class_name CurrencyGenerator
extends Node

## Handles generator economy behavior:
## - automatic production cycles
## - manual/hover click rewards with cooldown
## - purchasing and max-buy
## - generator state access through the GameState autoload

## Emitted after a successful purchase.
signal purchase_completed(amount: int, total_owned: int, total_purchased: int, total_cost: BigNumber)
## Emitted when a purchase is attempted but cannot be paid.
signal purchase_failed(requested_amount: int, required_cost: BigNumber, available_currency: BigNumber)
## Emitted when one or more automatic production cycles complete.
signal production_tick(amount: BigNumber, cycle_count: int, total_owned: int)

## Sentinel exponent used when cost math overflows float range.
const HUGE_COST_EXPONENT: int = 1000000

## Currency target updated by this generator.
@export var currency: GameState.CurrencyType = GameState.CurrencyType.gold
## Data resource containing balancing values and defaults.
@export var data: CurrencyGeneratorData
## Enables per-cycle automatic production when true.
@export var is_automatic: bool = true
## If true, `_on_pressed` buys one generator instead of granting click currency.
@export var press_buys_generator: bool = true
## Extra multiplier applied to automatic production output.
@export var run_multiplier: float = 1.0
## Fallback unlocked state when `data` is not assigned.
@export var starts_unlocked: bool = true
## Fallback availability state when `data` is not assigned.
@export var starts_available: bool = true

## Manual click reward fallback when no data is assigned.
@export var click_mantissa: float = 1.0
## Exponent for fallback click reward when no data is assigned.
@export var click_exponent: int = 0
## Cooldown between click/hover grants when no data is assigned.
@export var click_cooldown_seconds: float = 0.2
## If true, hovering grants click reward every cooldown without pressing.
@export var grants_click_while_hovering: bool = false

## True while the pointer is inside the generator Area2D.
var _mouse_entered: bool = false
## Time left until next click/hover grant is allowed.
var _remaining_click_cooldown_seconds: float = 0.0

## Number of currently owned generators.
## Backed by GameState via this generator's resolved id.
var owned: int:
	get:
		_ensure_registered()
		return GameState.get_generator_owned(_generator_id)
	set(value):
		_ensure_registered()
		GameState.set_generator_owned(_generator_id, value)

## Lifetime purchased generators (does not decrease if ownership drops).
var purchased_count: int:
	get:
		_ensure_registered()
		return GameState.get_generator_purchased_count(_generator_id)
	set(value):
		_ensure_registered()
		GameState.set_generator_purchased_count(_generator_id, value)

## Whether this generator is unlocked for the player.
var is_unlocked: bool:
	get:
		_ensure_registered()
		return GameState.is_generator_unlocked(_generator_id)
	set(value):
		_ensure_registered()
		GameState.set_generator_unlocked(_generator_id, value)

## Whether this unlocked generator is currently visible/usable to the player.
var is_available: bool:
	get:
		_ensure_registered()
		return GameState.is_generator_available(_generator_id)
	set(value):
		_ensure_registered()
		GameState.set_generator_available(_generator_id, value)

## Accumulated elapsed time toward the next automatic production cycle.
var cycle_progress_seconds: float = 0.0
## Stable id used to store/read generator state in GameState.
var _generator_id: StringName = &""
## Prevents duplicate state registration in GameState.
var _is_registered: bool = false


## Resolves and registers this generator state before gameplay updates.
func _ready() -> void:
	_generator_id = _resolve_generator_id()
	_ensure_registered()
	cycle_progress_seconds = 0.0

## Updates click cooldown/click grants and runs automatic production cycles.
func _process(delta: float) -> void:
	_remaining_click_cooldown_seconds = maxf(_remaining_click_cooldown_seconds - maxf(delta, 0.0), 0.0)
	_try_handle_mouse_click()

	if not is_automatic:
		return
	if not is_available_to_player():
		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)

## Adds automatic production from completed cycles and emits `production_tick`.
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)

