Added primitive search mechanism in backend.

Began implementing search mechanism for frontend.

Props/Services/Modules/LiveMetricsManager.cs

@@ -0,0 +1,85 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.Extensions.Logging;
+using Props.Data;
+using Props.Models.Search;
+using Props.Shop.Framework;
+
+namespace Props.Services.Modules
+{
+    public class LiveMetricsManager : IMetricsManager
+    {
+        private ILogger<LiveMetricsManager> logger;
+        ApplicationDbContext dbContext;
+        public LiveMetricsManager(ApplicationDbContext dbContext, ILogger<LiveMetricsManager> logger)
+        {
+            this.logger = logger;
+            this.dbContext = dbContext;
+        }
+        public IEnumerable<ProductListingInfo> RetrieveTopListings(int max)
+        {
+            if (dbContext.ProductListingInfos == null) return null;
+            return (from l in dbContext.ProductListingInfos
+                    orderby l.Hits descending
+                    select l).Take(max);
+        }
+
+        public IEnumerable<string> RetrieveCommonKeywords(int max)
+        {
+            if (dbContext.Keywords == null) return null;
+            return (from k in dbContext.Keywords
+                    orderby k.Hits descending
+                    select k.Word).Take(max);
+        }
+
+        public void RegisterSearchQuery(string query)
+        {
+            query = query.ToLower();
+            string[] tokens = query.Split(' ');
+            QueryWordInfo[] wordInfos = new QueryWordInfo[tokens.Length];
+            for (int wordIndex = 0; wordIndex < tokens.Length; wordIndex++)
+            {
+                QueryWordInfo queryWordInfo = dbContext.Keywords.Where((k) => k.Word.ToLower().Equals(tokens[wordIndex])).SingleOrDefault() ?? new QueryWordInfo();
+                if (queryWordInfo.Hits == 0)
+                {
+                    queryWordInfo.Word = tokens[wordIndex];
+                    dbContext.Keywords.Add(queryWordInfo);
+                }
+                queryWordInfo.Hits += 1;
+                wordInfos[wordIndex] = queryWordInfo;
+            }
+            for (int wordIndex = 0; wordIndex < tokens.Length; wordIndex++)
+            {
+                for (int beforeIndex = 0; beforeIndex < wordIndex; beforeIndex++)
+                {
+                    wordInfos[wordIndex].Preceding.Add(wordInfos[beforeIndex]);
+                }
+                for (int afterIndex = wordIndex; afterIndex < tokens.Length; afterIndex++)
+                {
+                    wordInfos[wordIndex].Following.Add(wordInfos[afterIndex]);
+                }
+            }
+            dbContext.SaveChanges();
+
+        }
+
+        public void RegisterListing(ProductListing productListing, string shopName)
+        {
+            ProductListingInfo productListingInfo =
+                (from info in dbContext.ProductListingInfos
+                 where info.ProductUrl.Equals(productListing.URL)
+                 select info).SingleOrDefault() ?? new ProductListingInfo();
+            if (productListingInfo.Hits == 0)
+            {
+                dbContext.Add(productListingInfo);
+            }
+            productListingInfo.ShopName = shopName;
+            productListingInfo.ProductName = productListing.Name;
+            productListingInfo.ProductUrl = productListing.URL;
+            productListingInfo.LastUpdated = DateTime.UtcNow;
+            productListingInfo.Hits += 1;
+            dbContext.SaveChanges();
+        }
+    }
+}