class_name ActionSelectionSystem
extends RefCounted

enum SchedulePeriod { WORK, SLEEP, MEAL, DISCRETIONARY }

const SLEEP_BEGIN := 0.88
const SLEEP_END := 0.15
const BREAKFAST_BEGIN := 0.25
const BREAKFAST_END := 0.35
const DINNER_BEGIN := 0.7
const DINNER_END := 0.8
const WORK_BEGIN := 0.28
const WORK_END := 0.85
const UNAVAILABLE_ACTION_SCORE := -1000000.0
const RELATIONSHIP_AID_PANTRY_THRESHOLD := 25.0

var relationship_system: RefCounted


func select_action(
	npc: SimNPC,
	village: SimVillage,
	time_of_day: float = 0.5,
	all_npcs: Array = [],
	opportunity_helper: OpportunityHelperResult = null,
	population_view: SimulationPopulationView = null
) -> ActionSelectionResult:
	if npc.is_dead:
		return null

	if npc.is_starving:
		if npc.get_inventory_amount(SimulationIds.RESOURCE_FOOD) >= 1.0:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_EAT, 1.0, "Starving and carrying food"
			)
		if village.food > 0:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_WITHDRAW_FOOD, 1.0, "Starving; pantry has food"
			)
		return ActionSelectionResult.new(
			SimulationIds.ACTION_GATHER_FOOD, -1.0, "Starving; must find food"
		)
	if npc.mourning_ticks > 0:
		if npc.energy < 40.0:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_REST, -1.0, "Mourning; seeking rest"
			)
		return ActionSelectionResult.new(
			SimulationIds.ACTION_WANDER, -1.0, "Mourning; wandering near home"
		)
	if npc.hunger > 80.0:
		if npc.get_inventory_amount(SimulationIds.RESOURCE_FOOD) >= 1.0:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_EAT, -1.0, "Critically hungry and carrying food"
			)
		if village.food > 0:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_WITHDRAW_FOOD, -1.0, "Critically hungry; pantry has food"
			)
		return ActionSelectionResult.new(
			SimulationIds.ACTION_GATHER_FOOD, -1.0, "Critically hungry; must find food"
		)

	var profession_def := SimulationDefinitions.get_profession(npc.profession)
	var offset: float = profession_def.schedule_offset if profession_def != null else 0.0
	var local_time := fmod(time_of_day + offset + 1.0, 1.0)
	var period := _get_period(local_time)

	if period == SchedulePeriod.SLEEP:
		if npc.energy < 60.0:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_SLEEP, -1.0, "Night-time sleep; energy is low"
			)
		if npc.hunger > 75.0 and npc.get_inventory_amount(SimulationIds.RESOURCE_FOOD) >= 1.0:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_EAT, -1.0, "Night-time hunger; eating from inventory"
			)
		return ActionSelectionResult.new(SimulationIds.ACTION_SLEEP, -1.0, "Night-time; going home")

	if period == SchedulePeriod.MEAL:
		if npc.hunger > 50.0:
			if npc.get_inventory_amount(SimulationIds.RESOURCE_FOOD) >= 1.0:
				return ActionSelectionResult.new(
					SimulationIds.ACTION_EAT, -1.0, "Meal-time hunger; eating from inventory"
				)
			if village.food > 0:
				return ActionSelectionResult.new(
					SimulationIds.ACTION_WITHDRAW_FOOD, -1.0, "Meal-time; pantry has food"
				)
			return ActionSelectionResult.new(
				SimulationIds.ACTION_GATHER_FOOD, -1.0, "Meal-time hunger; pantry is empty"
			)

	if npc.hunger > 75.0:
		if npc.get_inventory_amount(SimulationIds.RESOURCE_FOOD) >= 1.0:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_EAT, -1.0, "Hungry and carrying food"
			)
		if village.food > 0:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_WITHDRAW_FOOD, -1.0, "Hungry; pantry has food"
			)
		return ActionSelectionResult.new(
			SimulationIds.ACTION_GATHER_FOOD, -1.0, "Hungry; pantry is empty"
		)
	var is_opportunity_helper := _is_current_opportunity_helper(npc, opportunity_helper)
	if is_opportunity_helper and npc.energy < 25.0:
		return ActionSelectionResult.new(
			SimulationIds.ACTION_REST, -1.0, "Energy is low; resting before helping"
		)
	if is_opportunity_helper:
		return ActionSelectionResult.new(
			opportunity_helper.action_id,
			-1.0,
			"Responding to village need: %s" % opportunity_helper.reason
		)
	if npc.get_inventory_amount(SimulationIds.RESOURCE_FOOD) > 0.0:
		return ActionSelectionResult.new(
			SimulationIds.ACTION_DEPOSIT_FOOD, -1.0, "Carrying food for storage"
		)
	if npc.get_inventory_amount(SimulationIds.RESOURCE_WOOD) > 0.0:
		return ActionSelectionResult.new(
			SimulationIds.ACTION_DEPOSIT_WOOD, -1.0, "Carrying wood for storage"
		)
	if npc.energy < 25.0:
		return ActionSelectionResult.new(
			SimulationIds.ACTION_REST, -1.0, "Energy is below the rest threshold"
		)
	if village.food <= RELATIONSHIP_AID_PANTRY_THRESHOLD and relationship_system != null:
		var trusted_starving_npc: SimNPC = relationship_system.get_trusted_starving_subject(
			npc.id, all_npcs, population_view
		)
		if trusted_starving_npc != null:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_GATHER_FOOD,
				-1.0,
				"Helping %s, a trusted acquaintance who is starving" % trusted_starving_npc.npc_name
			)

