<?php
/**
 * The shop's own item details: fields of the order items shown under the name.
 *
 * @package Careback
 */

namespace Careback;

defined( 'ABSPATH' ) || exit;

/**
 * Extra item details (X-04): fields the shop picks from what its order items
 * carry — an engraving, a second color, anything a product add-on or the shop's
 * own code writes on the line — each shown on a line of its own under the
 * item's name, as "Label: value" (or the value alone without a label), exactly
 * like the details of a variation (N-16): in the form, its check step, the
 * emails and the request card, through Order_Lookup::item_parts().
 *
 * A field is read from the order item first; a field the item does not carry
 * is read from its product, then from the parent product of a variation (ACF's
 * get_field() first where ACF is active), so a detail the shop keeps on the
 * product shows as well. A hidden field (its key starts with "_") is never
 * offered, stored or shown.
 *
 * Replaces the custom mode of earlier releases (two colour fields with their
 * labels): what a shop stored there becomes this list (from_retired(), on the
 * next admin load through Settings::retire(), and read that way until then).
 *
 * The row stands under Settings → Portal and form → Item variation details,
 * added through the screen's own hooks. Developers change the lines through
 * `careback_item_details` (api/customer.md).
 */
class Item_Fields {

	/** Settings key: a list of [ 'key' => field, 'label' => label ]. */
	const SETTING = 'item_fields';

	/**
	 * Filter: the detail lines of an item ( string[] $details, WC_Order_Item_Product $item, Settings $settings ).
	 * Returns the lines, one string each.
	 */
	const FILTER = 'careback_item_details';

	/** Section of the settings screen the row is printed in. */
	const SECTION = 'variation';

	/** The most fields a shop picks. */
	const MAX_FIELDS = 10;

	/** The longest label. */
	const LABEL_MAX = 60;

	/** The longest field name (a meta key's column). */
	const KEY_MAX = 255;

	/** Empty rows printed under the shop's fields. */
	const BLANK_ROWS = 2;

	/** How many of the latest orders the offered fields are read from. */
	const RECENT_ORDERS = 20;

	/** Field of the form that says the rows were on it. */
	const SHOWN = 'careback_item_fields_shown';

	/** Field of the form holding the rows. */
	const POSTED = 'careback_item_fields';

	/** Prefix of the short-lived option holding the rows and messages of a refused save, per user. */
	const ERRORS = 'careback_item_fields_errors_';

	/** The keys of the custom mode of earlier releases (Settings::RETIRED). */
	const RETIRED = array( 'variation_mode', 'variation_ext_key', 'variation_ext_label', 'variation_int_taxonomy', 'variation_int_label' );

	/**
	 * Hooks the row and its save.
	 *
	 * @return void
	 */
	public static function init() {
		add_filter( Admin::FIELDS_FILTER, array( __CLASS__, 'fields' ), 10, 2 );
		add_filter( Admin::SAVE_FILTER, array( __CLASS__, 'save' ), 10, 4 );
	}

	/**
	 * Whether a field is hidden: its key starts with "_", as WooCommerce's own
	 * bookkeeping and most plugins' private values do.
	 *
	 * @param string $key Field.
	 * @return bool
	 */
	public static function hidden( $key ) {
		return '_' === substr( (string) $key, 0, 1 );
	}

	/**
	 * A list of fields made safe to use: a row with a field that is not hidden,
	 * each field once, at most MAX_FIELDS, labels trimmed.
	 *
	 * @param mixed $rows Stored or given rows.
	 * @return array<int,array{key:string,label:string}>
	 */
	public static function clean( $rows ) {
		$out  = array();
		$seen = array();

		foreach ( is_array( $rows ) ? $rows : array() as $row ) {
			if ( ! is_array( $row ) || ! isset( $row['key'] ) || ! is_scalar( $row['key'] ) ) {
				continue;
			}

			$key = trim( (string) $row['key'] );

			if ( '' === $key || self::hidden( $key ) || isset( $seen[ $key ] ) ) {
				continue;
			}

			$seen[ $key ] = true;
			$out[]        = array(
				'key'   => $key,
				'label' => isset( $row['label'] ) && is_scalar( $row['label'] ) ? trim( (string) $row['label'] ) : '',
			);

			if ( count( $out ) >= self::MAX_FIELDS ) {
				break;
			}
		}

		return $out;
	}

	/**
	 * The fields the shop picked.
	 *
	 * @param Settings $settings Plugin settings.
	 * @return array<int,array{key:string,label:string}>
	 */
	public static function picked( Settings $settings ) {
		return self::clean( $settings->get( self::SETTING, array() ) );
	}

