Google search tool and cleanup

src/libs/LangChain.Core/Chains/StackableChains/Agents/ReActAgentExecutorChain.cs

@@ -6,6 +6,7 @@
 using LangChain.Providers;
 using LangChain.Schema;
 using System.Reflection;
+using LangChain.Chains.StackableChains.Agents.Tools;
 using static LangChain.Chains.Chain;
 
 namespace LangChain.Chains.StackableChains.Agents;
@@ -27,9 +28,9 @@ public class ReActAgentExecutorChain : BaseStackableChain
 
 Question: the input question you must answer
 Thought: you should always think about what to do
-Action: the action to take, should be one of [{tool_names}]
-Action Input: the input to the action
-Observation: the result of the action
+Action: the tool name, should be one of [{tool_names}]
+Action Input: the input to the tool
+Observation: the result of the tool
 (this Thought/Action/Action Input/Observation can repeat multiple times)
 Thought: I now know the final answer
 Final Answer: the final answer to the original input question
@@ -42,7 +43,7 @@ Always add [END] after final answer
 
     private StackChain? _chain;
     private bool _useCache;
-    Dictionary<string, ReActAgentTool> _tools = new();
+    Dictionary<string, AgentTool> _tools = new();
     private readonly IChatModel _model;
     private readonly string _reActPrompt;
     private readonly int _maxActions;
@@ -133,8 +134,8 @@ protected override async Task<IChainValues> InternalCall(IChainValues values)
             if (res.Value[ReActAnswer] is AgentAction)
             {
                 var action = (AgentAction)res.Value[ReActAnswer];
-                var tool = _tools[action.Action];
-                var toolRes = tool.ToolCall(action.ActionInput);
+                var tool = _tools[action.Action.ToLower()];
+                var toolRes = await tool.ToolTask(action.ActionInput);
                 await _conversationBufferMemory.ChatHistory.AddMessage(new Message("Observation: " + toolRes, MessageRole.System))
                     .ConfigureAwait(false);
                 await _conversationBufferMemory.ChatHistory.AddMessage(new Message("Thought:", MessageRole.System))
@@ -144,7 +145,7 @@ await _conversationBufferMemory.ChatHistory.AddMessage(new Message("Thought:", M
             else if (res.Value[ReActAnswer] is AgentFinish)
             {
                 var finish = (AgentFinish)res.Value[ReActAnswer];
-                values.Value.Add(OutputKeys[0], finish.Output);
+                values.Value[OutputKeys[0]]= finish.Output;
                 return values;
             }
         }
@@ -170,7 +171,7 @@ public ReActAgentExecutorChain UseCache(bool enabled = true)
     /// </summary>
     /// <param name="tool"></param>
     /// <returns></returns>
-    public ReActAgentExecutorChain UseTool(ReActAgentTool tool)
+    public ReActAgentExecutorChain UseTool(AgentTool tool)
     {
         tool = tool ?? throw new ArgumentNullException(nameof(tool));
 

src/libs/LangChain.Core/Chains/StackableChains/Agents/Tools/BuiltIn/Classes/GoogleResults.cs

@@ -0,0 +1,15 @@
+
+
+namespace LangChain.Chains.StackableChains.Agents.Tools.BuiltIn.Classes;
+
+public class GoogleResult
+{
+    public class Item
+    {
+        public string title { get; set; }
+        public string link { get; set; }
+        public string snippet { get; set; }
+
+    }
+    public List<Item> items { get; set; }
+}

src/libs/LangChain.Core/Chains/StackableChains/Agents/Tools/BuiltIn/GoogleCustomSearchTool.cs

@@ -0,0 +1,82 @@
+using System.Net.Http;
+using System.Text.Json.Serialization;
+using System.Text.Json;
+using System.Text;
+using System.Security.Cryptography;
+using LangChain.Chains.StackableChains.Agents.Tools.BuiltIn.Classes;
+
+namespace LangChain.Chains.StackableChains.Agents.Tools.BuiltIn;
+
+public class GoogleCustomSearchTool(string key, string cx, bool useCache = true, int resultsLimit=3) : AgentTool("google",
+    "to search information on internet")
+{
+    private const string CACHE_DIR = "cache";
+
+    private string Hash(string prompt)
+    {
+        using var sha256 = SHA256.Create();
+        var hash = sha256.ComputeHash(Encoding.UTF8.GetBytes(prompt));
+        string resultHex = "";
+        foreach (var b in hash)
+            resultHex += $"{b:x2}";
+        return resultHex;
+    }
+
+    string? GetCachedAnswer(string prompt)
+    {
+        var file = Path.Combine(CACHE_DIR, $"{Hash(prompt)}.googlecache");
+        if (File.Exists(file))
+        {
+            return File.ReadAllText(file);
+        }
+
+        return null;
+    }
+
+    void SaveCachedAnswer(string prompt, string answer)
+    {
+        Directory.CreateDirectory(CACHE_DIR);
+        var file = Path.Combine(CACHE_DIR, $"{Hash(prompt)}.googlecache");
+        File.WriteAllText(file, answer);
+    }
+
+    public override async Task<string> ToolTask(string input, CancellationToken token = default)
+    {
+        string responseString;
+        if (!useCache||(responseString = GetCachedAnswer(input))==null)
+        {
+            using var httpClient = new HttpClient();
+            httpClient.BaseAddress = new Uri("https://www.googleapis.com");
+            var response = await httpClient.GetAsync(
+                $"/customsearch/v1?key={key}&cx={cx}&q={input}", token).ConfigureAwait(false);
+            response.EnsureSuccessStatusCode();
+            responseString = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
+        }
+
+
+        GoogleResult results = JsonSerializer.Deserialize<GoogleResult>(responseString!)!;
+
+
+        var stringBuilder = new StringBuilder();
+        int cnt = 0;
+        foreach (var result in results.items)
+        {
+            stringBuilder.AppendLine($"{result.title}");
+            stringBuilder.AppendLine($"{result.snippet}");
+            stringBuilder.AppendLine($"Source url: {result.link}");
+            stringBuilder.AppendLine();
+            if (++cnt >= resultsLimit)
+                break;
+        }
+
+        if (results.items.Count == 0)
+        {
+            stringBuilder.AppendLine("No results found");
+            stringBuilder.AppendLine();
+        }
+
+        if (useCache)
+            SaveCachedAnswer(input, responseString);
+        return stringBuilder.ToString();
+    }
+}