package service

import (
	"context"
	"errors"
	"fmt"
	"log"
	"strings"
	"time"

	"oci-portal/internal/model"
	"oci-portal/internal/oci"
)

// ErrRelayNotConfigured 表示 P1 引导创建不可用:面板地址未配置或依赖未注入。
var ErrRelayNotConfigured = errors.New("日志回传引导创建需要配置面板地址(设置 → 安全 → 面板地址,或 PUBLIC_URL 环境变量)")

// 订阅确认轮询节奏:创建订阅后 ONS 向面板投递确认消息,面板回访后订阅转 ACTIVE。
const (
	relaySubPollTick    = 5 * time.Second
	relaySubPollTimeout = 90 * time.Second
	relayRollbackWait   = 60 * time.Second
)

// RelayCriticalEvents 是回传的关键事件清单(Connector Log Filter 与 P2 告警共用):
// 实例生命周期、用户与凭据、区域订阅、策略变更、控制台登录。
var RelayCriticalEvents = []string{
	"LaunchInstance", "TerminateInstance", "InstanceAction",
	"CreateUser", "DeleteUser", "UpdateUser",
	"CreateApiKey", "DeleteApiKey", "UpdateUserCapabilities",
	"CreateRegionSubscription",
	"CreatePolicy", "UpdatePolicy", "DeletePolicy",
	"InteractiveLogin",
}

// relayCriticalSet 供 P2 按事件短名 O(1) 判定。
var relayCriticalSet = func() map[string]bool {
	m := make(map[string]bool, len(RelayCriticalEvents))
	for _, e := range RelayCriticalEvents {
		m[e] = true
	}
	return m
}()

// relayEventClass 把关键事件归入通知子类,对应设置键 notify_event_log_event_<class>;
// 通知管理「云端事件」按此细分开关。
func relayEventClass(name string) string {
	switch name {
	case "LaunchInstance", "TerminateInstance", "InstanceAction":
		return "instance"
	case "CreateUser", "DeleteUser", "UpdateUser",
		"CreateApiKey", "DeleteApiKey", "UpdateUserCapabilities":
		return "identity"
	case "CreatePolicy", "UpdatePolicy", "DeletePolicy":
		return "policy"
	case "CreateRegionSubscription":
		return "region"
	case "InteractiveLogin", "FederatedInteractiveLogin":
		return "login"
	}
	return ""
}

// RelayView 是 OCI 侧链路状态视图;Events 为关键事件清单,Ready 表示全链路可用。
type RelayView struct {
	Webhook      *LogWebhookInfo   `json:"webhook,omitempty"`
	Endpoint     string            `json:"endpoint,omitempty"`
	Topic        oci.RelayResource `json:"topic"`
	Subscription oci.RelayResource `json:"subscription"`
	Connector    oci.RelayResource `json:"connector"`
	Policy       oci.RelayResource `json:"policy"`
	Ready        bool              `json:"ready"`
	Events       []string          `json:"events"`
}

// SetRelayDeps 注入 P1 引导创建依赖;publicURL 为面板公网基址(如 https://demo.example.com)。
func (s *LogEventService) SetRelayDeps(configs *OciConfigService, client oci.Client, publicURL string) {
	s.configs = configs
	s.relayClient = client
	s.publicURL = strings.TrimRight(publicURL, "/")
}

// SetNotifier 注入 P2 告警联动依赖;settings 控制 log_event 事件开关。
func (s *LogEventService) SetNotifier(n *Notifier, settings *SettingService) {
	s.notifier = n
	s.settings = settings
}

// relayBase 返回生效的公网基址:设置里的 app_url 优先(经 settings),回退启动时的 PUBLIC_URL。
func (s *LogEventService) relayBase() string {
	if s.settings != nil {
		if u := s.settings.EffectiveAppURL(); u != "" {
			return u
		}
	}
	return s.publicURL
}

// relayEndpoint 以公网基址拼接回调完整 URL。
func (s *LogEventService) relayEndpoint(path string) string {
	return s.relayBase() + path
}

// relayCreds 加载配置凭据与 home region(IAM 写操作路由用)。
func (s *LogEventService) relayCreds(ctx context.Context, cfgID uint) (oci.Credentials, string, error) {
	var cfg model.OciConfig
	if err := s.db.WithContext(ctx).First(&cfg, cfgID).Error; err != nil {
		return oci.Credentials{}, "", fmt.Errorf("find oci config %d: %w", cfgID, err)
	}
	cred, err := s.configs.credentialsOf(&cfg)
	if err != nil {
		return oci.Credentials{}, "", err
	}
	return cred, cfg.HomeRegionKey, nil
}

