# Entry point.
#
# P1 shows one exported screen, statically, so that its pixels can be diffed
# against `sylpheed-cli screen render` of the same build. The boot sequence
# proper (splash -> intro -> title -> menu) is P3 and is not here.
#
#   godot --path port -- --screen=main_menu
#   godot --path port -- --screen=main_menu --capture=/tmp/godot.png
#   godot --path port -- --screen=main_menu --time=0.5 --capture=/tmp/at-half.png
#   godot --path port -- --screen=main_menu --pose=rest --capture=/tmp/rest.png
#   godot --path port -- --boot                      # the whole boot sequence
#   godot --path port -- --boot --film=/tmp/boot     # ...and a frame every 0.25 s
#
# `--time` is in SECONDS and freezes the timeline there; without it the screen
# animates in real time from t=0. `--pose=rest` draws the export's declared
# resting pose instead of the timeline -- what the reference renderer draws, so
# that a renderer-vs-renderer diff compares like with like.
#
# The screen is drawn into a SubViewport sized to the export's own `design`
# rectangle and shown through a container that scales it to the window. That is
# the same separation the project settings already make -- design space is
# fixed, the window is not -- and it makes `--capture` exact: the PNG is the
# design rectangle itself, never the window, so it is directly comparable with
# `screen render`'s composite with no cropping or rescaling.
extends Node

const DEFAULT_SCREEN := "main_menu"

var view: ScreenView = null
var viewport: SubViewport = null


func _ready() -> void:
	var args := _args()
	var export_tree := ExportTree.locate()
	if export_tree.root == "":
		push_error(export_tree.error)
		get_tree().quit(2)
		return

	_flow = export_tree.authored("flow.json")
	if args.has("boot"):
		if _flow == null:
			push_error(export_tree.error)
			get_tree().quit(2)
			return
		for step: Dictionary in _flow["boot"]:
			_sequence.append(step)
		_film = args.get("film", "")

	var name: String = String(_sequence[0].get("screen", "")) if not _sequence.is_empty() \
		else args.get("screen", DEFAULT_SCREEN)
	if name == "":
		name = DEFAULT_SCREEN  # the sequence opens on a video; load something to size the viewport
	var screen: Dictionary = export_tree.screen(name)
	if screen.is_empty():
		push_error(export_tree.error)
		print("screens in this export: ", ", ".join(export_tree.screen_names()))
		get_tree().quit(2)
		return
	var design: Array = screen.get("design", [1280, 720])

	var container := SubViewportContainer.new()
	container.stretch = true
	container.set_anchors_preset(Control.PRESET_FULL_RECT)
	add_child(container)

	viewport = SubViewport.new()
	viewport.size = Vector2i(int(design[0]), int(design[1]))
	viewport.transparent_bg = false
	viewport.render_target_update_mode = SubViewport.UPDATE_ALWAYS
	container.add_child(viewport)

	view = ScreenView.new()
	# The export is a 1:1 copy of the disc's texels and elements are drawn at up
	# to 500 %. Nearest is also what the reference renderer does
	# (`ui_layout::blit` maps destination to source by integer division), so a
	# filter difference cannot masquerade as a placement difference in the diff.
	view.texture_filter = CanvasItem.TEXTURE_FILTER_NEAREST
	view.focused_id = args.get("focus", "")
	if args.get("pose", "") == "rest":
		view.pose_mode = ScreenView.Pose.REST

	# The keyframe unit is MEASURED, not on the disc, so it is authored and read
	# in exactly one place -- here.
	var timing: Variant = export_tree.authored("timing.json")
	if timing == null:
		push_error(export_tree.error)
		get_tree().quit(2)
		return
	view.units_per_second = float(timing["keyframe_units_per_second"])
	# The one unknown duration per screen: the ramp into the final untimed
	# keyframe. Authored, because the disc has no time slot there.
	view.exit_ramp_units = float(timing["exit_ramp_units"])
	viewport.add_child(view)

	if not view.load_screen(export_tree, name):
		push_error(export_tree.error)
		get_tree().quit(2)
		return

	var settle := view.settle_time()
	print("screen %s: %d elements, %d in paint order, design %dx%d, settles at t=%d (%.3f s)" % [
		name, view.screen["elements"].size(), view.screen["paint_order"].size(),
		design[0], design[1], settle, settle / view.units_per_second])

	if args.has("time"):
		_frozen = true
		view.time_units = float(args["time"]) * view.units_per_second
		view.queue_redraw()

	if _film != "":
		set_process(true)
		_film_capture()

	if args.has("capture"):
		await _capture(args["capture"])
		get_tree().quit(0)


var _frozen := false
var _flow: Variant = null
var _sequence: Array[Dictionary] = []
var _player: VideoStreamPlayer = null
var _step := 0
var _film := ""
var _film_frame := 0
var _film_next := 0.0
var _elapsed := 0.0
var _boot_done := false


func _process(delta: float) -> void:
	if _frozen or view == null:
		return
	view.time_units += delta * view.units_per_second
	_elapsed += delta
	view.queue_redraw()

