const FileMIMEDirectory = "inode/directory"

var ErrNoDirectory = errors.New("http: there is no such directory")

type ActivitiesReadRequest struct {
	// UserID is unique identifier of user who owns requested activities.
	UserID uuid.UUID

	// Last is identifier of the last activity from previous query.
	Last uuid.UUID
}

type ActivitiesReadResponse struct {
	// ID is unique id of new activity record.
	ID uuid.UUID

	// Type of activity record.
	Type string

	// CreatedAt points to the point in time when given activity
	// was created.
	CreatedAt time.Time

	// Details consist flat map of key/value records that will be
	// presented to user and system administrator, to provide useful
	// debug informations related to given action.
	Details map[string]any
}

type ActivitiesReader interface {
	// ActivitiesReadInit initializes querying user activities. It returns
	// limited number of user activities. You can use last user's activity ID
	// from given slice and ActivitiesReadFrom method to query for more entries.
	ActivitiesReadInit(ctx context.Context, userID uuid.UUID) ([]ActivitiesReadResponse, error)

	// ActivitiesRead returns list of activities owned by user with given user ID that were
	// created before activity with given last ID.
	ActivitiesRead(ctx context.Context, req ActivitiesReadRequest) ([]ActivitiesReadResponse, error)
}

type DirectoryCreator interface {
	// DirectoryCreate creates new directory with requested properties.
	DirectoryCreate(ctx context.Context, req NewDirectoryRequest) (*NewFileResponse, error)
}

type DirectoryReadResponse struct {
	// Name of directory.
	Name string

	// Parent of current directory. Can be null if it's root directory.
	Parent uuid.NullUUID

	// Children are filed stored in requested directory.
	Children []FileMetadata
}

type DirectoryReader interface {
	// DirectoryRead returns useful metadata of directory with given ID and
	// its children files.
	DirectoryRead(context.Context, uuid.UUID) (*DirectoryReadResponse, error)
}

type FileCommandService interface {
	FileSystemCreator
	FileContentUpdater
	FileNameUpdater
	FileDeleter
}

type FileContentUpdater interface {
	// FileUpdateContent updates content of the file with given unique ID.
	FileUpdateContent(ctx context.Context, req FileUpdateContentRequest) error
}

type FileCreator interface {
	// FileCreate creates new file with requested properties.
	FileCreate(ctx context.Context, req NewFileRequest) (*NewFileResponse, error)
}

type FileDeleter interface {
	// FileDelete removes file or directory with given unique ID from
	// filesystem. All children of removed directory are also removed.
	//
	// It is impossible to delete any root file with this method.
	FileDelete(ctx context.Context, id uuid.UUID) error
}

type FileDirectoryReader interface {
	FileReader
	DirectoryReader
}

type FileMetadata struct {
	// Name of the file.
	Name string

	// FileID is unique file's ID.
	FileID uuid.UUID

	// MIME is media type of the file.
	MIME string
}

type FileNameUpdater interface {
	// FileUpdateName updates name of the file with given unique ID.
	FileUpdateName(ctx context.Context, req FileUpdateNameRequest) error
}

type FileQueryService interface {
	RootDirectoryDiscoverer
	FileDirectoryReader
}

type FileReadResponse struct {
	FileMetadata

	// Parent of the requested file.
	Parent uuid.NullUUID

	// Content of the file.
	Content []byte
}

type FileReader interface {
	// FileRead returns metadata and content of the file with given ID.
	FileRead(context.Context, uuid.UUID) (*FileReadResponse, error)
}

type FileService struct {
	FileQueryService
	FileCommandService
}

type FileSystemCreator interface {
	FileCreator
	DirectoryCreator
}

type FileUpdateContentRequest struct {
	// ID is unique identifier of file.
	ID uuid.UUID

	// Content is the new content of the file.
	Content []byte
}

type FileUpdateNameRequest struct {
	// ID is unique identifier of file.
	ID uuid.UUID

	// Name is new file's name.
	Name string
}

type HandlersDependencies struct {
	Config  *config.Service
	Session *httpx.CookiesSession
	UsersReader
	UserRegisterer
	UsersBatchRegisterer
	UserPasswordChanger
	UserPasswordUpdater
	UserDeleter
	ActivitiesReader
	*FileService
}

type NewDirectoryRequest struct {
	// Owner is unique identifier of owner user.
	Owner uuid.UUID

