package main

import (
	"errors"
	"log"
	"os"
	"time"
)

//start a procedure
func startProcedure(openID, procedure string) (err error) {
	//init procedure state
	init := getProcedureInit(openID, procedure)
	if init == nil {
		msg := "FATAL: cannot initialize procedure [" + procedure + "] "
		err = errors.New(msg)
		return
	}
	//init and get initial state
	state := init(openID)

	//save it
	setCurrentState(openID, procedure, state)

	//next is to waiting for user's input
	//which may or may not happen very soon
	return
}

//resume a previous Procedure's state
func resumeProcedure(openID, procedure string) (err error) {
	state, err := getCurrentState(openID, procedure)
	if err != nil {
		return
	}
	//re-introduce what we are doing
	//	showProcIntro(openID, peocedure)
	//tell user what has been achieved
	//	showProcSumary(openID, procedure)

	return processProcedureState(state)
}

//finish a procedure, regardless its been finished or not
//normally not finished normally
func cleanProcedure(openID, procedure string) {
	path := getProcedurePath(openID, procedure)
	os.Remove(path)
	log.Println("Clearing [" + openID + "] @ [" + procedure + "]")

	//TODO: save session to "" procedure
}

func processProcedureState(state chatState) (err error) {
	//send what we need to send
	if isExpired(state.Expire) {
		return errors.New("State has expired " + state.Name)
	}
	//mark we have sent.

	//do we need input? waiting for input

	//if not, what is next state

	log.Println(state)
	return
}

func getProcedureInit(openID, procedure string) initProcFunc {
	initFunc := map[string]initProcFunc{
		"TestDummy":        nil,
		"TestEcho":         initTestEcho,
		"GetBasicUserInfo": initGetBasicUserInfo,
		"GetEmailAddr":     initGetBasicUserInfo,
	}
	return initFunc[procedure]
}

func initTestEcho(openid string) (r chatState) {
	r.Name = openid
	r.Expire = int32(time.Now().Unix() + 100)
	return
}

//are we inside a procedure, and not finished?
func isInProc(openID string) (result bool, state chatState) {
	r, err := getCurrentSesssion(openID)
	if err != nil {
		return false, state
	}

	if isExpired(r.Expire) {
		return false, state
	}

	state, err = getCurrentState(openID, r.Procedure)
	if err != nil || isExpired(state.Expire) {
		return false, state
	}
	return true, state
}

//follow procedure, if there is any
func serveProc(state chatState, input InWechatMsg) (next chatState) {
	return
}