<?php
namespace Decicus\Scraper;
require __DIR__ . '/vendor/autoload.php';

use Symfony\Component\DomCrawler\Crawler;
use GuzzleHttp\Cookie\CookieJar;
use GuzzleHttp\Client as HttpClient;
use GuzzleHttp\Psr7\Request;
use GuzzleHttp\RequestOptions;

if (file_exists(__DIR__ . '/.env')) {
    /**
     * Make `.env` variables via getenv().
     */
    $env = \Dotenv\Dotenv::createImmutable(__DIR__, '.env');
    $env->load();
}

class Oda
{
    /**
     * CookieJar for Guzzle
     *
     * @var GuzzleHttp\Cookie\CookieJar
     */
    private CookieJar $cookies;

    /**
     * URL to send the initial request (for cookies).
     * 
     * @var string
     */
    private string $initUrl = 'https://oda.com/no/products/popular/';

    /**
     * URL for querying the API.
     *
     * @var string
     */
    private string $apiProductsUrl = 'https://oda.com/api/v1/products/popular/';

    /**
     * Base HTTP headers
     * 
     * API requires additional headers:
     * - Accept: application/json (probably)
     * - Cookie
     * - X-CSRFToken
     *
     * @var array
     */
    private array $headers = [
        'Origin' => 'https://oda.com',
        'User-Agent' => 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/106.0.0.0 Safari/537.36',
    ];

    /**
     * CSRF token used for API requests
     * 
     * @var string
     */
    private ?string $csrfToken = null;

    /**
     * HTTP Client
     *
     * @var \GuzzleHttp\Client
     */
    private ?HttpClient $client;

    public function __construct()
    {
        $this->cookies = new CookieJar();
        $this->client = new HttpClient(['cookies' => true]);

        if (!empty($_ENV['USER_AGENT'])) {
            $this->headers['User-Agent'] = $_ENV['USER_AGENT'];
        }
    }

    /**
     * Does the initial request to get the CSRF token and cookies.
     */
    public function initialize() : void
    {
        $options = [
            RequestOptions::HEADERS => $this->headers,
            RequestOptions::COOKIES => $this->cookies,
        ];

        $this->client->request('GET', $this->initUrl, $options);
        $csrfToken = $this->cookies->getCookieByName('csrftoken')->getValue() ?? null;

        $this->csrfToken = $csrfToken;
    }

    /**
     * Helper function for sending requests via the HTTP client.
     *
     * @param string $url
     * @param string $method HTTP method (GET, POST, PUT etc.)
     * @param array $options Guzzle options
     *
     * @return string
     */
    private function getRequestBody(string $url, string $method = 'GET', array $options = []) : string
    {
        if (empty($options)) {
            $options = [
                RequestOptions::HEADERS => $this->headers,
                RequestOptions::COOKIES => $this->cookies,
            ];
        }

        $response = $this->client->request($method, $url, $options);
        $body = $response->getBody()->getContents();
        return $body;
    }

    /**
     * Helper function for making products API requests.
     *
     * @param array $excludeIds
     *
     * @return array
     */
    public function getPopularProducts($excludeIds = []) : array
    {
        $headers = $this->headers;
        $headers['Accept'] = 'application/json';
        $headers['X-CSRFToken'] = $this->csrfToken;

        $options = [
            RequestOptions::HEADERS => $headers,
            RequestOptions::COOKIES => $this->cookies,
            RequestOptions::JSON => [
                'exclude_ids' => $excludeIds,
            ],
        ];

        $body = $this->getRequestBody($this->apiProductsUrl, 'POST', $options);

        return json_decode($body, true);
    }

    /**
     * Runs the scraper to scrape popular products
     * 
     * This relies on the Oda API, unlike the scraping.
     *
     * @return void
     */
    public function fetchPopular() : void
    {
        $this->initialize();

        $excludeIds = [];
        $count = 0;
        $products = [];

        $initialRequest = $this->getPopularProducts();

        $results = $initialRequest['results'];

        $products = array_merge($products, $results);
        $productIds = array_column($results, 'id');
        $excludeIds = array_merge($excludeIds, $productIds);