	/**
	 * The settings of earlier releases with the custom mode turned into this
	 * list: the exterior and the interior field with their labels, in that
	 * order, and WooCommerce's own details off — the custom mode showed the two
	 * fields alone. Nothing changes while a list is stored, or while the custom
	 * mode was not in use (another mode, or the details switched off). The old
	 * keys stay; Settings::retire() drops them.
	 *
	 * @param array $values Settings values.
	 * @return array
	 */
	public static function from_retired( array $values ) {
		if ( ! isset( $values['variation_mode'] ) || 'custom' !== $values['variation_mode'] || empty( $values['variation_display'] ) || ! empty( $values[ self::SETTING ] ) ) {
			return $values;
		}

		$rows = array();

		$pairs = array(
			'variation_ext_key'      => 'variation_ext_label',
			'variation_int_taxonomy' => 'variation_int_label',
		);

		foreach ( $pairs as $key => $label ) {
			$rows[] = array(
				'key'   => isset( $values[ $key ] ) && is_scalar( $values[ $key ] ) ? (string) $values[ $key ] : '',
				'label' => isset( $values[ $label ] ) && is_scalar( $values[ $label ] ) ? (string) $values[ $label ] : '',
			);
		}

		$values[ self::SETTING ]     = self::clean( $rows );
		$values['variation_display'] = 0;

		return $values;
	}

	/**
	 * An item's title and detail lines: WooCommerce's details as given, a
	 * field the shop picked in place of WooCommerce's line for it, the other
	 * picked fields after them, then `careback_item_details`. A picked field's
	 * value is dropped from the end of the title ("Bag - Black" with "Black"
	 * shown reads "Bag"), so it is not said twice.
	 *
	 * @param \WC_Order_Item $item     Order line item.
	 * @param string         $title    The item's name.
	 * @param array          $woo      WooCommerce's details: [ field, line ] pairs.
	 * @param Settings       $settings Plugin settings.
	 * @return array{title:string,details:string[]}
	 */
	public static function apply( $item, $title, array $woo, Settings $settings ) {
		$own = array();

		foreach ( self::picked( $settings ) as $field ) {
			$value = self::value( $item, $field['key'] );

			if ( '' === $value ) {
				continue;
			}

			$own[ rawurldecode( $field['key'] ) ] = '' !== $field['label'] ? $field['label'] . ': ' . $value : $value;

			$shorter = preg_replace( '/\s*[-–—]\s*' . preg_quote( $value, '/' ) . '\s*$/iu', '', $title );
			$title   = is_string( $shorter ) && '' !== $shorter ? $shorter : $title;
		}

		$lines = array();

		foreach ( $woo as $pair ) {
			$key = rawurldecode( (string) $pair[0] );

			if ( isset( $own[ $key ] ) ) {
				$lines[] = $own[ $key ];
				unset( $own[ $key ] );
				continue;
			}

			$lines[] = (string) $pair[1];
		}

		$lines = array_merge( $lines, array_values( $own ) );

		/**
		 * Filters the detail lines shown under an item's name, one string each,
		 * in the form, its check step, the emails and the request card. See
		 * api/customer.md.
		 *
		 * @param string[]       $lines    The lines.
		 * @param \WC_Order_Item $item     The order item.
		 * @param Settings       $settings Plugin settings.
		 */
		$filtered = apply_filters( self::FILTER, $lines, $item, $settings ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.DynamicHooknameFound -- careback_item_details, the final prefix.
		$details  = array();

		foreach ( is_array( $filtered ) ? $filtered : $lines as $line ) {
			$line = is_scalar( $line ) ? trim( wp_strip_all_tags( (string) $line ) ) : '';

			if ( '' !== $line ) {
				$details[] = $line;
			}
		}

		return array(
			'title'   => $title,
			'details' => $details,
		);
	}

	/**
	 * A field's value for an item: the item's own, a term's name for an
	 * attribute's slug; else its product's; else the parent product's. '' when
	 * none has it, or the field is hidden.
	 *
	 * @param \WC_Order_Item $item Order line item.
	 * @param string         $key  Field.
	 * @return string
	 */
	public static function value( $item, $key ) {
		$key = (string) $key;

		if ( '' === $key || self::hidden( $key ) ) {
			return '';
		}

		$value = is_callable( array( $item, 'get_meta' ) ) ? self::text( $item->get_meta( $key, true ) ) : '';

