class_name TitleScreen
extends Control
## The entry-point screen (mock Title Screen). Editor-first (ADR 0001): the whole
## composition lives in TitleScreen.tscn; this script drives selection, input, and
## dispatches the menu. §2: presentation/state — no AI here (the DM enters at the
## shell). The atmosphere (warm bg shader, pulsing glow, drifting embers) is
## configured in code from Palette (the DarkBay precedent) — see _apply_background,
## _configure_embers, _pulse_glow.

signal menu_activated(id: StringName)

const SHELL := "res://scenes/shell/MainWindowShell.tscn"

var _rows: Array = []
var _sel: int = 0

@onready var _menu: VBoxContainer = $Content/Menu
@onready var _footer_left: Label = $FooterLeft
@onready var _background: ColorRect = $Background
@onready var _glow: ColorRect = $Glow
@onready var _embers: GPUParticles2D = $Embers
@onready var _rule: ColorRect = $Content/Rule


func _ready() -> void:
	# Root Control run via F6 is not sized by full-rect anchors — size explicitly.
	_fit_to_viewport()
	get_viewport().size_changed.connect(_fit_to_viewport)

	_background.color = Palette.STAGE_1
	_rule.color = Palette.GOLD
	_glow.color = Palette.BLOOD
	_apply_background()
	_configure_embers()
	_pulse_glow()

	_rows = []
	for row in _menu.get_children():
		if row.has_meta("action"):
			_rows.append(row)
			(row.get_node("Marker") as Label).add_theme_color_override("font_color", Palette.GOLD)
	_wire_row_mouse()

	_footer_left.text = Version.new().footer()
	menu_activated.connect(_on_menu_activated)
	_update_selection()


func _fit_to_viewport() -> void:
	size = get_viewport_rect().size


func _apply_background() -> void:
	# Palette-driven shader material set in code (the DarkBay precedent) so no hex
	# lives in the shader/scene; the editor shows the ColorRect fallback.
	var mat := ShaderMaterial.new()
	mat.shader = load("res://assets/theme/shaders/title_background.gdshader")
	mat.set_shader_parameter("warm", Palette.TITLE_WARM)
	mat.set_shader_parameter("mid", Palette.TITLE_MID)
	mat.set_shader_parameter("edge", Palette.STAGE_1)
	_background.material = mat


func _configure_embers() -> void:
	var pm := ParticleProcessMaterial.new()
	pm.emission_shape = ParticleProcessMaterial.EMISSION_SHAPE_BOX
	pm.emission_box_extents = Vector3(760, 4, 0)  # a wide strip along the bottom
	pm.direction = Vector3(0, -1, 0)
	pm.spread = 12.0
	pm.gravity = Vector3(0, -18, 0)
	pm.initial_velocity_min = 24.0
	pm.initial_velocity_max = 52.0
	pm.scale_min = 0.4
	pm.scale_max = 1.0
	pm.color = Palette.GOLD_BRIGHT
	# fade out over life
	var ramp := Gradient.new()
	ramp.set_color(0, Color(Palette.GOLD_BRIGHT, 0.0))
	ramp.set_color(1, Color(Palette.GOLD_BRIGHT, 0.0))
	ramp.add_point(0.15, Palette.GOLD_BRIGHT)
	var tex := GradientTexture1D.new()
	tex.gradient = ramp
	pm.color_ramp = tex
	_embers.process_material = pm


func _pulse_glow() -> void:
	# A slow warm pulse (the off-screen fire). A code tween, not an AnimationPlayer:
	# a 2-keyframe modulate loop is trivial in code and motion is runtime-only anyway.
	var tween := create_tween().set_loops().set_trans(Tween.TRANS_SINE)
	tween.tween_property(_glow, "modulate:a", 0.8, 3.0)
	tween.tween_property(_glow, "modulate:a", 0.5, 3.0)


func _wire_row_mouse() -> void:
	for i in range(_rows.size()):
		var idx := i  # fresh per-iteration binding for the closures
		var row: Control = _rows[idx]
		row.mouse_entered.connect(func():
			_sel = idx
			_update_selection())
		row.gui_input.connect(func(e: InputEvent):
			if e is InputEventMouseButton and e.pressed and e.button_index == MOUSE_BUTTON_LEFT:
				_activate(idx))


func _unhandled_input(event: InputEvent) -> void:
	if event.is_action_pressed("ui_down"):
		_move(1)
	elif event.is_action_pressed("ui_up"):
		_move(-1)
	elif event.is_action_pressed("ui_accept"):
		_activate(_sel)


func _move(delta: int) -> void:
	if _rows.is_empty():
		return
	_sel = wrapi(_sel + delta, 0, _rows.size())
	_update_selection()


func _activate(i: int) -> void:
	if i < 0 or i >= _rows.size():
		return
	menu_activated.emit(_rows[i].get_meta("action"))


func _on_menu_activated(id: StringName) -> void:
	match id:
		&"new_game":
			get_tree().change_scene_to_file(SHELL)
		&"quit":
			get_tree().quit()
		_:
			pass  # inert placeholder — the screen lands in a later milestone


func _update_selection() -> void:
	for i in range(_rows.size()):
		var row: Control = _rows[i]
		var selected := i == _sel
		(row.get_node("Marker") as Label).modulate.a = 1.0 if selected else 0.0
		var label := row.get_node("Body/Label") as Label
		label.add_theme_color_override("font_color", Palette.CREAM_BRIGHT if selected else Palette.MUTED_MONO)