package poker

import (
	"sort"

	gopoker "github.com/chehsunliu/poker"
)

// HandRank evaluates the best 5-card hand from the given cards (hole + community).
// Returns a rank value where lower is better (1 = royal flush).
func HandRank(cards []string) int32 {
	gocards := make([]gopoker.Card, len(cards))
	for i, c := range cards {
		gocards[i] = gopoker.NewCard(c)
	}
	return gopoker.Evaluate(gocards)
}

// HandDescription returns a human-readable description of the best hand.
func HandDescription(cards []string) string {
	gocards := make([]gopoker.Card, len(cards))
	for i, c := range cards {
		gocards[i] = gopoker.NewCard(c)
	}
	return gopoker.RankString(gopoker.Evaluate(gocards))
}

// Winner represents a player and their hand rank at showdown.
type Winner struct {
	Username string
	Rank     int32
	Desc     string
}

// Showdown evaluates all active players' hands against the community cards
// and returns winners sorted best to worst. Ties are included.
// hands maps username -> []string of hole cards (2 cards).
// community is the board (3-5 cards).
func Showdown(hands map[string][]string, community []string) []Winner {
	results := make([]Winner, 0, len(hands))
	for username, hole := range hands {
		all := append(hole, community...)
		rank := HandRank(all)
		results = append(results, Winner{
			Username: username,
			Rank:     rank,
			Desc:     HandDescription(all),
		})
	}
	// Sort ascending — lower rank value = better hand
	sort.Slice(results, func(i, j int) bool {
		return results[i].Rank < results[j].Rank
	})
	return results
}

// Winners returns only the players who tied for best hand.
func Winners(hands map[string][]string, community []string) []Winner {
	all := Showdown(hands, community)
	if len(all) == 0 {
		return nil
	}
	best := all[0].Rank
	var winners []Winner
	for _, w := range all {
		if w.Rank == best {
			winners = append(winners, w)
		}
	}
	return winners
}