN   TestAdvanceRejectsInvalidTransitions
--- PASS: TestAdvanceRejectsInvalidTransitions (0.00s)
=== RUN   TestExportableSkipsInternalFields
--- PASS: TestExportableSkipsInternalFields (0.00s)
PASS
ok  	webapp/internal/profile	0.271s