package main

import (
	"fmt"
	"slices"
	"strconv"
	"strings"

	"git.mstar.dev/mstar/aoc24/util"
	"git.mstar.dev/mstar/goutils/other"
	"git.mstar.dev/mstar/goutils/sliceutils"
)

/*
Gameplan:
1. Einlesen als roh linien
2. Linien bis \n\n sind Regeln
3. Jede Linie danach muss den Regeln folgen
4. Regeln in zwei maps speichern
  - 1. Map zuvor -> []danach: Jede nr hat eine Liste an nr, welche nach key kommen müssen
  - 2. Map danach -> []zuvor: Jede nr hat eine liste an nr, welche vor key kommen müssen
5.
*/

type RulePair struct {
	Left, Right int
}

func parseRule(rule string) (int, int) {
	tmp := strings.Split(rule, "|")
	return other.Must(strconv.Atoi(tmp[0])), other.Must(strconv.Atoi(tmp[1]))
}

func parseUpdate(line string) []int {
	tmp := strings.Split(line, ",")
	return sliceutils.Map(tmp, func(t string) int { return other.Must(strconv.Atoi(t)) })
}

func checkUpdateWithRules(rulesAfter, rulesBefore map[int][]int, update []int) bool {
	for i, num := range update {
		for _, elem := range update[:i] {
			if sliceutils.Contains(rulesAfter[num], elem) {
				// fmt.Printf("%v failed rule %d: %v\n", update, num, rulesAfter[num])
				return false
			}
		}
		for _, elem := range update[i:] {
			if sliceutils.Contains(rulesBefore[num], elem) {
				// fmt.Printf("%v failed rule %d: %v\n", update, num, rulesBefore[num])
				return false
			}
		}
	}
	return true
}

func getCenterVal(elems []int) int {
	return elems[len(elems)/2]
}

func sortByRules(nrsIn []int, rules []RulePair) []int {
	nrsToUse := slices.Clone(nrsIn)
	_ = nrsToUse
	nrsOut := []int{}
	sortedAfterRules := slices.Clone(rules)
	slices.SortFunc(
		rules,
		func(a, b RulePair) int { return a.Left - b.Left },
	)
	for len(sortedAfterRules) != 0 {
		popAt := []int{}
		for i, rule := range sortedAfterRules {
			if !sliceutils.Contains(nrsToUse, rule.Left) ||
				!sliceutils.Contains(nrsToUse, rule.Right) {
				popAt = append(popAt, i)
			}
		}
	}

	return nrsOut
}

func findLowestIndex(inSlice, elems []int) int {
	index := len(inSlice)
	for _, elem := range elems {
		i := slices.Index(inSlice, elem)
		if i < index {
			index = i
		}
	}
	if index == len(inSlice) {
		return -1
	}
	return index
}

func main() {
	blocks := strings.Split(string(util.LoadFileFromArgs()), "\n\n")
	ruleLines := sliceutils.Filter(
		strings.Split(blocks[0], "\n"),
		func(t string) bool { return len(t) != 0 },
	)
	applyLines := sliceutils.Filter(
		strings.Split(blocks[1], "\n"),
		func(t string) bool { return len(t) != 0 },
	)

	rulesAfter := map[int][]int{}
	rulesBefore := map[int][]int{}
	rulePairs := []RulePair{}

	for _, rule := range ruleLines {
		before, after := parseRule(rule)
		rulesAfter[before] = append(rulesAfter[before], after)
		rulesBefore[after] = append(rulesBefore[after], before)
		rulePairs = append(rulePairs, RulePair{before, after})
	}
	for k, nums := range rulesBefore {
		slices.Sort(nums)
		rulesBefore[k] = sliceutils.RemoveDuplicate(nums)
	}
	for k, nums := range rulesAfter {
		slices.Sort(nums)
		rulesAfter[k] = sliceutils.RemoveDuplicate(nums)
	}
	// fmt.Printf("Rules before a number: %v\nRules after a number: %v\n", rulesBefore, rulesAfter)
	updates := sliceutils.Map(applyLines, func(t string) []int { return parseUpdate(t) })
	correctUpdates := [][]int{}
	incorrectUpdates := [][]int{}
	for _, update := range updates {
		if checkUpdateWithRules(rulesAfter, rulesBefore, update) {
			correctUpdates = append(correctUpdates, update)
		} else {
			incorrectUpdates = append(incorrectUpdates, update)
		}
	}
	_ = incorrectUpdates

	acc := 0
	for _, elems := range correctUpdates {
		acc += getCenterVal(elems)
	}
	fmt.Printf("Task 1: %d\n", acc)
	// fmt.Printf("#rulesBefore: %d, #rulesAfter: %d\n", len(rulesBefore), len(rulesAfter))
	// allRuleNumbers := []int{}
	// for k, _ := range rulesBefore {
	// allRuleNumbers = append(allRuleNumbers, k)
	// }
	// for k, _ := range rulesAfter {
	// allRuleNumbers = append(allRuleNumbers, k)
	// }
	// allRuleNumbers = sliceutils.RemoveDuplicate(allRuleNumbers)
	// fmt.Printf("#allRuleNumbers: %d, allRuleNumbers: %v \n", len(allRuleNumbers), allRuleNumbers)
	for i := range incorrectUpdates {
		fmt.Printf("Checking invalid update %v\n", incorrectUpdates[i])
		for !checkUpdateWithRules(rulesAfter, rulesBefore, incorrectUpdates[i]) {
			// Go over every element in the update
		updateLoop:
			for ie, elem := range incorrectUpdates[i] {
				// Get all rules where the current number is on the right side of the rule (has to come after)
				appliedRulesLeft := sliceutils.Filter(rulePairs, func(t RulePair) bool {
					return elem == t.Right
				})
				// Same but current number is on the left (has to come before)
				appliedRulesRight := sliceutils.Filter(rulePairs, func(t RulePair) bool {
					return elem == t.Left
				})
				for _, rule := range appliedRulesLeft {
					// If rule violation, swap the two elements
					if il := slices.Index(incorrectUpdates[i][:ie], rule.Left); il != -1 {
						fmt.Printf("Swapping according to rule %#v\n", rule)
						incorrectUpdates[i][ie] = rule.Left
						incorrectUpdates[i][il] = elem
						break updateLoop
					}
				}
				for _, rule := range appliedRulesRight {
					if ir := slices.Index(incorrectUpdates[i][ie:], rule.Right); ir != -1 {
						fmt.Printf("Swapping according to rule %#v\n", rule)
						incorrectUpdates[i][ie] = rule.Right
						incorrectUpdates[i][ir] = elem
						break updateLoop
					}
				}
			}
		}
	}

	acc = 0
	for _, elems := range incorrectUpdates {
		acc += getCenterVal(elems)
	}
	fmt.Printf("Task 2: %d\n", acc)
}