<?php

namespace App\Http\Controllers;

use App\Models\PageVisit;
use App\Support\UserAgentParser;
use Illuminate\Http\Request;
use Illuminate\Http\Response;
use Illuminate\Support\Facades\Cache;

class PageHitController extends Controller
{
    private const GIF_1X1 = "GIF89a\x01\x00\x01\x00\x80\x00\x00\xff\xff\xff\x00\x00\x00!\xf9\x04\x01\x00\x00\x00\x00,\x00\x00\x00\x00\x01\x00\x01\x00\x00\x02\x02D\x01\x00;";

    public function __invoke(Request $request): Response
    {
        $channelId = strtolower(trim((string) $request->query('c', $request->input('c', ''))));
        $clientUid = trim((string) $request->query('u', $request->input('u', '')));
        $path = trim((string) $request->query('p', $request->input('p', '')));

        if (! preg_match('/^[0-9a-f]{32}$/', $channelId)) {
            return $this->pixel();
        }
        if (! preg_match('/^[0-9a-fA-F-]{8,64}$/', $clientUid) && ! preg_match('/^tmp_[0-9a-f]+$/i', $clientUid)) {
            return $this->pixel();
        }
        if (strlen($path) > 255) {
            $path = substr($path, 0, 255);
        }

        $debounceKey = 'page_hit:'.$channelId.':'.$clientUid;
        if (! Cache::add($debounceKey, 1, now()->addSeconds(8))) {
            return $this->pixel();
        }

        $ua = substr((string) $request->userAgent(), 0, 512);
        $parsed = UserAgentParser::parse($ua);
        $referer = $this->referer($request);

        PageVisit::query()->create([
            'channel_id' => $channelId,
            'client_uid' => substr($clientUid, 0, 64),
            'user_agent' => $ua !== '' ? $ua : null,
            'os' => $parsed['os'],
            'os_version' => $parsed['os_version'] !== '' ? $parsed['os_version'] : null,
            'browser' => $parsed['browser'],
            'browser_version' => $parsed['browser_version'] !== '' ? $parsed['browser_version'] : null,
            'ip' => $request->ip(),
            'path' => $path !== '' ? $path : null,
            'referer' => $referer,
            'created_at' => now(),
        ]);

        return $this->pixel();
    }

    private function referer(Request $request): ?string
    {
        $referer = trim((string) $request->query('r', $request->input('r', '')));
        if ($referer === '') {
            $referer = trim((string) $request->headers->get('referer', ''));
        }
        if ($referer === '') {
            return null;
        }

        return substr($referer, 0, 512);
    }

    private function pixel(): Response
    {
        return response(self::GIF_1X1, 200, [
            'Content-Type' => 'image/gif',
            'Content-Length' => (string) strlen(self::GIF_1X1),
            'Cache-Control' => 'no-store, no-cache, must-revalidate, max-age=0',
            'Pragma' => 'no-cache',
        ]);
    }
}