terminal-config-manager

This is an application to manage selected values scattered over many different files quickly. A common use case will probably be to quickly switch single values inside of a set of config files without having to:

• navigate to the file
• open it in a text editor
• search the target value
• modify it
• save the file

In order to know which files to manipulate a few things will need to be specified beforehand inside of a config file for each value we want to manage:

• a title
• the absolute path of the target (config) file
• the current value of the config entry in question
• a pattern with which to identify the parts of the target file surrounding the config entry in question
• a list of possible values for the config entry in question

The application displays one line per managed value, its title/a brief description of the use case and the current value inside of the associated file.

use case description one → value
use case description two → anotherValue
use case description three → yetAnotherValue

The up/down arrow keys select the value to change, left/right arrows change the value to the next or previous possible value.

Usage

• prepare a config file
• run

  terminal-config-manager
  

• select a config entry using the up/down arrow keys
• change the value using the left/right arrow keys
• hit q to quit

View the dependency graph

Make sure you've got graphmod (generating the graph) and xdot (viewing the graph) installed. Then, navigate to the project root directory and run

tool/generate-dependency-graph.sh

Known issues

• an underlying library which is tasked with querying information about the terminal the program is run with apparently contains a bug which can result in the coloring of the config value being wrong. The value will be rendered using the default text color instead of being highlighted. The frequency of this issue is once every few dozens to hundreds of program startups.
• another library vty seems to exhibit an issue where it can throw a segfault when receiving input before being properly inizialized. This issue should crop up either infrequently or never, usually only when quickly quitting and restarting the program.

TODOs

• find and handle every operation that can fail
• handle the case where the pattern does not match anything, for instance when (currently, no value is displayed on startup and on value change an error Data.Text.replace: empty input occurs) the file was modified some other way during runtime
• invert the dependency between UI and Application
• allow common locations for the config file
• throw away the current value config entry
• provide a yaml schema for the config file
• handle the case where the value marker is not contained in the pattern
• find and prevent the case where the target file is emptied completely
• warn if there are obvious signs of sensitive data inside of the config file
• evaluate disallowing using the config file as a target file
• handle missing target file permissions, asking for the password seems out of reach for the moment -> check if everything is writable on startup
• warn if pattern is too generic?
• add information to errorInvalidPattern, resolve the cyclic dependency when referring to valueMarker
• remove the need to check if the target value changed while the program was running by extracting the current value on substitution as well, that way the substitution is guaranteed to work while the displayed value may not be accurate, also, explore System.FSNotify.Streaming
• fix patterns like '{{value}}abc' matching backwards across line breaks
• check rendering of long lists / scrolling (scrolling applies to the terminal, it is possible to navigate to places outside of the viewport) try the brick list widget, which might supply srolling
• evaluate Acceptance testing via docker container (wtype or xdotool)
• possible values cannot contain an empty string

Design considerations, unordered

• domain concepts line(?) selection, value selection, old file content, new file content
• mode = LineSelection | ValueSelection
• LineSelection = NextLine | PreviousLine
• ValueSelection = NextValue | PreviousValue
• DomainFunction :: mode -> OldFile -> NewFile
• ModificationCommand

Glossary

• item: An element of the list inside of the config file. It corresponds to one substring inside of one file which you want to manage. This also sometimes refers to a line as it is rendered on the screen, where you are shown the description and the current value.
• value: A part of an item which specifies the current state of the substring you want to manage. It is rendered as the latter, highlighted part of a line.