Add RFC: Plugin Manager

accepted/0003-plugin-manager.md

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+- Start Date: 2019-12-30
+- RFC PR: #4
+- Mantis Issue: N/A
+
+# Summary
+Create a plugin manager that is capable of configuring the loading of plugins as
+well as providing an easier means of installing plugins. Perhaps - later down
+the line - creating a online database that individuals can search and seamlessly
+install plugins.
+
+# Motivation
+Varying from plugin to plugin, there are a variety of different intallation
+methods for each plugin. On top of that, once installed, there is no easy way to
+disable, or even configure, each individual plugin. In addition, if one plugin
+doesn't behave correctly because of another, it can become difficult to diagnose
+which plugins are causing the error. By implementing a plugin manager, it allows
+users to seamlessly install plugins and have finer control over the loading of
+their plugins. Furthermore, having a plugin manager opens up many more
+possibilties for both users and developers.
+
+# Design
+## Functionality
+### Loading
+Currently, when plugins cause issues, the only way to disable them is by
+outright uninstalling them. However, this could be mitigated at startup by
+having an internal record of which plugins are installed. By keeping a list -
+perhaps in the configuration file - of the disabled plugins, they could be
+ignored during initilizaiton.
+
+Furthermore, if a plugin causes a major failure while loading or doing use, it
+will be automatically disabled on the next startup with a popup warning the
+user. The popup will allow the user to re-enable the plugin (perhaps they
+knowingly used a experimental feature, etc.) or keep the plugin disabled. It
+would also be helpful to show an error code to the user to help them and the
+developer debug.
+
+### Installation
+To further ease the user with their plugin (once downloaded), installation could be handled in 3
+different ways.
+- A file explorer in the manager to install a compressed package that contains:
+  a manifest, locales, the actual plugin, and other needed components.
+- A file explorer that installs plugins by themselves - mostly for compatibilty
+  with previous plugins
+- A compressed package that is associated with OBS so when double clicked, it
+  can be automatically installed in the correct locations.
+
+If the user installs a compressed package, the package would be decompressed and
+the contents would be copied to a directory in the plugins folder.
+
+### Manifest
+As outlined in installed, a compressed package will contain multiple components
+including a manifest. The manifest will be responsible for outlining all
+important information about the plugin. An example of a barebones manifest is
+shown below:
+
+```json
+{
+    "name": "Plugin Name",
+    "author": "Author Name",
+    "description": "Description that would be displayed to user",
+    "locale": {
+        "en": "file path"
+    },
+    "plugin": {
+        "64": "file path",
+        "32": "file path"
+    },
+    "categories": ["PRODUCTIVITY", "CLASSIC", "THEMES"], //etc
+    "version": "^24.0.0"
+}
+```
+
+The purpose of the metadata in the manifest is for 3 main reasons: 1) Allowing
+for easier parsing of the compressed package, 2) allowing more flexibility for 
+plugin creators, and 3) reducing mental overhead for users organizing their
+plugins.
+
+Some notable entries on the manifest are categores and version. Version
+numbering allows the plugin creator to specifiy a specific version or range that
+the plugin can be loaded in. The categories affects the UX.
+
+Note: The options in the manifest are predefined. A plugin developer can not
+have random options that can be searched as outlined in UX.
+
+### UX
+To access the plugin manager, it would be under Settings -> Plugins or File ->
+Plugins. The plugin manager itself would have a searchbar at the top that allows
+searching through the metadata as provided in the manifest file and displays the
+results in the list below. Moreover, there would be a simple list view that
+outlines all the installed plugins in alphabetical order. The list would show
+the name, description, and categories of each plugin. All the way to the right,
+would be a button that outlines whether the plugin is disabled or currently
+active. Another feature would to allow the plugin to have its own settings menu
+which would display a button next to the disable button that opens its settings menu.
+
+When a user disables a plugin, it will add the plugin to a list to prevent
+loading during initilization. It will also attempt to unlink the plugin, but a
+restart might be necessary. Likewise, when a user re-enables or installs a
+plugin, it will attempt to initialize the plugin.
+
+If the plugin has its own settings menu, the information could be stored in its
+manifest which would be unpacked and installed.
+
+### Future Considerations
+It would also help plugins be discovered if there was a built in browser for
+searching through plugins on a server. A user could search by name or other
+metadata (again outlined in the manifest) which would be in another list. Then,
+they could click on an install button next to the options to automatically
+download and install the plugin.
+
+# How We Teach This
+It would be provided in the documentation. However, the bare functionality would
+hopefully be designed well enough that it can become plainly clear to the user
+how it works.