<?php
/**
 * Resolves product/order-item COGS via the merchant canonical source.
 *
 * @package Kayvandra\MarginBeacon
 */

declare(strict_types=1);

namespace Kayvandra\MarginBeacon\Application\Cost;

use Kayvandra\MarginBeacon\Application\Entitlement\EntitlementService;
use Kayvandra\MarginBeacon\Domain\Money\MoneyAmount;
use Kayvandra\MarginBeacon\Domain\Money\MoneyException;
use Kayvandra\MarginBeacon\Support\Constants;

/**
 * Cost resolver — one active canonical Exact source; no silent cross-source fallback.
 *
 * When canonical = woocommerce: native only (Missing if absent; never legacy manual).
 * When canonical = marginbeacon: manual → optional custom meta → optional assumed estimates.
 */
final class CostResolver {

	/**
	 * @var ProductCostStore
	 */
	private $store;

	/**
	 * @var CanonicalCostSource
	 */
	private $canonical;

	/**
	 * @param ProductCostStore|null    $store     Store.
	 * @param CanonicalCostSource|null $canonical Canonical source service.
	 */
	public function __construct( $store = null, $canonical = null ) {
		$this->store     = $store ? $store : new ProductCostStore();
		$this->canonical = $canonical ? $canonical : new CanonicalCostSource();
	}

	/**
	 * Resolve catalog cost for a product or variation.
	 *
	 * @param int $product_id   Product ID.
	 * @param int $variation_id Variation ID (0 for simple).
	 * @return CostResolution
	 */
	public function resolve_catalog( $product_id, $variation_id = 0 ) {
		$cost_settings = get_option( Constants::OPTION_COST_SETTINGS, array() );
		if ( ! is_array( $cost_settings ) ) {
			$cost_settings = array();
		}

		if ( ! empty( $cost_settings['cogs_tax_basis'] ) && 'inclusive' === $cost_settings['cogs_tax_basis'] ) {
			return new CostResolution( null, 'merchant_declared', 'missing', 'missing', 'MB_COGS_TAX_BASIS_INVALID' );
		}

		$target_id = $variation_id > 0 ? $variation_id : $product_id;
		$source    = $this->canonical->get();

		if ( CanonicalCostSource::WOOCOMMERCE === $source ) {
			return $this->resolve_woocommerce_catalog( $target_id );
		}

		return $this->resolve_marginbeacon_catalog( $product_id, $variation_id, $target_id, $cost_settings );
	}

	/**
	 * Resolve cost for an order line.
	 *
	 * Historical order-item native snapshots are used only when canonical is WooCommerce.
	 * Findings already persisted keep their historical evidence untouched.
	 *
	 * @param mixed $item         WC_Order_Item_Product.
	 * @param int   $product_id   Product ID.
	 * @param int   $variation_id Variation ID.
	 * @return CostResolution
	 */
	public function resolve_for_order_item( $item, $product_id, $variation_id = 0 ) {
		$cost_settings = get_option( Constants::OPTION_COST_SETTINGS, array() );
		if ( ! is_array( $cost_settings ) ) {
			$cost_settings = array();
		}
		if ( ! empty( $cost_settings['cogs_tax_basis'] ) && 'inclusive' === $cost_settings['cogs_tax_basis'] ) {
			return new CostResolution( null, 'merchant_declared', 'missing', 'missing', 'MB_COGS_TAX_BASIS_INVALID' );
		}

		if ( CanonicalCostSource::WOOCOMMERCE === $this->canonical->get() ) {
			if ( $item && is_object( $item ) && ( new CogsEnvironment() )->native_cogs_feature_enabled() ) {
				$from_item = $this->read_order_item_cogs( $item );
				if ( null !== $from_item ) {
					return $from_item;
				}
			}
		}

		return $this->resolve_catalog( $product_id, $variation_id );
	}

	/**
	 * @param int $target_id Product or variation ID.
	 * @return CostResolution
	 */
	private function resolve_woocommerce_catalog( $target_id ) {
		if ( ! ( new CogsEnvironment() )->native_cogs_feature_enabled() ) {
			return new CostResolution( null, 'native_cogs', 'missing', 'missing', 'MB_COST_SOURCE_UNAVAILABLE' );
		}

