Signed-off-by: vadasambar <[email protected]>

feat: update scale down status after every scale up
- move scaledown delay status to cluster state/registry
- enable scale down if  `ScaleDownDelayTypeLocal` is enabled
- add new funcs on cluster state to get and update scale down delay status
- use timestamp instead of booleans to track scale down delay status
Signed-off-by: vadasambar <[email protected]>

refactor: use existing fields on clusterstate
- uses `scaleUpRequests`, `scaleDownRequests` and `scaleUpFailures` instead of `ScaleUpDelayStatus`
- changed the above existing fields a little to make them more convenient for use
- moved initializing scale down delay processor to static autoscaler (because clusterstate is not available in main.go)
Signed-off-by: vadasambar <[email protected]>

refactor: remove note saying only `scale-down-after-add` is supported
- because we are supporting all the flags
Signed-off-by: vadasambar <[email protected]>

fix: evaluate `scaleDownInCooldown` the old way only if `ScaleDownDelayTypeLocal` is set to `false`
Signed-off-by: vadasambar <[email protected]>

refactor: remove line saying `--scale-down-delay-type-local` is only supported for `--scale-down-delay-after-add`
- because it is not true anymore
- we are supporting all `--scale-down-delay-after-*` flags per nodegroup
Signed-off-by: vadasambar <[email protected]>

test: fix clusterstate tests failing
Signed-off-by: vadasambar <[email protected]>

refactor: move back initializing processors logic to from static autoscaler to main
- we don't want to initialize processors in static autoscaler because anyone implementing an alternative to static_autoscaler has to initialize the processors
- and initializing specific processors is making static autoscaler aware of an implementation detail which might not be the best practice
Signed-off-by: vadasambar <[email protected]>

refactor: revert changes related to `clusterstate`
- since I am going with observer pattern
Signed-off-by: vadasambar <[email protected]>

feat: add observer interface for state of scaling
- to implement observer pattern for tracking state of scale up/downs (as opposed to using clusterstate to do the same)
- refactor `ScaleDownCandidatesDelayProcessor` to use fields from the new observer
Signed-off-by: vadasambar <[email protected]>

refactor: remove params passed to `clearScaleUpFailures`
- not needed anymore
Signed-off-by: vadasambar <[email protected]>

refactor: revert clusterstate tests
- approach has changed
- I am not making any changes in clusterstate now
Signed-off-by: vadasambar <[email protected]>

refactor: add accidentally deleted lines for clusterstate test
Signed-off-by: vadasambar <[email protected]>

feat: implement `Add` fn for scale state observer
- to easily add new observers
- re-word comments
- remove redundant params from `NewDefaultScaleDownCandidatesProcessor`
Signed-off-by: vadasambar <[email protected]>

fix: CI complaining because no comments on fn definitions
Signed-off-by: vadasambar <[email protected]>

feat: initialize parent `ScaleDownCandidatesProcessor`
- instead  of `ScaleDownCandidatesSortingProcessor` and `ScaleDownCandidatesDelayProcessor` separately
Signed-off-by: vadasambar <[email protected]>

refactor: add scale state notifier to list of default processors
- initialize processors for `NewDefaultScaleDownCandidatesProcessor` outside and pass them to the fn
- this allows more flexibility
Signed-off-by: vadasambar <[email protected]>

refactor: add observer interface
- create a separate observer directory
- implement `RegisterScaleUp` function in the clusterstate
- TODO: resolve syntax errors
Signed-off-by: vadasambar <[email protected]>

feat: use `scaleStateNotifier` in place of `clusterstate`
- delete leftover `scale_stateA_observer.go` (new one is already present in `observers` directory)
- register `clustertstate` with `scaleStateNotifier`
- use `Register` instead of `Add` function in `scaleStateNotifier`
- fix `go build`
- wip: fixing tests
Signed-off-by: vadasambar <[email protected]>

test: fix syntax errors
- add utils package `pointers` for converting `time` to pointer (without having to initialize a new variable)
Signed-off-by: vadasambar <[email protected]>

feat: wip track scale down failures along with scale up failures
- I was tracking scale up failures but not scale down failures
- fix copyright year 2017 -> 2023 for the new `pointers` package
Signed-off-by: vadasambar <[email protected]>

feat: register failed scale down with scale state notifier
- wip writing tests for `scale_down_candidates_delay_processor`
- fix CI lint errors
- remove test file for `scale_down_candidates_processor` (there is not much to test as of now)
Signed-off-by: vadasambar <[email protected]>

test: wip tests for `ScaleDownCandidatesDelayProcessor`
Signed-off-by: vadasambar <[email protected]>

