class_name VillageOpportunitySystem
extends RefCounted

const CARE_HUNGER_THRESHOLD := 80.0
const WEAK_ENERGY_THRESHOLD := 25.0

var opportunities: Array[OpportunityStateRecord] = []
var next_opportunity_id := 0


func consider_event(
	event: EconomicEventRecord,
	current_tick: int,
	pantry: StorageStateRecord,
	npcs: Array[SimNPC],
	knowledge_system: EventKnowledgeSystem,
	resource_states: Dictionary,
	woodpile: StorageStateRecord = null
) -> OpportunityStateRecord:
	if event == null or pantry == null or current_tick < 0:
		return null
	var event_tick := int(event.data["tick"])
	if event_tick < 0 or event_tick > current_tick:
		return null
	var resolved := _try_resolve(event, pantry, woodpile, npcs, resource_states)
	if resolved != null:
		return resolved
	var opened := _try_open_food(event, current_tick, pantry, npcs, knowledge_system)
	if opened != null:
		return opened
	if woodpile == null:
		return null
	opened = _try_open_wood(event, current_tick, woodpile, npcs, knowledge_system)
	if opened != null:
		return opened
	opened = _try_open_weak(event, current_tick, pantry, npcs, knowledge_system)
	if opened != null:
		return opened
	return _try_open_roof(event, current_tick, woodpile, npcs, knowledge_system)


func maintain_open_opportunity(
	current_tick: int,
	max_age: int,
	npcs: Array[SimNPC],
	pantry: StorageStateRecord,
	woodpile: StorageStateRecord
) -> OpportunityStateRecord:
	var opportunity := get_open_opportunity()
	if opportunity == null or current_tick < opportunity.get_created_tick():
		return null
	if (
		opportunity.get_opportunity_type()
		not in [
			SimulationIds.OPPORTUNITY_SUPPLY_MISSING_WOOD,
			SimulationIds.OPPORTUNITY_FEED_WEAK_VILLAGER,
			SimulationIds.OPPORTUNITY_REPAIR_HOME_ROOF,
		]
	):
		return null
	var interested := _find_npc(opportunity.get_interested_npc_id(), npcs)
	if interested == null or interested.is_dead:
		return (
			opportunity
			if opportunity.invalidate(
				SimulationIds.OPPORTUNITY_INVALIDATED_INTERESTED_DIED, current_tick
			)
			else null
		)
	var condition_is_stale := current_tick - opportunity.get_created_tick() >= maxi(max_age, 1)
	if opportunity.get_opportunity_type() != SimulationIds.OPPORTUNITY_FEED_WEAK_VILLAGER:
		var target_storage := _get_target_storage(opportunity, pantry, woodpile)
		condition_is_stale = (
			condition_is_stale
			or target_storage == null
			or (
				target_storage.get_amount(opportunity.get_resource_id())
				>= opportunity.get_target_amount()
			)
		)
	if not condition_is_stale:
		return null
	return (
		opportunity
		if opportunity.invalidate(
			SimulationIds.OPPORTUNITY_INVALIDATED_EVIDENCE_STALE, current_tick
		)
		else null
	)


func restore(records: Array[OpportunityStateRecord], restored_next_id: int) -> void:
	opportunities = records.duplicate()
	opportunities.sort_custom(_sort_by_id)
	next_opportunity_id = maxi(restored_next_id, 0)


func get_all_sorted() -> Array[OpportunityStateRecord]:
	var sorted := opportunities.duplicate()
	sorted.sort_custom(_sort_by_id)
	return sorted


func get_open_sorted() -> Array[OpportunityStateRecord]:
	var open_records: Array[OpportunityStateRecord] = []
	for opportunity in opportunities:
		if opportunity.is_open():
			open_records.append(opportunity)
	open_records.sort_custom(_sort_by_id)
	return open_records


func get_open_opportunity() -> OpportunityStateRecord:
	var open_records := get_open_sorted()
	return open_records[0] if not open_records.is_empty() else null


func get_open_trigger_event_id() -> int:
	var opportunity := get_open_opportunity()
	return (
		opportunity.get_trigger_event_id()
		if opportunity != null
		else OpportunityStateRecord.NO_EVENT_ID
	)


