Add option to filter games not available on the current platform

The new 'Only show games available on this platform' checkbox in the
plugin settings drops games whose platforms don't include the OS
OpenGamepadUI is running on (e.g. Windows-only games on Linux). Games
with no platform info at all (HTML5) are kept since there's nothing to
filter on. The setting is read on every library load, so toggling it
reloads the itch.io library without a restart.

core/itch_settings.gd

@@ -18,6 +18,7 @@ const icon := preload("res://plugins/itch/assets/itch.svg")
 @onready var api_key_box: LineEdit = $%ApiKeyInput
 @onready var save_button: Button = $%SaveButton
 @onready var help_label: Label = $%HelpLabel
+@onready var filter_check: CheckBox = $%FilterUnsupported
 
 @onready var itch: ItchClient = get_tree().get_first_node_in_group("itch_client")
 
@@ -27,6 +28,8 @@ func _ready() -> void:
 	api_key_box.text = api_key
 	api_key_box.secret = true
 
+	filter_check.button_pressed = settings_manager.get_value("plugin.itch", "filter_unsupported", true) as bool
+
 	help_label.text = "Get an API key from https://itch.io/user/settings/api-keys"
 
 	_update_status()
@@ -34,6 +37,7 @@ func _ready() -> void:
 	itch.logged_in.connect(_on_login)
 
 	save_button.pressed.connect(_on_save_button)
+	filter_check.toggled.connect(_on_filter_toggled)
 
 
 func _update_status() -> void:
@@ -68,3 +72,13 @@ func _on_save_button() -> void:
 	if api_key == "":
 		return
 	itch.login_with_api_key(api_key)
+
+
+## Persists the platform filter and reloads the itch.io library so the
+## change applies without restarting. The setting is read back by
+## library_itch.gd on every library load, so toggling just re-filters.
+func _on_filter_toggled(pressed: bool) -> void:
+	settings_manager.set_value("plugin.itch", "filter_unsupported", pressed)
+	var library_manager := load("res://core/global/library_manager.tres") as LibraryManager
+	if library_manager:
+		library_manager.load_library("itch")

core/itch_settings.tscn

@@ -42,6 +42,11 @@ layout_mode = 2
 autowrap_mode = 2
 text = "Get an API key from https://itch.io/user/settings/api-keys"
 
+[node name="FilterUnsupported" type="CheckBox" parent="VBoxContainer"]
+unique_name_in_owner = true
+layout_mode = 2
+text = "Only show games available on this platform"
+
 [node name="SaveButton" type="Button" parent="VBoxContainer"]
 unique_name_in_owner = true
 layout_mode = 2

core/library_itch.gd

@@ -3,6 +3,8 @@ extends Library
 const ItchClient := preload("res://plugins/itch/core/itch_client.gd")
 const _apps_cache_file: String = "apps.json"
 
+var settings_manager := load("res://core/global/settings_manager.tres") as SettingsManager
+
 @onready var itch: ItchClient = get_tree().get_first_node_in_group("itch_client")
 
 ## The item currently being installed/updated/uninstalled. OGPU's InstallManager
@@ -84,13 +86,38 @@ func _on_install_progressed(_id: String, current: int, total: int) -> void:
 	install_progressed.emit(_active_item, float(current) / float(total))
 
 
+## Returns true unless the "only show games available on this platform"
+## filter is enabled and the game's platforms don't include the OS
+## OpenGamepadUI is running on. Games with no platform info at all (e.g.
+## HTML5) are kept, since there's nothing to filter on.
+func _game_available_on_current_platform(game: Dictionary) -> bool:
+	if not _filter_unsupported():
+		return true
+	var platforms: Dictionary = game.get("platforms", {})
+	if platforms.is_empty():
+		return true
+	var current := "windows"
+	if OS.get_name() == "Linux":
+		current = "linux"
+	elif OS.get_name() == "macOS":
+		current = "osx"
+	return not (platforms.get(current, "") as String).is_empty()
+
+
+func _filter_unsupported() -> bool:
+	return settings_manager.get_value("plugin.itch", "filter_unsupported", true) as bool
+
+
 ## Builds a LibraryLaunchItem for a game, or null when the entry isn't an
-## actual game (itch.io also hosts tools, assets, soundtracks, comics, ...).
+## actual game (itch.io also hosts tools, assets, soundtracks, comics, ...)
+## or is filtered out by the "available on this platform" setting.
 func _make_item(game: Dictionary, caves_by_game_id: Dictionary) -> Variant:
 	if game.is_empty():
 		return null
 	if game.get("classification", "game") != "game":
 		return null
+	if not _game_available_on_current_platform(game):
+		return null
 	var game_id: int = game.get("id", 0)
 	var cave: Dictionary = caves_by_game_id.get(game_id, {})
 
@@ -121,7 +148,11 @@ func _load_library(caching_flags: int = Cache.FLAGS.LOAD | Cache.FLAGS.SAVE) ->
 			logger.info("itch.io apps found in cache. Using cache.")
 			var items := [] as Array[LibraryLaunchItem]
 			for i in json_items:
-				items.append(LibraryLaunchItem.from_dict(i))
+				var item := LibraryLaunchItem.from_dict(i)
+				var game: Dictionary = item.metadata.get("game", {})
+				if not _game_available_on_current_platform(game):
+					continue
+				items.append(item)
 			_queue_boxart(items)
 			return items