		if ( '' !== $value ) {
			$value = rawurldecode( $value );

			if ( taxonomy_exists( $key ) ) {
				$term  = get_term_by( 'slug', $value, $key );
				$value = $term && ! is_wp_error( $term ) ? (string) $term->name : $value;
			}
		} elseif ( is_callable( array( $item, 'get_product' ) ) ) {
			$product = $item->get_product();

			if ( $product ) {
				$value = self::product_value( (int) $product->get_id(), $key );

				if ( '' === $value && $product->get_parent_id() ) {
					$value = self::product_value( (int) $product->get_parent_id(), $key );
				}
			}
		}

		return trim( wp_strip_all_tags( $value ) );
	}

	/**
	 * A product's field: ACF's get_field() first (it formats the field), else
	 * its post meta.
	 *
	 * @param int    $product_id Product or variation.
	 * @param string $key        Field.
	 * @return string
	 */
	private static function product_value( $product_id, $key ) {
		if ( $product_id <= 0 ) {
			return '';
		}

		if ( function_exists( 'get_field' ) ) {
			$value = self::text( get_field( $key, $product_id ) );

			if ( '' !== $value ) {
				return $value;
			}
		}

		return self::text( get_post_meta( $product_id, $key, true ) );
	}

	/**
	 * A stored value as text: a string or a number; anything else is none.
	 *
	 * @param mixed $value Value.
	 * @return string
	 */
	private static function text( $value ) {
		return is_string( $value ) || is_int( $value ) || is_float( $value ) ? (string) $value : '';
	}

	/**
	 * The fields the items of the latest orders carry, field => its name in
	 * WooCommerce (an attribute's label, else the field): what the screen
	 * offers. Hidden fields never; fields with no text value neither.
	 *
	 * @return array<string,string>
	 */
	public static function offered() {
		if ( ! function_exists( 'wc_get_orders' ) ) {
			return array();
		}

		$keys   = array();
		$orders = wc_get_orders(
			array(
				'limit'   => self::RECENT_ORDERS,
				'orderby' => 'date',
				'order'   => 'DESC',
				'type'    => 'shop_order',
			)
		);

		foreach ( is_array( $orders ) ? $orders : array() as $order ) {
			if ( ! $order instanceof \WC_Order ) {
				continue;
			}

			foreach ( $order->get_items() as $item ) {
				foreach ( $item->get_meta_data() as $meta ) {
					$key = (string) $meta->key;

					if ( '' === $key || self::hidden( $key ) || isset( $keys[ $key ] ) || '' === self::text( $meta->value ) ) {
						continue;
					}

					$keys[ $key ] = taxonomy_exists( $key ) ? (string) wc_attribute_label( $key ) : rawurldecode( $key );
				}
			}
		}

		return $keys;
	}

	/**
	 * Adds the row to the section of the item details, after its checkbox.
	 *
	 * @param array  $fields  Rows of the section.
	 * @param string $section Section key.
	 * @return array
	 */
	public static function fields( $fields, $section = '' ) {
		$fields = (array) $fields;

		if ( self::SECTION === $section ) {
			$fields[ self::SETTING ] = array(
				'position' => 20,
				'render'   => array( __CLASS__, 'render' ),
			);
		}

		return $fields;
	}

	/**
	 * The row: a table of field and label, the shop's fields and empty rows
	 * under them, the fields of recent orders offered in each field box. After
	 * a refused save, the rows as they were sent, each message under its field.
	 *
	 * @param array    $s        Stored settings.
	 * @param string   $screen   Screen id.
	 * @param Settings $settings The screen's settings.
	 * @return void
	 */
	public static function render( array $s, $screen = '', $settings = null ) {
		unset( $s, $screen );