		$product = function_exists( 'wc_get_product' ) ? wc_get_product( $target_id ) : null;
		$native  = $this->store->read_native( $product );
		if ( null === $native ) {
			return CostResolution::missing();
		}
		if ( ! $native->is_resolved() ) {
			// Ambiguous zero / invalid — Missing, never fall back to MarginBeacon legacy.
			return $native;
		}
		return $native;
	}

	/**
	 * @param int   $product_id    Parent product ID.
	 * @param int   $variation_id  Variation ID.
	 * @param int   $target_id     Target ID for meta.
	 * @param array $cost_settings Cost settings.
	 * @return CostResolution
	 */
	private function resolve_marginbeacon_catalog( $product_id, $variation_id, $target_id, array $cost_settings ) {
		$manual = $this->store->read_manual( $target_id );
		if ( null !== $manual ) {
			return $manual;
		}

		$meta_key = isset( $cost_settings['custom_meta_key'] ) ? sanitize_key( (string) $cost_settings['custom_meta_key'] ) : '';
		if ( '' !== $meta_key ) {
			$custom = get_post_meta( $target_id, $meta_key, true );
			if ( '' === $custom || null === $custom ) {
				$parent_id = $variation_id > 0 ? $product_id : 0;
				if ( $parent_id ) {
					$custom = get_post_meta( $parent_id, $meta_key, true );
				}
			}
			if ( '' !== $custom && null !== $custom ) {
				return $this->store->parse_amount( (string) $custom, 'custom_meta', 'exact' );
			}
		}

		if ( ! empty( $cost_settings['fallback_enabled'] ) ) {
			$product = function_exists( 'wc_get_product' ) ? wc_get_product( $target_id ) : null;

			if ( ( new EntitlementService() )->resolve()->can( 'category_assumed_cost' ) ) {
				$cat_rule = $this->resolve_category_assumed( $product, $product_id, $variation_id );
				if ( null !== $cat_rule ) {
					return $cat_rule;
				}
			}

			$percent = isset( $cost_settings['global_assumed_cost_percent'] ) ? $cost_settings['global_assumed_cost_percent'] : null;
			if ( null !== $percent && '' !== $percent ) {
				$assumed = $this->resolve_assumed_percent( $product, $percent, 'global_assumed_percent' );
				if ( null !== $assumed ) {
					return $assumed;
				}
			}

			if ( isset( $cost_settings['global_assumed_cost'] ) && null !== $cost_settings['global_assumed_cost'] && '' !== $cost_settings['global_assumed_cost'] ) {
				return $this->store->parse_amount( (string) $cost_settings['global_assumed_cost'], 'global_assumed', 'estimated' );
			}
		}

		return CostResolution::missing();
	}

	/**
	 * @param \WC_Product|null|false $product      Product.
	 * @param int                    $product_id   Product ID.
	 * @param int                    $variation_id Variation ID.
	 * @return CostResolution|null
	 */
	private function resolve_category_assumed( $product, $product_id, $variation_id ) {
		/**
		 * Pro category assumed-cost rule. Free returns null without companion.
		 *
		 * @param array{percent:string,term_id:int}|null $picked Prior.
		 * @param mixed                                 $product Product.
		 * @param int                                   $product_id Product ID.
		 * @param int                                   $variation_id Variation ID.
		 */
		$picked = apply_filters( 'aksmb_resolve_category_assumed_cost', null, $product, $product_id, $variation_id );
		if ( ! is_array( $picked ) || ! isset( $picked['percent'] ) ) {
			return null;
		}
		return $this->resolve_assumed_percent( $product, $picked['percent'], 'category_assumed_percent' );
	}

