package mcp

import (
	"crypto/rand"
	"encoding/hex"
	"sync"
)

type SessionStore struct {
	mu sync.RWMutex
	m  map[string]struct{}
}

func NewSessionStore() *SessionStore {
	return &SessionStore{m: make(map[string]struct{})}
}

func (s *SessionStore) Issue() string {
	b := make([]byte, 16)
	_, _ = rand.Read(b)
	id := hex.EncodeToString(b)

	s.mu.Lock()
	s.m[id] = struct{}{}
	s.mu.Unlock()
	return id
}

func (s *SessionStore) Valid(id string) bool {
	s.mu.RLock()
	defer s.mu.RUnlock()
	_, ok := s.m[id]
	return ok
}

func (s *SessionStore) Drop(id string) {
	s.mu.Lock()
	delete(s.m, id)
	s.mu.Unlock()
}