package day9

import (
	"fmt"
	"slices"

	"gitea.paas.celticinfo.fr/oabrivard/aoc2023/utils"
)

func SumLastTerms(lines []string, reverse bool) int {
	result := 0

	for _, line := range lines {
		values := utils.ParseIntArray(line, " ")
		if reverse {
			slices.Reverse(values)
		}

		stack := [][]int{}
		stack = append(stack, values)

		for {
			top := stack[len(stack)-1]

			allZeros := utils.Fold(true, top, func(acc bool, curr int) bool { return acc && curr == 0 })
			if allZeros {
				break
			}

			newTop := make([]int, len(top)-1)
			for i := 1; i < len(top); i++ {
				newTop[i-1] = top[i-1] - top[i]
			}

			stack = append(stack, newTop)
		}

		newVal := stack[len(stack)-1][0]
		for i := len(stack) - 2; i >= 0; i-- {
			newVal = stack[i][0] + newVal
		}

		fmt.Println(newVal)
		result += newVal
	}

	return result
}