func get_latest() -> OpportunityStateRecord:
	var sorted := get_all_sorted()
	return sorted[-1] if not sorted.is_empty() else null


func get_latest_for_npc(npc_id: int) -> OpportunityStateRecord:
	for index in range(opportunities.size() - 1, -1, -1):
		var opportunity := opportunities[index]
		if opportunity.get_interested_npc_id() == npc_id:
			return opportunity
	return null


func find_capable_helper(
	opportunity: OpportunityStateRecord,
	target_storage: StorageStateRecord,
	npcs: Array[SimNPC],
	knowledge_system: EventKnowledgeSystem,
	relationship_system: RefCounted,
	resource_states: Dictionary
) -> OpportunityHelperResult:
	if (
		opportunity == null
		or not opportunity.is_open()
		or target_storage == null
		or knowledge_system == null
		or relationship_system == null
	):
		return null
	var interested := _find_npc(opportunity.get_interested_npc_id(), npcs)
	if interested == null or interested.is_dead:
		return null
	var remaining := maxf(
		opportunity.get_target_amount() - target_storage.get_amount(opportunity.get_resource_id()),
		0.0
	)
	if remaining <= 0.0 or target_storage.get_available_capacity() < remaining:
		return null
	var action_ids := _get_supply_action_ids(opportunity.get_resource_id())
	if action_ids.is_empty():
		return null
	var gather_definition := SimulationDefinitions.get_action(action_ids["gather"])
	var deposit_definition := SimulationDefinitions.get_action(action_ids["deposit"])
	if gather_definition == null or deposit_definition == null:
		return null
	var candidates: Array[Dictionary] = []
	for npc in npcs:
		var candidate := _build_helper_candidate(
			npc,
			opportunity,
			remaining,
			gather_definition,
			deposit_definition,
			interested.npc_name,
			knowledge_system,
			relationship_system,
			resource_states
		)
		if not candidate.is_empty():
			candidates.append(candidate)
	if candidates.is_empty():
		return null
	candidates.sort_custom(_sort_helper_candidates)
	var best := candidates[0]
	return (
		OpportunityHelperResult
		. new(
			{
				"opportunity_id": opportunity.get_opportunity_id(),
				"helper_npc_id": (best["npc"] as SimNPC).id,
				"action_id": best["action_id"],
				"source_id": best["source_id"],
				"resource_id": opportunity.get_resource_id(),
				"trigger_event_id": opportunity.get_trigger_event_id(),
				"trust": best["trust"],
				"familiarity": best["familiarity"],
				"uses_inventory": best["uses_inventory"],
				"available_source_count": best["available_source_count"],
				"profession_match": best["profession_match"],
				"reason": best["reason"],
			}
		)
	)


func find_player_response(
	opportunity: OpportunityStateRecord,
	target_storage: StorageStateRecord,
	resource_states: Dictionary,
	has_capable_helper: bool
) -> OpportunityPlayerResponseResult:
	if (
		opportunity == null
		or not opportunity.is_open()
		or target_storage == null
		or target_storage.get_storage_id() != opportunity.get_target_id()
		or has_capable_helper
	):
		return null
	var remaining := maxf(
		opportunity.get_target_amount() - target_storage.get_amount(opportunity.get_resource_id()),
		0.0
	)
	if remaining <= 0.0 or target_storage.get_available_capacity() < remaining:
		return null
	var action_ids := _get_supply_action_ids(opportunity.get_resource_id())
	if action_ids.is_empty():
		return null
	var gather_definition := SimulationDefinitions.get_action(action_ids["gather"])
	if gather_definition == null:
		return null
	var available_source_count := _count_player_resource_sources(
		remaining, opportunity.get_resource_id(), gather_definition, resource_states
	)
	if available_source_count == 0:
		return null
	return (
		OpportunityPlayerResponseResult
		. new(
			{
				"opportunity_id": opportunity.get_opportunity_id(),
				"trigger_event_id": opportunity.get_trigger_event_id(),
				"action_id": gather_definition.action_id,
				"resource_id": opportunity.get_resource_id(),
				"target_id": target_storage.get_storage_id(),
				"available_source_count": available_source_count,
				"reason":
				(
					"No capable helper; %d player-usable finite %s source%s can supply %s"
					% [
						available_source_count,
						String(opportunity.get_resource_id()).capitalize(),
						"" if available_source_count == 1 else "s",
						String(target_storage.get_storage_id()),
					]
				),
			}
		)
	)