// SetupRelay 一键建立回传链路:secret → Topic → 订阅(等待面板自动确认)→ Policy → Connector;
// 任一步失败逆序回滚本次新建的资源。
func (s *LogEventService) SetupRelay(ctx context.Context, cfgID uint) (RelayView, error) {
	if s.relayClient == nil || s.relayBase() == "" {
		return RelayView{}, ErrRelayNotConfigured
	}
	info, err := s.EnsureSecret(ctx, cfgID)
	if err != nil {
		return RelayView{}, err
	}
	cred, home, err := s.relayCreds(ctx, cfgID)
	if err != nil {
		return RelayView{}, err
	}
	if err := s.buildRelay(ctx, cred, home, s.relayEndpoint(info.Path)); err != nil {
		return RelayView{}, err
	}
	return s.RelayStatus(ctx, cfgID)
}

// buildRelay 依序创建链路资源;失败时逆序删除本次新建的部分后返回原错误。
func (s *LogEventService) buildRelay(ctx context.Context, cred oci.Credentials, home, endpoint string) (err error) {
	var undo []func(context.Context) error
	defer func() {
		if err != nil {
			s.rollbackRelay(undo)
		}
	}()
	topic, err := s.relayClient.EnsureRelayTopic(ctx, cred)
	undo = appendRelayUndo(undo, topic, func(c context.Context) error { return s.relayClient.DeleteRelayTopic(c, cred, topic.ID) })
	if err != nil {
		return fmt.Errorf("创建 Topic: %w", err)
	}
	sub, err := s.relayClient.EnsureRelaySubscription(ctx, cred, topic.ID, endpoint)
	undo = appendRelayUndo(undo, sub, func(c context.Context) error { return s.relayClient.DeleteRelaySubscription(c, cred, sub.ID) })
	if err != nil {
		return fmt.Errorf("创建订阅: %w", err)
	}
	if err = s.waitSubscriptionActive(ctx, cred, sub.ID); err != nil {
		return err
	}
	policy, err := s.relayClient.EnsureRelayPolicy(ctx, cred, home)
	undo = appendRelayUndo(undo, policy, func(c context.Context) error { return s.relayClient.DeleteRelayPolicy(c, cred, home, policy.ID) })
	if err != nil {
		return fmt.Errorf("创建 Policy: %w", err)
	}
	conn, err := s.relayClient.EnsureRelayConnector(ctx, cred, topic.ID, oci.RelayEventCondition(RelayCriticalEvents))
	undo = appendRelayUndo(undo, conn, func(c context.Context) error { return s.relayClient.DeleteRelayConnector(c, cred, conn.ID) })
	if err != nil {
		return fmt.Errorf("创建 Connector: %w", err)
	}
	return nil
}

// appendRelayUndo 只为本次新建且拿到 ID 的资源登记回滚动作。
func appendRelayUndo(undo []func(context.Context) error, res oci.RelayResource, del func(context.Context) error) []func(context.Context) error {
	if res.Created && res.ID != "" {
		return append(undo, del)
	}
	return undo
}

// rollbackRelay 逆序执行回滚;使用独立超时上下文,原请求取消不影响清理。
func (s *LogEventService) rollbackRelay(undo []func(context.Context) error) {
	ctx, cancel := context.WithTimeout(context.Background(), relayRollbackWait)
	defer cancel()
	for i := len(undo) - 1; i >= 0; i-- {
		if err := undo[i](ctx); err != nil {
			log.Printf("relay rollback: %v", err)
		}
	}
}

// waitSubscriptionActive 轮询订阅至 ACTIVE;确认动作由 webhook 端点收到 ONS 消息后自动完成,
// 超时通常意味着面板公网不可达或回调地址配置有误。
func (s *LogEventService) waitSubscriptionActive(ctx context.Context, cred oci.Credentials, subID string) error {
	deadline := time.Now().Add(s.subPollTimeout())
	for {
		res, err := s.relayClient.GetRelaySubscription(ctx, cred, subID)
		if err != nil {
			return fmt.Errorf("查询订阅状态: %w", err)
		}
		if res.State == "ACTIVE" {
			return nil
		}
		if time.Now().After(deadline) {
			return fmt.Errorf("订阅确认超时(当前 %s):请确认面板公网可达后重试", res.State)
		}
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-time.After(s.subPollTick()):
		}
	}
}

// subPollTick / subPollTimeout 返回订阅轮询节奏;测试注入短间隔。
func (s *LogEventService) subPollTick() time.Duration {
	if s.relayPollTick > 0 {
		return s.relayPollTick
	}
	return relaySubPollTick
}

func (s *LogEventService) subPollTimeout() time.Duration {
	if s.relayPollTimeout > 0 {
		return s.relayPollTimeout
	}
	return relaySubPollTimeout
}

