package main

import (
	"fmt"
	"hash/fnv"
	"strconv"
	"sync"

	"git.mstar.dev/mstar/goutils/other"
	// "github.com/patrickmn/go-cache"
)

// var valCache = cache.New(time.Minute, time.Minute*2)
var valCacheMap = map[uint64]uint64{}
var mLock sync.RWMutex

func hash(val uint64, iter, maxIter int) uint64 {
	h := fnv.New64a()

	_, err := h.Write([]byte(fmt.Sprintf("%d.%d.%d", val, iter, maxIter)))
	if err != nil {
		panic(err)
	}
	return h.Sum64()
}

func fromCache(val uint64, iteration, maxIter int) (uint64, bool) {
	mLock.RLock()
	pv, ok := valCacheMap[hash(val, iteration, maxIter)]
	mLock.RUnlock()
	// v, ok := valCache.Get(strconv.FormatUint(hash(val, iteration, maxIter), 10))
	// if !ok {
	// 	return 0, false
	// }
	// pv, ok := v.(uint64)
	return pv, ok
}

func intoCache(val uint64, iteration, maxIter int, result uint64) {
	mLock.Lock()
	valCacheMap[hash(val, iteration, maxIter)] = result
	mLock.Unlock()
	// valCache.Set(strconv.FormatUint(hash(val, iteration, maxIter), 10), result, -1)
}

func Advance(val uint64, iteration int, maxIter int) (out uint64) {
	cacheVal, ok := fromCache(val, iteration, maxIter)
	if ok {
		return cacheVal
	}
	defer func() {
		if _, ok := fromCache(val, iteration, maxIter); !ok {
			intoCache(val, iteration, maxIter, out)
		}
	}()
	// fmt.Printf("Iteration %d with val %d\n", iteration, val)
	if iteration == maxIter {
		// fmt.Println("1")
		out = 1
		return
	}
	if val == 0 {
		// fmt.Println("0")
		out = Advance(1, iteration+1, maxIter)
		return
	}
	if len(strconv.FormatUint(val, 10))%2 == 0 {
		// fmt.Println("Split")
		str := strconv.FormatUint(val, 10)
		// fmt.Println("format")
		left := other.Must(strconv.ParseUint(string([]rune(str)[:len(str)/2]), 10, 64))
		right := other.Must(strconv.ParseUint(string([]rune(str)[len(str)/2:]), 10, 64))
		// fmt.Printf("l: %d, r: %d\n", left, right)
		out = Advance(left, iteration+1, maxIter) + Advance(right, iteration+1, maxIter)
		return
	}
	out = Advance(val*2024, iteration+1, maxIter)
	return out
}