<?php

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

/**
 * Pre/post-upgrade table-correctness work for ABJ_404_Solution_DatabaseUpgradesEtc.
 *
 * Originally inlined in DatabaseUpgradesEtc.php; extracted in 4.1.8 alongside
 * the new repairStrippedViewCacheTable() hardening and the _logs_hits recovery
 * path so the host class stays under its line budget (FileSizeLimitsTest).
 *
 * The methods are scoped to "make the schema match the file's intent": detect
 * tables that were corrupted by past DDL parsing bugs (3.3.3, 4.1.7) and either
 * drop them for clean recreation, or recreate them empty when the cache-style
 * table can be rebuilt by a later cron tick.
 */
trait ABJ_404_Solution_DatabaseUpgradesEtc_TableRepairTrait {

    /**
     * Run before runInitialCreateTables() during an upgrade.  Cleans up data
     * issues that would block the create/verify pass, then drops any table
     * whose live schema is positively known to have been stripped.
     *
     * @return void
     */
    function correctIssuesBefore() {
    	$this->dao->correctDuplicateLookupValues();

    	// 3.3.4+: Repair any plugin table that was stripped of all columns by a
    	// DDL parsing bug.  The 3.3.3 bug only affected view_cache, but any future
    	// DDL file shipped without parseable column syntax could wipe any table.
    	// Dropped tables are pure caches or safely recreatable; runInitialCreateTables()
    	// will recreate them immediately after.
    	$this->repairStrippedViewCacheTable();

    	$this->correctMatchData();
    }

    /**
     * Run after runInitialCreateTables() during an upgrade.  Cleans up data
     * issues that depend on the new schema, then recreates any cache table
     * that prior bugs may have dropped without recreating.
     *
     * @return void
     */
    function correctIssuesAfter() {
    	$this->correctMatchData();
    	$this->recoverMissingLogsHitsTable();
    }

    /**
     * For every permanent plugin table, check whether the table exists but is
     * missing its primary `id` column — the signature of the 3.3.3 column-drop
     * bug.  When a stripped table is detected, ALTER it to add back the `id`
     * AUTO_INCREMENT PRIMARY KEY in place; runInitialCreateTables() then runs
     * verifyColumns to fill in any other missing columns.
     *
     * Why ALTER, not DROP: dropping the table during a daily cron path was the
     * direct cause of the 4.1.6 → 4.1.7 incident, where ~93% of upgraded sites
     * lost their `_logs_hits` table because a mis-named DDL file caused this
     * method to mis-classify a runtime-rebuilt table as "stripped" and drop
     * it. Even with the 4.1.8 positive-evidence guard, dropping during cron
     * remains the wrong primitive: a future detection regression would again
     * wipe live data. ALTER preserves whatever rows the table already holds,
     * so the worst case of a mis-detection is a no-op rebuild of an index
     * column the table already has — a recoverable warning, not data loss.
     *
     * Generalised in 3.3.5 from a view_cache-only fix to cover all plugin tables:
     * the 3.3.3 bug only affected view_cache.sql, but any future DDL file shipped
     * without parseable backtick column syntax would trigger the same data wipe on
     * that table with no repair path.
     *
     * 4.1.8: Hardened to require POSITIVE evidence before repairing a table. The
     * 4.1.7 release shipped a DDL file whose placeholder mis-classified
     * `_logs_hits` (a runtime-rebuilt table with no `id` column) as permanent.
     * The previous "drop if no `id` in live DDL" check then wiped the table on
     * upgrade. The current check only fires when the *file's* DDL declares an
     * `id` column AND the live table is missing it — absence of `id` in a file
     * that never declared one is not evidence of stripping.
     *
     * 4.1.8: Also called from runInitialCreateTables() so that any caller of
     * createDatabaseTables() — including non-upgrade callers like the daily
     * insurance check — repairs stripped tables before CREATE TABLE IF NOT
     * EXISTS turns the broken state into a permanent table that verifyColumns
     * cannot fully repair.  Idempotent: when the live DDL already declares
     * `id`, every iteration short-circuits.
     *
     * @return void
     */
    function repairStrippedViewCacheTable() {
    	foreach ($this->discoverPermanentDDLFiles() as $ddlEntry) {
    		$tableName = $this->dao->doTableNameReplacements($ddlEntry['placeholder']);

    		// Positive evidence required: the file's intended DDL must declare `id`.
    		// If the file never had an `id` column, absence in the live table is
    		// not "stripping" — it's the table's normal shape.
    		$intendedDdl = $ddlEntry['ddlContent'];
    		if (!$this->ddlDeclaresIdColumn($intendedDdl)) {
    			continue;
    		}

    		$liveDdl = $this->dao->getCreateTableDDL($tableName);

