<?php
/**
 * State extraction.
 *
 * @package Recast\WCS
 */

namespace Recast\WCS\State;

use Recast\WCS\Support\Money;

defined( 'ABSPATH' ) || exit;

/**
 * Reads allow-listed fields from a subscription into a normalised array (public getters only).
 */
final class StateExtractor {

	/**
	 * Extracts the given fields. 'item:*:{prop}' patterns expand to every product line item.
	 *
	 * @param \WC_Subscription $subscription Subscription.
	 * @param string[]         $fields       Field keys / patterns.
	 * @return array<string, mixed> Keyed by concrete field key, sorted.
	 */
	public static function extract( \WC_Subscription $subscription, array $fields ) {
		$state = array();
		foreach ( self::expand( $subscription, $fields ) as $field ) {
			$state[ $field ] = self::read( $subscription, $field );
		}
		ksort( $state, SORT_STRING );
		return $state;
	}

	/**
	 * Expands item wildcards into concrete keys.
	 *
	 * @param \WC_Subscription $subscription Subscription.
	 * @param string[]         $fields       Fields.
	 * @return string[]
	 */
	public static function expand( \WC_Subscription $subscription, array $fields ) {
		$out = array();
		foreach ( $fields as $field ) {
			$parsed = Fields::parse( $field );
			if ( ! $parsed ) {
				continue;
			}
			if ( 'item' === $parsed['kind'] && '*' === $parsed['item_id'] ) {
				foreach ( $subscription->get_items() as $item_id => $item ) {
					if ( $item instanceof \WC_Order_Item_Product ) {
						$out[] = Fields::item( (int) $item_id, $parsed['prop'] );
					}
				}
				continue;
			}
			$out[] = $field;
		}
		return array_values( array_unique( $out ) );
	}

	/**
	 * Reads one concrete field.
	 *
	 * @param \WC_Subscription $subscription Subscription.
	 * @param string           $field        Field key.
	 * @return mixed
	 */
	public static function read( \WC_Subscription $subscription, $field ) {
		$parsed = Fields::parse( $field );
		if ( ! $parsed ) {
			return null;
		}
		switch ( $parsed['kind'] ) {
			case 'date':
				$date = (string) $subscription->get_date( $parsed['type'], 'gmt' );
				return ( '' === $date || '0' === $date ) ? '0' : $date;
			case 'meta':
				if ( ! \Recast\WCS\Operation\Field\MetaOperation::is_allowed( $parsed['key'] ) ) {
					return null; // Internal keys are read through their getters, never generic meta.
				}
				// An absent field is null, so undo can delete it again instead of leaving an empty value.
				if ( ! $subscription->meta_exists( $parsed['key'] ) ) {
					return null;
				}
				$value = $subscription->get_meta( $parsed['key'], true );
				return is_scalar( $value ) || null === $value ? ( null === $value ? '' : (string) $value ) : $value;
			case 'item':
				$item = $subscription->get_item( (int) $parsed['item_id'], false );
				if ( ! $item instanceof \WC_Order_Item_Product ) {
					return null;
				}
				return self::read_item( $item, $parsed['prop'] );
		}
		switch ( $field ) {
			case Fields::STATUS:
				return (string) $subscription->get_status();
			case Fields::REQUIRES_MANUAL_RENEWAL:
				return (bool) $subscription->get_requires_manual_renewal();
			case Fields::PAYMENT_METHOD:
				return (string) $subscription->get_payment_method();
			case Fields::PAYMENT_METHOD_TITLE:
				return (string) $subscription->get_payment_method_title();
			case Fields::BILLING_PERIOD:
				return (string) $subscription->get_billing_period();
			case Fields::BILLING_INTERVAL:
				return (int) $subscription->get_billing_interval();
			case Fields::CURRENCY:
				return (string) $subscription->get_currency();
			case Fields::TOTAL:
				return Money::format( $subscription->get_total() );
			case Fields::TOTAL_TAX:
				return Money::format( $subscription->get_total_tax() );
		}
		return null;
	}

	/**
	 * Reads one line item property.
	 *
	 * @param \WC_Order_Item_Product $item Item.
	 * @param string                 $prop Property.
	 * @return mixed
	 */
	private static function read_item( \WC_Order_Item_Product $item, $prop ) {
		switch ( $prop ) {
			case 'subtotal':
				return Money::format( $item->get_subtotal() );
			case 'total':
				return Money::format( $item->get_total() );
			case 'tax_class':
				return (string) $item->get_tax_class();
			case 'quantity':
				return (int) $item->get_quantity();
			case 'product_id':
				return (int) $item->get_product_id();
			case 'variation_id':
				return (int) $item->get_variation_id();
			case 'name':
				return (string) $item->get_name();
			case 'attributes':
				return self::item_attributes( $item );
			case 'taxes':
				$taxes = $item->get_taxes();
				$out   = array();
				foreach ( array( 'subtotal', 'total' ) as $bucket ) {
					$out[ $bucket ] = array();
					if ( ! empty( $taxes[ $bucket ] ) ) {
						foreach ( $taxes[ $bucket ] as $rate_id => $amount ) {
							$out[ $bucket ][ (string) $rate_id ] = Money::format( $amount );
						}
						ksort( $out[ $bucket ], SORT_STRING );
					}
				}
				return $out;
		}
		return null;
	}

	/**
	 * The variation attributes stored on a line item (for example "Size: Large"), keyed like the
	 * item meta. Only the attributes of the line's variation count, so other item meta stays out.
	 *
	 * @param \WC_Order_Item_Product $item Item.
	 * @return array<string, string>
	 */
	public static function item_attributes( \WC_Order_Item_Product $item ) {
		$out          = array();
		$variation_id = (int) $item->get_variation_id();
		$variation    = $variation_id ? wc_get_product( $variation_id ) : null;
		if ( ! $variation instanceof \WC_Product ) {
			return $out;
		}
		foreach ( array_keys( (array) $variation->get_attributes() ) as $key ) {
			$key = (string) $key;
			if ( $item->meta_exists( $key ) ) {
				$out[ $key ] = (string) $item->get_meta( $key, true );
			}
		}
		ksort( $out, SORT_STRING );
		return $out;
	}
}