package day7

import (
	"fmt"
	"log"
	"os"
	"slices"
	"strconv"
	"strings"
)

func Run() int {
	fmt.Print("hello day 7")
	filename := "day7/input"
	input := ReadFile(filename)
	slices.SortFunc(input, CompareHands)
	// log.Printf("read the input %+v\n", input)
	for _, hand := range input {
		// fmt.Printf("%+v\n", hand)
		fmt.Printf("%+s\t\t%d\n", hand.Cards, hand.HandType)
	}
	slices.SortFunc([]int{}, func(a int, b int) int { return 0 })
	result := 0
	for i, hand := range input {
		result += (i+1) * hand.Bid
	}
	return result
}

type HandType int

const (
	HighCard = iota
	OnePair
	TwoPair
	ThreeKind
	FullHouse
	FourKind
	FiveKind
)

type Hand struct {
	Cards    string
	Grouped  map[rune]int
	HandType HandType
	Bid      int
}

// cmp(a, b) should return a negative number when a < b, a positive number when
// a > b and zero when a == b.
const values string = "J23456789TQKA"

func CompareHands(a Hand, b Hand) int {
	if a.HandType != b.HandType {
		return int(a.HandType) - int(b.HandType)
	}
	return compareString(a.Cards, b.Cards)
}

func compareString(a string, b string) int {
	for i := 0; i < len(a); i++ {
		if a[i] == b[i] {
			continue
		}
		aVal := strings.IndexRune(values, rune(a[i]))
		bVal := strings.IndexRune(values, rune(b[i]))
		return aVal - bVal
	}
	return 0
}

func GetHandType(groupped map[rune]int) HandType {
	var handType HandType
	jokerSize, found := groupped['J']
	if !found {
		jokerSize = 0
	}
	sizes := make([]int, 0, len(groupped))
	for card, size := range groupped {
		if card != 'J' {
			sizes = append(sizes, size)
		}
	}
	slices.SortFunc(sizes, func (a, b int) int { return b - a })
	var highest int
	if len(sizes) == 0 {
		highest = jokerSize
	} else {
		highest = sizes[0] + jokerSize
	}
	if highest == 5 {
		return FiveKind
	}
	if highest == 4 {
		return FourKind
	}
	other := sizes[1]
	if highest == 3 {
		if other == 2 {
			return FullHouse
		}
		return ThreeKind
	}
	if highest == 2 {
		if other == 2 {
			return TwoPair
		}
		return OnePair
	}

	// log.Printf("calc type for %+v.\nsizes: %+v;\n %d", groupped, sizes, handType)
	return handType
}

func ReadFile(filename string) []Hand {
	bytes, err := os.ReadFile(filename)
	if err != nil {
		panic(fmt.Sprintln("error reading file : ", filename))
	}
	text := string(bytes)
	lines := strings.Split(text, "\n")
	linesLen := len(lines)
	result := make([]Hand, 0, linesLen)

	for _, line := range lines {
		log.Println("reading in line : ", line)
		if line == "" {
			continue
		}
		firstSplit := strings.Fields(line)
		cards := firstSplit[0]
		bidStr := firstSplit[1]
		bid, err := strconv.Atoi(bidStr)
		if err != nil {
			panic(fmt.Sprintln("error getting bid from : ", bidStr))
		}
		groupped := make(map[rune]int, 0)
		for _, card := range cards {
			groupped[card] += 1
		}
		hand := Hand{
			Cards:   cards,
			Grouped: groupped,
			Bid:     bid,
			HandType: GetHandType(groupped),
		}
		result = append(result, hand)
	}

	return result
}