Bing Connector should return more than 1 result

# Motivation and Context
fix issue microsoft#508 

# Description
WebSearch Results using the Bing Connector has a hard code value of
count=1.

We need to return more than 1 result or should be able to pass count of
result requested

# Contribution Checklist
 The code builds clean without any errors or warnings
The PR follows SK Contribution Guidelines
(https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
The code follows the .NET coding conventions
(https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions)
verified with dotnet format
 All unit tests pass, and I have added new tests where possible
 I didn't break anyone 😄

---------

Co-authored-by: Adrian Bonar <[email protected]>

Author: feiyun0112

dotnet/src/Skills/Skills.UnitTests/Web/WebSearchEngineSkillTests.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using System;
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.SemanticKernel.Memory;
@@ -28,10 +29,10 @@ public WebSearchEngineSkillTests(ITestOutputHelper output)
     public async Task SearchAsyncSucceedsAsync()
     {
         // Arrange
-        string expected = Guid.NewGuid().ToString();
+        IEnumerable<string> expected = new[] { Guid.NewGuid().ToString() };
 
         Mock<IWebSearchEngineConnector> connectorMock = new();
-        connectorMock.Setup(c => c.SearchAsync(It.IsAny<string>(), It.IsAny<CancellationToken>()))
+        connectorMock.Setup(c => c.SearchAsync(It.IsAny<string>(), It.IsAny<int>(), It.IsAny<int>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync(expected);
 
         WebSearchEngineSkill target = new(connectorMock.Object);

dotnet/src/Skills/Skills.Web/Bing/BingConnector.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using System;
+using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Net.Http;
@@ -16,7 +17,7 @@ namespace Microsoft.SemanticKernel.Skills.Web.Bing;
 /// <summary>
 /// Bing API connector.
 /// </summary>
-public class BingConnector : IWebSearchEngineConnector, IDisposable
+public sealed class BingConnector : IWebSearchEngineConnector, IDisposable
 {
     private readonly ILogger _logger;
     private readonly HttpClientHandler _httpClientHandler;
@@ -31,9 +32,13 @@ public BingConnector(string apiKey, ILogger<BingConnector>? logger = null)
     }
 
     /// <inheritdoc/>
-    public async Task<string> SearchAsync(string query, CancellationToken cancellationToken = default)
+    public async Task<IEnumerable<string>> SearchAsync(string query, int count = 1, int offset = 0, CancellationToken cancellationToken = default)
     {
-        Uri uri = new($"https://api.bing.microsoft.com/v7.0/search?q={Uri.EscapeDataString(query)}&count=1");
+        if (count <= 0) { throw new ArgumentOutOfRangeException(nameof(count)); }
+        if (count >= 50) { throw new ArgumentOutOfRangeException(nameof(count), "{nameof(count)} value must be less than 50."); }
+        if (offset < 0) { throw new ArgumentOutOfRangeException(nameof(offset)); }
+
+        Uri uri = new($"https://api.bing.microsoft.com/v7.0/search?q={Uri.EscapeDataString(query)}&count={count}&offset={offset}");
 
         this._logger.LogDebug("Sending request: {0}", uri);
         HttpResponseMessage response = await this._httpClient.GetAsync(uri, cancellationToken).ConfigureAwait(false);
@@ -44,17 +49,12 @@ public async Task<string> SearchAsync(string query, CancellationToken cancellati
         this._logger.LogTrace("Response content received: {0}", json);
 
         BingSearchResponse? data = JsonSerializer.Deserialize<BingSearchResponse>(json);
-        WebPage? firstResult = data?.WebPages?.Value?.FirstOrDefault();
-
-        this._logger.LogDebug("Result: {0}, {1}, {2}",
-            firstResult?.Name,
-            firstResult?.Url,
-            firstResult?.Snippet);
+        WebPage[]? results = data?.WebPages?.Value;
 
-        return firstResult?.Snippet ?? string.Empty;
+        return results == null ? Enumerable.Empty<string>() : results.Select(x => x.Snippet);
     }
 
-    protected virtual void Dispose(bool disposing)
+    private void Dispose(bool disposing)
     {
         if (disposing)
         {

dotnet/src/Skills/Skills.Web/Google/GoogleConnector.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using System;
+using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -14,7 +15,7 @@ namespace Microsoft.SemanticKernel.Skills.Web.Google;
 /// <summary>
 /// Google search connector.
 /// </summary>
-public class GoogleConnector : IWebSearchEngineConnector, IDisposable
+public sealed class GoogleConnector : IWebSearchEngineConnector, IDisposable
 {
     private readonly ILogger _logger;
     private readonly CustomSearchAPIService _search;
@@ -37,21 +38,28 @@ public GoogleConnector(
     }
 
