<?php

namespace base\common\service;

use DateTime;

/**
 * Nginx access log 解析器（Base 层）.
 *
 * 匹配 analytics log_format（11 字段）：
 *   remote_addr - remote_user [time_local] "request" status body_bytes_sent "referer" "ua" request_time upstream_response_time bytes_sent
 *
 * 示例行：
 *   192.168.32.1 - - [27/Jul/2026:16:20:15 +0000] "GET / HTTP/1.1" 499 0 "-" "Mozilla/5.0 (...)" 5.085 5.086 0
 *
 * 业务侧通过 app/common/service/NginxLogParser 覆盖本类方法.
 */
class NginxLogParserBase
{
    /** 爬虫 UA 关键词（大小写不敏感匹配） */
    public const SPIDER_KEYWORDS = [
        'Googlebot', 'Baiduspider', 'bingbot', 'Sogou', '360Spider',
        'YisouSpider', 'PetalBot', 'AhrefsBot', 'semrushbot', 'DotBot',
    ];

    /** 静态资源扩展名 */
    public const STATIC_EXTS = [
        'css', 'js', 'png', 'jpg', 'jpeg', 'gif', 'ico',
        'woff', 'woff2', 'ttf', 'svg', 'map',
    ];

    /** URI 最大存储长度 */
    protected const URI_MAX_LENGTH = 255;

    /** UA 最大存储长度 */
    protected const UA_MAX_LENGTH = 500;

    /** analytics log_format 正则（11 捕获组） */
    protected const LINE_PATTERN = '/^(\S+) - (\S+) \[(.+?)\] "([^"]*)" (\d+) (\d+) "([^"]*)" "([^"]*)" (\S+) (\S+) (\d+)$/';

    /** $request 拆分正则：METHOD URI HTTP/version */
    protected const REQUEST_PATTERN = '/^(\S+)\s+(\S+)\s+(HTTP\/\S+)$/';

    /**
     * 解析单行 nginx access log.
     *
     * @param string $line 原始日志行
     *
     * @return array|null 解析成功返回字段数组，正则不匹配或 request 畸形返回 null
     */
    public function parse(string $line): ?array
    {
        $line = trim($line);
        if ($line === '') {
            return null;
        }

        if (!preg_match(self::LINE_PATTERN, $line, $m)) {
            return null;
        }

        // $m[1..11] = 11 个捕获组
        $remoteAddr   = $m[1];
        $remoteUser   = $m[2];
        $timeLocalStr = $m[3];
        $request      = $m[4];
        $status       = (int) $m[5];
        $bodyBytes    = (int) $m[6];
        $referer      = $m[7];
        $userAgent    = $m[8];
        $requestTime  = $m[9];
        $upstreamTime = $m[10];
        $bytesSent    = (int) $m[11];

        // time_local 字符串 → Unix 时间戳（DateTime 自动转业务时区）
        $timeLocal = $this->parseTimeLocal($timeLocalStr);
        if ($timeLocal === null) {
            return null;
        }

        // 拆分 request → method / uri / http_version
        [$method, $uri, $httpVersion] = $this->splitRequest($request);
        if ($method === null) {
            // 畸形 request（含空格等），无法提取核心字段
            return null;
        }

        // URI 截断 + 拆 query_string
        $uri          = substr($uri, 0, self::URI_MAX_LENGTH);
        $queryString  = '';
        $qsPos        = strpos($uri, '?');
        if ($qsPos !== false) {
            $queryString = substr($uri, $qsPos + 1);
            $uri         = substr($uri, 0, $qsPos);
        }

        // UA 截断
        $userAgent = substr($userAgent, 0, self::UA_MAX_LENGTH);

        // referer 域名提取
        $refererDomain = $this->extractRefererDomain($referer);

