Intent interface for MainService

[bk138]

This refactors the code to enable starting the MainService from the outside via an Intent interface.

Closes #83, closes #71, closes #40, closes #50, closes #95, closes #118.

Builds upon and obsoletes #84.

• move eligible static methods to intents
• test service start when stopped -> service can be started from other app if startForegroundService() is used
• test START_REDELIVER_INTENT behaviour -> an intent where onStartCommand returns START_REDELIVER_INTENT gets redeliverd even if there was an onStartCommand that returned START_NOT_STICKY after it which is good 💡
• onStartCommand return value
• feedback on calls via broadcast
• remove SharedPrefs from MainService? -> no, it's needed
• make some prefs keys component-private
• add to onbootreceiver
• API docs
• extra settings in UI
• API examples, especially for Ability to create a VNC session under the control of another application #83, Run reverse connection on reboot #71 and Add possibility to start server when usb cable is plugged in #40.
• permissions like in ControlService: added possibility to manage the VNC under the control of another apps #84 (comment) ? -> won't work this way as most automater apps don't have permission asking and adb pm grant also does not work because those 3rd party apps have not declared to use our custom permission...
• custom access control

[bk138]

challenge w/ https://github.com/bk138/droidVNC-NG/tree/feat-intent-remote-control-orig

• onStartCommand returns START_REDELIVER_INTENT when an OK state was reached from ACTION_START
  • i.e. ACTION_HANDLE_MEDIA_PROJECTION_RESULT or ACTION_HANDLE_WRITE_STORAGE_RESULT will get redelivered
• onStartCommand for ACTION_CONNECT needs to return something as well, but it can't be START_REDELIVER_INTENT because an ACTION_START would be needed before to get the server started

approach 1

• ACTION_START starts, again does nothing
• ACTION_CONNECT only does sth after ACTION_START successful
• ACTION_STOP only stops after ACTION_START successful, otherwise does nothing

👎 introduces state into Intent interface
👍 extras clearly mapped to actions where they're actually consumed
👎 but CONNECT extras also in ACTION_START, no way to do more than 1 outbound connection w/ 1 Intent call

approach 2

• only one ACTION_START which can be called multiple times
• action decided on payload, i.e. extras

👎 some extras invalid, state went into extra valid/invalid
👎 with one set of CONNECT extras also in ACTION_START, no way to do more than 1 outbound connection w/ 1 Intent call

approach 3 (bit broader)

• give ACTION_APPLY a complete (JSON?) description of what should be started/stopped
• ACTION_QUERY for getting complete state (and modiifying and re-applying...)

👍 can init several outgoing conns at once
👍 usable for complete after-kill-reinstantiate
❗ way more complex impl w/ state management
⚠️ we would have a SET action (which could return START_REDELIVER_INTENT to get back to before-crashed) BUT would also need a GET action for cases where we want to change just one outgoing connection, for instance) -> what would the GET handling return? --> can not return START_REDELIVER_INTENT -> same problem class as with individual verbs...

[bk138]

intent interface, take 2

verb approach 1 ⛔

• PRO:
  • looks nice and semantic
  • not so much internal state tracking, we just react on commands from outside
• CON
  • does not map to internal structure, app does not work this way!! ⛔⛔

verbs w/ args

• start

  • pw
  • scaling
  • filetransfer
  • view_only

• listen ⛔

  • listen_port

• connect_reverse

  • reverse_port
  • reverse_host

• connect_repeater

  • repeater_port
  • repeater_host
  • repeater_id

• stop

verb approach 2

• bit like orig approach, but no connect args for start verb
• PRO
  • matches internal structure
  • less changes than approach 3 in Intent interface for MainService #98 (comment)
• CON
  • caller has to do 2 calls to connect outbound: start then connect_*
  • needs feedback on calls via broadcast

verbs w/ args

• start - does nothing on 2nd call

  • pw
  • scaling
  • filetransfer
  • view_only
  • listen_port

• connect_reverse - needs start before, connects to 2nd host on 2nd call

  • reverse_port
  • reverse_host

• connect_repeater - needs start before, connects to 2nd host on 2nd call

  • repeater_port
  • repeater_host
  • repeater_id

• stop - does nothing on 2nd call

[bk138]

https://commonsware.com/blog/2011/06/30/warning-activity-intent-extras-public.html

[FilipStadler]

DoidVNC-NG is very cool, I have been looking for a way to control a allwiner H313/X96Q smartbox/TV because it starts mumla client connected with a real radio via a soundcard making a analog to digital solution - both mumla app and DroidVNC-NG start at boot it give a warning and I need to confirm that remote control is allowed else its cool if I add maybe openvpn to the tv box.