package mux

import (
	"github.com/bwmarrin/discordgo"
	"time"
sc	"strconv"
	"container/list"
	"fmt"
	"os"
	"encoding/json"
	"strings"
)


// Channel for posting reminders -- inits in main
var RemChan chan Reminder

// Stores a reminder to be posted to a given user
type Reminder struct {
	NotifyAfter	time.Time
	Reason		string
	User			discordgo.User
	ChannelID	string
	Session		discordgo.Session
}

// Reminder daemon process that gets started in main and listens on RemChan
func Reminders() {
	// TODO -- Should be a heap and more robus (fix config first)
	
	rems := list.New()
	
	RD:
	f, err := os.Open("./cfg/reminders.cfg")
	
	write := func() (rerr error) {
		e := json.NewEncoder(f)
		err = e.Encode(rems)
		if err != nil {
			fmt.Println("Error writing config, see: remind.go")
			fmt.Printf("%s\n", err)
			rerr = err
		}
		return
	}
	
	setup := func() (rerr error) {
		
		err := os.Mkdir("./cfg", 0774)
		if err != nil {
			fmt.Println("Error in making cfg dir, see: remind.go")
			fmt.Println(err)
		}
		
		_, err = os.Create("cfg/reminders.cfg")
		if err != nil {
			fmt.Println("Error in making cfg file, see: remind.go")
			fmt.Println(err)
		}
		rerr = err
		return
	}
	
	defer f.Close()
	if err != nil {
		if strings.Contains(err.Error(), "no such file or directory") {
			// danger: this can go infinite
			setup()
			goto RD
		} else {
			fmt.Println("Error opening config (r), see: remind.go")
			fmt.Printf("%s\n", err)
		}
	} else {
		d := json.NewDecoder(f)
		err = d.Decode(&rems)
		if err != nil {
			fmt.Println("Error reading config, see: remind.go")
			fmt.Printf("%s\n", err)
			
			write()
		}
	}
	

	// Handle reminders
	for {
		select {
		case r := <- RemChan:
			// Handle new reminder
			rems.PushBack(r)
			write()
			
		default:
			// Check for any due reminders
			for e := rems.Front(); ; e = e.Next() {
				if e == nil {
					break
				}
				
				r, _ := e.Value.(Reminder)
				if time.Now().After(r.NotifyAfter) {
					// If we have passed the time of desired notification
					r.Session.ChannelMessageSend(r.ChannelID, r.User.Mention() + " -- " + r.Reason)
					rems.Remove(e)
					write()
				}
			}
		
			time.Sleep(50 * time.Millisecond)
		}
	}
}

// Reminds a user about a given reason after a specified time interval has passed
func (m *Mux) RemindMe(ds *discordgo.Session, dm *discordgo.Message, ctx *Context) {
	resp := ""
	
	// remindme 20m dothing
	if len(ctx.Fields) >= 3 {
		var rem Reminder
		periodLong := ctx.Fields[1]
		reasonLong := ctx.Fields[2 : len(ctx.Fields)]
		rem.User = *dm.Author
		rem.ChannelID = dm.ChannelID
		rem.Session = *ds
		
		reason := ""
		for _, v := range reasonLong {
			reason += v
			reason += " "
		}
		rem.Reason = reason
		
		interval := periodLong[len(periodLong)-1]
		period, err := sc.Atoi(periodLong[:len(periodLong)-1])
		if err != nil {
			resp += "Invalid period value."
			goto SEND
		}
		
		var dur time.Duration
		switch interval {
		case 's':
			dur = time.Second
		case 'm':
			dur = time.Minute
		case 'h':
			dur = time.Hour
		case 'd':
			dur = time.Hour * time.Duration(24)
		default:
			resp += "Invalid interval specifier."
			goto SEND
		}

		rem.NotifyAfter = time.Now().Add(time.Duration(period) * dur)
		
		RemChan <- rem
		
		resp += "Ok."
		
	} else {
		resp += "Please specify a time operator in the form [int][type] and a description (20h do thing)."
	}
	
	SEND:
	resp += "\n"

	ds.ChannelMessageSend(dm.ChannelID, resp)

	return
}