<?php
/**
 * Shared helpers for all migration phase Strategy objects.
 *
 * @package TMDO
 * @since 3.0.1
 */

// phpcs:disable Squiz.Commenting.FunctionComment,WordPress.DB.PreparedSQL.NotPrepared,WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.PHP.YodaConditions,WordPress.Security.EscapeOutput.OutputNotEscaped -- Internal helpers; SQL composed from registry-validated identifiers; exception messages not echoed.

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Shared helpers for all migration phase Strategy objects.
 *
 * Concrete phases extend this class, receive the entity type at construction,
 * and implement execute().  All database helpers delegate to
 * TMDO_Entity_Registry / TMDO_Schema_Manager so the entity type is the only
 * injection point needed for unit tests.
 */
abstract class TMDO_Migration_Phase_Base implements TMDO_Migration_Phase_Interface {

	const MAX_LOG_LINES = 50;

	/**
	 * Entity type this phase operates on (e.g. 'user', 'post').
	 *
	 * @var string
	 */
	protected string $entity_type;

	public function __construct( string $entity_type ) {
		$this->entity_type = $entity_type;
	}

	// ── Logging ───────────────────────────────────────────────────────────────

	protected function log( array &$job, string $message ): void {
		$line         = '[' . gmdate( 'H:i:s' ) . '] ' . $message;
		$job['log'][] = $line;
		if ( count( $job['log'] ) > self::MAX_LOG_LINES ) {
			$job['log'] = array_slice( $job['log'], -self::MAX_LOG_LINES );
		}
		$job['updated_at'] = time();
	}

	// ── Registry helpers ──────────────────────────────────────────────────────

	protected function get_managed_keys(): array {
		$keys = array();
		foreach ( TMDO_Entity_Registry::get_groups_for_type( $this->entity_type ) as $group ) {
			$keys = array_merge( $keys, TMDO_Entity_Registry::get_group_keys( $this->entity_type, $group ) );
		}
		return array_values( array_unique( $keys ) );
	}

	protected function group_has_json_field( string $group ): bool {
		foreach ( TMDO_Entity_Registry::get_group_fields( $this->entity_type, $group ) as $field ) {
			if ( 'json' === ( $field['type'] ?? '' ) ) {
				return true;
			}
		}
		return false;
	}

	// ── DB helpers ────────────────────────────────────────────────────────────

	/** Count EAV rows for the given meta keys (or all managed keys if empty). */
	protected function count_eav_residue( array $keys = array() ): int {
		global $wpdb;
		if ( empty( $keys ) ) {
			$keys = $this->get_managed_keys();
		}
		if ( empty( $keys ) ) {
			return 0;
		}
		$adapter      = TMDO_Entity_Registry::get_adapter( $this->entity_type );
		$meta_table   = $adapter->get_native_meta_table();
		$placeholders = implode( ',', array_fill( 0, count( $keys ), '%s' ) );
		return (int) $wpdb->get_var(
			$wpdb->prepare( "SELECT COUNT(*) FROM `{$meta_table}` WHERE meta_key IN ({$placeholders})", ...$keys )
		);
	}

	/**
	 * Bulk pivot for a text-only group via INSERT … SELECT … GROUP BY …
	 * ON DUPLICATE KEY UPDATE.
	 *
	 * @param string $group Entity group to pivot.
	 * @return int Number of rows affected.
	 * @throws \RuntimeException On DB failure.
	 */
	protected function execute_bulk_pivot( string $group ): int {
		global $wpdb;

		$fields = TMDO_Entity_Registry::get_group_fields( $this->entity_type, $group );
		if ( empty( $fields ) ) {
			return 0;
		}

		$adapter    = TMDO_Entity_Registry::get_adapter( $this->entity_type );
		$id_col     = $adapter->get_entity_id_column();
		$meta_table = $adapter->get_native_meta_table();
		$table      = TMDO_Schema_Manager::get_table_name( $this->entity_type, $group );

		$select_cases = array();
		$update_cols  = array();
		$col_names    = array();
		$keys         = array();

		foreach ( $fields as $f ) {
			$key            = $f['key'];
			$col            = TMDO_Schema_Manager::sanitize_column_name( $key );
			$keys[]         = $key;
			$col_names[]    = "`{$col}`";
			$select_cases[] = $wpdb->prepare(
				"MAX(CASE WHEN um.meta_key = %s THEN um.meta_value END) AS `{$col}`",
				$key
			);
			$update_cols[]  = "`{$col}` = COALESCE(VALUES(`{$col}`), `{$col}`)";
		}

		$placeholders = implode( ',', array_fill( 0, count( $keys ), '%s' ) );

		$sql = sprintf(
			'INSERT INTO `%s` (`%s`, %s)
			 SELECT um.user_id, %s
			 FROM `%s` um
			 WHERE um.meta_key IN (%s)
			 GROUP BY um.user_id
			 ON DUPLICATE KEY UPDATE %s',
			$table,
			$id_col,
			implode( ', ', $col_names ),
			implode( ', ', $select_cases ),
			$meta_table,
			$placeholders,
			implode( ', ', $update_cols )
		);

		$result = $wpdb->query( $wpdb->prepare( $sql, ...$keys ) );

		if ( false === $result ) {
			// phpcs:ignore WordPress.Security.EscapeOutput -- Exception message not echoed to browser.
			throw new \RuntimeException( 'Bulk pivot failed for group ' . $group . ': ' . $wpdb->last_error );
		}
		return (int) $result;
	}

	/** Loose equality check for EAV vs flat value comparison (null/empty/scalar). */
	protected function values_loose_equal( $a, $b ): bool {
		if ( null === $a && null === $b ) {
			return true;
		}
		if ( null === $a || null === $b ) {
			$other = null === $a ? $b : $a;
			return '' === $other || array() === $other || 0 === $other || '0' === $other;
		}
		if ( is_array( $a ) || is_array( $b ) ) {
			return wp_json_encode( $a ) === wp_json_encode( $b );
		}
		return (string) $a === (string) $b;
	}
}