deferred class
	ECD_RECOVERABLE_CHAIN [G -> EL_STORABLE create make_default end]

inherit
	ECD_CHAIN [G]
		rename
			delete as chain_delete
		redefine
			delete_file, header, make_default, make_from_file, rename_base, safe_store, is_closed
		end

	EL_MODULE_LIO; EL_MODULE_NAMING

	ECD_CONSTANTS

feature {NONE} -- Initialization

	make_from_default_encrypted_file (a_encrypter: EL_AES_ENCRYPTER)
		do
			make_from_encrypted_file (new_file_path, a_encrypter)
		end

	make_from_default_file
		do
			make_from_file (new_file_path)
		end

	make_from_encrypted_file (a_file_path: FILE_PATH; a_encrypter: EL_AES_ENCRYPTER)
			--
		do
			encrypter := a_encrypter
			make_from_file (a_file_path)
		end

	make_from_file (a_file_path: FILE_PATH)
		do
			Precursor (a_file_path)
			editions.set_attributes (editions_file_path)
			apply_editions
		end

	make_default
		do
			Precursor
			if is_encrypted then
				create {ECD_ENCRYPTABLE_EDITIONS_FILE [G]} editions.make (Current)
			else
				create editions.make (Current)
			end
		end

feature -- Access

	active_list: EL_ARRAYED_LIST [G]
		-- list of items that are not deleted
		do
			create Result.make_from_if (Current, agent is_active)
		end

	name: STRING
		do
			-- Use {Current} do prevent invariant violiation
			Result := Naming.class_as_snake_upper ({like Current}, 0, Trailing_word_count)
		end

	status: INTEGER_8

feature -- Status query

	is_closed: BOOLEAN
		do
			Result := editions.is_closed
		end

	is_integration_pending: BOOLEAN
			-- True when it becomes necessary to integrate editions into main list (chain) by calling `store'
		do
			Result := editions.kilo_byte_count > Compaction_threshold
						or else has_version_mismatch
						or else editions.has_checksum_mismatch
							-- A checksum mismatch indicates that the editions
							-- have become corrupted somewhere, so save
							-- what's good and start a clean editions.
		end


feature -- Element change

	extend (a_item: like item)
			--
		do
			chain_extend (a_item)
			if editions.is_open_write then
				editions.put_edition (editions.Code_extend, a_item)
			end
		end

	replace (a_item: like item)
			--
		do
			chain_replace (a_item)
			if editions.is_open_write then
				editions.put_edition (editions.Code_replace, a_item)
			end
		end

feature -- Status change

	reopen
		do
			editions.reopen
		end

feature -- Basic operations

	close
			--
		do
			if is_integration_pending then
				safe_store
				if last_store_ok and editions.is_reset then
					editions.close_and_delete
					status := Closed_safe_store
				else
					editions.close
					status := Closed_safe_store_failed
				end
			elseif not editions.is_reset then
				editions.close
				status := Closed_editions
			else
				editions.close_and_delete
				status := Closed_no_editions
			end
			-- This is so that incremental backups will work
			if editions.exists and then not editions.is_bigger then
				editions.restore_date
			end
		end

	print_status
		do
			inspect status
				when Closed_safe_store then
					lio.put_line ("Stored editions")

				when Closed_safe_store_failed then
					lio.put_line ("Failed to store editions")

				when Closed_no_editions then
					lio.put_line ("Closed editions")

				when Closed_editions then
					lio.put_line ("No editions made")

			else
			end
		end

	rename_base (new_name: READABLE_STRING_GENERAL; preserve_extension: BOOLEAN)
		-- rename basename of files preserving the extension if `preserve_extension' is true
		do
			Precursor (new_name, preserve_extension)
			if editions.exists then
				editions.rename_file (editions_file_path)
			else
				editions.set_path (editions_file_path)
			end
		ensure then
			editions_renamed: editions_file_path.same_base (editions.path.components.last.name)
		end

	safe_store
		do
			reader_writer.set_default_data_version
			Precursor
			if last_store_ok then
				editions.close_and_delete
				compact
				editions.reopen
			end
		ensure then
			editions_stripped: last_store_ok implies editions.is_reset
		end

feature -- Removal

	delete
		do
			if editions.is_open_write then
				editions.put_edition (editions.Code_delete, item)
			end
			chain_delete
		end

	delete_file
		do
			if editions.exists then
				editions.close_and_delete
			end
			Precursor
		end

	remove
		obsolete
			"Better to use `delete' as `remove' will interfere with the proper working of field indexing tables"
			--
		do
			if editions.is_open_write then
				editions.put_edition (editions.Code_remove, item)
			end
			chain_remove
		end

feature {NONE} -- Implementation

	is_active (v: G): BOOLEAN
		do
			Result := not v.is_deleted
		end

	apply_editions
		do
			editions.apply
		ensure
			valid_count: count = old count + editions.delta_count
		end

	editions_file_path: FILE_PATH
		do
			Result := header.editions_path (file_path)
		end

	new_file_path: FILE_PATH
		local
			file_name: STRING; l_name: like name
		do
			l_name := name
			create file_name.make (l_name.count)
			Naming.to_kebab_case_lower (l_name, file_name)
			Result := Default_data_dir + file_name
			Result.add_extension (Default_file_extension)
		end

feature {NONE} -- Deferred

	chain_extend (a_item: like item)
			--
		deferred
		end

	chain_remove
			--
		deferred
		end

	chain_replace (a_item: like item)
			--
		deferred
		end

feature {ECD_EDITIONS_FILE} -- Implementation atttributes

	editions: ECD_EDITIONS_FILE [G]
		-- editions file

	header: ECD_RECOVERABLE_CHAIN_HEADER

feature {NONE} -- Constants

	Compaction_threshold: REAL
			-- Minimum file size of editions in kb to trigger compaction
		once
			Result := 50 -- Kb
		end

	Trailing_word_count: INTEGER
		-- Number of trailing words to remove from class name when deriving file name
		once
			Result := 0
		end

note
	instructions: "[
		Items must implement the deferred class ${EL_STORABLE}.

		To implement the class you can use any Eiffel container which conforms to ${CHAIN},
		however it is recommended to use the class ${ECD_ARRAYED_LIST [EL_STORABLE]} as is offers
		the following functionality:

		* Ability to do complex queries in Eiffel with logial conjunctions using the features of
		${EL_QUERYABLE_CHAIN} and ${EL_QUERY_CONDITION_FACTORY}

		* Ability to store objects using class reflection with safe-guards for the integrity of the
		stores in the form of cyclical reduancy checks on the

		* Ability to export to CSV using class reflective naming
	]"

end