package emqx

import (
	mqtt "github.com/eclipse/paho.mqtt.golang"
	"strings"
)

type HookHandler func(*Context)
type HandlerFunc func(*Context)

type Engine struct {
	*Options
	Topic      string
	TopicLen   int
	Wildcard   bool
	Shared     bool
	ShareGroup string
	node       *node
	BeforeHook []HookHandler
	AfterHook  []HookHandler
}

func (o *Options) NewEngine(topic string, wildcard bool) (eng *Engine) {
	eng = &Engine{
		Options:  o,
		Topic:    topic,
		Wildcard: wildcard,
		node: &node{
			Options: o,
		},
	}
	eng.checkTopic()
	o.Engine = append(o.Engine, eng)
	return
}

func (e *Engine) checkTopic() {
	if e.Topic[0] == '/' {
		e.Logger.Fatal("topic禁止以'/'符号开头")
	}
	if e.Topic[len(e.Topic)-1] == '/' {
		e.Logger.Fatal("topic禁止以'/'符号开头")
	}
	e.TopicLen = len(strings.Split(e.Topic, "/"))
}

func (e *Engine) UseBefore(handler ...HookHandler) {
	e.BeforeHook = handler
}

func (e *Engine) UseAfter(handler ...HookHandler) {
	e.AfterHook = handler
}

// Register 注册方法到前缀树
func (e *Engine) Register(url string, handler HandlerFunc) {
	if handler == nil {
		e.Logger.Fatal("此topic未绑定方法")
	}
	e.checkUrl(url)
	path := e.splitUrl(url)
	for i, s := range path {
		if s == "" {
			path = append(path[:i], path[i+1:]...)
		}
	}
	e.node = e.node.addRoute(path, handler)
}

// WithShare 注册共享订阅
func (e *Engine) WithShare(group string) {
	e.Shared = true
	if group == "" {
		e.ShareGroup = "default"
	}
	e.ShareGroup = group
}

// distribute 接收到topic后进行分发
func (e *Engine) distribute(client mqtt.Client, msg mqtt.Message) {
	go e.handle(client, msg)
}

// handle 分发到具体的逻辑方法
func (e *Engine) handle(client mqtt.Client, msg mqtt.Message) {
	path := strings.Split(msg.Topic(), "/")[e.TopicLen:]
	logic := e.node.FindRoute(path)
	if logic == nil {
		e.Logger.Error("未找到对应的方法", msg.Topic())
		return
	}

	context := NewContext(client, msg, path)

	for _, hookHandler := range e.BeforeHook {
		hookHandler(context)
	}
	logic.Handler(context)
	for _, hookHandler := range e.AfterHook {
		hookHandler(context)
	}
}

func (e *Engine) splitUrl(url string) []string {
	urlList := strings.Split(url, "/")
	for i, s := range urlList {
		if s == "" {
			urlList = append(urlList[:i], urlList[i+1:]...)
		}
	}
	return urlList
}

func (e *Engine) checkUrl(url string) {
	if url == "" {
		return
	}
	if url[0] != '/' {
		e.Logger.Fatal("路由必须以'/'符号开头")
	}
	if url[len(url)-1] == '/' {
		e.Logger.Fatal("路由禁止以'/'符号开头")
	}
}