<?php


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

/**
 * Persistence layer for the "last sent error line" dedupe pointer used by
 * ABJ_404_Solution_Logging::emailErrorLogIfNecessary().
 *
 * Owns the round-trip across three storage locations:
 *
 *   1. The on-disk sentinel file (abj404_debug_sent_line.txt) -- authoritative
 *      across requests and survives cron restarts.
 *   2. The logging state store (the last-sent-line scalar inside the
 *      abj404_settings row) -- fallback when the sentinel file is absent or
 *      unreadable, and the only durable copy on hosts with ephemeral
 *      filesystems. Reached ONLY through ABJ_404_Solution_LoggingStateStore,
 *      whose raw accessors never re-enter the settings normalize-and-log
 *      pipeline (the 4.3.0 logging<->options recursion guard).
 *   3. Request-local statics -- prevent a single PHP request that triggers
 *      multiple emailErrorLogIfNecessary() calls (e.g. via shutdown handlers)
 *      from emitting duplicate sends before the on-disk pointer has caught up.
 *
 * Pure persistence: no policy, no presentation, no email dispatch. Returns
 * the current pointer, decides whether a candidate error-line is already
 * recorded, and writes the pointer forward.
 */
class ABJ_404_Solution_ErrorEmailDedupeState {

    /** @var int Latest error-log line emailed during this PHP request. */
    private static $lastSentErrorLineThisRequest = 0;
    /** @var string Latest error signature emailed during this PHP request. */
    private static $lastSentErrorSignatureThisRequest = '';
    /** @var string Debug file path associated with the request-local dedupe state. */
    private static $lastSentDebugFilePathThisRequest = '';

    /**
     * Recursion-safe accessor for the durable last-sent-line scalar. Owns the
     * storage key; reads/writes only via its raw accessors so the dedupe
     * pointer never passes through the settings normalize pipeline.
     *
     * @var ABJ_404_Solution_LoggingStateStore
     */
    private $loggingStateStore;

    /** @param ABJ_404_Solution_LoggingStateStore $loggingStateStore */
    public function __construct($loggingStateStore) {
        $this->loggingStateStore = $loggingStateStore;
    }

    /**
     * Read the latest known "last sent error line" pointer from disk, falling
     * back to the durable copy in the logging state store. Request-local
     * statics are merged in isAlreadySent() so a fresh read from this method
     * always reflects only the durable state.
     *
     * Precedence: the on-disk sentinel file first (when present and >= 1), else
     * the logging state store's last-sent-line scalar, else -1.
     *
     * @param string $sentinelFilePath
     * @return int Last-sent line number, or -1 when no record exists.
     */
    public function readSentLine(string $sentinelFilePath): int {
        $sentLine = -1;
        if (file_exists($sentinelFilePath)) {
            $sentLine = absint(
                ABJ_404_Solution_FileSystemService::readFileContents($sentinelFilePath, false));
        }
        if ($sentLine < 1) {
            $sentLine = $this->loggingStateStore->getLastSentLine();
        }
        return $sentLine;
    }

    /**
     * Decide whether the latest-found error line has already been emailed.
     *
     * Combines the durable pointer (sentLine) with the request-local high-
     * water marks. Two requests for the same debug file path within a single
     * PHP process are deduped on either:
     *
     *   - the line number having already advanced past the latest, OR
     *   - the error signature exactly matching the last one we sent (which
     *     catches cases where the log file has been rotated and line numbers
     *     reset but the same recurring error is still on top).
     *
     * @param int $sentLine Durable pointer (from readSentLine()).
     * @param array{num: int, line: string|null, total_error_count?: int} $latestErrorLineFound
     * @param string $debugFilePath
     * @return bool true if the latest-found line has already been sent.
     */
    public function isAlreadySent(int $sentLine, array $latestErrorLineFound, string $debugFilePath): bool {
        $latestNum = (int)($latestErrorLineFound['num'] ?? -1);
        $latestSignature = (string)($latestErrorLineFound['line'] ?? '');

        $effectiveSentLine = $sentLine;
        if (self::$lastSentDebugFilePathThisRequest === $debugFilePath) {
            $effectiveSentLine = max($effectiveSentLine, self::$lastSentErrorLineThisRequest);
        }
        if ($latestNum <= $effectiveSentLine) {
            return true;
        }
        if (self::$lastSentDebugFilePathThisRequest === $debugFilePath
            && $latestSignature !== ''
            && $latestSignature === self::$lastSentErrorSignatureThisRequest) {
            return true;
        }
        return false;
    }

    /**
     * Record the just-sent error line forward across all three layers:
     * logging state store, sentinel file, request-local statics.
     *
     * @param string $sentinelFilePath
     * @param string $debugFilePath
     * @param array{num: int, line: string|null, total_error_count?: int} $latestErrorLineFound
     * @return bool false if the sentinel file write failed verification
     *              (caller should bail before dispatching mail to avoid a
     *              dedupe-pointer regression on the next cron tick); true
     *              otherwise.
     */
    public function recordSent(string $sentinelFilePath, string $debugFilePath, array $latestErrorLineFound): bool {
        $latestNum = (int)($latestErrorLineFound['num'] ?? -1);
        $latestSignature = (string)($latestErrorLineFound['line'] ?? '');

        self::$lastSentErrorLineThisRequest = $latestNum;
        self::$lastSentErrorSignatureThisRequest = $latestSignature;
        self::$lastSentDebugFilePathThisRequest = $debugFilePath;

        $this->loggingStateStore->setLastSentLine($latestNum);

        @file_put_contents($sentinelFilePath, (string)$latestNum);
        $fileContents = @file_get_contents($sentinelFilePath);
        return ($fileContents === (string)$latestNum);
    }

    /**
     * Test seam: reset the request-local statics. Called from test setUp() to
     * keep ParaTest workers' Logging::emailErrorLogIfNecessary() runs from
     * leaking dedupe state across tests in the same worker. Not used in
     * production.
     */
    public static function resetRequestLocalsForTesting(): void {
        self::$lastSentErrorLineThisRequest = 0;
        self::$lastSentErrorSignatureThisRequest = '';
        self::$lastSentDebugFilePathThisRequest = '';
    }
}