func _build_helper_candidate(
	npc: SimNPC,
	opportunity: OpportunityStateRecord,
	remaining: float,
	gather_definition: ActionDefinition,
	deposit_definition: ActionDefinition,
	interested_name: String,
	knowledge_system: EventKnowledgeSystem,
	relationship_system: RefCounted,
	resource_states: Dictionary
) -> Dictionary:
	if npc.is_dead or npc.id == opportunity.get_interested_npc_id():
		return {}
	if not knowledge_system.knows_event(npc.id, opportunity.get_trigger_event_id()):
		return {}
	var relationship: RelationshipStateRecord = relationship_system.get_relationship(
		npc.id, opportunity.get_interested_npc_id()
	)
	if (
		relationship == null
		or not relationship_system.is_trusted_for_help(npc.id, opportunity.get_interested_npc_id())
	):
		return {}
	var carried := npc.get_inventory_amount(opportunity.get_resource_id())
	var uses_inventory := carried >= remaining
	var available_source_count := 0
	if not uses_inventory:
		available_source_count = _count_available_resource_sources(
			npc.id, remaining, opportunity.get_resource_id(), gather_definition, resource_states
		)
		if available_source_count == 0:
			return {}
	var action_definition := deposit_definition if uses_inventory else gather_definition
	var source_id := SimulationIds.npc_inventory_id(npc.id) if uses_inventory else &""
	var profession_match := (
		not gather_definition.preferred_profession_id.is_empty()
		and npc.profession == gather_definition.preferred_profession_id
	)
	var supply_fact := (
		"carries %.1f %s" % [carried, String(opportunity.get_resource_id()).capitalize()]
		if uses_inventory
		else (
			"has %d available finite %s source%s"
			% [
				available_source_count,
				String(opportunity.get_resource_id()).capitalize(),
				"" if available_source_count == 1 else "s",
			]
		)
	)
	return {
		"npc": npc,
		"action_id": action_definition.action_id,
		"source_id": source_id,
		"trust": relationship.get_trust(),
		"familiarity": relationship.get_familiarity(),
		"uses_inventory": uses_inventory,
		"available_source_count": available_source_count,
		"profession_match": profession_match,
		"reason":
		(
			"Knows the need; trust %.2f toward %s; %s"
			% [relationship.get_trust(), interested_name, supply_fact]
		),
	}


static func _get_supply_action_ids(resource_id: StringName) -> Dictionary:
	match resource_id:
		SimulationIds.RESOURCE_FOOD:
			return {
				"gather": SimulationIds.ACTION_GATHER_FOOD,
				"deposit": SimulationIds.ACTION_DEPOSIT_FOOD,
			}
		SimulationIds.RESOURCE_WOOD:
			return {
				"gather": SimulationIds.ACTION_GATHER_WOOD,
				"deposit": SimulationIds.ACTION_DEPOSIT_WOOD,
			}
	return {}


static func _count_available_resource_sources(
	npc_id: int,
	remaining: float,
	resource_id: StringName,
	gather_definition: ActionDefinition,
	resource_states: Dictionary
) -> int:
	var count := 0
	for value in resource_states.values():
		var state := value as ResourceStateRecord
		if (
			state == null
			or state.get_action_id() != gather_definition.resource_action_id
			or state.get_resource_id() != resource_id
			or not state.can_npc_use()
			or not state.is_available_for(npc_id)
			or state.get_yield_per_action() <= 0.0
			or state.get_amount_remaining() < remaining
		):
			continue
		count += 1
	return count


