package service

import (
	"atsflare/common"
	"atsflare/model"
	"encoding/json"
	"errors"
	"strings"
	"time"

	"gorm.io/gorm"
)

const (
	NodeStatusOnline  = "online"
	NodeStatusOffline = "offline"
	NodeStatusPending = "pending"
	ApplyResultOK     = "success"
	ApplyResultFailed = "failed"
)

type AgentNodePayload struct {
	NodeID         string `json:"node_id"`
	Name           string `json:"name"`
	IP             string `json:"ip"`
	AgentVersion   string `json:"agent_version"`
	NginxVersion   string `json:"nginx_version"`
	CurrentVersion string `json:"current_version"`
	LastError      string `json:"last_error"`
}

type ApplyLogPayload struct {
	NodeID  string `json:"node_id"`
	Version string `json:"version"`
	Result  string `json:"result"`
	Message string `json:"message"`
}

type AgentConfigResponse struct {
	Version        string        `json:"version"`
	Checksum       string        `json:"checksum"`
	RenderedConfig string        `json:"rendered_config"`
	SupportFiles   []SupportFile `json:"support_files"`
	CreatedAt      time.Time     `json:"created_at"`
}

type AgentSettings struct {
	HeartbeatInterval int    `json:"heartbeat_interval"`
	SyncInterval      int    `json:"sync_interval"`
	AutoUpdate        bool   `json:"auto_update"`
	UpdateRepo        string `json:"update_repo"`
	UpdateNow         bool   `json:"update_now"`
	UpdateChannel     string `json:"update_channel"`
	UpdateTag         string `json:"update_tag"`
}

type HeartbeatResponse struct {
	Node          *model.Node    `json:"node"`
	AgentSettings *AgentSettings `json:"agent_settings"`
}

type NodeView struct {
	ID                 uint       `json:"id"`
	NodeID             string     `json:"node_id"`
	Name               string     `json:"name"`
	IP                 string     `json:"ip"`
	AgentToken         string     `json:"agent_token"`
	AutoUpdateEnabled  bool       `json:"auto_update_enabled"`
	UpdateRequested    bool       `json:"update_requested"`
	UpdateChannel      string     `json:"update_channel"`
	UpdateTag          string     `json:"update_tag"`
	AgentVersion       string     `json:"agent_version"`
	NginxVersion       string     `json:"nginx_version"`
	Status             string     `json:"status"`
	CurrentVersion     string     `json:"current_version"`
	LastSeenAt         time.Time  `json:"last_seen_at"`
	LastError          string     `json:"last_error"`
	LatestApplyResult  string     `json:"latest_apply_result"`
	LatestApplyMessage string     `json:"latest_apply_message"`
	LatestApplyAt      *time.Time `json:"latest_apply_at"`
	CreatedAt          time.Time  `json:"created_at"`
	UpdatedAt          time.Time  `json:"updated_at"`
}

func RegisterNode(node *model.Node, payload AgentNodePayload) (*AgentRegistrationResponse, error) {
	return RegisterNodeWithAgentToken(node, payload)
}

func HeartbeatNode(node *model.Node, payload AgentNodePayload) (*HeartbeatResponse, error) {
	common.SysLog("agent heartbeat received: node_id=" + node.NodeID + " current_version=" + strings.TrimSpace(payload.CurrentVersion))
	payload.NodeID = node.NodeID
	payload = normalizeAgentNodePayload(payload)
	if err := validateAgentNodePayload(payload); err != nil {
		return nil, err
	}
	updateNow := node.UpdateRequested
	updateChannel := normalizeReleaseChannel(node.UpdateChannel)
	updateTag := strings.TrimSpace(node.UpdateTag)
	applyNodeRuntime(node, payload, true)
	node.UpdateRequested = false
	node.UpdateChannel = ReleaseChannelStable.String()
	node.UpdateTag = ""
	if err := model.DB.Model(node).Select("ip", "agent_version", "nginx_version", "status", "current_version", "last_seen_at", "last_error", "update_requested", "update_channel", "update_tag").Updates(node).Error; err != nil {
		return nil, err
	}
	return &HeartbeatResponse{
		Node: node,
		AgentSettings: &AgentSettings{
			HeartbeatInterval: common.AgentHeartbeatInterval,
			SyncInterval:      common.AgentSyncInterval,
			AutoUpdate:        node.AutoUpdateEnabled,
			UpdateRepo:        common.AgentUpdateRepo,
			UpdateNow:         updateNow,
			UpdateChannel:     updateChannel.String(),
			UpdateTag:         updateTag,
		},
	}, nil
}

