package main

import (
	"fmt"

	h "git.bullercodeworks.com/brian/adventofcode/helpers"
)

type Node struct {
	value int
	prev  *Node
	next  *Node
}

func main() {
	inp := h.StdinToStringSlice()
	part1(inp)
	part2(inp)
}

func part1(inp []string) {
	var list []*Node
	var first *Node
	for i := range inp {
		n := &Node{value: h.Atoi(inp[i])}
		if n.value == 0 {
			first = n
		}
		list = append(list, n)
	}
	initList(list)
	mixAll(list)
	fmt.Println("# Part 1")
	fmt.Println(getCoords(first))
}

func part2(inp []string) {
	key := 811589153
	var list []*Node
	var first *Node
	for i := range inp {
		n := &Node{value: h.Atoi(inp[i]) * key}
		if n.value == 0 {
			first = n
		}
		list = append(list, n)
	}
	initList(list)
	for i := 0; i < 10; i++ {
		mixAll(list)
	}
	fmt.Println("# Part 2")
	fmt.Println(getCoords(first))
}

func initList(list []*Node) {
	list[0].prev = list[len(list)-1]
	list[len(list)-1].next = list[0]
	for i := 1; i < len(list); i++ {
		list[i].prev = list[i-1]
		list[i-1].next = list[i]
	}
}

func move(n *Node, count int) *Node {
	for count < 0 {
		n = n.prev
		count++
	}
	for count > 0 {
		n = n.next
		count--
	}
	return n
}

func mix(n *Node, listLen int) {
	t := n.prev
	n.prev.next = n.next
	n.next.prev = n.prev
	t = move(t, n.value%(listLen-1))
	n.prev = t
	n.next = t.next
	n.prev.next = n
	n.next.prev = n
}

func mixAll(list []*Node) {
	for _, n := range list {
		mix(n, len(list))
	}
}

func getCoords(first *Node) int {
	var res int
	for i, n := 0, first; i < 3; i++ {
		n = move(n, 1000)
		res += n.value
	}
	return res
}