package memory

import (
	"context"
	"sync"

	"git.threesix.ai/jordan/slack-auth-1770277926/services/auth-api/internal/domain"
	"git.threesix.ai/jordan/slack-auth-1770277926/services/auth-api/internal/port"
)

// Compile-time verification that UserRepository implements port.UserRepository.
var _ port.UserRepository = (*UserRepository)(nil)

// UserRepository is a thread-safe in-memory implementation of port.UserRepository.
type UserRepository struct {
	mu    sync.RWMutex
	users map[domain.UserID]*domain.User
}

// NewUserRepository creates a new in-memory user repository.
func NewUserRepository() *UserRepository {
	return &UserRepository{
		users: make(map[domain.UserID]*domain.User),
	}
}

// Get returns a user by ID.
// Returns domain.ErrUserNotFound if not found.
func (r *UserRepository) Get(ctx context.Context, id domain.UserID) (*domain.User, error) {
	r.mu.RLock()
	defer r.mu.RUnlock()

	u, ok := r.users[id]
	if !ok {
		return nil, domain.ErrUserNotFound
	}
	// Return a copy to prevent external mutation
	cpy := *u
	return &cpy, nil
}

// GetByEmail returns a user by email address.
// Returns domain.ErrUserNotFound if not found.
func (r *UserRepository) GetByEmail(ctx context.Context, email string) (*domain.User, error) {
	r.mu.RLock()
	defer r.mu.RUnlock()

	for _, u := range r.users {
		if u.Email == email {
			// Return a copy to prevent external mutation
			cpy := *u
			return &cpy, nil
		}
	}
	return nil, domain.ErrUserNotFound
}

// Create stores a new user.
func (r *UserRepository) Create(ctx context.Context, user *domain.User) error {
	r.mu.Lock()
	defer r.mu.Unlock()

	// Store a copy to prevent external mutation
	cpy := *user
	r.users[user.ID] = &cpy
	return nil
}

// ExistsByEmail checks if a user with the given email exists.
func (r *UserRepository) ExistsByEmail(ctx context.Context, email string) (bool, error) {
	r.mu.RLock()
	defer r.mu.RUnlock()

	for _, u := range r.users {
		if u.Email == email {
			return true, nil
		}
	}
	return false, nil
}