blah/main.go

package main

import (
	"flag"
	"fmt"
	"log"
	"math/rand"
	"os"
	"strings"
)

const (
	identifierURL = "https://mtgjson.com/api/v5/AllIdentifiers.json"
	pricesURL     = "https://mtgjson.com/api/v5/AllPricesToday.json"
)

type CardRecord struct {
	card  Card           `json:"card"`
	price CardPriceEntry `json:"price"`
}

func main() {
	identifierFile := flag.String("i", "AllIdentifiers.json", "identifier file (AllIdentifiers.json), if not found it will be downloaded")
	pricesFile := flag.String("p", "AllPricesToday.json", "prices file (AllPricesToday.json), if not found it will be downloaded")
	priceFilter := flag.Float64("price", 0.04, "Maximum card price allowed (in whole units of any currency)")
	typeFilter := flag.String("remove-types", "token,emblem,sticker,card,hero,plane,scheme", "comma-separated list of card types to remove")
	cardsPerDraft := flag.Int("packSize", 100, "How many cards to put in each \"dollar store\" pack")
	packCount := flag.Int("packCount", 2, "How many \"dollar store\" pack to generate")
	landLimit := flag.Int("landLimit", 5, "Limit how many lands to put in each pack (0 to disable)")
	flag.Parse()

	priceChan := make(chan []CardPriceEntry)
	cardChan := make(chan map[string]Card)

	log.Println(" == Loading data... ==")
	go loadAsync(loadCardInfos(*identifierFile), cardChan)
	go loadAsync(loadPrices(*pricesFile, *priceFilter), priceChan)

	cards := <-cardChan
	prices := <-priceChan

	// Filter cards
	forbiddenTypes := make(map[string]struct{})
	for _, t := range strings.Split(*typeFilter, ",") {
		forbiddenTypes[t] = struct{}{}
	}

	var filtered []CardRecord
	for _, price := range prices {
		entry := cards[price.UUID]

		// Filter card types we don't want
		typeOk := true
		for _, t := range entry.Types {
			if _, ok := forbiddenTypes[strings.ToLower(t)]; ok {
				typeOk = false
				break
			}
		}
		if !typeOk {
			continue
		}

		filtered = append(filtered, CardRecord{
			card:  entry,
			price: price,
		})
	}

	types := make(map[string]int)
	for _, record := range filtered {
		log.Printf("Price for %s: %.2f %s at %s\n", record.card.Name, record.price.Price, record.price.Currency, record.price.Seller)
		for _, t := range record.card.Types {
			types[strings.ToUpper(t)[0:1]+t[1:]]++
		}
	}

	log.Println(" == Stats ==")
	log.Printf("Found %d cards\n", len(filtered))
	for t, count := range types {
		log.Printf(" - %s: %d\n", t, count)
	}

	log.Println(" == Generating packs... ==")
	for i := 0; i < *packCount; i++ {
		pack := generatePack(filtered, *cardsPerDraft, *landLimit)
		checkErr(os.WriteFile(fmt.Sprintf("pack-%d.txt", i), []byte(serializePack(pack)), 0644))
	}

	log.Println(" == Done ==")
}

func isType(card Card, askingType string) bool {
	for _, t := range card.Types {
		if strings.ToLower(t) == strings.ToLower(askingType) {
			return true
		}
	}
	return false
}

func serializePack(pack []CardRecord) (out string) {
	for _, card := range pack {
		out += "1 " + card.card.Name + "\n"
	}
	return
}

func generatePack(filtered []CardRecord, cardsPerDraft, landLimit int) []CardRecord {
	// Pick random cards
	randCards := make([]CardRecord, 0)
	landCount := 0
	for len(randCards) < cardsPerDraft {
		pick := filtered[rand.Intn(len(filtered))]
		if isType(pick.card, "land") {
			if landLimit > 0 && landCount >= landLimit {
				continue
			} else {
				landCount++
			}
		}
		randCards = append(randCards, pick)
	}
	return randCards
}

func checkErr(err error) {
	if err != nil {
		log.Printf("Fatal error: %s\n", err.Error())
		os.Exit(1)
	}
}

func loadAsync[T any](fn func() (T, error), chn chan T) {
	out, err := fn()
	checkErr(err)
	chn <- out
}