<?php
/**
 * Error and Activity Logger
 *
 * Logs messages to both the WordPress debug.log (via error_log) and a
 * custom rotating log file stored in wp-content/ai-schema-gen-logs/.
 *
 * @package    Schema_AI
 * @subpackage Schema_AI/includes/utilities
 * @since      1.0.0
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

class Schema_AI_Logger {

    /**
     * Allowed log levels ordered by severity.
     *
     * @var array
     */
    const LEVELS = array( 'debug', 'info', 'warning', 'error' );

    /**
     * Maximum log file size in bytes before rotation (5 MB).
     *
     * @var int
     */
    const MAX_FILE_SIZE = 5242880;

    /**
     * Absolute path to the custom log directory.
     *
     * @var string
     */
    private $log_dir;

    /**
     * Absolute path to the current log file.
     *
     * @var string
     */
    private $log_file;

    /**
     * Constructor.
     *
     * Sets up the log directory and file paths and ensures the directory
     * exists with proper .htaccess protection.
     */
    public function __construct() {
        $upload         = wp_upload_dir();
        $this->log_dir  = $upload['basedir'] . '/ai-schema-gen-logs';
        $this->log_file = $this->log_dir . '/ai-schema-gen.log';

        $this->ensure_log_directory();
    }

    /**
     * Log a message at a given severity level.
     *
     * @param string $message The log message.
     * @param string $level   One of: debug, info, warning, error. Default 'info'.
     * @param array  $context Optional associative array of contextual data.
     */
    public function log( $message, $level = 'info', $context = array() ) {
        $level = strtolower( $level );

        if ( ! in_array( $level, self::LEVELS, true ) ) {
            $level = 'info';
        }

        $formatted = $this->format( $message, $level, $context );

        // Write to WordPress debug.log via error_log.
        error_log( '[Schema AI] ' . $formatted ); // phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log

        // Write to custom log file.
        $this->write( $formatted );
    }

    /**
     * Log an error-level message.
     *
     * @param string $message The log message.
     * @param array  $context Optional contextual data.
     */
    public function error( $message, $context = array() ) {
        $this->log( $message, 'error', $context );
    }

    /**
     * Log a warning-level message.
     *
     * @param string $message The log message.
     * @param array  $context Optional contextual data.
     */
    public function warning( $message, $context = array() ) {
        $this->log( $message, 'warning', $context );
    }

    /**
     * Log an info-level message.
     *
     * @param string $message The log message.
     * @param array  $context Optional contextual data.
     */
    public function info( $message, $context = array() ) {
        $this->log( $message, 'info', $context );
    }

    /**
     * Log a debug-level message.
     *
     * @param string $message The log message.
     * @param array  $context Optional contextual data.
     */
    public function debug( $message, $context = array() ) {
        $this->log( $message, 'debug', $context );
    }

    /**
     * Retrieve log entries, optionally filtered by level.
     *
     * Reads the log file from the end so the most recent entries come first.
     *
     * @param string|null $level  Filter by level (debug, info, warning, error) or null for all.
     * @param int         $limit  Maximum number of entries to return. Default 100.
     * @return array List of log line strings.
     */
    public function get_logs( $level = null, $limit = 100 ) {
        if ( ! file_exists( $this->log_file ) ) {
            return array();
        }

        $lines = file( $this->log_file, FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES );

        if ( false === $lines ) {
            return array();
        }

        // Most recent first.
        $lines = array_reverse( $lines );

        // Filter by level when requested.
        if ( null !== $level ) {
            $level  = strtoupper( $level );
            $lines  = array_filter(
                $lines,
                function ( $line ) use ( $level ) {
                    return false !== strpos( $line, '[' . $level . ']' );
                }
            );
            // Re-index after filtering.
            $lines = array_values( $lines );
        }

        return array_slice( $lines, 0, (int) $limit );
    }

    /**
     * Format a log entry.
     *
     * Format: [YYYY-MM-DD HH:mm:ss] [LEVEL] Message | Context JSON
     *
     * @param string $message The message.
     * @param string $level   The severity level.
     * @param array  $context Contextual data.
     * @return string Formatted log line.
     */
    private function format( $message, $level, $context ) {
        $timestamp = current_time( 'Y-m-d H:i:s' );
        $level_tag = strtoupper( $level );

        $entry = sprintf( '[%s] [%s] %s', $timestamp, $level_tag, $message );

        if ( ! empty( $context ) ) {
            $entry .= ' | ' . wp_json_encode( $context );
        }

        return $entry;
    }

    /**
     * Write a formatted line to the custom log file.
     *
     * Handles auto-rotation when the file exceeds MAX_FILE_SIZE.
     *
     * @param string $line The formatted log entry.
     */
    private function write( $line ) {
        $this->maybe_rotate();

        // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents
        file_put_contents( $this->log_file, $line . PHP_EOL, FILE_APPEND | LOCK_EX );
    }

    /**
     * Rotate the log file if it exceeds 5 MB.
     *
     * The current file is renamed with a timestamp suffix and a new empty
     * file is created automatically on the next write.
     */
    private function maybe_rotate() {
        if ( ! file_exists( $this->log_file ) ) {
            return;
        }

        $size = filesize( $this->log_file );

        if ( false === $size || $size < self::MAX_FILE_SIZE ) {
            return;
        }

        $rotated_name = $this->log_dir . '/ai-schema-gen-' . gmdate( 'Y-m-d-His' ) . '.log';

        // phpcs:ignore WordPress.WP.AlternativeFunctions.rename_rename
        rename( $this->log_file, $rotated_name );
    }

    /**
     * Create the log directory if it does not exist and protect it.
     *
     * Writes an .htaccess file that denies all HTTP access to the logs.
     */
    private function ensure_log_directory() {
        if ( ! is_dir( $this->log_dir ) ) {
            // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_mkdir
            wp_mkdir_p( $this->log_dir );
        }

        // Add .htaccess protection.
        $htaccess = $this->log_dir . '/.htaccess';
        if ( ! file_exists( $htaccess ) ) {
            // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents
            file_put_contents( $htaccess, "Order deny,allow\nDeny from all\n" );
        }

        // Add an index.php for extra safety.
        $index = $this->log_dir . '/index.php';
        if ( ! file_exists( $index ) ) {
            // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents
            file_put_contents( $index, "<?php\n// Silence is golden.\n" );
        }
    }
}