Unified Cordova npm save & restore Proposal

Status: Proposed

Current

Existing save/restore functionality

cordova plugin add/rm PLUGINNAME||gitURL||localPlugin --save
- adds/rms <plugin name="cordova-plugin-device" spec="../../cordova-plugin-device" /> to config.xml.
- plugin add: https://github.com/apache/cordova-lib/blob/master/cordova-lib/src/cordova/plugin.js#L210-L235
- plugin rm: https://github.com/apache/cordova-lib/blob/master/cordova-lib/src/cordova/plugin.js#L291-L298
cordova platform add/rm Platform||gitURL||localPath --save
- adds/rms <engine name="ios" spec="~4.2.1" /> to config.xml
- platform rm: https://github.com/apache/cordova-lib/blob/master/cordova-lib/src/cordova/platform.js#L247-L263
- platform add: https://github.com/apache/cordova-lib/blob/master/cordova-lib/src/cordova/platform.js#L227-L238
cordova platform/plugin save
- adds installed but not saved plugins + platforms to config.xml
- platforms: https://github.com/apache/cordova-lib/blob/master/cordova-lib/src/cordova/platform.js#L247-L263
- plugins: https://github.com/apache/cordova-lib/blob/master/cordova-lib/src/cordova/plugin.js#L409-L451
autosave for platforms and plugins (didn't test, not documented)
- manually create .cordova/config.json, add "auto_save_plugins":"true" and "auto_save_platforms":"true"
- https://github.com/apache/cordova-lib/blob/master/cordova-lib/src/cordova/platform.js#L76
- https://github.com/apache/cordova-lib/blob/master/cordova-lib/src/cordova/plugin.js#L538-L542
cordova prepare restores missing plugins and platforms based on config.xml

Proposal:

Move saved plugins/platforms to package.json. Introduce new cordova key in package.json that stores what plugins and platforms have been saved. This is required for restoring.

{
...
    "dependencies": {
        "cordova-plugin-device": "^1.1.3",
        "cordova-android": "^5.2.2" 
    }
    "cordova": {
        "platforms": ["andoid"],
        "plugins": ["cordova-plugin-device"]
    }
...
}

Update --save logic to save to package.json. cordova-fetch allows us to pass the --save flag down to our npm install PLUGIN/PLATFORM command. Plugins and Platforms get added as regular dependencies in package.json this way. cordova plugin/platform add/rm would also add/rm the plugin/platform to/from the new cordova key in package.json.
autosave: remove functionality. Have docs telling users they can set autosave in npm config if they want it. npm config set save=true. cordova-fetch will use system npm, so this should work, but we will have to test it.
restore: continue restoring during prepare. Instead of looking in config.xml, look in package.json at cordova key.
cordova platform/plugin save: Adds existing, unsaved platforms/plugins to package.json's cordova key and edits dependencies with platoform/plugins + versions.
cordova plugin fetching logic will still be respected. If you don't specify a version, the proper version based on cordovaDependencies will be fetched.
cordova platform fetching logic will also stay intact. cordova will grab the pinned platform version unless a different version is specified.

My plan is to keep the existing save/restore config.xml logic for cordova@6.x and start adding the package.json logic beside it. If your project has a package.json, it will start saving to it as well as config.xml. In cordova@7, I want to rip out saving to config.xml logic.

The reason for this change is to add package.json in a standard cordova app and have it work as it would in a node style project. This will lead to cordova developers able to use npm modules while building their apps.

New Requirements

Need to create a easy way to migrate config.xml saved platforms and plugins into package.json. I'm thinking this happens during the restore phase which runs on prepare. Alternatively, we could create a new command to do it.
Automatically add package.json to existing cordova projects which don't have it.

Quirks

Running npm install on your projects will fetch the dependencies in package.json, but a cordova prepare (restore) will be needed to install them to your cordova project.
Running npm install cordova-plugin-device will fetch the plugin, but won't install it. cordova plugin add cordova-plugin-device --save will still be required. Same goes for platforms. Positive is, the plugin/platform will already be fetched.
cordova git subdirectories syntax will not be supported anymore for adding plugins. Ex: http://cordova.apache.org/docs/en/latest/reference/cordova-cli/index.html#plugin-spec

Future goals