card_id/common/game/card/deck.go

package card

import (
	"fmt"

	"git.tuxpa.in/a/card_id/common/data"
	"lukechampine.com/frand"
)

// a table is a collection of results

type Deck struct {
	Cards []Card

	TotalProbability float64
}

func NewDeck(r data.Results) *Deck {
	out := &Deck{}
	out.Cards = make([]Card, 0, len(r))
	for _, v := range r {
		out.Cards = append(out.Cards, new(Card).FromResult(v))
		out.TotalProbability = out.TotalProbability + v.Rate
	}
	return out
}

func (t *Deck) Draw() Card {
	selector := frand.Float64() * t.TotalProbability
	sofar := 0.0
	for _, v := range t.Cards {
		sofar = sofar + v.Rate
		if sofar >= selector-0.000000001 {
			return v
		}
	}
	return Card{
		Id:   0,
		Name: fmt.Sprintf("please report this bug: %v", selector),
		Rate: selector,
	}
}