        // UA 分类
        [$uaType, $uaName] = $this->classifyUa($userAgent);

        return [
            'remote_addr'            => $remoteAddr,
            'remote_user'            => $remoteUser,
            'time_local'             => $timeLocal,
            'method'                 => $method,
            'uri'                    => $uri,
            'query_string'           => $queryString,
            'http_version'           => $httpVersion,
            'status'                 => $status,
            'body_bytes_sent'        => $bodyBytes,
            'http_referer'           => $referer,
            'referer_domain'         => $refererDomain,
            'http_user_agent'        => $userAgent,
            'ua_type'                => $uaType,
            'ua_name'                => $uaName,
            'request_time'           => $requestTime !== '-' ? (float) $requestTime : 0.0,
            'upstream_response_time' => $upstreamTime !== '-' ? (float) $upstreamTime : null,
            'bytes_sent'             => $bytesSent,
        ];
    }

    /**
     * 首行格式自检：判断给定行是否匹配 analytics log_format.
     */
    public function isFormatMatch(string $sampleLine): bool
    {
        return preg_match(self::LINE_PATTERN, trim($sampleLine)) === 1;
    }

    /**
     * UA 分类.
     *
     * @param string $ua User-Agent 字符串
     *
     * @return array{0:string,1:string} [ua_type, ua_name]；spider 时 ua_name = 匹配的关键词
     */
    public function classifyUa(string $ua): array
    {
        if ($ua === '' || $ua === '-') {
            return ['unknown', ''];
        }

        foreach (self::SPIDER_KEYWORDS as $keyword) {
            if (stripos($ua, $keyword) !== false) {
                return ['spider', $keyword];
            }
        }

        return ['browser', ''];
    }

    /**
     * 提取 referer 域名.
     *
     * @param string $referer 原始 referer 值
     *
     * @return string 域名；空或 "-" 返回 'direct'；解析失败返回 'unknown'
     */
    public function extractRefererDomain(string $referer): string
    {
        if ($referer === '' || $referer === '-') {
            return 'direct';
        }

        $host = parse_url($referer, PHP_URL_HOST);
        if ($host === false || $host === null || $host === '') {
            return 'unknown';
        }

        return $host;
    }

    /**
     * 拆分 request → [method, uri, http_version].
     *
     * @param string $request 原始 request 字段（"GET /path HTTP/1.1"）
     *
     * @return array{0:?string,1:?string,2:?string} 匹配失败三项均为 null
     */
    public function splitRequest(string $request): array
    {
        if (preg_match(self::REQUEST_PATTERN, $request, $m)) {
            return [$m[1], $m[2], $m[3]];
        }

        return [null, null, null];
    }

    /**
     * 判断 URI 是否为静态资源.
     *
     * 取 URI 路径部分的扩展名，命中 STATIC_EXTS 返回 true.
     */
    public function isStaticResource(string $uri): bool
    {
        // 去掉 query string
        $path  = $uri;
        $qsPos = strpos($path, '?');
        if ($qsPos !== false) {
            $path = substr($path, 0, $qsPos);
        }

        $dotPos = strrpos($path, '.');
        if ($dotPos === false) {
            return false;
        }

        $ext = strtolower(substr($path, $dotPos + 1));

        return in_array($ext, self::STATIC_EXTS, true);
    }

    /**
     * time_local 字符串 → Unix 时间戳.
     *
     * 格式示例：27/Jul/2026:16:20:15 +0000
     * DateTime::createFromFormat 自动处理时区偏移，
     * getTimestamp() 返回 UTC Unix 时间戳，
     * 后续 date() 按业务时区（Asia/Shanghai）格式化.
     *
     * @param string $timeLocalStr nginx time_local 字段值
     *
     * @return int|null Unix 时间戳；解析失败返回 null
     */
    protected function parseTimeLocal(string $timeLocalStr): ?int
    {
        $dt = DateTime::createFromFormat('d/M/Y:H:i:s O', $timeLocalStr);
        if ($dt === false) {
            return null;
        }

        return $dt->getTimestamp();
    }
}