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<?php |
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/** |
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* WCPOS POS-visibility change observer. |
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* |
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* @package WCPOS\WooCommercePOS\Sync |
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*/ |
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|
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namespace WCPOS\WooCommercePOS\Sync; |
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|
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/** |
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* Journals the moment a record enters or leaves the POS servable set. |
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* |
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* # Why this exists |
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* |
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* The catalogue change stream ({@see \WCPOS\WooCommercePOS\API\V2\Changes_Controller::sequence_log}) |
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* drops update rows for records {@see Pos_Visibility} hides, because the catalog lane will never |
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* serve them: announcing one costs every till a targeted pull that comes back empty, inflates the |
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* replay backlog the client re-baselines on, and moves a head no till can act on. |
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* |
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* Dropping them is only safe because the TRANSITION is announced. A record that just became hidden |
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* is still resident on every till, and the one message about it a client must still receive is |
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* "drop this" — so hiding appends a TOMBSTONE and un-hiding appends an ordinary update row. The |
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* stream never filters tombstones, so the removal always lands. |
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* |
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* To the stream, hiding a record is indistinguishable from trashing it and un-hiding it from |
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* untrashing it, which is why both directions go through the journal's existing |
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* `record_post_deleted()` / `record_post_untrashed()` handlers rather than re-deriving the object |
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* type, the revision and the parent-product re-announcement. A client needs no new vocabulary: the |
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* `deleted` row runs through the same local-work-protected delete path a real delete does. |
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* |
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* # Why it observes OPTIONS rather than the settings API |
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* |
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* `Visibility_Section::update_visibility_settings()` is only one of the writers. The POS app PATCHes |
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* the whole section through the settings REST endpoint, and another plugin or wp-cli can call |
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* `update_option()` directly. Every one of those paths funnels through `update_option()`, so |
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* observing the options is what makes this self-healing in the same way |
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* {@see Config_Fingerprint} recomputes from live options instead of trusting a hook counter. |
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* |
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* The diff is taken over the RESOLVED hidden set — `Pos_Visibility::hidden_ids()`, the same call the |
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* stream filters on — not over the raw stored id lists. That is what makes the `pos_only_products` |
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* feature toggle work: flipping it moves the entire hidden set without touching a single id list. |
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* It also means an extension filtering the visibility settings is honoured here exactly as it is on |
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* every read lane. |
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*/ |
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final class Visibility_Observer { |
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/** |
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* Bump when the seeded set changes shape and every install must re-announce it. |
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* |
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* @var int |
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*/ |
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public const SEED_VERSION = 1; |
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|
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/** |
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* The one-time seed latch. |
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* |
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* @var string |
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*/ |
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public const SEED_VERSION_OPTION = 'woocommerce_pos_sync_visibility_tombstone_seed'; |
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|
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/** |
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* The journal rows are appended to. |
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* |
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* @var Sync_Journal |
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*/ |
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private Sync_Journal $journal; |
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|
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/** |
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* The POS servable-set authority. |
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* |
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* @var Pos_Visibility |
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*/ |
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private Pos_Visibility $visibility; |
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|
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/** |
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* The resolved hidden set as it stood before an in-flight option write, keyed by option name. |
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* |
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* Keyed per option because a no-op write fires `pre_update_option_{$option}` and then NO |
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* `update_option_{$option}`; an unkeyed snapshot would be consumed by whichever option wrote |
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* next and diffed against the wrong baseline. |
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* |
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* @var array<string, int[]> |
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*/ |
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private array $hidden_before = array(); |
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|
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/** |
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* Constructor. |
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* |
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* @param null|Sync_Journal $journal Journal to append to. |
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* @param null|Pos_Visibility $visibility Servable-set authority. |
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*/ |
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public function __construct( ?Sync_Journal $journal = null, ?Pos_Visibility $visibility = null ) { |
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$this->journal = $journal ?? new Sync_Journal(); |
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$this->visibility = $visibility ?? new Pos_Visibility(); |
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} |
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|
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/** |
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* Watch every option that can move the POS servable set. |
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*/ |
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public function register_hooks(): void { |
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// `delete_option` is the GENERIC pre-delete action — WordPress has no per-option form that |
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// fires before the row is gone (`delete_option_{$option}` fires after). Registered once and |
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// gated on the option name inside the callback. |
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add_action( 'delete_option', array( $this, 'snapshot_before_delete' ), 10, 1 ); |
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|
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foreach ( Pos_Visibility::source_options() as $option ) { |
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add_filter( "pre_update_option_{$option}", array( $this, 'snapshot_hidden_ids' ), 10, 3 ); |
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add_action( "update_option_{$option}", array( $this, 'record_updated_option' ), 10, 3 ); |
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add_action( "add_option_{$option}", array( $this, 'record_added_option' ), 10, 2 ); |
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add_action( "delete_option_{$option}", array( $this, 'record_deleted_option' ), 10, 1 ); |
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} |
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} |
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|
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/** |
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* Announce every record that was hidden before this observer existed. |
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* |
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* An install that already had records hidden transitioned them while nothing was watching, so no |
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* tombstone was ever written for them. A till still holding one used to drop it on that record's |
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* next edit — the update row, the empty pull, the client's shortfall prune — and the stream no |
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* longer carries that update row. Without this pass the upgrade would strand exactly those |
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* records until a tier 2 sweep. |
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* |
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* Latched by its own option rather than the sync schema version: no table changed, and bumping |
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* the schema would re-run the unrelated customer compensation pass on every install. Two |
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* concurrent requests can both seed before either latches; the duplicate rows are identical |
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* tombstones at different sequences and a client applies them idempotently, which is the right |
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* trade at this tier. |
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*/ |
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public function maybe_seed_hidden_tombstones(): void { |
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if ( (int) get_option( self::SEED_VERSION_OPTION, 0 ) >= self::SEED_VERSION ) { |
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return; |
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} |
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|
