extends SceneTree
## Build animation-pack.res from animation-0.glb (original Blender bone names).
##
## Usage:
##   godot --headless --path <project> --script tools/build_animation_pack.gd
##
## No rest-pose correction — animations are copied verbatim from the source GLB.
## All characters share the same rig structure (identical 25 bones), so the same
## animation works on all of them.

const SOURCE_GLB := "res://assets/characters/animation-0.glb"
const OUTPUT_PATH := "res://assets/characters/animations/animation-pack.res"

func _init() -> void:
	print("[build_animation_pack] Starting build...")

	# Step 1: Load source animations
	var src_doc := GLTFDocument.new()
	var src_state := GLTFState.new()
	var err := src_doc.append_from_file(
		ProjectSettings.globalize_path(SOURCE_GLB), src_state
	)
	if err != OK:
		push_error("[build_animation_pack] Failed to load source GLB: error %d" % err)
		quit(1)
		return

	var src_scene: Node = src_doc.generate_scene(src_state)
	if not src_scene:
		push_error("[build_animation_pack] Failed to generate source scene")
		quit(1)
		return

	# Step 2: Extract animations
	var anim_player: AnimationPlayer = src_scene.find_child("AnimationPlayer", true, false)
	if not anim_player:
		push_error("[build_animation_pack] No AnimationPlayer in source")
		src_scene.queue_free()
		quit(1)
		return

	var out_lib := AnimationLibrary.new()
	var count := 0
	var total_tracks := 0

	for lib_name in anim_player.get_animation_library_list():
		var src_lib := anim_player.get_animation_library(lib_name)
		for anim_name in src_lib.get_animation_list():
			var src_anim: Animation = src_lib.get_animation(anim_name)
			if not src_anim:
				continue

			var new_anim := Animation.new()
			new_anim.loop_mode = src_anim.loop_mode

			# holding_1 must loop while player carries tekton
			if anim_name == "holding_1":
				new_anim.loop_mode = Animation.LOOP_LINEAR

			var max_time := 0.0
			for i in src_anim.get_track_count():
				var path_str: String = str(src_anim.track_get_path(i))
				var track_type: int = src_anim.track_get_type(i)

				# Skip the GLB root "retarget" node
				if "retarget" in path_str and ":" not in path_str:
					continue

				# Convert track path: "retarget/Skeleton3D:bone" -> "Character/Skeleton3D:bone"
				if "retarget/Skeleton3D:" in path_str:
					path_str = path_str.replace("retarget/Skeleton3D:", "Character/Skeleton3D:")

				var track_last := _copy_track(src_anim, i, new_anim, path_str, track_type)
				if track_last > max_time:
					max_time = track_last
				total_tracks += 1

			new_anim.length = max_time

			if out_lib.has_animation(anim_name):
				push_warning("[build_animation_pack] Duplicate: %s" % anim_name)
				continue
			out_lib.add_animation(anim_name, new_anim)
			count += 1
			print("  [%d] %s (%d tracks, %.3fs)" % [count, anim_name, new_anim.get_track_count(), max_time])

	# Step 4: Build holding_walk (walk legs + holding arms)
	if out_lib.has_animation("walk_forward") and out_lib.has_animation("holding_1"):
		var holding_walk := _build_holding_walk(
			out_lib.get_animation("walk_forward"),
			out_lib.get_animation("holding_1")
		)
		out_lib.add_animation("holding_walk", holding_walk)
		var hw_path := "res://assets/characters/animations/holding_walk.res"
		var err_hw := ResourceSaver.save(holding_walk, ProjectSettings.globalize_path(hw_path))
		if err_hw != OK:
			push_warning("[build_animation_pack] Failed to save holding_walk: %d" % err_hw)
		else:
			print("  [+] holding_walk (%d tracks, %.3fs, looped)" % [holding_walk.get_track_count(), holding_walk.length])

	# Step 5: Save animation-pack.res
	var err_save := ResourceSaver.save(out_lib, ProjectSettings.globalize_path(OUTPUT_PATH))
	if err_save != OK:
		push_error("[build_animation_pack] Failed to save: error %d" % err_save)
		src_scene.queue_free()
		quit(1)
		return

	# Step 4: Save individual clip .res files alongside animation-pack.res
	for anim_name in out_lib.get_animation_list():
		var clip_path := "res://assets/characters/animations/%s.res" % anim_name
		var clip_res: Animation = out_lib.get_animation(anim_name)
		var err_clip := ResourceSaver.save(clip_res, ProjectSettings.globalize_path(clip_path))
		if err_clip != OK:
			push_warning("[build_animation_pack] Failed to save clip %s: %d" % [anim_name, err_clip])

