Add invidious companion support (#4985)

* add support for invidious companion

* redirect latest_version and dash manifest to invidious companion

* fix Shadowing outer local variable `response`

* fixing condition for Content-Security-Policy

* throw error if inv_sig_helper and invidious_companion used same time

* Use sample instead of Random.rand

Co-authored-by: syeopite <70992037+syeopite@users.noreply.github.com>

* Remove debug puts functions

Co-authored-by: syeopite <70992037+syeopite@users.noreply.github.com>

* modify the description for config.example.yaml about invidious companion

* move config checks for invidious companion

* separate invidious_companion logic + better config.yaml config

* fixing "end" misplacement

* fix linting + use .empty?

* crystal handle decompression already by itself

* fix download function when invidious companion used

* fix linting

* invidious companion always used so always add CSP and redirect latest_version

* apply all the suggestions + rework invidious_companion parameter

* format watch.cr

* fix ameba Redundant use of `Object#to_s` in interpolation

* add ability for invidious companion to check request from invidious

* Better document private_url and public_url

* Better doc for invidious_companion_key

* !empty? to present?

* skip proxy for invidious companion

* fixing format

* missing ,

* add companion pooling http

* fix: don't use http proxy when sending requests to companion

* fix: logic where we want to have the invidious logic if companion is not used

* chore: remove baseurl usage from invidious companion

* chore: change from inv-sig-helper to companion for required playback

* fix: use puts + add warning for inv-sig-helper deprecated

---------

Co-authored-by: syeopite <70992037+syeopite@users.noreply.github.com>

config/config.example.yml

@@ -54,6 +54,53 @@ db:
 ##
 #signature_server:
 
+##
+## Invidious companion is an external program
+## for loading the video streams from YouTube servers.
+##
+## When this setting is commented out, Invidious companion is not used.
+## Otherwise, Invidious will proxy the requests to Invidious companion.
+## 
+## Note: multiple URL can be configured. In this case, invidious will
+## randomly pick one every time video data needs to be retrieved. This
+## URL is then kept in the video metadata cache to allow video playback
+## to work. Once said cache has expired, requesting that video's data
+## again will cause a new companion URL to be picked.
+##
+## The parameter private_url needs to be configured for the internal
+## communication between the companion and Invidious.
+## And public_url is the public URL from which companion is listening
+## to the requests from the user(s).
+##
+## If you are using a reverse proxy then you will probably need to
+## configure the public_url to be the same as the domain used for Invidious.
+## Also apply when used from an external IP address (without a domain).
+## Examples: https://MYINVIDIOUSDOMAIN or http://192.168.1.100:8282
+##
+## Both parameter can have identical URL when Invidious is hosted in
+## an internal network or at home or locally (localhost).
+##
+## Accepted values: "http(s)://<IP-HOSTNAME>:<Port>"
+## Default: <none>
+##
+#invidious_companion:
+#  - private_url: "http://localhost:8282"
+#    public_url: "http://localhost:8282"
+
+##
+## API key for Invidious companion, used for securing the communication
+## between Invidious and Invidious companion.
+## The size of the key needs to be more or equal to 16.
+##
+## Note: This parameter is mandatory when Invidious companion is enabled
+## and should be a random string.
+## Such random string can be generated on linux with the following
+## command: `pwgen 16 1`
+##
+## Accepted values: a string
+## Default: <none>
+##
+#invidious_companion_key: "CHANGE_ME!!"
 
 #########################################
 #