        $hasMore = $initialRequest['has_more'];

        echo sprintf('Scraped %d products', count($products)) . PHP_EOL;

        while ($hasMore) {
            $count++;
            $request = $this->getPopularProducts($excludeIds);

            $results = $request['results'];
            $products = array_merge($products, $results);

            echo sprintf('Scraped %d/%d products', count($results), count($products)) . PHP_EOL;

            $productIds = array_column($results, 'id');
            $excludeIds = array_merge($excludeIds, $productIds);

            $hasMore = $request['has_more'];

            if (!$hasMore) {
                break;
            }
        }

        $filename = sprintf('%s/data/%s.json', __DIR__, time());
        file_put_contents($filename, json_encode($products));
    }

    /**
     * Takes a Oda product page URL and scrapes the product data.
     *
     * @param string $url
     *
     * @return array
     */
    public function scrapeProductPage(string $url) : array
    {
        $body = $this->getRequestBody($url);
        $crawler = new Crawler($body);

        $name = trim((string) $crawler->filter('h1')->text());
        $price = (float) $crawler->filter('.price')->attr('content');

        /**
         * Unit price handler.
         * Example: "kr 187,50 per unit"
         */
        $priceUnitText = trim((string) $crawler->filter('.unit-price')->text());
        
        // Remove redundant text
        $priceUnitText = str_replace(['kr ', ' per'], '', $priceUnitText);

        /**
         * Split the price and unit.
         * 
         * In theory the results should be something like:
         * - [0] => 187.50
         * - [1] => unit
         */
        $priceUnit = explode(' ', trim($priceUnitText));

        return [
            'name' => $name,
            'price' => $price,
            'unit_price' => (float) $priceUnit[0],
            'unit' => $priceUnit[1],
        ];
    }

    /**
     * Writes the scraped data to a CSV & a JSON file.
     *
     * @param array $products
     * 
     * @return void
     */
    private function writeProductsToFile(array $products) : void
    {
        if (empty($products)) {
            return;
        }

        $outputFile = $_ENV['PRODUCT_OUTPUT_FILE'];

        if (empty($outputFile)) {
            echo 'No output format or file specified in environment variables or .env, skipping...' . PHP_EOL;
            return;
        }

        // Output JSON
        $jsonFile = str_replace('.csv', '.json', $outputFile);
        file_put_contents($jsonFile, json_encode($products, JSON_PRETTY_PRINT));

        $csvFile = str_replace('.json', '.csv', $jsonFile);
        $handle = fopen($csvFile, 'w');

        // Add the first row as headers. Assuming all products are formatted the same, of course.
        $csvSeparator = $_ENV['CSV_SEPARATOR'] ?? ';';
        $columns = array_keys($products[0]);
        fputcsv($handle, $columns, $csvSeparator);


        foreach ($products as $product)
        {
            /**
             * Special handler for arrays inside the product array.
             * To retain the data, we 'convert' the array to a string.
             */
            foreach ($product as $subIdx => $subItem)
            {
                if (is_array($subItem))
                {
                    $product[$subIdx] = implode(',', $subItem);
                }
            }

            fputcsv($handle, $product, $csvSeparator);
        }

        fclose($handle);
    }

    /**
     * Scrapes products from the specified `PRODUCT_URL_LIST` file.
     * Returns the scraped products as an array with name (string) + price (float), with maybe more values in the future.
     * 
     * Will also write the `PRODUCT_OUTPUT_FILE` file with the `PRODUCT_OUTPUT_FORMAT` format.
     *
     * @return array
     */
    public function scrapeFromFile() : array
    {
        $filename = $_ENV['PRODUCT_URL_LIST'];

        if (empty($filename)) {
            echo 'No product URL list specified in environment variables or .env, skipping...' . PHP_EOL;
            return [];
        }

        $inputHandle = fopen($filename, 'r');
        $products = [];

        while (($line = fgets($inputHandle)) !== false) {
            $url = trim($line);
            $product = $this->scrapeProductPage($url);
            $products[] = $product;
        }

        fclose($inputHandle);

        $this->writeProductsToFile($products);
        return $products;
    }
}

$oda = new Oda();
$oda->scrapeFromFile();