class_name CurrencyGenerator
extends Node

signal purchase_completed(amount: int, total_owned: int, total_purchased: int, total_cost: BigNumber)
signal purchase_failed(requested_amount: int, required_cost: BigNumber, available_currency: BigNumber)
signal production_tick(amount: BigNumber, cycle_count: int, total_owned: int)

const HUGE_COST_EXPONENT: int = 1000000

@export var currency: GameState.CurrencyType = GameState.CurrencyType.gold
@export var data: CurrencyGeneratorData
@export var is_automatic: bool = true
@export var press_buys_generator: bool = true
@export var run_multiplier: float = 1.0

## Manual click fallback when no data is assigned.
@export var click_mantissa: float = 1.0
@export var click_exponent: int = 0

var owned: int = 0
var purchased_count: int = 0
var cycle_progress_seconds: float = 0.0

func _ready() -> void:
	cycle_progress_seconds = 0.0

func _process(delta: float) -> void:
	if not is_automatic:
		return
	if data == null or owned <= 0:
		return

	var cycle_seconds: float = maxf(data.initial_time, 0.0001)
	cycle_progress_seconds += maxf(delta, 0.0)
	if cycle_progress_seconds < cycle_seconds:
		return

	var completed_cycles: int = floori(cycle_progress_seconds / cycle_seconds)
	cycle_progress_seconds -= cycle_seconds * float(completed_cycles)
	_grant_cycle_income(completed_cycles)

func _grant_cycle_income(cycle_count: int) -> void:
	if data == null or cycle_count <= 0:
		return

	var per_cycle: float = data.production_per_cycle(owned, run_multiplier, purchased_count)
	if per_cycle <= 0.0:
		return

	var produced: BigNumber = BigNumber.from_float(per_cycle).multiply(BigNumber.from_float(float(cycle_count)))
	_add_currency(produced)
	production_tick.emit(produced, cycle_count, owned)

func get_next_cost() -> BigNumber:
	return get_cost_for_amount(1)

func get_cost_for_amount(amount: int = 1) -> BigNumber:
	if data == null:
		return BigNumber.from_float(0.0)

	var safe_amount: int = maxi(amount, 1)
	var raw_cost: float = data.cost_for_amount(owned, safe_amount)
	return _float_to_big_number(raw_cost)

func can_buy(amount: int = 1) -> bool:
	var cost: BigNumber = get_cost_for_amount(amount)
	var current: BigNumber = _get_currency_amount()
	return current.is_greater_than(cost) or current.is_equal_to(cost)

func buy(amount: int = 1) -> bool:
	if data == null:
		return false

	var safe_amount: int = maxi(amount, 1)
	var total_cost: BigNumber = get_cost_for_amount(safe_amount)
	if not _spend_currency(total_cost):
		purchase_failed.emit(safe_amount, total_cost, _get_currency_amount())
		return false

	owned += safe_amount
	purchased_count += safe_amount
	purchase_completed.emit(safe_amount, owned, purchased_count, total_cost)
	return true

func buy_max() -> int:
	if data == null:
		return 0

	var available_currency: float = _big_number_to_float(_get_currency_amount())
	var estimated_max: int = data.max_affordable(owned, available_currency)
	if estimated_max <= 0:
		return 0

	# Keep max-buy accurate by validating affordability with BigNumber comparisons.
	var low: int = 1
	var high: int = estimated_max
	var best: int = 0
	while low <= high:
		var mid: int = floori((float(low) + float(high)) * 0.5)
		if can_buy(mid):
			best = mid
			low = mid + 1
		else:
			high = mid - 1

	if best <= 0:
		return 0
	return best if buy(best) else 0

func _on_pressed() -> void:
	if data != null and press_buys_generator:
		buy(1)
		return

	_add_currency(BigNumber.new(click_mantissa, click_exponent))

func grant_currency(amount: BigNumber) -> void:
	_add_currency(amount)

func _add_currency(amount: BigNumber) -> void:
	match currency:
		GameState.CurrencyType.gold:
			GameState.add_gold(amount)
		GameState.CurrencyType.gems:
			GameState.add_gems(amount)
		_:
			push_error("Unknown currency type in CurrencyGenerator._add_currency")

func _spend_currency(cost: BigNumber) -> bool:
	match currency:
		GameState.CurrencyType.gold:
			return GameState.spend_gold(cost)
		GameState.CurrencyType.gems:
			return GameState.spend_gems(cost)
		_:
			push_error("Unknown currency type in CurrencyGenerator._spend_currency")
			return false

func _get_currency_amount() -> BigNumber:
	match currency:
		GameState.CurrencyType.gold:
			return GameState.gold
		GameState.CurrencyType.gems:
			return GameState.gems
		_:
			return BigNumber.from_float(0.0)

func _float_to_big_number(value: float) -> BigNumber:
	if value <= 0.0:
		return BigNumber.from_float(0.0)
	if not is_finite(value):
		return BigNumber.new(1.0, HUGE_COST_EXPONENT)
	return BigNumber.from_float(value)

func _big_number_to_float(value: BigNumber) -> float:
	if value.mantissa <= 0.0:
		return 0.0
	if value.exponent > 308:
		return INF
	if value.exponent < -308:
		return 0.0
	return value.mantissa * pow(10.0, float(value.exponent))