	if _sequence.is_empty() or _player != null:
		return

	# A screen holds at `rest` until it has arrived, then plays itself out and
	# the next one begins. Nothing waits on a timer the disc does not carry: the
	# pacing is each group's own timeline (authored/flow.json, `dwell`).
	if view.holding and view.time_units >= view.settle_time():
		# The LAST screen in the sequence keeps holding. A screen plays itself
		# out because something is taking its place; nothing is taking the
		# title's place here, and a boot that ends by fading to black is a boot
		# that looks like it crashed. P4 puts the intro video in front of the
		# title, and P5 gives the title somewhere to go.
		if _step + 1 < _sequence.size():
			view.holding = false
		elif not _boot_done:
			_boot_done = true
			print("boot sequence complete after %.2f s, holding on %s" % [_elapsed, _sequence[_step]])
			if _film == "":
				get_tree().quit(0)
	elif not view.holding and view.time_units >= view.exit_time():
		_advance()


func _advance() -> void:
	_step += 1
	var next: Dictionary = _sequence[_step]
	if next.has("video"):
		_play_video(String(next["video"]), bool(next.get("skippable", false)))
		return
	var name := String(next["screen"])
	print("  -> %s at %.2f s" % [name, _elapsed])
	view.holding = true
	view.time_units = 0.0
	if not view.load_screen(view.tree, name):
		push_error(view.tree.error)
		get_tree().quit(2)


## Play one transcoded movie, full-bleed over the screen.
##
## The port never reads WMV: the exporter transcoded this to Ogg Theora and
## recorded the exact ffmpeg command in the manifest (MISSION §6), so a modder
## who dislikes the quality re-runs one line.
func _play_video(name: String, skippable: bool) -> void:
	var v := view.tree.video(name)
	if v.is_empty():
		push_error(view.tree.error)
		get_tree().quit(2)
		return
	print("  -> video %s at %.2f s (%s)" % [name, _elapsed, v["path"]])

	var stream := VideoStreamTheora.new()
	stream.file = v["path"]
	_player = VideoStreamPlayer.new()
	_player.stream = stream
	_player.expand = true
	_player.set_anchors_preset(Control.PRESET_FULL_RECT)
	# Into the SubViewport, not beside it. Everything this port draws composes in
	# the export's own 1280x720 design space; a player parented to the Boot node
	# renders to the window instead and is invisible to `--capture`, which reads
	# the SubViewport. That is not only a capture artefact -- it would also put
	# the movie outside the space every screen coordinate is expressed in.
	viewport.add_child(_player)
	_skippable = skippable
	# `play()` needs the node in the tree; calling it before that is an error
	# the engine reports and then ignores, which looks like a video that simply
	# never starts.
	await get_tree().process_frame
	_player.finished.connect(_video_finished)
	_player.play()


var _skippable := false


func _video_finished() -> void:
	print("     video ended at %.2f s" % _elapsed)
	_player.queue_free()
	_player = null
	_advance()


func _unhandled_input(event: InputEvent) -> void:
	# HANDOFF Q9, measured: one (A) press skips a movie -- the title was reached
	# at 57 s against a 193 s baseline. This is the only input the port handles
	# so far; menu navigation is P5.
	if _player == null or not _skippable:
		return
	if event.is_action_pressed("ui_accept") or event.is_action_pressed("ui_cancel"):
		print("     video skipped at %.2f s" % _elapsed)
		_player.stop()
		_video_finished()


func _capture(path: String) -> void:
	# Two frames: the first is the one this callback is still inside of.
	await RenderingServer.frame_post_draw
	await RenderingServer.frame_post_draw
	var img := viewport.get_texture().get_image()
	print("t = %.2f units (%.3f s), pose = %s" % [
		view.time_units, view.time_units / view.units_per_second,
		"rest" if view.pose_mode == ScreenView.Pose.REST else "timeline"])
	print("drew %d: %s" % [view.drawn.size(), ", ".join(view.drawn)])
	if not view.skipped.is_empty():
		print("not drawn %d: %s" % [view.skipped.size(), ", ".join(view.skipped)])
	var err := img.save_png(path)
	if err != OK:
		push_error("cannot write %s (%d)" % [path, err])
		return
	print("captured %dx%d -> %s" % [img.get_width(), img.get_height(), path])


## A frame every 0.25 s for the whole run, so an unattended boot leaves a
## filmstrip behind rather than requiring someone to be watching it.
func _film_capture() -> void:
	while true:
		await RenderingServer.frame_post_draw
		if _elapsed >= _film_next:
			var img := viewport.get_texture().get_image()
			img.save_png("%s_%03d.png" % [_film, _film_frame])
			_film_frame += 1
			_film_next += 0.25


# Godot passes everything after `--` through untouched; take `--key=value`.
static func _args() -> Dictionary:
	var out := {}
	for arg in OS.get_cmdline_user_args():
		if arg.begins_with("--") and arg.contains("="):
			var pair := arg.substr(2).split("=", true, 1)
			out[pair[0]] = pair[1]
		elif arg.begins_with("--"):
			out[arg.substr(2)] = "1"
	return out