	/**
	 * @param \WC_Product|null|false $product Product.
	 * @param mixed                  $percent Percent 0–100.
	 * @param string                 $source  Source key.
	 * @return CostResolution|null
	 */
	private function resolve_assumed_percent( $product, $percent, $source = 'global_assumed_percent' ) {
		if ( ! $product ) {
			return null;
		}
		$percent_s = trim( (string) $percent );
		if ( '' === $percent_s || ! preg_match( '/^\d+(?:\.\d+)?$/', $percent_s ) ) {
			return new CostResolution( null, $source, 'missing', 'explicit', 'MB_COST_INVALID' );
		}
		if ( ! function_exists( 'bccomp' ) ) {
			return new CostResolution( null, $source, 'missing', 'explicit', 'MB_COST_INVALID' );
		}
		if ( bccomp( $percent_s, '0', 6 ) < 0 || bccomp( $percent_s, '100', 6 ) > 0 ) {
			return new CostResolution( null, $source, 'missing', 'explicit', 'MB_COST_INVALID' );
		}

		$regular = $product->get_regular_price();
		if ( '' === $regular || null === $regular ) {
			return null;
		}

		try {
			$price = MoneyAmount::from_decimal_string( (string) $regular, Constants::DEFAULT_MONEY_SCALE );
			if ( null === $price ) {
				return null;
			}
			$units  = (string) $price->units();
			$scaled = bcdiv( bcmul( $units, $percent_s, 8 ), '100', 0 );
			$cost   = new MoneyAmount( $scaled, $price->scale() );
			return new CostResolution( $cost, $source, 'estimated', 'explicit' );
		} catch ( MoneyException $e ) {
			return new CostResolution( null, $source, 'missing', 'explicit', $e->error_code() );
		}
	}

	/**
	 * Native WooCommerce order-item COGS snapshot (positive line totals only).
	 *
	 * @param object $item Order item.
	 * @return CostResolution|null
	 */
	private function read_order_item_cogs( $item ) {
		if ( is_callable( array( $item, 'get_cogs_value' ) ) ) {
			$value = $item->get_cogs_value();
			if ( null === $value || '' === $value || ! is_numeric( $value ) ) {
				return null;
			}
			$zero_or_less = function_exists( 'bccomp' )
				? bccomp( (string) $value, '0', 8 ) <= 0
				: preg_match( '/^-?(?:0(?:\.0*)?|\.0+)$/', trim( (string) $value ) ) || preg_match( '/^-/', trim( (string) $value ) );
			if ( $zero_or_less ) {
				return null;
			}
			try {
				$amount = MoneyAmount::from_decimal_string( (string) $value, Constants::DEFAULT_MONEY_SCALE );
				if ( null === $amount || $amount->is_negative() || $amount->is_zero() ) {
					return null;
				}
				return new CostResolution( $amount, 'native_order_item_cogs', 'exact', 'explicit' );
			} catch ( MoneyException $e ) {
				return null;
			}
		}

		if ( is_callable( array( $item, 'get_meta' ) ) ) {
			$meta = $item->get_meta( '_cogs_total_value', true );
			if ( '' !== $meta && null !== $meta && is_numeric( $meta ) ) {
				$positive = function_exists( 'bccomp' )
					? bccomp( (string) $meta, '0', 8 ) > 0
					: preg_match( '/^\+?0*\.?[1-9]/', ltrim( (string) $meta, '0' ) ) || preg_match( '/^[1-9]/', (string) $meta );
				if ( ! $positive ) {
					return null;
				}
				try {
					$amount = MoneyAmount::from_decimal_string( (string) $meta, Constants::DEFAULT_MONEY_SCALE );
					if ( null === $amount || $amount->is_negative() || $amount->is_zero() ) {
						return null;
					}
					return new CostResolution( $amount, 'native_order_item_cogs', 'exact', 'explicit' );
				} catch ( MoneyException $e ) {
					return null;
				}
			}
		}

		return null;
	}
}