// Package handler provides HTTP handlers for various endpoints.
package handler

import (
	"context"
	"fmt"
	"net/http"
	"sync"

	"modelRT/constants"
	"modelRT/logger"
	"modelRT/network"

	"github.com/gin-gonic/gin"
	"github.com/gofrs/uuid"
)

var globalMonitorState *SharedMonitorState

func init() {
	globalMonitorState = NewSharedMonitorState()
}

// RealTimeMonitorHandler define real time data monitor process API
// @Summary 开始或结束实时数据监控
// @Description 根据用户输入的组件token,从 modelRT 服务中开始或结束对于实时数据的监控
// @Tags RealTime Component
// @Accept json
// @Produce json
// @Router /data/realtime [get]
func RealTimeMonitorHandler(c *gin.Context) {
	var request network.RealTimeQueryRequest
	var monitorAction string
	var monitorID string

	if err := c.ShouldBindJSON(&request); err != nil {
		logger.Error(c, "failed to unmarshal real time query request", "error", err)
		c.JSON(http.StatusOK, network.FailureResponse{
			Code: http.StatusBadRequest,
			Msg:  err.Error(),
		})
		return
	}

	if request.Action == constants.MonitorStartAction && request.MonitorID == "" {
		monitorAction = request.Action
		id, err := uuid.NewV4()
		if err != nil {
			logger.Error(c, "failed to generate monitor id", "error", err)
			c.JSON(http.StatusOK, network.FailureResponse{
				Code: http.StatusBadRequest,
				Msg:  err.Error(),
			})
			return
		}
		monitorID = id.String()
	} else if request.Action == constants.MonitorStartAction && request.MonitorID != "" {
		monitorAction = constants.MonitorAppendAction
		monitorID = request.MonitorID
	} else if request.Action == constants.MonitorStopAction && request.MonitorID != "" {
		monitorAction = request.Action
		monitorID = request.MonitorID
	}

	switch monitorAction {
	case constants.MonitorStartAction:
		err := globalMonitorState.CreateConfig(monitorID, request.Components)
		if err != nil {
			logger.Error(c, "create real time data monitor config failed", "error", err)
			c.JSON(http.StatusOK, network.FailureResponse{
				Code: http.StatusBadRequest,
				Msg:  err.Error(),
			})
			return
		}

		c.JSON(http.StatusOK, network.SuccessResponse{
			Code: http.StatusOK,
			Msg:  "success",
			PayLoad: map[string]interface{}{
				"monitor_id": monitorID,
			},
		})
		return
	case constants.MonitorStopAction:
		globalMonitorState.RemoveTargets(c, monitorID, request.Components)
	case constants.MonitorAppendAction:
		err := globalMonitorState.AppendTargets(monitorID, request.Components)
		if err != nil {
			logger.Error(c, "append target to real time data monitor config failed", "error", err)
			c.JSON(http.StatusOK, network.FailureResponse{
				Code: http.StatusBadRequest,
				Msg:  err.Error(),
			})
			return
		}
	default:
		err := fmt.Errorf("%w: %s", constants.ErrUnsupportedAction, request.Action)
		logger.Error(c, "unsupported action of real time data monitor request", "error", err)
		c.JSON(http.StatusOK, network.FailureResponse{
			Code: http.StatusBadRequest,
			Msg:  err.Error(),
		})
		return
	}
}

// RealTimeMonitorComponent define struct of real time monitor component
type RealTimeMonitorComponent struct {
	targets []string
}

// RealTimeMonitorConfig define struct of real time monitor config
type RealTimeMonitorConfig struct {
	noticeChan chan struct{}
	components map[string]*RealTimeMonitorComponent
}

// SharedMonitorState define struct of shared monitor state with mutex
type SharedMonitorState struct {
	monitorMap map[string]*RealTimeMonitorConfig
	mutex      sync.RWMutex
}

// NewSharedMonitorState define function to create new SharedMonitorState
func NewSharedMonitorState() *SharedMonitorState {
	return &SharedMonitorState{
		monitorMap: make(map[string]*RealTimeMonitorConfig),
	}
}

