for TimeWeb

yml_update.php

<?php
/**
 * Created by PhpStorm.
 * User: renskiy
 * Date: 15.02.14
 * Time: 19:41
 */

class YmlUpdater {

    /**
     * Where to take updates
     * @var string
     */
    protected static $UPDATES_FILENAME = 'updates.yml';

    /**
     * Temporary file for currently processing updates
     * @var string
     */
    protected static $TEMP_UPDATES_FILENAME = '_updates.yml';

    /**
     * Where to place final result
     * @var string
     */
    protected static $PRODUCTS_FILENAME = 'products.yml';

    /**
     * Temporary file for products
     * @var string
     */
    protected static $TEMP_PRODUCTS_FILENAME = '_products.yml';

    /**
     * Template used for $PRODUCTS_FILENAME generation
     * @var string
     */
    protected static $PRODUCTS_TEMPLATE = 'products.tpl.yml';

    /**
     * Dynamic array used for storing currently processing product updates
     * @var array
     */
    protected $updated_products = [];

    /**
     * Entry point
     */
    public function run() {
        $this->load_updated_products();
        $this->generate_products_file();
        $this->remove_temp_files();
    }

    /**
     * Build products file based on predefined template
     */
    protected function generate_products_file() {
        $template = file_get_contents(self::$PRODUCTS_TEMPLATE);
        if ($template === false) {
            die(sprintf("Template %s was not found", self::$PRODUCTS_TEMPLATE));
        }
        list($prefix, $suffix) = explode('{{OFFERS}}', $template, 2);
        $new_products = fopen(self::$TEMP_PRODUCTS_FILENAME, 'w');
        fwrite($new_products, "$prefix\n");
        $this->add_updated_products($new_products);
        $this->add_unchanged_products($new_products);
        fwrite($new_products, $suffix);
        fclose($new_products);
    }

    /**
     * Adds updated products to the given file
     * @param resource $new_products
     */
    protected function add_updated_products($new_products) {
        foreach ($this->updated_products as $product) {
            fwrite($new_products, $product);
        }
    }

    /**
     * Adds to the given file those products that are not changed
     * since last update check
     * @param resource $new_products
     */
    protected function add_unchanged_products($new_products) {
        if (! file_exists(self::$PRODUCTS_FILENAME)) {
            return;
        }
        $old_products = fopen(self::$PRODUCTS_FILENAME, 'r');
        while (($product = fgets($old_products)) !== false) {
            if ($product_id = self::get_product_id($product)) {
                if (! array_key_exists($product_id, $this->updated_products)) {
                    fwrite($new_products, $product);
                }
            }
        }
        fclose($old_products);
    }

    /**
     * Removes all temporary files
     */
    protected function remove_temp_files() {
        rename(self::$TEMP_PRODUCTS_FILENAME, self::$PRODUCTS_FILENAME);
        unlink(self::$TEMP_UPDATES_FILENAME);
    }

    /**
     * Fills $this->updated_products with latest product updates
     */
    protected function load_updated_products() {
        $updates = $this->get_updates_file();
        while (($product = fgets($updates)) !== false) {
            if ($product_id = self::get_product_id($product)) {
                $this->updated_products[$product_id] = $product;
            }
        }
        fclose($updates);
    }

    /**
     * Tries to get product_id from the given product string in YML format
     * @param string $product
     * @return string|false
     */
    protected static function get_product_id($product) {
        if (preg_match('/^\\s*<offer[^>]*\\sid="(\\d+)"/', $product, $match)) {
            return $match[1];
        }
        return false;
    }

    /**
     * File object with product updates
     * @return resource
     */
    protected static function get_updates_file() {
        if (! file_exists(self::$TEMP_UPDATES_FILENAME)) {
            if (! file_exists(self::$UPDATES_FILENAME)) {
                die("Update file was not found");
            }
            rename(self::$UPDATES_FILENAME, self::$TEMP_UPDATES_FILENAME);
        }
        return fopen(self::$TEMP_UPDATES_FILENAME, 'r');
    }
}