package tickets

import (
	"sync"
	"time"
)

// Discord doesn't send a dropdown's value along with a button click, so the
// panel's category pick is remembered here between the two interactions:
// per guild and member, for a short while, in memory. A bot restart forgets
// it, which only means picking the category again.
const (
	pickTTL  = 15 * time.Minute
	maxPicks = 10000 // a ceiling, so a flood of picks can't grow this forever
)

type pickKey struct{ guild, user int64 }

type pick struct {
	category int64
	at       time.Time
}

var (
	picksMu sync.Mutex
	picks   = map[pickKey]pick{}
	now     = time.Now
)

// RememberPick records the category a member chose in the panel dropdown.
func RememberPick(guildID, userID, categoryID int64) {
	picksMu.Lock()
	defer picksMu.Unlock()
	t := now()
	k := pickKey{guildID, userID}
	if _, ok := picks[k]; !ok && len(picks) >= maxPicks {
		for k, p := range picks {
			if t.Sub(p.at) > pickTTL {
				delete(picks, k)
			}
		}
		if len(picks) >= maxPicks {
			return
		}
	}
	picks[k] = pick{categoryID, t}
}

// PickedCategory returns the category a member chose, if they did recently.
func PickedCategory(guildID, userID int64) (int64, bool) {
	picksMu.Lock()
	defer picksMu.Unlock()
	p, ok := picks[pickKey{guildID, userID}]
	if !ok || now().Sub(p.at) > pickTTL {
		delete(picks, pickKey{guildID, userID})
		return 0, false
	}
	return p.category, true
}