		$settings = $settings instanceof Settings ? $settings : new Settings();
		$last     = self::last();
		$rows     = $last ? $last['rows'] : self::picked( $settings );
		$errors   = $last ? $last['errors'] : array();
		$blank    = max( 0, min( self::BLANK_ROWS, self::MAX_FIELDS - count( $rows ) ) );
		$offered  = self::offered();

		for ( $i = 0; $i < $blank; $i++ ) {
			$rows[] = array(
				'key'   => '',
				'label' => '',
			);
		}
		?>
		<tr>
			<th scope="row"><?php esc_html_e( 'Extra item details', 'careback' ); ?></th>
			<td>
				<input type="hidden" name="<?php echo esc_attr( self::SHOWN ); ?>" value="1" />
				<table class="widefat striped careback-item-fields" aria-describedby="careback-item-fields-help">
					<thead>
						<tr>
							<th scope="col"><?php esc_html_e( 'Field', 'careback' ); ?></th>
							<th scope="col"><?php esc_html_e( 'Label (optional)', 'careback' ); ?></th>
						</tr>
					</thead>
					<tbody>
						<?php foreach ( array_values( $rows ) as $i => $row ) : ?>
							<?php
							$id     = 'careback-item-field-' . $i;
							$name   = self::POSTED . '[' . $i . ']';
							$on_key = isset( $errors[ $i . ':key' ] ) ? (string) $errors[ $i . ':key' ] : '';
							$on_lab = isset( $errors[ $i . ':label' ] ) ? (string) $errors[ $i . ':label' ] : '';
							?>
							<tr>
								<td>
									<input type="text" id="<?php echo esc_attr( $id . '-key' ); ?>" class="code" name="<?php echo esc_attr( $name . '[key]' ); ?>" value="<?php echo esc_attr( $row['key'] ); ?>" list="careback-item-field-keys" maxlength="<?php echo esc_attr( (string) self::KEY_MAX ); ?>" aria-label="<?php esc_attr_e( 'Field', 'careback' ); ?>"<?php echo '' !== $on_key ? ' aria-invalid="true" aria-describedby="' . esc_attr( $id . '-key-error' ) . '"' : ''; ?> />
									<?php if ( '' !== $on_key ) : ?>
										<p class="careback-field-error" id="<?php echo esc_attr( $id . '-key-error' ); ?>" role="alert"><?php echo esc_html( $on_key ); ?></p>
									<?php endif; ?>
								</td>
								<td>
									<input type="text" id="<?php echo esc_attr( $id . '-label' ); ?>" name="<?php echo esc_attr( $name . '[label]' ); ?>" value="<?php echo esc_attr( $row['label'] ); ?>" maxlength="<?php echo esc_attr( (string) self::LABEL_MAX ); ?>" aria-label="<?php esc_attr_e( 'Label', 'careback' ); ?>"<?php echo '' !== $on_lab ? ' aria-invalid="true" aria-describedby="' . esc_attr( $id . '-label-error' ) . '"' : ''; ?> />
									<?php if ( '' !== $on_lab ) : ?>
										<p class="careback-field-error" id="<?php echo esc_attr( $id . '-label-error' ); ?>" role="alert"><?php echo esc_html( $on_lab ); ?></p>
									<?php endif; ?>
								</td>
							</tr>
						<?php endforeach; ?>
					</tbody>
				</table>
				<datalist id="careback-item-field-keys">
					<?php foreach ( $offered as $key => $label ) : ?>
						<option value="<?php echo esc_attr( $key ); ?>"><?php echo esc_html( $label ); ?></option>
					<?php endforeach; ?>
				</datalist>
				<p class="description" id="careback-item-fields-help"><?php esc_html_e( 'Your own fields on the order items, such as an engraving, each on its own line under the item, like the details above. Pick a field found on your recent orders or type its name. A field the item does not have is read from its product. Without a label, the value is shown alone.', 'careback' ); ?></p>
				<?php if ( ! $offered ) : ?>
					<p class="description"><?php esc_html_e( 'No fields found on the items of your recent orders yet.', 'careback' ); ?></p>
				<?php endif; ?>
			</td>
		</tr>
		<?php
	}

	/**
	 * Adds the list to what the settings screen stores, when its rows were on
	 * the form: the rows with a field, in their order. A list with a row that
	 * cannot be stored (a hidden field, a label without a field, a field twice,
	 * too long, too many) is not stored; the screen shows the rows as sent with
	 * each message under its field. Runs inside the screen's save handler, after
	 * its capability and nonce checks.
	 *
	 * @param array         $values   Values the screen stores.
	 * @param string        $screen   Id of the screen being saved.
	 * @param Settings|null $settings The screen's settings (not used).
	 * @param array         $form     The posted form (Admin::save(), after its capability and nonce checks).
	 * @return array
	 */
	public static function save( $values, $screen = '', $settings = null, $form = array() ) {
		$values = (array) $values;
		$form   = (array) $form;
		unset( $settings );

		if ( Admin::SCREEN !== $screen || ! isset( $form[ self::SHOWN ] ) ) {
			return $values;
		}

