package authz

import (
	"context"
	"tercul/internal/domain"
	platform_auth "tercul/internal/platform/auth"
)

// Service provides authorization checks for the application.
type Service struct {
	workRepo        domain.WorkRepository
	authorRepo      domain.AuthorRepository
	userRepo        domain.UserRepository
	translationRepo domain.TranslationRepository
}

// NewService creates a new authorization service.
func NewService(workRepo domain.WorkRepository, authorRepo domain.AuthorRepository, userRepo domain.UserRepository, translationRepo domain.TranslationRepository) *Service {
	return &Service{
		workRepo:        workRepo,
		authorRepo:      authorRepo,
		userRepo:        userRepo,
		translationRepo: translationRepo,
	}
}

// CanEditWork checks if a user has permission to edit a work.
// For now, we'll implement a simple rule: only an admin or the work's author can edit it.
func (s *Service) CanEditWork(ctx context.Context, userID uint, work *domain.Work) (bool, error) {
	claims, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}

	// Admins can do anything.
	if claims.Role == string(domain.UserRoleAdmin) {
		return true, nil
	}

	user, err := s.userRepo.GetByID(ctx, userID)
	if err != nil {
		return false, err
	}

	author, err := s.authorRepo.FindByName(ctx, user.Username)
	if err != nil {
		// If the author profile doesn't exist for the user, they can't be the author.
		return false, nil
	}

	// Check if the user is an author of the work.
	isAuthor, err := s.workRepo.IsAuthor(ctx, work.ID, author.ID)
	if err != nil {
		return false, err
	}
	if isAuthor {
		return true, nil
	}

	return false, domain.ErrForbidden
}

// CanDeleteWork checks if a user has permission to delete a work.
func (s *Service) CanDeleteWork(ctx context.Context, userID uint, work *domain.Work) (bool, error) {
	claims, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}

	// Admins can do anything.
	if claims.Role == string(domain.UserRoleAdmin) {
		return true, nil
	}

	user, err := s.userRepo.GetByID(ctx, userID)
	if err != nil {
		return false, err
	}

	author, err := s.authorRepo.FindByName(ctx, user.Username)
	if err != nil {
		// If the author profile doesn't exist for the user, they can't be the author.
		return false, nil
	}

	// Check if the user is an author of the work.
	isAuthor, err := s.workRepo.IsAuthor(ctx, work.ID, author.ID)
	if err != nil {
		return false, err
	}
	if isAuthor {
		return true, nil
	}

	return false, domain.ErrForbidden
}

// CanEditEntity checks if a user has permission to edit a specific translatable entity.
func (s *Service) CanEditEntity(ctx context.Context, userID uint, translatableType string, translatableID uint) (bool, error) {
	switch translatableType {
	case "works":
		// For works, we can reuse the CanEditWork logic.
		// First, we need to fetch the work.
		work, err := s.workRepo.GetByID(ctx, translatableID)
		if err != nil {
			return false, err // Handles not found, etc.
		}
		return s.CanEditWork(ctx, userID, work)
	default:
		// For now, deny all other types by default.
		// This can be expanded later.
		return false, domain.ErrForbidden
	}
}

// CanDeleteTranslation checks if a user can delete a translation.
func (s *Service) CanDeleteTranslation(ctx context.Context, userID uint, translationID uint) (bool, error) {
	claims, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}

	// Admins can do anything.
	if claims.Role == string(domain.UserRoleAdmin) {
		return true, nil
	}

	translation, err := s.translationRepo.GetByID(ctx, translationID)
	if err != nil {
		return false, err
	}

	if translation.TranslatorID != nil && *translation.TranslatorID == userID {
		return true, nil
	}

	return false, domain.ErrForbidden
}

// CanUpdateUser checks if a user has permission to update another user's profile.
func (s *Service) CanCreateWork(ctx context.Context) (bool, error) {
	claims, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}
	if claims.Role == string(domain.UserRoleAdmin) {
		return true, nil
	}
	return false, domain.ErrForbidden
}

func (s *Service) CanCreateTranslation(ctx context.Context) (bool, error) {
	_, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}
	return true, nil
}

func (s *Service) CanEditTranslation(ctx context.Context, userID uint, translationID uint) (bool, error) {
	claims, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}

	// Admins can do anything.
	if claims.Role == string(domain.UserRoleAdmin) {
		return true, nil
	}

	// Check if the user is the translator of the translation.
	translation, err := s.translationRepo.GetByID(ctx, translationID)
	if err != nil {
		return false, err
	}

	if translation.TranslatorID != nil && *translation.TranslatorID == userID {
		return true, nil
	}

	return false, domain.ErrForbidden
}

func (s *Service) CanCreateBook(ctx context.Context) (bool, error) {
	_, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}
	return true, nil
}

func (s *Service) CanUpdateBook(ctx context.Context) (bool, error) {
	claims, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}
	if claims.Role == string(domain.UserRoleAdmin) {
		return true, nil
	}
	return false, domain.ErrForbidden
}

func (s *Service) CanDeleteBook(ctx context.Context) (bool, error) {
	claims, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}
	if claims.Role == string(domain.UserRoleAdmin) {
		return true, nil
	}
	return false, domain.ErrForbidden
}

func (s *Service) CanUpdateUser(ctx context.Context, actorID, targetUserID uint) (bool, error) {
	claims, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}

	// Admins can do anything.
	if claims.Role == string(domain.UserRoleAdmin) {
		return true, nil
	}

	// Users can update their own profile.
	if actorID == targetUserID {
		return true, nil
	}

	return false, domain.ErrForbidden
}

// CanDeleteComment checks if a user has permission to delete a comment.
// For now, we'll implement a simple rule: only an admin or the comment's author can delete it.
func (s *Service) CanDeleteComment(ctx context.Context, userID uint, comment *domain.Comment) (bool, error) {
	claims, ok := platform_auth.GetClaimsFromContext(ctx)
	if !ok {
		return false, domain.ErrUnauthorized
	}

	// Admins can do anything.
	if claims.Role == string(domain.UserRoleAdmin) {
		return true, nil
	}

	// Check if the user is the author of the comment.
	if comment.UserID == userID {
		return true, nil
	}

	return false, domain.ErrForbidden
}