// CreateConfig define function to create config in SharedMonitorState
func (s *SharedMonitorState) CreateConfig(monitorID string, components []network.RealTimeComponentItem) error {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	if _, exist := s.monitorMap[monitorID]; exist {
		return fmt.Errorf("monitorID %s already exists. Use AppendTargets to modify existing config", monitorID)
	}

	config := &RealTimeMonitorConfig{
		noticeChan: make(chan struct{}),
		components: make(map[string]*RealTimeMonitorComponent),
	}

	for _, compent := range components {
		config.components[compent.Interval] = &RealTimeMonitorComponent{
			targets: compent.Targets,
		}
	}

	s.monitorMap[monitorID] = config
	return nil
}

// AppendTargets define function to append targets in SharedMonitorState
func (s *SharedMonitorState) AppendTargets(monitorID string, components []network.RealTimeComponentItem) error {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	config, exist := s.monitorMap[monitorID]
	if !exist {
		return fmt.Errorf("monitorID %s not found. Use CreateConfig to start a new config", monitorID)
	}

	for _, compent := range components {
		interval := compent.Interval
		comp, compExist := config.components[interval]
		if !compExist {
			comp = &RealTimeMonitorComponent{
				targets: comp.targets,
			}
			config.components[interval] = comp

		} else {
			comp.targets = append(comp.targets, comp.targets...)
		}
	}

	config.noticeChan <- struct{}{}
	return nil
}

// UpsertTargets define function to upsert targets in SharedMonitorState
func (s *SharedMonitorState) UpsertTargets(monitorID string, interval string, newTargets []string) (isNewMonitor bool, err error) {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	config, exist := s.monitorMap[monitorID]
	if !exist {
		config = &RealTimeMonitorConfig{
			noticeChan: make(chan struct{}),
			components: make(map[string]*RealTimeMonitorComponent),
		}
		config.components[interval] = &RealTimeMonitorComponent{
			targets: newTargets,
		}
		s.monitorMap[monitorID] = config
		return true, nil
	}

	comp, compExist := config.components[interval]
	if !compExist {
		comp = &RealTimeMonitorComponent{
			targets: newTargets,
		}
		config.components[interval] = comp
	} else {
		comp.targets = append(comp.targets, newTargets...)
	}
	return false, nil
}

// Get define function to get value from SharedMonitorState
func (s *SharedMonitorState) Get(monitorID, interval string) ([]string, bool) {
	s.mutex.RLock()
	defer s.mutex.RUnlock()

	config, ok := s.monitorMap[monitorID]
	if !ok {
		return nil, false
	}

	component, ok := config.components[interval]
	if !ok {
		return nil, false
	}
	return component.targets, true
}

// RemoveTargets define function to remove targets in SharedMonitorState
func (s *SharedMonitorState) RemoveTargets(ctx context.Context, monitorID string, components []network.RealTimeComponentItem) error {
	s.mutex.Lock()
	defer s.mutex.Unlock()

	config, exist := s.monitorMap[monitorID]
	if !exist {
		return fmt.Errorf("monitorID %s not found", monitorID)
	}

	for _, compent := range components {
		interval := compent.Interval
		comp, compExist := config.components[interval]
		if !compExist {
			logger.Error(ctx, fmt.Sprintf("component with interval %s not found under monitorID %s", interval, monitorID), "monitorID", monitorID, "interval", interval)
			continue
		}

		targetsToRemoveMap := make(map[string]struct{})
		for _, target := range compent.Targets {
			targetsToRemoveMap[target] = struct{}{}
		}

		var newTargets []string
		for _, existingTarget := range comp.targets {
			if _, found := targetsToRemoveMap[existingTarget]; !found {
				newTargets = append(newTargets, existingTarget)
			}
		}
		comp.targets = newTargets

		if len(comp.targets) == 0 {
			delete(config.components, interval)
		}
	}

	if len(config.components) == 0 {
		delete(s.monitorMap, monitorID)
	}

	config.noticeChan <- struct{}{}
	return nil
}