## Convenience helper for the next single-unit purchase cost.
func get_next_cost() -> BigNumber:
	return get_cost_for_amount(1)

## Returns cumulative cost to buy `amount` units from current ownership.
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)

## Checks whether enough target currency is available for `amount` units.
func can_buy(amount: int = 1) -> bool:
	if not is_available_to_player():
		return false

	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)

## Attempts to buy `amount` units and emits purchase success/failure signals.
func buy(amount: int = 1) -> bool:
	if data == null:
		return false
	if not is_available_to_player():
		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

## Computes and buys the maximum affordable units with current currency.
func buy_max() -> int:
	if data == null:
		return 0
	if not is_available_to_player():
		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

## Handles external "pressed" interaction: buy if configured, otherwise click-grant.
func _on_pressed() -> void:
	if not is_available_to_player():
		return

	if data != null and press_buys_generator:
		buy(1)
		return

	_try_grant_click_currency()

## Adds currency directly through the configured currency target.
func grant_currency(amount: BigNumber) -> void:
	_add_currency(amount)

## Processes pointer interaction while hovering (hold click or hover-only mode).
func _try_handle_mouse_click() -> void:
	if not _mouse_entered:
		return
	if not is_available_to_player():
		return
	if not (_grants_click_while_hovering() or Input.is_action_pressed("click")):
		return

	_try_grant_click_currency()

## Grants one click/hover reward if cooldown has elapsed.
func _try_grant_click_currency() -> void:
	if _remaining_click_cooldown_seconds > 0.0:
		return

	_add_currency(_get_click_value())
	_remaining_click_cooldown_seconds = _get_click_cooldown_seconds()

## Resolves click reward from data, with exported fallback when data is missing.
func _get_click_value() -> BigNumber:
	if data != null:
		return BigNumber.new(data.click_mantissa, data.click_exponent)
	return BigNumber.new(click_mantissa, click_exponent)

## Resolves click cooldown from data, with exported fallback when data is missing.
func _get_click_cooldown_seconds() -> float:
	if data != null:
		return maxf(data.click_cooldown_seconds, 0.0)
	return maxf(click_cooldown_seconds, 0.0)

## Resolves hover-only click-grant mode from data, with exported fallback.
func _grants_click_while_hovering() -> bool:
	if data != null:
		return data.grants_click_while_hovering
	return grants_click_while_hovering

## Returns this generator's resolved state id.
func get_generator_id() -> StringName:
	_ensure_registered()
	return _generator_id

## True when the generator is both unlocked and available.
func is_available_to_player() -> bool:
	return is_unlocked and is_available

## Routes positive/negative currency deltas to the configured currency bucket.
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")

## Attempts to spend target currency; returns false when insufficient.
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

## Returns the current amount for the configured currency type.
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)

## Safely converts finite float values into BigNumber costs.
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)

## Converts BigNumber to float for approximate estimate math.
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))

## Builds a stable state id from data id, node name, or fallback string.
func _resolve_generator_id() -> StringName:
	if data != null:
		var data_id: String = String(data.id)
		if not data_id.is_empty():
			return StringName(data_id)

	if not String(name).is_empty():
		return StringName(String(name))

	return &"generator"

## Ensures this generator has a state entry in GameState.
func _ensure_registered() -> void:
	if _is_registered:
		return

	if _generator_id == &"":
		_generator_id = _resolve_generator_id()
	if _generator_id == &"":
		return

	GameState.register_generator(_generator_id, _default_unlocked_state(), _default_available_state())
	_is_registered = true

## Default unlocked state used at registration time.
func _default_unlocked_state() -> bool:
	if data != null:
		return data.starts_unlocked
	return starts_unlocked

## Default available state used at registration time.
func _default_available_state() -> bool:
	if data != null:
		return data.starts_available
	return starts_available

## Area2D callback: pointer entered generator interaction region.
func _on_area_2d_mouse_entered() -> void:
	_mouse_entered = true

## Area2D callback: pointer exited generator interaction region.
func _on_area_2d_mouse_exited() -> void:
	_mouse_entered = false