extends Control
## World list screen — browses public worlds via GET /api/worlds.
##
## Displays a scrollable list of world cards (name + description).
## Handles loading, empty list, errors, and refresh.


# UI references
@onready var scroll_container: ScrollContainer = $VBoxContainer/ScrollContainer
@onready var world_list: VBoxContainer = $VBoxContainer/ScrollContainer/WorldList
@onready var loading_label: Label = $VBoxContainer/LoadingLabel
@onready var error_label: Label = $VBoxContainer/ErrorLabel
@onready var refresh_button: Button = $VBoxContainer/HeaderHBox/RefreshButton
@onready var back_button: Button = $VBoxContainer/HeaderHBox/BackButton
@onready var empty_label: Label = $VBoxContainer/EmptyLabel

## Cached so each world card can decide whether to show "Edit World"
## (docs/architecture/world_persistence_impl.md §5.3: chunk writes require
## `world.owner_id == caller`, same as `update_world`) without an extra
## round trip per card. -1 until resolved / on failure, in which case no
## card shows the edit entry point.
var _current_user_id: int = -1


func _ready() -> void:
	refresh_button.disabled = false
	back_button.disabled = false
	loading_label.visible = false
	error_label.visible = false
	empty_label.visible = false
	world_list.visible = false

	var me_result: Dictionary = await ApiClient.get_me()
	if me_result.ok and me_result.data is Dictionary:
		_current_user_id = int((me_result.data as Dictionary).get("id", -1))

	_refresh_worlds()


func _on_refresh_button_pressed() -> void:
	_refresh_worlds()


func _on_back_button_pressed() -> void:
	get_tree().change_scene_to_file("res://scenes/main_menu.tscn")


## Fetch the world list from the backend and update the UI.
func _refresh_worlds() -> void:
	# Reset UI state
	loading_label.visible = true
	error_label.visible = false
	empty_label.visible = false
	world_list.visible = false
	refresh_button.disabled = true

	# Clear previous world cards
	for child in world_list.get_children():
		child.queue_free()

	var result := await ApiClient.get_worlds()

	loading_label.visible = false
	refresh_button.disabled = false

	if not result.ok:
		# Show error message (401, network failure, etc.)
		error_label.text = "Error: %s" % result.detail
		error_label.visible = true
		empty_label.visible = false
		world_list.visible = false
		return

	var data = result.data
	if not data is Array:
		error_label.text = "Unexpected response format."
		error_label.visible = true
		empty_label.visible = false
		world_list.visible = false
		return

	if data.is_empty():
		empty_label.text = "No worlds yet. Check back later!"
		empty_label.visible = true
		error_label.visible = false
		world_list.visible = false
		return

	# Render world cards
	world_list.visible = true
	empty_label.visible = false
	error_label.visible = false

	for world_dict in data:
		if not world_dict is Dictionary:
			continue
		var card := _create_world_card(world_dict)
		world_list.add_child(card)


## Create a visual card for a single world entry.
func _create_world_card(world_dict: Dictionary) -> Control:
	# PanelContainer for the background, not a ColorRect moved to child index
	# 0 of a VBoxContainer -- a VBoxContainer lays out ALL its children in a
	# vertical sequence, it has no concept of "float this one child behind
	# the others as an overlay". That version rendered as an empty dark bar
	# sitting above the text, not a background behind it.
	var panel := PanelContainer.new()
	panel.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	panel.custom_minimum_size = Vector2(0, 80)
	var style := StyleBoxFlat.new()
	style.bg_color = Color(0.15, 0.15, 0.15, 1.0)
	style.content_margin_left = 12
	style.content_margin_right = 12
	style.content_margin_top = 8
	style.content_margin_bottom = 8
	panel.add_theme_stylebox_override("panel", style)

	var card := VBoxContainer.new()
	card.size_flags_horizontal = Control.SIZE_EXPAND_FILL
	card.add_theme_constant_override("separation", 4)
	panel.add_child(card)