func GetActiveConfigForAgent() (*AgentConfigResponse, error) {
	version, err := model.GetActiveConfigVersion()
	if err != nil {
		common.SysError("agent requested active config but no active version is available")
		return nil, err
	}
	var supportFiles []SupportFile
	if version.SupportFilesJSON != "" {
		if err = json.Unmarshal([]byte(version.SupportFilesJSON), &supportFiles); err != nil {
			return nil, err
		}
	}
	common.SysLog("agent fetched active config: version=" + version.Version + " checksum=" + version.Checksum)
	return &AgentConfigResponse{
		Version:        version.Version,
		Checksum:       version.Checksum,
		RenderedConfig: version.RenderedConfig,
		SupportFiles:   supportFiles,
		CreatedAt:      version.CreatedAt,
	}, nil
}

func ReportApplyLog(payload ApplyLogPayload) (*model.ApplyLog, error) {
	now := time.Now()
	payload.NodeID = strings.TrimSpace(payload.NodeID)
	payload.Version = strings.TrimSpace(payload.Version)
	payload.Result = strings.TrimSpace(strings.ToLower(payload.Result))
	payload.Message = strings.TrimSpace(payload.Message)
	if payload.NodeID == "" {
		return nil, errors.New("node_id 不能为空")
	}
	if payload.Version == "" {
		return nil, errors.New("version 不能为空")
	}
	if payload.Result != ApplyResultOK && payload.Result != ApplyResultFailed {
		return nil, errors.New("result 仅支持 success 或 failed")
	}
	common.SysLog("agent apply log received: node_id=" + payload.NodeID + " version=" + payload.Version + " result=" + payload.Result)

	log := &model.ApplyLog{
		NodeID:    payload.NodeID,
		Version:   payload.Version,
		Result:    payload.Result,
		Message:   payload.Message,
		CreatedAt: now,
	}
	err := model.DB.Transaction(func(tx *gorm.DB) error {
		node := &model.Node{}
		if err := tx.Where("node_id = ?", payload.NodeID).First(node).Error; err != nil {
			return err
		}
		node.Status = NodeStatusOnline
		node.LastSeenAt = now
		if payload.Result == ApplyResultOK {
			node.CurrentVersion = payload.Version
			node.LastError = ""
		} else {
			node.LastError = payload.Message
		}
		if err := tx.Create(log).Error; err != nil {
			return err
		}
		return tx.Model(node).Select("status", "last_seen_at", "current_version", "last_error").Updates(node).Error
	})
	if err != nil {
		return nil, err
	}
	if payload.Result == ApplyResultOK {
		common.SysLog("agent apply reported success: node_id=" + payload.NodeID + " version=" + payload.Version)
	} else {
		common.SysError("agent apply reported failure: node_id=" + payload.NodeID + " version=" + payload.Version + " message=" + payload.Message)
	}
	return log, nil
}

func ListNodeViews() ([]*NodeView, error) {
	nodes, err := model.ListNodes()
	if err != nil {
		return nil, err
	}
	views := make([]*NodeView, 0, len(nodes))
	for _, node := range nodes {
		computedStatus := computeNodeStatus(node)
		if node.Status != computedStatus {
			if computedStatus == NodeStatusOffline {
				common.SysError("node offline: node_id=" + node.NodeID + " name=" + node.Name + " ip=" + node.IP + " last_seen_at=" + node.LastSeenAt.Format(time.RFC3339))
			} else if computedStatus == NodeStatusOnline {
				common.SysLog("node online: node_id=" + node.NodeID + " name=" + node.Name + " ip=" + node.IP)
			}
			_ = model.DB.Model(node).Update("status", computedStatus).Error
			node.Status = computedStatus
		}
		view := buildNodeView(node)
		view.Status = computedStatus
		if log, err := model.GetLatestApplyLog(node.NodeID); err == nil {
			view.LatestApplyResult = log.Result
			view.LatestApplyMessage = log.Message
			view.LatestApplyAt = &log.CreatedAt
		}
		views = append(views, view)
	}
	return views, nil
}

func ListApplyLogs(nodeID string) ([]*model.ApplyLog, error) {
	return model.ListApplyLogs(strings.TrimSpace(nodeID))
}

func upsertNode(payload AgentNodePayload) (*model.Node, error) {
	return nil, errors.New("不再支持匿名自动注册")
}

func computeNodeStatus(node *model.Node) string {
	if node == nil {
		return NodeStatusOffline
	}
	if node.LastSeenAt.IsZero() {
		return NodeStatusPending
	}
	if time.Since(node.LastSeenAt) > common.NodeOfflineThreshold {
		return NodeStatusOffline
	}
	return NodeStatusOnline
}