<?php
declare(strict_types=1);

/**
 * Minimal structured logger. Writes JSON lines to a private log file and
 * redacts anything that looks like personal data or a secret.
 */
final class Log
{
    private static string $file = '';
    private static int $level = 1;
    private const LEVELS = ['debug' => 0, 'info' => 1, 'warn' => 2, 'error' => 3];
    private const REDACT_KEYS = ['email', 'phone', 'firstname', 'first_name', 'lastname', 'last_name', 'authorization', 'api_key', 'apikey', 'secret', 'token', 'password', 'questions', 'destination_number', 'email_address'];

    public static function init(string $file, ?string $level = 'info'): void
    {
        self::$file = $file;
        self::$level = self::LEVELS[strtolower($level ?? 'info')] ?? 1;
        $dir = dirname($file);
        if (!is_dir($dir)) {
            @mkdir($dir, 0750, true);
        }
    }

    /** @param array<string,mixed> $ctx */
    public static function debug(string $msg, array $ctx = []): void { self::write('debug', $msg, $ctx); }
    /** @param array<string,mixed> $ctx */
    public static function info(string $msg, array $ctx = []): void { self::write('info', $msg, $ctx); }
    /** @param array<string,mixed> $ctx */
    public static function warn(string $msg, array $ctx = []): void { self::write('warn', $msg, $ctx); }
    /** @param array<string,mixed> $ctx */
    public static function error(string $msg, array $ctx = []): void { self::write('error', $msg, $ctx); }

    /** @param array<string,mixed> $ctx */
    private static function write(string $level, string $msg, array $ctx): void
    {
        if ((self::LEVELS[$level] ?? 1) < self::$level) {
            return;
        }
        $line = json_encode([
            'ts' => gmdate('c'),
            'level' => $level,
            'msg' => $msg,
            'ctx' => self::redact($ctx),
        ], JSON_UNESCAPED_SLASHES) . "\n";
        if (self::$file !== '' && (is_writable(dirname(self::$file)) || is_writable(self::$file))) {
            @file_put_contents(self::$file, $line, FILE_APPEND | LOCK_EX);
        } else {
            error_log(rtrim($line));
        }
    }

    /** @param mixed $value */
    public static function redact($value, string $key = ''): mixed
    {
        if (is_array($value)) {
            $out = [];
            foreach ($value as $k => $v) {
                $out[$k] = self::redact($v, (string)$k);
            }
            return $out;
        }
        if (is_string($value)) {
            if (in_array(strtolower($key), self::REDACT_KEYS, true)) {
                return self::mask($value);
            }
            // Inline redaction of emails, phone numbers and bearer-like tokens inside free text
            $value = preg_replace('/[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}/i', '[email]', $value) ?? $value;
            $value = preg_replace('/\+?\d[\d\s().-]{8,}\d/', '[phone]', $value) ?? $value;
            return preg_replace('/(Basic|Bearer)\s+[A-Za-z0-9+\/=._-]{8,}/', '$1 [redacted]', $value) ?? $value;
        }
        return $value;
    }

    private static function mask(string $v): string
    {
        $len = strlen($v);
        if ($len === 0) {
            return '';
        }
        if ($len <= 4) {
            return str_repeat('*', $len);
        }
        return substr($v, 0, 2) . str_repeat('*', max(1, $len - 4)) . substr($v, -2);
    }
}