<?php
/**
 * The real-profit calculation model.
 *
 * @package ProfitEngine
 */

declare( strict_types=1 );

namespace ProfitEngine\Profit;

defined( 'ABSPATH' ) || exit;

/**
 * Pure, side-effect-free profit math.
 *
 * Deliberately free of WordPress dependencies so it can be unit-tested in
 * isolation and reasoned about. All order/refund extraction and allocation of
 * order-level costs across lines happens in CostSnapshotService; this class only
 * combines already-resolved figures into profit and margin, plus a couple of
 * small helpers for the order-level costs it owns.
 *
 * Profit definition (per line):
 *   profit = revenue − cost_total − shipping_alloc − payment_fee − other_cost
 *            − (tax_in_profit ? tax : 0)
 *
 * where `revenue` is the line total net of discounts and refunds, excluding tax.
 * Tax is treated as pass-through (excluded) by default.
 */
class CostModel {

	/**
	 * Resolved configuration.
	 *
	 * @var array<string,mixed>
	 */
	private array $config;

	/**
	 * Constructor.
	 *
	 * @param array<string,mixed> $config Settings (tax_in_profit, payment_fee_*, shipping_alloc, other_cost_*).
	 */
	public function __construct( array $config ) {
		$this->config = wp_parse_args(
			$config,
			array(
				'tax_in_profit'       => false,
				'payment_fee_percent' => 0.0,
				'payment_fee_fixed'   => 0.0,
				'shipping_alloc'      => 'value',
				'other_cost_percent'  => 0.0,
				'other_cost_fixed'    => 0.0,
			)
		);
	}

	/**
	 * Whether tax should be subtracted as a cost.
	 */
	public function tax_is_cost(): bool {
		return (bool) $this->config['tax_in_profit'];
	}

	/**
	 * Whether shipping cost should be allocated to lines.
	 */
	public function allocates_shipping(): bool {
		return 'value' === $this->config['shipping_alloc'];
	}

	/**
	 * The total payment-gateway fee for an order.
	 *
	 * @param float $order_total Order grand total (what the customer paid).
	 */
	public function order_payment_fee( float $order_total ): float {
		$pct   = (float) $this->config['payment_fee_percent'];
		$fixed = (float) $this->config['payment_fee_fixed'];
		return ( $order_total * $pct / 100 ) + $fixed;
	}

	/**
	 * The total "other" configurable cost for an order.
	 *
	 * @param float $order_revenue Order revenue (net, excl tax).
	 */
	public function order_other_cost( float $order_revenue ): float {
		$pct   = (float) $this->config['other_cost_percent'];
		$fixed = (float) $this->config['other_cost_fixed'];
		return ( $order_revenue * $pct / 100 ) + $fixed;
	}

	/**
	 * Allocate an order-level amount to a line by its revenue share.
	 *
	 * @param float $amount        Order-level amount to spread.
	 * @param float $line_revenue  This line's revenue.
	 * @param float $total_revenue Sum of all lines' revenue.
	 */
	public function allocate_by_share( float $amount, float $line_revenue, float $total_revenue ): float {
		if ( $total_revenue <= 0.0 ) {
			return 0.0;
		}
		return $amount * ( $line_revenue / $total_revenue );
	}

	/**
	 * Compute profit for a line from its resolved cost buckets.
	 *
	 * @param array{revenue:float,cost_total:float,tax:float,shipping_alloc:float,payment_fee:float,other_cost:float} $line Line buckets.
	 * @return array{profit:float,margin:float}
	 */
	public function line_profit( array $line ): array {
		$revenue = (float) ( $line['revenue'] ?? 0.0 );

		$profit = $revenue
			- (float) ( $line['cost_total'] ?? 0.0 )
			- (float) ( $line['shipping_alloc'] ?? 0.0 )
			- (float) ( $line['payment_fee'] ?? 0.0 )
			- (float) ( $line['other_cost'] ?? 0.0 );

		if ( $this->tax_is_cost() ) {
			$profit -= (float) ( $line['tax'] ?? 0.0 );
		}

		$margin = $revenue > 0.0 ? ( $profit / $revenue ) : 0.0;

		return array(
			'profit' => $profit,
			'margin' => $margin,
		);
	}
}