AmazonUkStoreParser.cs

using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using HtmlAgilityPack;

namespace AmazonPriceCheck
{
    public class AmazonUkStoreParser : IHtmlParser
    {
        public string GetItemCodeFromUrl(string url)
        {
            var itemCode = url.Substring(url.IndexOf("/dp/") + 4);
            itemCode = itemCode.Substring(0, itemCode.IndexOf("/"));
            return itemCode;
        }

        public decimal GetPriceForUrl(string url)
        {
            decimal thePrice = -1;
            if (string.IsNullOrEmpty(url))
            {
                return -1;
            }

            if (!url.Contains(".co.uk"))
            {
                return -1;
            }

            if (!url.Contains("amazon.co.uk"))
            {
                return -1;
            }

            var pageString = HttpUtils.GetHtmlFromUrl(url);
            thePrice = ParseDocumentForPrice(pageString);

            return thePrice;
        }

        private decimal ParseDocumentForPrice(string pageString)
        {
            var document = new HtmlDocument();
            document.LoadHtml(pageString);

            var nodes = document.DocumentNode.SelectNodes(
                "/html/body/div[@id='a-page'][1]"
                + "/div[@id='dp'][1]"
                + "/div[@id='dp-container'][1]"
                + "/div[@id='centerCol'][1]"
                + "/div[@id='desktop_unifiedPrice'][1]"
                + "/div[@id='unifiedPrice_feature_div'][1]"
                + "/div[@id='price'][1]"
                + "/table"
                + "/tr[@id='priceblock_ourprice_row'][1]"
                + "/td[2]"
                + "/span[@id='priceblock_ourprice']");

            var formattedNode = nodes.First().InnerHtml;
            formattedNode = formattedNode.Replace(" ", "");
            formattedNode = formattedNode.Replace("\n", "");
            formattedNode = formattedNode.Replace("£", "");

            decimal price = -1;
            Decimal.TryParse(formattedNode, out price);
            return price;
        }
    }
}