static func _count_player_resource_sources(
	remaining: float,
	resource_id: StringName,
	gather_definition: ActionDefinition,
	resource_states: Dictionary
) -> int:
	var count := 0
	for value in resource_states.values():
		var state := value as ResourceStateRecord
		if (
			state == null
			or state.get_action_id() != gather_definition.resource_action_id
			or state.get_resource_id() != resource_id
			or not state.can_player_use_resource()
			or not state.can_extract()
			or state.get_yield_per_action() <= 0.0
			or state.get_amount_remaining() < remaining
		):
			continue
		count += 1
	return count


static func _sort_helper_candidates(first: Dictionary, second: Dictionary) -> bool:
	if first["uses_inventory"] != second["uses_inventory"]:
		return bool(first["uses_inventory"])
	if first["trust"] != second["trust"]:
		return float(first["trust"]) > float(second["trust"])
	if first["profession_match"] != second["profession_match"]:
		return bool(first["profession_match"])
	if first["familiarity"] != second["familiarity"]:
		return float(first["familiarity"]) > float(second["familiarity"])
	return (first["npc"] as SimNPC).id < (second["npc"] as SimNPC).id


func _try_open_food(
	event: EconomicEventRecord,
	current_tick: int,
	pantry: StorageStateRecord,
	npcs: Array[SimNPC],
	knowledge_system: EventKnowledgeSystem
) -> OpportunityStateRecord:
	if knowledge_system == null or get_open_opportunity() != null:
		return null
	if pantry.get_amount(SimulationIds.RESOURCE_FOOD) > 0.0:
		return null
	if not _is_food_withdrawal(event):
		return null
	var interested_npc := _select_interested_npc(
		int(event.data["event_id"]), npcs, knowledge_system
	)
	if interested_npc == null:
		return null
	var opportunity := OpportunityStateRecord.create(
		next_opportunity_id, current_tick, int(event.data["event_id"]), interested_npc.id
	)
	next_opportunity_id += 1
	opportunities.append(opportunity)
	return opportunity


func _try_open_wood(
	event: EconomicEventRecord,
	current_tick: int,
	woodpile: StorageStateRecord,
	npcs: Array[SimNPC],
	knowledge_system: EventKnowledgeSystem
) -> OpportunityStateRecord:
	if knowledge_system == null or get_open_opportunity() != null:
		return null
	if not _is_missing_wood_block(event):
		return null
	var target_amount := float(event.data.get("required_amount", 0.0))
	if woodpile.get_amount(SimulationIds.RESOURCE_WOOD) >= target_amount:
		return null
	var actor := _find_npc(int(event.data["actor_id"]), npcs)
	if (
		actor == null
		or actor.is_dead
		or not knowledge_system.knows_event(actor.id, int(event.data["event_id"]))
	):
		return null
	var opportunity := OpportunityStateRecord.create(
		next_opportunity_id,
		current_tick,
		int(event.data["event_id"]),
		actor.id,
		target_amount,
		SimulationIds.OPPORTUNITY_SUPPLY_MISSING_WOOD,
		SimulationIds.STORAGE_VILLAGE_WOODPILE,
		SimulationIds.RESOURCE_WOOD
	)
	next_opportunity_id += 1
	opportunities.append(opportunity)
	return opportunity


func _try_open_weak(
	event: EconomicEventRecord,
	current_tick: int,
	pantry: StorageStateRecord,
	npcs: Array[SimNPC],
	knowledge_system: EventKnowledgeSystem
) -> OpportunityStateRecord:
	if knowledge_system == null or get_open_opportunity() != null:
		return null
	if not _is_weak_trigger(event):
		return null
	if pantry.get_amount(SimulationIds.RESOURCE_FOOD) > 0.0:
		return null
	var actor := _find_npc(int(event.data["actor_id"]), npcs)
	if (
		actor == null
		or actor.is_dead
		or actor.hunger < CARE_HUNGER_THRESHOLD
		or actor.energy >= WEAK_ENERGY_THRESHOLD
		or not knowledge_system.knows_event(actor.id, int(event.data["event_id"]))
	):
		return null
	var opportunity := OpportunityStateRecord.create(
		next_opportunity_id,
		current_tick,
		int(event.data["event_id"]),
		actor.id,
		OpportunityStateRecord.DEFAULT_TARGET_AMOUNT,
		SimulationIds.OPPORTUNITY_FEED_WEAK_VILLAGER,
		SimulationIds.STORAGE_VILLAGE_PANTRY,
		SimulationIds.RESOURCE_FOOD
	)
	next_opportunity_id += 1
	opportunities.append(opportunity)
	return opportunity