	# Step 5: Build holding_walk (walk legs + holding arms)
	if out_lib.has_animation("walk_forward") and out_lib.has_animation("holding_1"):
		var holding_walk := _build_holding_walk(
			out_lib.get_animation("walk_forward"),
			out_lib.get_animation("holding_1")
		)
		out_lib.add_animation("holding_walk", holding_walk)
		var hw_path := "res://assets/characters/animations/holding_walk.res"
		var err_hw := ResourceSaver.save(holding_walk, ProjectSettings.globalize_path(hw_path))
		if err_hw != OK:
			push_warning("[build_animation_pack] Failed to save holding_walk: %d" % err_hw)
		else:
			print("  [+] holding_walk (%d tracks, %.3fs, looped)" % [holding_walk.get_track_count(), holding_walk.length])

	src_scene.queue_free()
	print("[build_animation_pack] Extracted %d animations, %d tracks" % [count, total_tracks])
	print("[build_animation_pack] Saved to %s + %d clips" % [OUTPUT_PATH, count])
	quit(0)


func _copy_track(src: Animation, src_idx: int, dst: Animation, new_path: String, track_type: int) -> float:
	var track_idx := dst.add_track(track_type)
	dst.track_set_path(track_idx, new_path)

	var key_count := src.track_get_key_count(src_idx)
	var last_time := 0.0
	for k in key_count:
		var t := src.track_get_key_time(src_idx, k)
		dst.track_insert_key(track_idx, t, src.track_get_key_value(src_idx, k))
		if t > last_time:
			last_time = t
	return last_time


func _build_holding_walk(walk: Animation, hold: Animation) -> Animation:
	"""Merge walk_forward (full body) with holding_1 (upper body override).
Lower body bones (spine, thighs, legs) come from walk_forward.
Upper body bones (spine.001, head, shoulders, arms) come from holding_1.
	"""
	# Upper body bone prefixes — holding_1 overrides these
	var upper_bones := [
		"spine.001", "head",
		"shoulder.L", "upper_arm.L", "forearm.L", "hand.L",
		"shoulder.R", "upper_arm.R", "forearm.R", "hand.R",
	]
	var result := Animation.new()
	result.loop_mode = Animation.LOOP_LINEAR
	result.length = walk.length

	# Collect all track bone names from both animations
	var walk_tracks: Dictionary = {}  # bone_name -> [track_idx, ...]
	for i in walk.get_track_count():
		var path := str(walk.track_get_path(i))
		if "Skeleton3D:" in path:
			var bone := path.split(":")[1]
			if not walk_tracks.has(bone):
				walk_tracks[bone] = []
			walk_tracks[bone].append(i)

	var hold_tracks: Dictionary = {}
	for i in hold.get_track_count():
		var path := str(hold.track_get_path(i))
		if "Skeleton3D:" in path:
			var bone := path.split(":")[1]
			if not hold_tracks.has(bone):
				hold_tracks[bone] = []
			hold_tracks[bone].append(i)

	# Add all walk_forward tracks as base
	for bone in walk_tracks:
		for idx in walk_tracks[bone]:
			var path := str(walk.track_get_path(idx))
			var track_type := walk.track_get_type(idx)
			_copy_track(walk, idx, result, path, track_type)

	# Override upper body tracks with holding_1 values
	for bone in upper_bones:
		if hold_tracks.has(bone) and walk_tracks.has(bone):
			# Replace matching walk tracks with hold values
			var h_indices: Array = hold_tracks[bone]
			var w_indices: Array = walk_tracks[bone]
			for hi in h_indices:
				var hold_path := str(hold.track_get_path(hi))
				var hold_type := hold.track_get_type(hi)
				# Find matching walk track (same type)
				for wi in w_indices:
					if walk.track_get_type(wi) == hold_type:
						# Remove the walk track from result, add hold track
						var result_path := str(result.track_get_path(wi))
						# Find this track in result and remove it
						for ri in result.get_track_count():
							if str(result.track_get_path(ri)) == result_path and result.track_get_type(ri) == hold_type:
								result.remove_track(ri)
								break
						# Copy hold track
						_copy_track(hold, hi, result, hold_path, hold_type)
						w_indices.erase(wi)
						break

	return result