extends Node3D

## Merges every animation in the AnimationPlayer into a single looping clip and
## plays it, so meshes driven by different animations (e.g. ted_bones and
## fishing_acc) all animate simultaneously instead of overwriting each other.
## Attach to any node that has an AnimationPlayer child.

@onready var anim_player: AnimationPlayer = $AnimationPlayer

const MERGED_LIB := "merged"
const MERGED_NAME := "merged/all"

func _ready() -> void:
	if not anim_player:
		push_warning("tekton_fishing_autoplay: No AnimationPlayer found")
		return

	# Wait one frame for the scene tree to settle
	await get_tree().process_frame

	var source_names := anim_player.get_animation_list()
	if source_names.is_empty():
		return

	var merged := _build_merged_animation(source_names)
	if not merged:
		return

	var lib := AnimationLibrary.new()
	lib.add_animation("all", merged)
	if anim_player.has_animation_library(MERGED_LIB):
		anim_player.remove_animation_library(MERGED_LIB)
	anim_player.add_animation_library(MERGED_LIB, lib)

	anim_player.play(MERGED_NAME)


## Combines the tracks of every source animation into one Animation. The source
## animations target disjoint node sets, so simply concatenating their tracks
## drives all meshes at once.
func _build_merged_animation(source_names: Array) -> Animation:
	var merged := Animation.new()
	merged.loop_mode = Animation.LOOP_LINEAR

	var max_length := 0.0
	for anim_name in source_names:
		var src: Animation = anim_player.get_animation(anim_name)
		if not src:
			continue
		max_length = max(max_length, src.length)
		for t in src.get_track_count():
			_copy_track(src, t, merged)

	merged.length = max_length
	return merged


func _copy_track(src: Animation, src_track: int, dst: Animation) -> void:
	var new_track := dst.add_track(src.track_get_type(src_track))
	dst.track_set_path(new_track, src.track_get_path(src_track))
	dst.track_set_interpolation_type(new_track, src.track_get_interpolation_type(src_track))
	dst.track_set_interpolation_loop_wrap(new_track, src.track_get_interpolation_loop_wrap(src_track))
	dst.track_set_enabled(new_track, src.track_is_enabled(src_track))

	for k in src.track_get_key_count(src_track):
		var time := src.track_get_key_time(src_track, k)
		var value = src.track_get_key_value(src_track, k)
		var transition := src.track_get_key_transition(src_track, k)
		dst.track_insert_key(new_track, time, value, transition)