func _try_open_roof(
	event: EconomicEventRecord,
	current_tick: int,
	woodpile: StorageStateRecord,
	npcs: Array[SimNPC],
	knowledge_system: EventKnowledgeSystem
) -> OpportunityStateRecord:
	if knowledge_system == null or get_open_opportunity() != null:
		return null
	if not _is_home_damaged_trigger(event):
		return null
	if (
		woodpile.get_amount(SimulationIds.RESOURCE_WOOD)
		>= OpportunityStateRecord.DEFAULT_TARGET_AMOUNT
	):
		return null
	var actor := _find_npc(int(event.data["actor_id"]), npcs)
	if (
		actor == null
		or actor.is_dead
		or not knowledge_system.knows_event(actor.id, int(event.data["event_id"]))
	):
		return null
	var opportunity := OpportunityStateRecord.create(
		next_opportunity_id,
		current_tick,
		int(event.data["event_id"]),
		actor.id,
		OpportunityStateRecord.DEFAULT_TARGET_AMOUNT,
		SimulationIds.OPPORTUNITY_REPAIR_HOME_ROOF,
		SimulationIds.STORAGE_VILLAGE_WOODPILE,
		SimulationIds.RESOURCE_WOOD
	)
	next_opportunity_id += 1
	opportunities.append(opportunity)
	return opportunity


static func _is_weak_trigger(event: EconomicEventRecord) -> bool:
	return (
		StringName(event.data["event_type"]) == SimulationIds.EVENT_VILLAGER_WEAK
		and int(event.data["actor_id"]) >= 0
	)


static func _is_home_damaged_trigger(event: EconomicEventRecord) -> bool:
	return (
		StringName(event.data["event_type"]) == SimulationIds.EVENT_HOME_DAMAGED
		and int(event.data["actor_id"]) >= 0
	)


func _try_resolve(
	event: EconomicEventRecord,
	pantry: StorageStateRecord,
	woodpile: StorageStateRecord,
	npcs: Array[SimNPC],
	resource_states: Dictionary
) -> OpportunityStateRecord:
	var opportunity := get_open_opportunity()
	if opportunity == null:
		return null
	if (
		opportunity.get_opportunity_type() == SimulationIds.OPPORTUNITY_FEED_WEAK_VILLAGER
		and _is_valid_supply(event, opportunity, npcs, resource_states)
	):
		if int(event.data["tick"]) < opportunity.get_created_tick():
			return null
		if int(event.data["event_id"]) <= opportunity.get_trigger_event_id():
			return null
		if not opportunity.resolve(int(event.data["event_id"]), int(event.data["tick"])):
			return null
		return opportunity
	var target_storage := _get_target_storage(opportunity, pantry, woodpile)
	if (
		target_storage == null
		or (
			target_storage.get_amount(opportunity.get_resource_id())
			< opportunity.get_target_amount()
		)
	):
		return null
	if not _is_valid_supply(event, opportunity, npcs, resource_states):
		return null
	if int(event.data["tick"]) < opportunity.get_created_tick():
		return null
	if int(event.data["event_id"]) <= opportunity.get_trigger_event_id():
		return null
	if not opportunity.resolve(int(event.data["event_id"]), int(event.data["tick"])):
		return null
	return opportunity


func _select_interested_npc(
	event_id: int, npcs: Array[SimNPC], knowledge_system: EventKnowledgeSystem
) -> SimNPC:
	var candidates: Array[SimNPC] = []
	for npc in npcs:
		if npc.is_dead or npc.hunger < CARE_HUNGER_THRESHOLD:
			continue
		if not knowledge_system.knows_event(npc.id, event_id):
			continue
		candidates.append(npc)
	candidates.sort_custom(_sort_by_care)
	return candidates[0] if not candidates.is_empty() else null


