package day19

import (
	"fmt"
	"log"
	"os"
	"regexp"
	"strconv"
	"strings"
	"sync"
)

func Run() int {
	fmt.Println("hello day 19. sorting parts")
	filename := "day19/example"

	bytes, err := os.ReadFile(filename)
	if err != nil {
		panic(fmt.Sprint("cannot read file ", filename))
	}

	text := string(bytes)

	split := strings.Split(text, "\n\n")

	sorters := ReadSorters(split[0])
	details := ReadDetailsPart(split[1])

	log.Printf("yay, got sorters\n%+v\nand details\n%+v", sorters, details)

	countApproved := CountApprovedDetails(details, sorters)

	return countApproved
}

func CountApprovedDetails(details []DetailData, sorters map[string]SorterData) int {
	var wg sync.WaitGroup
	wg.Add(len(details))

	approvedDetails := make(chan DetailData)

	go func(){
		wg.Wait()
		close(approvedDetails)
	}()

	count := 0
	acceptedScore := 0

	done := make(chan any)

	go func(){
		for detail := range approvedDetails {
			log.Println("got approved ", detail)
			count += 1
			for _, attrValue := range detail.Attrs {
				acceptedScore += attrValue
			}
		}
		close(done)
	}()

	for _, d := range details {
		go func(d DetailData) {
			log.Print("> starting for ", d)
			isAccepted := ProcessDetail(d, sorters)
			if isAccepted {
				log.Println("> accepting ", d)
				approvedDetails <- d
			} else {
				log.Println("> rejecting ", d)
			}
			wg.Done()
		}(d)
	}

	<- done

	return acceptedScore
}

type Operation rune
const (LessThan Operation = '<'
	MoreThan Operation = '>'
)

type OperationData struct {
	AttrName string
	Operation Operation
	Num int
	SentToName string
	String string
}

type SorterData struct {
	Name string
	DefaultState string
	Operations []OperationData
}

func ReadSorters(sortersText string) map[string]SorterData {
	result := make(map[string]SorterData)
	sortersText = strings.TrimSpace(sortersText)
	lines := strings.Split(sortersText, "\n")

	for _, line := range lines {
		sorter := ReadSorterLine(line)
		result[sorter.Name] = sorter
	}

	return result
}

// qqz{s>2770:qs,m<1801:hdj,R}
func ReadSorterLine(line string) (result SorterData) {
	re1 := regexp.MustCompile(`(?P<NAME>\D+){(?P<OPERATIONS>.+)}`)

	firstSplit := re1.FindStringSubmatch(line)

	result.Name = firstSplit[1]

	operationLines := strings.Split(firstSplit[2], ",")
	operations := make([]OperationData, len(operationLines) - 1)
	result.Operations = operations

	result.DefaultState = operationLines[len(operationLines) - 1]

	for i, line := range operationLines[:len(operationLines) - 1] {
		operations[i] = ReadOperationLine(line)
	}

	log.Printf("mathed %s got %+v; operations : %+v\n", line, firstSplit, operations)

	return
}

// s>2770:qs
func ReadOperationLine(line string) (result OperationData) {
	result.String = line
	re := regexp.MustCompile(`(?P<ATTRNAME>\D)(?P<OPERATION>[\>\<])(?P<NUMBER>\d+):(?P<TARGET>\D+)`)
	split := re.FindStringSubmatch(line)
	log.Printf("matching operation %s into %+v\n", line, split)
	result.AttrName = split[1]
	result.Operation = Operation([]rune(split[2])[0])
	result.SentToName = split[4]
	num, err := strconv.Atoi(split[3])
	if err != nil {
		panic(fmt.Sprintf("error getting number %s in line %s. %s", split[3], line, err))
	}
	result.Num = num
	return
}

// drop last operations which target same 'next' as default. these check are not necessary
func SimplifyOperation(sorter SorterData) SorterData {
	actualLast := len(sorter.Operations) - 1
	for i := actualLast; i >= 0; i-- {
		if sorter.Operations[i].SentToName != sorter.DefaultState {
			break
		}
		actualLast -= 1
	}

	sorter.Operations = sorter.Operations[:actualLast+1]

	return sorter
}

type DetailData struct {
	Attrs map[string]int
}

func ReadDetailsPart(text string) (result []DetailData) {
	text = strings.TrimSpace(text)
	for _, line := range strings.Split(text, "\n") {
		result = append(result, ReadDetailLine(line))
	}
	return
}

// {x=787,m=2655,a=1222,s=2876}
func ReadDetailLine(line string) (result DetailData) {
	attrs := make(map[string]int)
	result.Attrs = attrs
	line = line[1:len(line)-1]
	attrsLine := strings.Split(line, ",")
	re := regexp.MustCompile(`(?P<ATTR>\D)=(?P<NUM>\d+)`)
	for _, attrLine := range attrsLine {
		split := re.FindStringSubmatch(attrLine)
		attrName := split[1]
		num, err := strconv.Atoi(split[2])
		if err != nil {
			panic(fmt.Sprint("error parsing detail ", line))
		}

		attrs[attrName] = num
	}
	return
}

func ProcessDetail(d DetailData, sorters map[string]SorterData) (isAccepted bool) {
	curSorterName := "in"
	for (curSorterName != "A" && curSorterName != "R") {
		sorter, found := sorters[curSorterName]
		if !found {
			panic(fmt.Sprint("error finding soter ", curSorterName))
		}
		curSorterName = sorter.NextSorterNameFor(d)
	}
	return curSorterName == "A"
}

func (s SorterData)NextSorterNameFor(d DetailData) string {
	for _, operation := range s.Operations {
		if operation.IsDetailPassing(d) {
			return operation.SentToName
		}
	}

	return s.DefaultState
}

func (o OperationData)IsDetailPassing(d DetailData) bool {
	detailValue := d.Attrs[o.AttrName]
	switch o.Operation {
	case LessThan:
		return detailValue < o.Num
	case MoreThan:
		return detailValue > o.Num
	}

	panic(fmt.Sprint("unknown operation. ", o, d))
}