	var name_label := Label.new()
	name_label.text = world_dict.get("name", "Unnamed World")
	name_label.autowrap_mode = TextServer.AUTOWRAP_WORD
	name_label.size_flags_horizontal = Control.SIZE_FILL
	name_label.size_flags_vertical = Control.SIZE_SHRINK_BEGIN
	name_label.add_theme_font_size_override("font_size", 18)

	var desc_label := Label.new()
	var description: String = str(world_dict.get("description", ""))
	desc_label.text = description if description != "" else "No description."
	desc_label.autowrap_mode = TextServer.AUTOWRAP_WORD
	desc_label.size_flags_horizontal = Control.SIZE_FILL
	desc_label.size_flags_vertical = Control.SIZE_EXPAND_FILL
	desc_label.add_theme_font_size_override("font_size", 14)
	desc_label.add_theme_color_override("font_color", Color(0.7, 0.7, 0.7, 1.0))

	var meta_label := Label.new()
	var visibility: String = str(world_dict.get("visibility", "public"))
	var created: String = str(world_dict.get("created_at", ""))
	meta_label.text = "Visibility: %s%s" % [visibility, " | Created: " + created if created != "" else ""]
	meta_label.autowrap_mode = TextServer.AUTOWRAP_WORD
	meta_label.size_flags_horizontal = Control.SIZE_FILL
	meta_label.size_flags_vertical = Control.SIZE_SHRINK_BEGIN
	meta_label.add_theme_font_size_override("font_size", 12)
	meta_label.add_theme_color_override("font_color", Color(0.5, 0.5, 0.5, 1.0))

	# "Enter World" asks the backend to host this world (POST /join) and then
	# loads scenes/game.tscn networked. If the backend has no game-server
	# orchestration (a plain dev instance), it falls back to local
	# single-player. All worlds still load the same test level -- per-world
	# content is a later milestone.
	var world_id := int(world_dict.get("id", 0))
	var enter_button := Button.new()
	enter_button.text = "Enter World"
	enter_button.size_flags_horizontal = Control.SIZE_SHRINK_BEGIN
	enter_button.pressed.connect(_on_enter_world_pressed.bind(world_id, enter_button))

	var buttons_row := HBoxContainer.new()
	buttons_row.add_child(enter_button)

	# "Edit World" (world_persistence_impl.md §6 D4): a non-joined entry
	# point into the in-game editor -- it does NOT call POST /join. Only
	# shown for the world's owner, matching the write-side authorization the
	# save path itself enforces (§5.3), so a non-owner never sees a button
	# that would just 403 on the first save.
	var owner_id := int(world_dict.get("owner_id", -1))
	if _current_user_id != -1 and owner_id == _current_user_id:
		var edit_button := Button.new()
		edit_button.text = "Edit World"
		edit_button.size_flags_horizontal = Control.SIZE_SHRINK_BEGIN
		edit_button.pressed.connect(_on_edit_world_pressed.bind(world_id))
		buttons_row.add_child(edit_button)

	card.add_child(name_label)
	card.add_child(desc_label)
	card.add_child(meta_label)
	card.add_child(buttons_row)

	return panel


func _on_enter_world_pressed(world_id: int, button: Button) -> void:
	button.disabled = true
	button.text = "Joining…"

	var result := await ApiClient.join_world(world_id)

	if result.ok and result.data is Dictionary:
		var d: Dictionary = result.data
		Session.begin(world_id, str(d.get("host", "")), int(d.get("port", 0)))
		get_tree().change_scene_to_file("res://scenes/game.tscn")
		return

	if result.status == 503:
		# This backend can't host game servers -- go in local single-player.
		Session.clear()
		get_tree().change_scene_to_file("res://scenes/game.tscn")
		return

	button.disabled = false
	button.text = "Enter World"
	error_label.text = "Couldn't join: %s" % result.detail
	error_label.visible = true


## Enter build mode for this world without joining it
## (world_persistence_impl.md §6 D4). No /join call, no ENet connection, no
## dedicated server -- game.gd loads/saves the world's chunks over HTTP.
func _on_edit_world_pressed(world_id: int) -> void:
	Session.begin_edit(world_id)
	get_tree().change_scene_to_file("res://scenes/game.tscn")