     /// <inheritdoc/>
-    public async Task<string> SearchAsync(string query, CancellationToken cancellationToken = default)
+    public async Task<IEnumerable<string>> SearchAsync(
+        string query,
+        int count,
+        int offset,
+        CancellationToken cancellationToken)
     {
+        if (count <= 0) { throw new ArgumentOutOfRangeException(nameof(count)); }
+        if (count > 10) { throw new ArgumentOutOfRangeException(nameof(count), "{nameof(count)} value must be between 0 and 10, inclusive."); }
+        if (offset < 0) { throw new ArgumentOutOfRangeException(nameof(offset)); }
+
         var search = this._search.Cse.List();
         search.Cx = this._searchEngineId;
         search.Q = query;
+        search.Num = count;
+        search.Start = offset;
 
         var results = await search.ExecuteAsync(cancellationToken).ConfigureAwait(false);
 
-        var first = results.Items?.FirstOrDefault();
-        this._logger.LogDebug("Result: {Title}, {Link}, {Snippet}", first?.Title, first?.Link, first?.Snippet);
-
-        return first?.Snippet ?? string.Empty;
+        return results.Items.Select(item => item.Snippet);
     }
 
-    protected virtual void Dispose(bool disposing)
+    private void Dispose(bool disposing)
     {
         if (disposing)
         {

dotnet/src/Skills/Skills.Web/IWebSearchEngineConnector.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -14,7 +15,9 @@ public interface IWebSearchEngineConnector
     /// Execute a web search engine search.
     /// </summary>
     /// <param name="query">Query to search.</param>
+    /// <param name="count">Number of results.</param>
+    /// <param name="offset ">Number of results to skip.</param>
     /// <param name="cancellationToken">The <see cref="CancellationToken"/> to monitor for cancellation requests. The default is <see cref="CancellationToken.None"/>.</param>
     /// <returns>First snippet returned from search.</returns>
-    Task<string> SearchAsync(string query, CancellationToken cancellationToken = default);
+    Task<IEnumerable<string>> SearchAsync(string query, int count = 1, int offset = 0, CancellationToken cancellationToken = default);
 }

dotnet/src/Skills/Skills.Web/WebSearchEngineSkill.cs

@@ -1,5 +1,8 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using System.Globalization;
+using System.Linq;
+using System.Text.Json;
 using System.Threading.Tasks;
 using Microsoft.SemanticKernel.Orchestration;
 using Microsoft.SemanticKernel.SkillDefinition;
@@ -11,6 +14,12 @@ namespace Microsoft.SemanticKernel.Skills.Web;
 /// </summary>
 public class WebSearchEngineSkill
 {
+    public const string CountParam = "count";
+    public const string OffsetParam = "offset";
+
+    private const string DefaultCount = "1";
+    private const string DefaultOffset = "0";
+
     private readonly IWebSearchEngineConnector _connector;
 
     public WebSearchEngineSkill(IWebSearchEngineConnector connector)
@@ -19,16 +28,28 @@ public WebSearchEngineSkill(IWebSearchEngineConnector connector)
     }
 
     [SKFunction("Perform a web search.")]
+    [SKFunctionName("Search")]
     [SKFunctionInput(Description = "Text to search for")]
-    [SKFunctionName("search")]
+    [SKFunctionContextParameter(Name = CountParam, Description = "Number of results", DefaultValue = DefaultCount)]
+    [SKFunctionContextParameter(Name = OffsetParam, Description = "Number of results to skip", DefaultValue = DefaultOffset)]
     public async Task<string> SearchAsync(string query, SKContext context)
     {
-        string result = await this._connector.SearchAsync(query, context.CancellationToken).ConfigureAwait(false);
-        if (string.IsNullOrWhiteSpace(result))
+        var count = context.Variables.ContainsKey(CountParam) ? context[CountParam] : DefaultCount;
+        if (string.IsNullOrWhiteSpace(count)) { count = DefaultCount; }
+
+        var offset = context.Variables.ContainsKey(OffsetParam) ? context[OffsetParam] : DefaultOffset;
+        if (string.IsNullOrWhiteSpace(offset)) { offset = DefaultOffset; }
+
+        int countInt = int.Parse(count, CultureInfo.InvariantCulture);
+        int offsetInt = int.Parse(offset, CultureInfo.InvariantCulture);
+        var results = await this._connector.SearchAsync(query, countInt, offsetInt, context.CancellationToken).ConfigureAwait(false);
+        if (!results.Any())
         {
             context.Fail("Failed to get a response from the web search engine.");
         }
 
-        return result;
+        return countInt == 1
+            ? results.FirstOrDefault() ?? string.Empty
+            : JsonSerializer.Serialize(results);
     }
 }