	// Parent is parent's unique identifier.
	Parent uuid.UUID

	// Name of new directory.
	Name string
}

type NewFileRequest struct {
	// Owner is unique identifier of owner user.
	Owner uuid.UUID

	// Parent is parent's unique identifier.
	Parent uuid.UUID

	// Filename is the name of new file.
	Filename string

	// FilenameExtension is the filename extension of new file.
	FilenameExtension string
}

type NewFileResponse struct {
	// ID is unique identifier of new file or directory.
	ID uuid.UUID
}

type RootDirectoryDiscoverer interface {
	// RootDirectory returns unique identifier of root file for user
	// with given user ID.
	RootDirectory(context.Context, uuid.UUID) (uuid.UUID, error)
}

type UserDeleter interface {
	// UserDelete removes user with given unique ID from the system.
	UserDelete(context.Context, uuid.UUID) error
}

type UserPasswordChangeRequest struct {
	// ID is unique user's identifier.
	ID uuid.UUID

	// NewPassword is new password for user.
	NewPassword string
}

type UserPasswordChanger interface {
	// UserChangePassword changes password of user with given user ID to the
	// provided new password.
	UserChangePassword(context.Context, UserPasswordChangeRequest) error
}

type UserPasswordUpdateRequest struct {
	// ID is unique user's identifier.
	ID uuid.UUID

	// OldPassword is old user's password.
	OldPassword string

	// NewPassword is new password requested by the user.
	NewPassword string
}

type UserPasswordUpdater interface {
	// UserPasswordUpdate updates user's password on his/her behalf. It returns error if
	// authorization with old password fails or new password is invalid.
	UserPasswordUpdate(context.Context, UserPasswordUpdateRequest) error
}

type UserReadResponse struct {
	// ID is unique user identifier.
	ID uuid.UUID

	// Username is unique login name.
	Username string

	// CreatedAt is time when user account was created.
	CreatedAt time.Time
}

type UserRegisterRequest struct {
	// Username is unique login name.
	Username string

	// Password is secret phrase use to access user's account.
	Password string
}

type UserRegisterResponse struct {
	// ID is unique user's identifier.
	ID uuid.UUID

	// CreatedAt is time of account creation.
	CreatedAt time.Time
}

type UserRegisterer interface {
	// UserRegister creates new account for user.
	UserRegister(context.Context, UserRegisterRequest) (*UserRegisterResponse, error)
}

type UsersBatchRegisterer interface {
	// UsersRegister creates multiple user accounts. It should fail if
	// creation of at least single user account also fails.
	UsersRegister(context.Context, []UserRegisterRequest) error
}

type UsersReadFromRequest struct {
	// ID is last user's unique identifier. UsersReadFrom returns slice
	// of users' informations, which were created after account with given
	// ID.
	ID uuid.UUID

	// Query is an optional query string. It can be prefix, suffix or substring
	// of username of user that you are looking for.
	Query string
}

type UsersReadFromUsernameRequest struct {
	// Username is last user's unique username. UsersReadFromUsername returns slice
	// of users' informations, which were created after account with given
	// username.
	Username string

	// Query is an optional query string. It can be prefix, suffix or substring
	// of username of user that you are looking for.
	Query string
}

type UsersReader interface {
	// UsersReadInit initialize querying user accounts. It returns
	// limited number of user accounts. You can use last user ID from
	// given slice and UserReadFrom method to query for more entries.
	//
	// Query is optional query string. See UsersReadFromRequest for more
	// informations about query string.
	UsersReadInit(ctx context.Context, query string) ([]UserReadResponse, error)

	// UserReadFrom reads limited number of user accounts that
	// were created after account with given ID.
	UsersReadFrom(context.Context, UsersReadFromRequest) ([]UserReadResponse, error)

	// UsersReadFromUsername reads limited number of user accounts that
	// were created after account with given username.
	UsersReadFromUsername(context.Context, UsersReadFromUsernameRequest) ([]UserReadResponse, error)
}