    		// Table doesn't exist at all — nothing to repair (recovery handled elsewhere).
    		if (empty($liveDdl)) {
    			continue;
    		}

    		// Live table has the column the file declares — table is intact.
    		if ($this->ddlDeclaresIdColumn($liveDdl)) {
    			continue;
    		}

    		// File declares `id`, live table is missing it — stripped.
    		// ALTER (not DROP): preserve whatever rows the table holds so a
    		// false-positive detection cannot lose user data.  Both MySQL 5.7+
    		// and MariaDB 10.x accept retro-adding an AUTO_INCREMENT PRIMARY
    		// KEY in this single-statement form; the prior comment claiming
    		// otherwise (rationale for the original DROP) was incorrect.
    		$this->logger->infoMessage("Repairing stripped plugin table " . $tableName .
    			" (missing id column — caused by DDL parsing bug). Adding id column via ALTER.");
    		$this->dao->queryAndGetResults(
    			"ALTER TABLE `" . $tableName . "` " .
    			"ADD COLUMN `id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY FIRST"
    		);
    	}
    }

    /**
     * Returns true if the DDL declares a column literally named `id` (in
     * backticks, the only style permitted in plugin DDL files since 3.3.5 —
     * see DDLColumnParsingRobustnessTest::testEveryDdlFileUsesBacktickColumnStyle).
     *
     * Matching `\bid\b` against raw DDL is unsafe — it hits the `id` substring
     * in `auto_increment`, `void`, and any column name containing those letters.
     *
     * @param string $ddl
     * @return bool
     */
    private function ddlDeclaresIdColumn(string $ddl): bool {
    	return stripos($ddl, '`id`') !== false;
    }

    /**
     * Recover the {prefix}_abj404_logs_hits table if it is missing.
     *
     * The 4.1.6 → 4.1.7 upgrade dropped this table on ~93% of sites because a
     * mis-named DDL file caused repairStrippedViewCacheTable() to treat it as
     * a permanent table that had been "stripped" (see git log for 731fec2e and
     * the 4.1.7 → 4.1.8 changelog). This method creates the table empty so
     * that the scheduled rebuild (createRedirectsForViewHitsTable) can
     * re-populate it. It is safe to run on any site — getCreateTableDDL()
     * detects an existing table and we skip the create.
     *
     * Idempotent. Cheap. Safe to call on every upgrade.
     *
     * @return void
     */
    private function recoverMissingLogsHitsTable(): void {
    	$tableName = $this->dao->doTableNameReplacements('{wp_abj404_logs_hits}');
    	if ($this->dao->getCreateTableDDL($tableName) !== '') {
    		return;
    	}

    	$tempDdl = ABJ_404_Solution_Functions::readFileContents(
    		__DIR__ . '/sql/createLogsHitsTempTable.sql');
    	if (!is_string($tempDdl) || trim($tempDdl) === '') {
    		return;
    	}

    	// The temp DDL targets `{wp_abj404_logs_hits}_temp`. Strip the `_temp`
    	// suffix to recreate the final table at its real name.
    	$finalDdl = str_replace(
    		'{wp_abj404_logs_hits}_temp',
    		'{wp_abj404_logs_hits}',
    		$tempDdl);
    	$finalDdl = $this->applyPluginTableCharsetCollate($finalDdl);
    	$finalDdl = $this->dao->doTableNameReplacements($finalDdl);

    	$this->logger->infoMessage("Recreating missing " . $tableName .
    		" (lost during the 4.1.6→4.1.7 upgrade). The scheduled rebuild will repopulate it.");
    	$this->dao->queryAndGetResults($finalDdl);

    	// The missing-table notice (set when ALTER TABLE failed during the 4.1.7
    	// activation) is now stale — the table has been recovered.  Clear it so
    	// the admin does not see an error notice on the next page load.
    	if (function_exists('delete_transient')) {
    		delete_transient('abj404_plugin_db_notice');
    	}
    }

    /**
     * Drop spelling-cache rows whose match data was never populated.  These
     * are remnants from interrupted background workers; the cache fills in
     * organically on the next 404, so it's safe to delete the empty rows.
     *
     * Called from correctIssuesBefore() *and* correctIssuesAfter() during
     * the upgrade flow.  The "before" call may run when the spelling_cache
     * table doesn't exist (fresh install, or after stripped-table drop), so
     * suppress errors and skip the table-repair retry: there's nothing to
     * delete if the table doesn't exist, and we don't want this maintenance
     * call to set the missing_table admin notice transient.
     *
     * @return void
     */
    function correctMatchData() {
    	$this->dao->queryAndGetResults(
    		"delete from {wp_abj404_spelling_cache} where matchdata is null or matchdata = ''",
    		array('log_errors' => false, 'skip_repair' => true)
    	);
    }
}