package nodes

import (
	"fmt"
	"log"
	"strings"
	"sync"
	"time"

	"github.com/TeaOSLab/EdgeCommon/pkg/rpc/pb"
	"github.com/TeaOSLab/EdgeHttpDNS/internal/rpc"
)

type LoadedDomain struct {
	Domain *pb.HTTPDNSDomain
	Rules  []*pb.HTTPDNSCustomRule
}

type LoadedApp struct {
	App     *pb.HTTPDNSApp
	Domains map[string]*LoadedDomain // key: lower(domain)
}

type LoadedSnapshot struct {
	LoadedAt int64

	NodeID    int64
	ClusterID int64

	Clusters map[int64]*pb.HTTPDNSCluster
	Apps     map[string]*LoadedApp // key: lower(appId)
}

type SnapshotManager struct {
	quitCh <-chan struct{}
	ticker *time.Ticker

	locker   sync.RWMutex
	snapshot *LoadedSnapshot

	timezone string
}

func NewSnapshotManager(quitCh <-chan struct{}) *SnapshotManager {
	return &SnapshotManager{
		quitCh: quitCh,
		ticker: time.NewTicker(30 * time.Second),
	}
}

func (m *SnapshotManager) Start() {
	defer m.ticker.Stop()

	if err := m.RefreshNow("startup"); err != nil {
		log.Println("[HTTPDNS_NODE][snapshot]initial refresh failed:", err.Error())
	}

	for {
		select {
		case <-m.ticker.C:
			if err := m.RefreshNow("periodic"); err != nil {
				log.Println("[HTTPDNS_NODE][snapshot]periodic refresh failed:", err.Error())
			}
		case <-m.quitCh:
			return
		}
	}
}

func (m *SnapshotManager) Current() *LoadedSnapshot {
	m.locker.RLock()
	defer m.locker.RUnlock()
	return m.snapshot
}

func (m *SnapshotManager) RefreshNow(reason string) error {
	rpcClient, err := rpc.SharedRPC()
	if err != nil {
		return err
	}

	nodeResp, err := rpcClient.HTTPDNSNodeRPC.FindHTTPDNSNode(rpcClient.Context(), &pb.FindHTTPDNSNodeRequest{
		NodeId: 0,
	})
	if err != nil {
		return err
	}
	if nodeResp.GetNode() == nil {
		return fmt.Errorf("httpdns node info not found")
	}

	clusterResp, err := rpcClient.HTTPDNSClusterRPC.FindAllHTTPDNSClusters(rpcClient.Context(), &pb.FindAllHTTPDNSClustersRequest{})
	if err != nil {
		return err
	}
	clusters := map[int64]*pb.HTTPDNSCluster{}
	for _, cluster := range clusterResp.GetClusters() {
		if cluster == nil || cluster.GetId() <= 0 {
			continue
		}
		clusters[cluster.GetId()] = cluster
	}

	appResp, err := rpcClient.HTTPDNSAppRPC.FindAllHTTPDNSApps(rpcClient.Context(), &pb.FindAllHTTPDNSAppsRequest{})
	if err != nil {
		return err
	}

	apps := map[string]*LoadedApp{}
	for _, app := range appResp.GetApps() {
		if app == nil || app.GetId() <= 0 || len(app.GetAppId()) == 0 {
			continue
		}

		domainResp, err := rpcClient.HTTPDNSDomainRPC.ListHTTPDNSDomainsWithAppId(rpcClient.Context(), &pb.ListHTTPDNSDomainsWithAppIdRequest{
			AppDbId: app.GetId(),
		})
		if err != nil {
			log.Println("[HTTPDNS_NODE][snapshot]list domains failed, appId:", app.GetAppId(), "err:", err.Error())
			continue
		}

		domains := map[string]*LoadedDomain{}
		for _, domain := range domainResp.GetDomains() {
			if domain == nil || domain.GetId() <= 0 || len(domain.GetDomain()) == 0 {
				continue
			}
			ruleResp, err := rpcClient.HTTPDNSRuleRPC.ListHTTPDNSCustomRulesWithDomainId(rpcClient.Context(), &pb.ListHTTPDNSCustomRulesWithDomainIdRequest{
				DomainId: domain.GetId(),
			})
			if err != nil {
				log.Println("[HTTPDNS_NODE][snapshot]list rules failed, domain:", domain.GetDomain(), "err:", err.Error())
				continue
			}

			domains[strings.ToLower(strings.TrimSpace(domain.GetDomain()))] = &LoadedDomain{
				Domain: domain,
				Rules:  ruleResp.GetRules(),
			}
		}

		apps[strings.ToLower(strings.TrimSpace(app.GetAppId()))] = &LoadedApp{
			App:     app,
			Domains: domains,
		}
	}

	snapshot := &LoadedSnapshot{
		LoadedAt:  time.Now().UnixNano(),
		NodeID:    nodeResp.GetNode().GetId(),
		ClusterID: nodeResp.GetNode().GetClusterId(),
		Clusters:  clusters,
		Apps:      apps,
	}

	m.locker.Lock()
	m.snapshot = snapshot
	m.locker.Unlock()

	reportRuntimeLog("info", "config", "snapshot", "snapshot refreshed: "+reason, fmt.Sprintf("snapshot-%d", time.Now().UnixNano()))

	// timezone sync - prefer current node's cluster timezone
	var timeZone string
	if snapshot.ClusterID > 0 {
		if cluster := clusters[snapshot.ClusterID]; cluster != nil && len(cluster.GetTimeZone()) > 0 {
			timeZone = cluster.GetTimeZone()
		}
	}
	// fallback to any non-empty cluster timezone for compatibility
	if len(timeZone) == 0 {
		for _, cluster := range clusters {
			if cluster != nil && len(cluster.GetTimeZone()) > 0 {
				timeZone = cluster.GetTimeZone()
				break
			}
		}
	}
	if len(timeZone) == 0 {
		timeZone = "Asia/Shanghai"
	}
	if m.timezone != timeZone {
		location, err := time.LoadLocation(timeZone)
		if err != nil {
			log.Println("[HTTPDNS_NODE][TIMEZONE]change time zone failed:", err.Error())
		} else {
			log.Println("[HTTPDNS_NODE][TIMEZONE]change time zone to '" + timeZone + "'")
			time.Local = location
			m.timezone = timeZone
		}
	}

	return nil
}