package backendupdate

import (
	"context"
	"os"
	"path/filepath"
	"testing"

	"yms-daemon/internal/systemd"
	"yms-daemon/internal/transaction"
)

// TestPathOperationReplacesRegularCompatibilityJarAndRestoresIt 验证 pathOperation 能把普通文件形态的
// 兼容 JAR 替换为目标软链接，随后又能依据快照恢复为原始普通文件内容。
func TestPathOperationReplacesRegularCompatibilityJarAndRestoresIt(t *testing.T) {
	root := t.TempDir()
	activePath := filepath.Join(root, "glory-soft-yms.jar")
	original := []byte("original backend JAR")
	if err := os.WriteFile(activePath, original, 0o644); err != nil {
		t.Fatalf("write original compatibility JAR: %v", err)
	}
	before, err := snapshotPath(activePath, filepath.Join(root, "transaction", "active.before"))
	if err != nil {
		t.Fatalf("snapshot compatibility JAR: %v", err)
	}
	installedPath := filepath.Join(root, "releases", "new.jar")
	if err := os.MkdirAll(filepath.Dir(installedPath), 0o750); err != nil {
		t.Fatalf("create release directory: %v", err)
	}
	if err := os.WriteFile(installedPath, []byte("new backend JAR"), 0o640); err != nil {
		t.Fatalf("write new backend JAR: %v", err)
	}

	apply := &pathOperation{path: activePath, before: before, desired: pathState{Kind: pathKindSymlink, Target: installedPath}}
	if err := apply.Apply(context.Background()); err != nil {
		t.Fatalf("replace compatibility JAR with link: %v", err)
	}
	if target, err := os.Readlink(activePath); err != nil || target != installedPath {
		t.Fatalf("unexpected compatibility link: target=%q err=%v", target, err)
	}

	restore := &pathOperation{path: activePath, before: pathState{Kind: pathKindSymlink, Target: installedPath}, desired: before}
	if err := restore.Apply(context.Background()); err != nil {
		t.Fatalf("restore compatibility JAR: %v", err)
	}
	actual, err := os.ReadFile(activePath)
	if err != nil || string(actual) != string(original) {
		t.Fatalf("unexpected restored compatibility JAR: content=%q err=%v", actual, err)
	}
}

// TestResolveCurrentUnitSupportsFirstLegacyMigrationAndTemplateRotation 验证 resolveCurrentUnit 在
// 首次从旧版单元迁移和模板单元轮换两种场景下，都能选出当前真正运行的单元。
func TestResolveCurrentUnitSupportsFirstLegacyMigrationAndTemplateRotation(t *testing.T) {
	tests := []struct {
		name       string
		configured string
		legacy     string
		want       string
	}{
		{name: "legacy", configured: "inactive", legacy: "activating", want: legacyUnit8081},
		{name: "template", configured: "active", legacy: "failed", want: "yms-backend@8081.service"},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			units := &unitStateManager{units: map[string]systemd.Unit{
				"yms-backend@8081.service": {Name: "yms-backend@8081.service", LoadState: "loaded", ActiveState: test.configured},
				legacyUnit8081:             {Name: legacyUnit8081, LoadState: "loaded", ActiveState: test.legacy},
			}}
			updater := &Updater{units: units}
			actual, err := updater.resolveCurrentUnit(context.Background(), 8081, "yms-backend@8081.service")
			if err != nil || actual != test.want {
				t.Fatalf("unexpected current unit: unit=%q err=%v", actual, err)
			}
		})
	}
}

// TestUnitStopOperationAcceptsSystemdFailedAsStopped 验证 unitStopOperation 的 Inspect 把 systemd 的
// failed 状态视为已停止（InspectionApplied），因为旧服务在 JVM 以 SIGTERM 退出后常表现为 failed。
func TestUnitStopOperationAcceptsSystemdFailedAsStopped(t *testing.T) {
	units := &unitStateManager{units: map[string]systemd.Unit{
		legacyUnit8081: {Name: legacyUnit8081, LoadState: "loaded", ActiveState: "failed"},
	}}
	operation := &unitStopOperation{units: units, name: legacyUnit8081}
	inspection, err := operation.Inspect(context.Background())
	if err != nil {
		t.Fatalf("inspect stopped legacy unit: %v", err)
	}
	if inspection.Status != transaction.InspectionApplied {
		t.Fatalf("unexpected stopped legacy unit inspection: %+v", inspection)
	}
}

// unitStateManager systemd 单元管理器的只读测试替身，仅返回预先配置的单元状态，
// 用于隔离 resolveCurrentUnit 与 unitStopOperation 的检查逻辑。
type unitStateManager struct {
	units map[string]systemd.Unit
}

// Inspect 返回指定名称的单元状态。
func (m *unitStateManager) Inspect(_ context.Context, name string) (systemd.Unit, error) {
	return m.units[name], nil
}

// Start 空实现，测试中不涉及启动单元。
func (m *unitStateManager) Start(context.Context, string) error { return nil }

// Stop 空实现，测试中不涉及停止单元。
func (m *unitStateManager) Stop(context.Context, string) error { return nil }