	if period == SchedulePeriod.DISCRETIONARY:
		var roll := npc.random_source.randf()
		if roll < 0.3:
			return ActionSelectionResult.new(
				SimulationIds.ACTION_WANDER, -1.0, "Discretionary wander"
			)

	return _choose_best_work_action(npc, village)


func _is_current_opportunity_helper(
	npc: SimNPC, opportunity_helper: OpportunityHelperResult
) -> bool:
	return (
		opportunity_helper != null
		and opportunity_helper.helper_npc_id == npc.id
		and (
			opportunity_helper.action_id
			in [
				SimulationIds.ACTION_GATHER_FOOD,
				SimulationIds.ACTION_GATHER_WOOD,
				SimulationIds.ACTION_DEPOSIT_FOOD,
				SimulationIds.ACTION_DEPOSIT_WOOD,
			]
		)
	)


func _choose_best_work_action(npc: SimNPC, village: SimVillage) -> ActionSelectionResult:
	var scores := {
		SimulationIds.ACTION_GATHER_FOOD:
		_calculate_score(
			npc,
			SimulationIds.ACTION_GATHER_FOOD,
			village.food_priority,
			village.food,
			15.0,
			30.0,
			3.0,
			1.5
		),
		SimulationIds.ACTION_GATHER_WOOD:
		_calculate_score(
			npc,
			SimulationIds.ACTION_GATHER_WOOD,
			village.wood_priority,
			village.wood,
			10.0,
			20.0,
			2.5,
			1.0
		),
		SimulationIds.ACTION_PATROL:
		_calculate_score(
			npc,
			SimulationIds.ACTION_PATROL,
			village.safety_priority,
			village.safety,
			30.0,
			50.0,
			3.0,
			1.5
		),
		SimulationIds.ACTION_STUDY:
		_calculate_score(
			npc,
			SimulationIds.ACTION_STUDY,
			village.knowledge_priority,
			village.knowledge,
			10.0,
			25.0,
			1.5,
			0.75
		)
	}
	var rejections := {}
	for action_id in scores:
		var definition := SimulationDefinitions.get_action(action_id)
		var rejection := _get_cost_rejection(definition, village)
		if not rejection.is_empty():
			scores[action_id] = UNAVAILABLE_ACTION_SCORE
			rejections[action_id] = rejection
	var best_action := SimulationIds.ACTION_GATHER_FOOD
	var best_score: float = scores[best_action]
	for action_id in [
		SimulationIds.ACTION_GATHER_WOOD, SimulationIds.ACTION_PATROL, SimulationIds.ACTION_STUDY
	]:
		var score: float = scores[action_id]
		if score > best_score:
			best_action = action_id
			best_score = score
	return ActionSelectionResult.new(
		best_action, -1.0, "Highest current work utility", scores, rejections
	)


func _get_cost_rejection(definition: ActionDefinition, village: SimVillage) -> String:
	if definition == null or not definition.has_completion_cost():
		return ""
	var available := _get_village_resource_amount(village, definition.completion_cost_resource_id)
	if available >= definition.completion_cost_amount:
		return ""
	return (
		"Needs %.0f %s (%.1f available)"
		% [
			definition.completion_cost_amount,
			String(definition.completion_cost_resource_id).capitalize(),
			available,
		]
	)


func _get_village_resource_amount(village: SimVillage, resource_id: StringName) -> float:
	match resource_id:
		SimulationIds.RESOURCE_FOOD:
			return village.food
		SimulationIds.RESOURCE_WOOD:
			return village.wood
	return 0.0


func _calculate_score(
	npc: SimNPC,
	action_id: StringName,
	base_priority: float,
	resource_amount: float,
	critical_threshold: float,
	low_threshold: float,
	critical_bonus: float,
	low_bonus: float
) -> float:
	var score := base_priority
	if resource_amount < critical_threshold:
		score += critical_bonus
	elif resource_amount < low_threshold:
		score += low_bonus
	var definition := SimulationDefinitions.get_action(action_id)
	if (
		definition != null
		and not definition.preferred_profession_id.is_empty()
		and npc.profession == definition.preferred_profession_id
	):
		score += 2.0
	if action_id == npc.last_task:
		score -= 1.5
	score += npc.random_source.randf_range(0.0, 0.5)
	if npc.debug_logs:
		print("[ActionSelection] ", npc.npc_name, " score ", action_id, " = ", score)
	return score


static func _get_period(time_of_day: float) -> int:
	if _in_wrap_range(time_of_day, SLEEP_BEGIN, SLEEP_END):
		return SchedulePeriod.SLEEP
	if _in_range(time_of_day, BREAKFAST_BEGIN, BREAKFAST_END):
		return SchedulePeriod.MEAL
	if _in_range(time_of_day, DINNER_BEGIN, DINNER_END):
		return SchedulePeriod.MEAL
	if _in_range(time_of_day, WORK_BEGIN, WORK_END):
		return SchedulePeriod.WORK
	return SchedulePeriod.DISCRETIONARY


static func _in_range(value: float, begin: float, end: float) -> bool:
	return value >= begin and value <= end


static func _in_wrap_range(value: float, begin: float, end: float) -> bool:
	return value >= begin or value <= end