test: add unit tests for `ScaleDownCandidatesDelayProcessor`
Signed-off-by: vadasambar <[email protected]>

refactor: don't track scale up failures in `ScaleDownCandidatesDelayProcessor`
- not needed
Signed-off-by: vadasambar <[email protected]>

test: better doc comments for `TestGetScaleDownCandidates`
Signed-off-by: vadasambar <[email protected]>

refactor: don't ignore error in `NGChangeObserver`
- return it instead and let the caller decide what to do with it
Signed-off-by: vadasambar <[email protected]>

refactor: change pointers to values in `NGChangeObserver` interface
- easier to work with
- remove `expectedAddTime` param from `RegisterScaleUp` (not needed for now)
- add tests for clusterstate's `RegisterScaleUp`
Signed-off-by: vadasambar <[email protected]>

refactor: conditions in `GetScaleDownCandidates`
- set scale down in cool down if the number of scale down candidates is 0
Signed-off-by: vadasambar <[email protected]>

test: use `ng1` instead of `ng2` in existing test
Signed-off-by: vadasambar <[email protected]>

feat: wip static autoscaler tests
Signed-off-by: vadasambar <[email protected]>

refactor: assign directly instead of using `sdProcessor` variable
- variable is not needed
Signed-off-by: vadasambar <[email protected]>

test: first working test for static autoscaler
Signed-off-by: vadasambar <[email protected]>

test: continue working on static autoscaler tests
Signed-off-by: vadasambar <[email protected]>

test: wip second static autoscaler test
Signed-off-by: vadasambar <[email protected]>

refactor: remove `Println` used for debugging
Signed-off-by: vadasambar <[email protected]>

test: add static_autoscaler tests for scale down delay per nodegroup flags
Signed-off-by: vadasambar <[email protected]>

chore: rebase off the latest `master`
- change scale state observer interface's `RegisterFailedScaleup` to reflect latest changes around clusterstate's `RegisterFailedScaleup` in `master`
Signed-off-by: vadasambar <[email protected]>

test: fix clusterstate test failing
Signed-off-by: vadasambar <[email protected]>

test: fix failing orchestrator test
Signed-off-by: vadasambar <[email protected]>

refactor: rename `defaultScaleDownCandidatesProcessor` -> `combinedScaleDownCandidatesProcessor`
- describes the processor better
Signed-off-by: vadasambar <[email protected]>

refactor: replace `NGChangeObserver` -> `NodeGroupChangeObserver`
- makes it easier to understand for someone not familiar with the codebase
Signed-off-by: vadasambar <[email protected]>

docs: reword code comment `after` -> `for which`
Signed-off-by: vadasambar <[email protected]>

refactor: don't return error from `RegisterScaleDown`
- not needed as of now (no implementer function returns a non-nil error for this function)
Signed-off-by: vadasambar <[email protected]>

refactor: address review comments around ng change observer interface
- change dir structure of nodegroup change observer package
- stop returning errors wherever it is not needed in the nodegroup change observer interface
- rename `NGChangeObserver` -> `NodeGroupChangeObserver` interface (makes it easier to understand)
Signed-off-by: vadasambar <[email protected]>

refactor: make nodegroupchange observer thread-safe
Signed-off-by: vadasambar <[email protected]>

docs: add TODO to consider using multiple mutexes in nodegroupchange observer
Signed-off-by: vadasambar <[email protected]>

refactor: use `time.Now()` directly instead of assigning a variable to it
Signed-off-by: vadasambar <[email protected]>

refactor: share code for checking if there was a recent scale-up/down/failure
Signed-off-by: vadasambar <[email protected]>

test: convert `ScaleDownCandidatesDelayProcessor` into table tests
Signed-off-by: vadasambar <[email protected]>

refactor: change scale state notifier's `Register()` -> `RegisterForNotifications()`
- makes it easier to understand what the function does
Signed-off-by: vadasambar <[email protected]>

test: replace scale state notifier `Register` -> `RegisterForNotifications` in test
- to fix syntax errors since it is already renamed in the actual code
Signed-off-by: vadasambar <[email protected]>

refactor: remove `clusterStateRegistry` from `delete_in_batch` tests
- not needed anymore since we have `scaleStateNotifier`
Signed-off-by: vadasambar <[email protected]>

refactor: address PR review comments
Signed-off-by: vadasambar <[email protected]>

fix: add empty `RegisterFailedScaleDown` for clusterstate
- fix syntax error in static autoscaler test
Signed-off-by: vadasambar <[email protected]>
(cherry picked from commit 5de49a1)