package main

import (
	"errors"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
	"sync/atomic"
	"syscall"
	"time"

	"fyne.io/fyne/v2"
	"git.gensokyo.uk/cat/discord"
)

var (
	pidS        = strconv.Itoa(os.Getpid())
	hostname    string
	launchTime  = time.Now().UTC()
	replCounter atomic.Uint64
)

var substitute = map[string]func(s *applyState) string{
	"pid": func(_ *applyState) string {
		return pidS
	},
	"hostname": func(_ *applyState) string {
		return hostname
	},
	"1min": func(s *applyState) string {
		s.populateLoadavg()
		return s.loadavg[0]
	},
	"5min": func(s *applyState) string {
		s.populateLoadavg()
		return s.loadavg[1]
	},
	"15min": func(s *applyState) string {
		s.populateLoadavg()
		return s.loadavg[2]
	},
	"used": func(s *applyState) string {
		s.populateMem()
		return fmt.Sprintf("%.1f GiB", float64(s.mem[1]-s.mem[0])/(1<<20))
	},

	"total": func(s *applyState) string {
		s.populateMem()
		return fmt.Sprintf("%.1f GiB", float64(s.mem[1])/(1<<20))
	},
}

type applyState struct {
	loadavg *[3]string
	mem     *[2]int
}

func (s *applyState) replace(t string) string {
	for k, f := range substitute {
		t = strings.ReplaceAll(t, "%"+k, f(s))
		go func() {
			replCounter.Add(uint64(len(t)))
			statusReplaces.SetText(strconv.Itoa(int(replCounter.Load())) + " bytes")
		}()
	}
	return t
}

func apply() {
	prof := conf.profile()

	// open new client if ID changes
	if d.ID() != prof.ID {
		// close previous client
		if err := d.Close(); err != nil {
			log.Fatalf("error closing previous client: %s", err)
		}

		// open new client
		d = discord.New(prof.ID)
	}

	confLock.RLock()
	act := *prof.Activity
	s := &applyState{}

	act.State = s.replace(act.State)
	act.Details = s.replace(act.Details)
	act.Timestamps = &discord.ActivityTimestamps{Start: launchTime.Unix()}
	act.Assets = &discord.ActivityAssets{
		LargeImage: act.Assets.LargeImage,
		LargeText:  s.replace(act.Assets.LargeText),
		SmallImage: act.Assets.SmallImage,
		SmallText:  s.replace(act.Assets.SmallText),
	}
	confLock.RUnlock()

	if nonce, err := retry(&act, s); err != nil {
		log.Fatalf("error setting activity: %s", err)
	} else {
		log.Printf("activity updated with nonce %s", nonce)
	}
}

var retryTicker = time.NewTicker(100 * time.Millisecond)

func retry(act *discord.Activity, s *applyState) (nonce string, err error) {
	fyne.DoAndWait(func() { uiUpdateClientInfo(s) })

	for range retryTicker.C {
		nonce, err = d.SetActivity(act)
		if err == nil {
			break
		}

		if errors.Is(err, syscall.EINTR) || errors.Is(err, discord.ErrNonce) {
			log.Println("retrying in 100 milliseconds...")
		} else {
			log.Printf("cannot set activity: %v", err)
		}
		fyne.DoAndWait(func() { uiSetFailureState(false) })
	}
	fyne.DoAndWait(func() { uiSetFailureState(true) })

	return
}