extends Node
class_name ShipInventory

signal inventory_changed

const CARGO_SIZE := 20
const WEAPON_SLOT_COUNT := 2
const MODULE_SLOT_COUNT := 6

var cargo: Array[ItemInstance] = []
var weapon_slots: Array[ItemInstance] = []
var module_slots: Array[ItemInstance] = []

@onready var ship: CharacterBody2D = get_parent()

func _ready() -> void:
	add_to_group("ship_inventory")
	cargo.resize(CARGO_SIZE)
	weapon_slots.resize(WEAPON_SLOT_COUNT)
	module_slots.resize(MODULE_SLOT_COUNT)
	if GameState.restart_inventory.is_empty():
		_add_starter_items()
	else:
		cargo.assign(GameState.restart_inventory["cargo"])
		weapon_slots.assign(GameState.restart_inventory["weapon"])
		module_slots.assign(GameState.restart_inventory["module"])
		GameState.restart_inventory.clear()
	_recalculate_ship_stats()
	inventory_changed.emit()

func get_cargo_used() -> int:
	var used := 0
	for item in cargo:
		if item != null:
			used += 1
	return used

func preserve_for_restart() -> void:
	# Copy the slot arrays; resources retain levels and individual modifiers.
	GameState.restart_inventory = {
		"cargo": cargo.duplicate(),
		"weapon": weapon_slots.duplicate(),
		"module": module_slots.duplicate(),
	}

func get_item(slot_kind: String, index: int) -> ItemInstance:
	var slots := _get_slots(slot_kind)
	if index < 0 or index >= slots.size():
		return null
	return slots[index]

func can_move_item(from_kind: String, from_index: int, to_kind: String, to_index: int) -> bool:
	var source := _get_slots(from_kind)
	var destination := _get_slots(to_kind)
	if from_index < 0 or from_index >= source.size() or to_index < 0 or to_index >= destination.size():
		return false
	if from_kind == to_kind and from_index == to_index:
		return false
	var item := source[from_index]
	if item == null or item.definition == null:
		return false
	if to_kind == "weapon" and item.definition.category != ItemDefinition.Category.WEAPON:
		return false
	if to_kind == "module" and item.definition.category == ItemDefinition.Category.WEAPON:
		return false
	var displaced := destination[to_index]
	if displaced != null and displaced.definition != null:
		if from_kind == "weapon" and displaced.definition.category != ItemDefinition.Category.WEAPON:
			return false
		if from_kind == "module" and displaced.definition.category == ItemDefinition.Category.WEAPON:
			return false
	return true

func move_item(from_kind: String, from_index: int, to_kind: String, to_index: int) -> bool:
	if not can_move_item(from_kind, from_index, to_kind, to_index):
		return false
	var source := _get_slots(from_kind)
	var destination := _get_slots(to_kind)
	var displaced := destination[to_index]
	destination[to_index] = source[from_index]
	source[from_index] = displaced
	_recalculate_ship_stats()
	inventory_changed.emit()
	return true

func _get_slots(slot_kind: String) -> Array[ItemInstance]:
	match slot_kind:
		"cargo":
			return cargo
		"weapon":
			return weapon_slots
		"module":
			return module_slots
	return []

func _recalculate_ship_stats() -> void:
	var bonuses := {}
	for item in weapon_slots + module_slots:
		if item == null or item.definition == null:
			continue
		for stat_key in ["max_hull", "max_shields", "max_energy", "max_speed", "energy_regeneration", "shield_regeneration"]:
			bonuses[stat_key] = float(bonuses.get(stat_key, 0.0)) + item.get_stat_total(stat_key)
	ship.call("apply_equipment_bonuses", bonuses)

func _add_starter_items() -> void:
	var starter_items := [
		"res://resources/items/plasma_cannon.tres",
		"res://resources/items/beam_laser.tres",
		"res://resources/items/machine_gun.tres",
		"res://resources/items/missile_launcher.tres",
		"res://resources/items/reinforced_shield.tres",
		"res://resources/items/hull_plating.tres",
		"res://resources/items/compact_generator.tres",
		"res://resources/items/engine_extension.tres",
		"res://resources/items/tuned_thrusters.tres",
		"res://resources/items/shield_recharger.tres",
	]
	var cargo_index := 0
	var weapon_index := 0
	for path in starter_items:
		var definition := load(path) as ItemDefinition
		if definition == null:
			push_warning("Could not load starter item: %s" % path)
			continue
		var item := ItemInstance.new()
		item.definition = definition
		item.item_level = 1
		if definition.category == ItemDefinition.Category.WEAPON and weapon_index < WEAPON_SLOT_COUNT:
			weapon_slots[weapon_index] = item
			weapon_index += 1
		else:
			cargo[cargo_index] = item
			cargo_index += 1