		// Each value is sanitised below.
		$posted = isset( $form[ self::POSTED ] ) && is_array( $form[ self::POSTED ] ) ? $form[ self::POSTED ] : array();

		$rows   = array();
		$errors = array();
		$seen   = array();

		foreach ( $posted as $row ) {
			if ( ! is_array( $row ) ) {
				continue;
			}

			// A field is a meta key: tags and line breaks out, nothing else
			// changed — a key may hold "%" sequences, as WooCommerce writes an
			// attribute named in another script.
			$key   = isset( $row['key'] ) && is_scalar( $row['key'] ) ? trim( wp_strip_all_tags( wp_check_invalid_utf8( (string) $row['key'] ), true ) ) : '';
			$label = isset( $row['label'] ) && is_scalar( $row['label'] ) ? trim( sanitize_text_field( (string) $row['label'] ) ) : '';

			if ( '' === $key && '' === $label ) {
				continue;
			}

			$i      = count( $rows );
			$rows[] = array(
				'key'   => $key,
				'label' => $label,
			);

			if ( '' === $key ) {
				$errors[ $i . ':key' ] = __( 'Choose a field for this label, or clear the label.', 'careback' );
			} elseif ( self::hidden( $key ) ) {
				$errors[ $i . ':key' ] = __( 'Fields that start with _ are hidden and never shown. Choose another field.', 'careback' );
			} elseif ( mb_strlen( $key ) > self::KEY_MAX ) {
				/* translators: %d: the most characters the field takes. */
				$errors[ $i . ':key' ] = sprintf( _n( 'Use up to %d character.', 'Use up to %d characters.', self::KEY_MAX, 'careback' ), self::KEY_MAX );
			} elseif ( isset( $seen[ $key ] ) ) {
				$errors[ $i . ':key' ] = __( 'This field is already in the list.', 'careback' );
			} elseif ( $i >= self::MAX_FIELDS ) {
				/* translators: %d: the most fields the list takes. */
				$errors[ $i . ':key' ] = sprintf( _n( 'Add up to %d field.', 'Add up to %d fields.', self::MAX_FIELDS, 'careback' ), self::MAX_FIELDS );
			}

			if ( mb_strlen( $label ) > self::LABEL_MAX ) {
				/* translators: %d: the most characters the field takes. */
				$errors[ $i . ':label' ] = sprintf( _n( 'Use up to %d character.', 'Use up to %d characters.', self::LABEL_MAX, 'careback' ), self::LABEL_MAX );
			}

			$seen[ $key ] = true;
		}

		$last = array();

		if ( $errors ) {
			$last = array(
				'rows'   => $rows,
				'errors' => $errors,
			);
		}

		self::keep( $last );

		if ( ! $errors ) {
			$values[ self::SETTING ] = self::clean( $rows );
		}

		return $values;
	}

	/**
	 * Keeps the rows and messages of a refused save for the screen the save
	 * returns to; clears them after a save that went through.
	 *
	 * @param array $last Rows and messages, or none.
	 * @return void
	 */
	private static function keep( array $last ) {
		$user = get_current_user_id();

		if ( ! $user ) {
			return;
		}

		if ( $last ) {
			set_transient( self::ERRORS . $user, $last, 5 * MINUTE_IN_SECONDS );
		} else {
			delete_transient( self::ERRORS . $user );
		}
	}

	/**
	 * The rows and messages the last refused save left, or null. Read once and
	 * then cleared, so they show on the screen right after the save only.
	 *
	 * @return array{rows:array,errors:array}|null
	 */
	private static function last() {
		$user   = get_current_user_id();
		$stored = $user ? get_transient( self::ERRORS . $user ) : false;

		if ( false === $stored ) {
			return null;
		}

		delete_transient( self::ERRORS . $user );

		if ( ! is_array( $stored ) || ! isset( $stored['rows'], $stored['errors'] ) || ! is_array( $stored['rows'] ) || ! is_array( $stored['errors'] ) ) {
			return null;
		}

		$rows = array();

		foreach ( $stored['rows'] as $row ) {
			$rows[] = array(
				'key'   => is_array( $row ) && isset( $row['key'] ) && is_scalar( $row['key'] ) ? (string) $row['key'] : '',
				'label' => is_array( $row ) && isset( $row['label'] ) && is_scalar( $row['label'] ) ? (string) $row['label'] : '',
			);
		}

		return array(
			'rows'   => $rows,
			'errors' => $stored['errors'],
		);
	}
}