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$this->journal->append_catalogue_tombstones( $this->visibility->hidden_ids( Pos_Visibility::CATALOG ) ); |
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|
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// Latched even when the hidden set is empty — otherwise every request on a store that hides |
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// nothing would resolve the set again forever. |
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update_option( self::SEED_VERSION_OPTION, self::SEED_VERSION, false ); |
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} |
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|
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/** |
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* Capture the hidden set before the write lands. |
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* |
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* Runs on `pre_update_option_{$option}`, which fires BEFORE the option row and its cache are |
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* updated — so `hidden_ids()` here still resolves the pre-write state. A pass-through filter: |
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* the value is returned untouched. |
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* |
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* @param mixed $value The value about to be written. |
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* @param mixed $old_value The value being replaced. |
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* @param string $option Option name. |
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* |
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* @return mixed |
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*/ |
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public function snapshot_hidden_ids( $value, $old_value = null, $option = '' ) { |
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if ( \is_string( $option ) && '' !== $option ) { |
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$this->hidden_before[ $option ] = $this->visibility->hidden_ids( Pos_Visibility::CATALOG ); |
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} |
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|
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return $value; |
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} |
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|
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/** |
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* Journal the transitions an option update caused. |
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* |
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* @param mixed $old_value The replaced value. |
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* @param mixed $value The written value. |
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* @param string $option Option name. |
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*/ |
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public function record_updated_option( $old_value = null, $value = null, $option = '' ): void { |
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$this->consume_snapshot( $option ); |
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} |
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|
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/** |
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* Capture the hidden set before an option is deleted. |
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* |
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* Deleting either source moves the set exactly as writing it does: dropping the visibility option |
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* reveals every id it listed, and dropping the General option takes the `pos_only_products` |
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* feature down with it. Both are reachable from `Settings::delete_settings()`. |
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* |
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* @param string $option Option about to be deleted. |
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*/ |
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public function snapshot_before_delete( $option = '' ): void { |
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if ( ! \is_string( $option ) || ! \in_array( $option, Pos_Visibility::source_options(), true ) ) { |
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return; |
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} |
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|
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$this->hidden_before[ $option ] = $this->visibility->hidden_ids( Pos_Visibility::CATALOG ); |
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} |
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|
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/** |
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* Journal the transitions deleting the option caused. |
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* |
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* @param string $option Option name. |
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*/ |
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public function record_deleted_option( $option = '' ): void { |
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$this->consume_snapshot( $option ); |
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} |
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|
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/** |
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* Journal the transitions adding the option caused. |
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* |
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* `add_option_{$option}` fires after the insert and has no pre-write counterpart, but it needs |
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* none: with the option absent the hidden set is necessarily empty — an unconfigured visibility |
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* option hides nothing, and an unconfigured general option leaves the `pos_only_products` |
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* feature off, which reports an empty set whatever the id lists hold. |
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* |
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* @param string $option Option name. |
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* @param mixed $value The inserted value. |
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*/ |
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public function record_added_option( $option = '', $value = null ): void { |
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$this->record_transitions( array() ); |
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} |
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|
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/** |
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* Diff against the snapshot this option's pre-write hook left, then discard it. |
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* |
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* The snapshot is consumed rather than merely read: a post-write hook that somehow arrives |
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* without its own pre-write counterpart must not diff against a stale baseline. A missing |
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* snapshot means the before state is unknown, and announcing the whole current set would be |
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* worse than announcing nothing. |
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* |
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* @param mixed $option Option name from the hook. |
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*/ |
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private function consume_snapshot( $option ): void { |
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if ( ! \is_string( $option ) || ! \array_key_exists( $option, $this->hidden_before ) ) { |
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return; |
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} |
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|
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$before = $this->hidden_before[ $option ]; |
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unset( $this->hidden_before[ $option ] ); |
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|
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$this->record_transitions( $before ); |
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} |
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|
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/** |
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* Append one journal row per record that entered or left the servable set. |
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* |
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* @param int[] $before The hidden set before the write. |
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*/ |
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private function record_transitions( array $before ): void { |
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$after = $this->visibility->hidden_ids( Pos_Visibility::CATALOG ); |
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|
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foreach ( array_diff( $after, $before ) as $id ) { |
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$this->record_transition( (int) $id, true ); |
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} |
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|
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foreach ( array_diff( $before, $after ) as $id ) { |
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$this->record_transition( (int) $id, false ); |
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} |
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} |
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|
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/** |
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* Record one record's servability change as the trash/untrash event it is. |
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* |
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* The post type is read from the post itself rather than from the id list the id came from: the |
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* lists are merchant-supplied, and a stale or mistyped id must not make the journal announce a |
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* change to whatever unrelated record now holds that number. An id with no post — deleted since |
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* it was hidden — resolves to no type and is skipped. |
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* |
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* @param int $id Post id whose POS servability changed. |
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* @param bool $hidden True when the record just left the servable set. |
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*/ |
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private function record_transition( int $id, bool $hidden ): void { |
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$post_type = get_post_type( $id ); |
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if ( 'product' !== $post_type && 'product_variation' !== $post_type ) { |
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return; |
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} |
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|
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if ( $hidden ) { |
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$this->journal->record_post_deleted( $id ); |
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|
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return; |
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} |
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|
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$this->journal->record_post_untrashed( $id ); |
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} |
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} |
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|
