package main

import (
	"encoding/json"
	"errors"
	"io/ioutil"
	"log"
	"os"
)

//chat state that we might be use for collecting infomation from user
type chatState struct {
	//back pointer style information, managed by general process
	OpenID    string `json:"OpenID"`    //whom is this belongs to
	Procedure string `json:"Procedure"` //which procedure this belongs to

	//below is managed by procedure only
	//real state information
	Name   string `json:"Name"`   //state name
	Expire int32  `json:"Expire"` //unix timestamp  when this state expire

	//persistant sate
	Save map[string]string `json:"Save"` //the state save some data for later usage

	//runtime memory only
	response string //被动回复消息的内容
}

//for individual state
func getCurrentState(openID string, procedure string) (result chatState, err error) {
	path := getProcedurePath(openID, procedure)
	//log.Printf("read state from %s\r\n", path)
	body, err := ioutil.ReadFile(path)
	if err != nil { //read file error
		if isFileExist(path) {
			log.Println("Error session reading " + path)
		}
		return //empty and expired session
	}
	err = json.Unmarshal(body, &result)
	if err != nil {
		log.Printf("Session Content [path=%s] not correct: ", path)
		log.Println(err)
	}
	err = sanityCheckState(openID, procedure, result)
	return
}

func sanityCheckState(openID, procedure string, result chatState) (err error) {
	//check whether state is for the correct openID and procedure
	if result.OpenID != openID {
		err = errors.New("Error: State for " + openID + " is actually for " + result.OpenID)
		return
	}

	if result.Procedure != procedure {
		err = errors.New("Error: Proecdure for " + procedure + " is actually for " + result.Procedure)
		return
	}
	return
}

func setCurrentState(openID, procedure string, state chatState) (newState chatState, err error) {
	state.OpenID = openID
	state.Procedure = procedure

	j, err := json.Marshal(state)
	if err != nil {
		return
	}
	path := getProcedurePath(openID, procedure)
	err = ioutil.WriteFile(path, j, 0600)
	if err != nil {
		log.Println("write state error" + path)
		log.Println(err)
		return
	}
	newState = state
	return
}

func deleteChatState(openID, procedure string) (err error) {
	path := getProcedurePath(openID, procedure)
	err = os.Remove(path)
	return
}

//ValidationResult After input validation, what is the result
type ValidationResult struct {
	accept  bool
	Hint    string
	Error   string
	Warning string
}

//Validator function type for validating all wechat inputs
type Validator func(s chatState) ValidationResult

func saveChatState(state chatState) {

}