static func _is_food_withdrawal(event: EconomicEventRecord) -> bool:
	var actor_id := int(event.data["actor_id"])
	return (
		StringName(event.data["event_type"]) == SimulationIds.EVENT_STORAGE_WITHDRAWN
		and actor_id >= 0
		and StringName(event.data["source_id"]) == SimulationIds.STORAGE_VILLAGE_PANTRY
		and StringName(event.data["destination_id"]) == SimulationIds.npc_inventory_id(actor_id)
		and StringName(event.data["item_id"]) == SimulationIds.RESOURCE_FOOD
		and float(event.data["amount"]) > 0.0
	)


static func _is_missing_wood_block(event: EconomicEventRecord) -> bool:
	return (
		StringName(event.data["event_type"]) == SimulationIds.EVENT_TASK_BLOCKED
		and int(event.data["actor_id"]) >= 0
		and StringName(event.data["source_id"]) == SimulationIds.STORAGE_VILLAGE_WOODPILE
		and StringName(event.data["item_id"]) == SimulationIds.RESOURCE_WOOD
		and (
			StringName(event.data.get("action_id", &""))
			in [SimulationIds.ACTION_PATROL, SimulationIds.ACTION_STUDY]
		)
		and float(event.data.get("required_amount", 0.0)) > 0.0
	)


static func _is_valid_supply(
	event: EconomicEventRecord,
	opportunity: OpportunityStateRecord,
	npcs: Array[SimNPC],
	resource_states: Dictionary
) -> bool:
	if opportunity.get_opportunity_type() == SimulationIds.OPPORTUNITY_FEED_WEAK_VILLAGER:
		return (
			StringName(event.data["event_type"]) == SimulationIds.EVENT_ITEM_CONSUMED
			and int(event.data["actor_id"]) == opportunity.get_interested_npc_id()
			and StringName(event.data["item_id"]) == SimulationIds.RESOURCE_FOOD
			and float(event.data["amount"]) > 0.0
		)
	if (
		StringName(event.data["item_id"]) != opportunity.get_resource_id()
		or StringName(event.data["destination_id"]) != opportunity.get_target_id()
		or float(event.data["amount"]) <= 0.0
	):
		return false
	var event_type := StringName(event.data["event_type"])
	var actor_id := int(event.data["actor_id"])
	if event_type == SimulationIds.EVENT_STORAGE_DEPOSITED:
		if actor_id == SimulationIds.PLAYER_ACTOR_ID:
			return (
				StringName(event.data["source_id"])
				in [SimulationIds.PLAYER_INVENTORY_ID, &"player_carry"]
			)
		return (
			_find_npc(actor_id, npcs) != null
			and StringName(event.data["source_id"]) == SimulationIds.npc_inventory_id(actor_id)
		)
	if event_type != SimulationIds.EVENT_RESOURCE_EXTRACTED or actor_id != -1:
		return false
	var resource_state := (
		resource_states.get(StringName(event.data["source_id"])) as ResourceStateRecord
	)
	return (
		resource_state != null
		and resource_state.get_resource_id() == opportunity.get_resource_id()
		and resource_state.can_player_use_resource()
	)


static func _get_target_storage(
	opportunity: OpportunityStateRecord, pantry: StorageStateRecord, woodpile: StorageStateRecord
) -> StorageStateRecord:
	match opportunity.get_target_id():
		SimulationIds.STORAGE_VILLAGE_PANTRY:
			return pantry
		SimulationIds.STORAGE_VILLAGE_WOODPILE:
			return woodpile
	return null


static func _sort_by_care(first: SimNPC, second: SimNPC) -> bool:
	if first.hunger != second.hunger:
		return first.hunger > second.hunger
	return first.id < second.id


static func _find_npc(npc_id: int, npcs: Array[SimNPC]) -> SimNPC:
	for npc in npcs:
		if npc.id == npc_id:
			return npc
	return null


static func _sort_by_id(first: OpportunityStateRecord, second: OpportunityStateRecord) -> bool:
	return first.get_opportunity_id() < second.get_opportunity_id()