// RelayStatus 查询 OCI 侧链路现状与关键事件清单。
func (s *LogEventService) RelayStatus(ctx context.Context, cfgID uint) (RelayView, error) {
	if s.relayClient == nil {
		return RelayView{}, ErrRelayNotConfigured
	}
	info, exists, err := s.SecretInfo(ctx, cfgID)
	if err != nil {
		return RelayView{}, err
	}
	view := RelayView{Events: RelayCriticalEvents}
	endpoint := ""
	if exists && s.relayBase() != "" {
		endpoint = s.relayEndpoint(info.Path)
		view.Webhook, view.Endpoint = &info, endpoint
	}
	cred, _, err := s.relayCreds(ctx, cfgID)
	if err != nil {
		return RelayView{}, err
	}
	st, err := s.relayClient.RelayState(ctx, cred, endpoint)
	if err != nil {
		return RelayView{}, fmt.Errorf("查询链路状态: %w", err)
	}
	view.Topic, view.Subscription, view.Connector, view.Policy = st.Topic, st.Subscription, st.Connector, st.Policy
	view.Ready = relayReady(exists, st)
	return view, nil
}

// relayReady 判定全链路可用:secret 已生成且四资源均处于活跃状态。
func relayReady(secretExists bool, st oci.RelayState) bool {
	return secretExists && st.Topic.State == "ACTIVE" && st.Subscription.State == "ACTIVE" &&
		st.Connector.State == "ACTIVE" && st.Policy.ID != ""
}

// TeardownRelay 逆序销毁链路(Connector → Policy → 订阅 → Topic)并撤销 secret。
func (s *LogEventService) TeardownRelay(ctx context.Context, cfgID uint) error {
	if s.relayClient == nil {
		return ErrRelayNotConfigured
	}
	info, exists, err := s.SecretInfo(ctx, cfgID)
	if err != nil {
		return err
	}
	cred, home, err := s.relayCreds(ctx, cfgID)
	if err != nil {
		return err
	}
	endpoint := ""
	if exists {
		endpoint = s.relayEndpoint(info.Path)
	}
	st, err := s.relayClient.RelayState(ctx, cred, endpoint)
	if err != nil {
		return fmt.Errorf("查询链路状态: %w", err)
	}
	if err := s.teardownResources(ctx, cred, home, st); err != nil {
		return err
	}
	return s.RevokeSecret(ctx, cfgID)
}

// teardownResources 按依赖逆序删除存在的链路资源。
func (s *LogEventService) teardownResources(ctx context.Context, cred oci.Credentials, home string, st oci.RelayState) error {
	if st.Connector.ID != "" {
		if err := s.relayClient.DeleteRelayConnector(ctx, cred, st.Connector.ID); err != nil {
			return fmt.Errorf("删除 Connector: %w", err)
		}
	}
	if st.Policy.ID != "" {
		if err := s.relayClient.DeleteRelayPolicy(ctx, cred, home, st.Policy.ID); err != nil {
			return fmt.Errorf("删除 Policy: %w", err)
		}
	}
	if st.Subscription.ID != "" {
		if err := s.relayClient.DeleteRelaySubscription(ctx, cred, st.Subscription.ID); err != nil {
			return fmt.Errorf("删除订阅: %w", err)
		}
	}
	if st.Topic.ID != "" {
		if err := s.relayClient.DeleteRelayTopic(ctx, cred, st.Topic.ID); err != nil {
			return fmt.Errorf("删除 Topic: %w", err)
		}
	}
	return nil
}

// ---- P2 告警联动:解析出关键事件后经 Notifier 推送 ----

// relayEventShortName 取 CloudEvents type 末段(com.oraclecloud.ComputeApi.LaunchInstance → LaunchInstance)。
func relayEventShortName(eventType string) string {
	if i := strings.LastIndex(eventType, "."); i >= 0 {
		return eventType[i+1:]
	}
	return eventType
}

// criticalEventVars 判定关键事件并生成模板变量;非关键事件 ok 为 false。
func criticalEventVars(alias string, p parsedEvent) (map[string]string, bool) {
	name := relayEventShortName(p.EventType)
	if name == "" || !relayCriticalSet[name] {
		return nil, false
	}
	return map[string]string{"tenant": alias, "event": name, "resource": p.ResourceName}, true
}

// notifyCritical 对关键事件推送告警;依赖未注入或对应子类开关关闭时跳过。
// MessageID 幂等入库保证同一事件只解析一次,天然防重复推送。
func (s *LogEventService) notifyCritical(ctx context.Context, e *model.LogEvent, p parsedEvent) {
	if s.notifier == nil {
		return
	}
	vars, ok := criticalEventVars(s.configAlias(ctx, e.OciConfigID), p)
	if !ok {
		return
	}
	class := relayEventClass(relayEventShortName(p.EventType))
	if s.settings != nil && !s.settings.NotifyEventEnabled(ctx, "log_event_"+class) {
		return
	}
	s.notifier.SendTemplateAsync("log_event_"+class, vars)
}

// configAlias 查配置别名,失败时退化为编号占位。
func (s *LogEventService) configAlias(ctx context.Context, cfgID uint) string {
	var cfg model.OciConfig
	if err := s.db.WithContext(ctx).Select("alias").First(&cfg, cfgID).Error; err != nil {
		return fmt.Sprintf("租户#%d", cfgID)
	}
	return cfg.Alias
}