Clarify year transition

The routing of year information has changed so that it goes through
coroutines. This means that, unlike with signals, we can await on a
function's completion. The current approach to showing the year
transition is simple text with the Continue button. This is not great,
but it does solve a lot of problems: the player is already looking
there, and they know how to click "continue" to move on.

project/ui/game_screen.gd

@@ -10,7 +10,8 @@ var world : World:
 	set(value):
 		world = value
 		%CharacterDisplay.character = world.character
-		%YearIndicator.world = world
+		%YearIndicator.set_year(world.year)
+		%YearIndicator.presenter = weakref(self)
 
 ## This box holds the whole top interaction area. It is the container
 ## whose content is swapped out by the ending screen at the end of
@@ -172,6 +173,13 @@ func show_text(story) -> void:
 		push_error("Unexpected parameter type: " + story.get_class())
 
 
+## Advance the year to the given value.
+##
+## This is a coroutine that completes when the animation is done.
+func show_year_advancement(new_year:Year.Name) -> void:
+	await %YearIndicator.show_advancement(new_year)
+
+
 ## Remove all the children from the given container.
 func _clear(container:Control) -> void:
 	while container.get_child_count() > 0:

project/ui/main_scene.gd

@@ -79,7 +79,9 @@ func _run_next_story() -> void:
 	## Load the story and start it
 	var story = load(story_path).new()
 	await story.run(_game_screen)
-	world.turns += 1
+	var year_changed := world.end_turn()
+	if year_changed:
+		await _game_screen.show_year_advancement(world.year)
 
 
 func _draw_random_story() -> String:

project/ui/year_indicator.gd

@@ -1,16 +1,8 @@
 extends HBoxContainer
 
-var world: World:
-	set(value):
-		if world != null:
-			if world != value:
-				world.years_changed.disconnect(_year_progressed)
+var presenter : WeakRef # Circular dependency
 
-		world = value
-		world.years_changed.connect(_year_progressed)
-		_update_display(world.year)
-
-@onready var _year_name: Label = %YearName
+@onready var _year_name := %YearName
 @onready var _year_circles := {
 	Year.Name.FRESHMAN: %Year1,
 	Year.Name.SOPHOMORE: %Year2,
@@ -19,10 +11,18 @@ var world: World:
 }
 
 
-func _year_progressed(years: int) -> void:
-	_update_display(years)
+## Set the year programatically and instantly
+func set_year(year:Year.Name) -> void:
+	_year_circles[year].year_passed = true
+	_year_name.text = Year.as_string(year)
 
 
-func _update_display(new_year: Year.Name) -> void:
+## Animate the year transition
+##
+## This is a coroutine.
+func show_advancement(new_year:Year.Name) -> void:
 	_year_circles[new_year].year_passed = true
 	_year_name.text = Year.as_string(new_year)
+	presenter.get_ref().show_text("%s Year!" % Year.as_string(new_year))
+	await presenter.get_ref().show_continue()
+

project/ui/year_progress_circle.gd

@@ -5,7 +5,7 @@ extends Control
 @export var inner_border := 2
 
 
-var year_passed : bool:
+@export var year_passed : bool:
 	set(value):
 		year_passed = value
 		queue_redraw()

project/world/world.gd

@@ -1,9 +1,6 @@
 ## The state of the game world
 class_name World extends RefCounted
 
-signal turns_changed(new_turn: int)
-signal years_changed(new_year: int)
-
 ## The maximum number of turns that can be taken in a year
 const MAX_TURNS_PER_YEAR := 3
 
@@ -26,25 +23,10 @@ var game_map := GameMap.new()
 
 var turns_per_year := MAX_TURNS_PER_YEAR
 
-## The number of turns the player has taken.
-##
-## A turn is a complete story, from beginning to end, that consists of one
-## logical unit of time.
-var turns := 0:
-	set(value):
-		turns = value
-
-		if turns >= turns_per_year:
-			turns = 0
-			if Year.has_next(year):
-				year = Year.next(year)
-
-		turns_changed.emit(turns)
+var year := Year.Name.FRESHMAN
 
-var year := Year.Name.FRESHMAN:
-	set(value):
-		year = value
-		years_changed.emit(year)
+## The number of turns the player has taken this year.
+var _turns_this_year := 0
 
 
 ## Add all the stories in the given directory to the list
@@ -63,6 +45,21 @@ func add_stories(dir:DirAccess) -> Array[String]:
 	return results
 
 
+## Mark the end of the current turn.
+##
+## The result is true if the year changed and false otherwise.
+## Finishing senior year does not count as the year changing.
+func end_turn() -> bool:
+	_turns_this_year += 1
+
+	if _turns_this_year >= turns_per_year:
+		_turns_this_year = 0
+		if Year.has_next(year):
+			year = Year.next(year)
+			return true
+	return false
+
+
 ## Remove all the stories in the given directory from the list
 ## of available stories
 ##