wehub-resource-sync
101 lines
3.3 KiB
C#
101 lines
3.3 KiB
C#
// Copyright (c) Microsoft. All rights reserved.
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using System.Text.RegularExpressions;
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using Microsoft.SemanticKernel;
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using ModelContextProtocol.Protocol;
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using ModelContextProtocol.Server;
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namespace MCPServer.Resources;
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/// <summary>
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/// Represents a resource template definition.
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/// </summary>
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public sealed class ResourceTemplateDefinition
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{
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/// <summary>
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/// The regular expression to match the resource template.
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/// </summary>
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private Regex? _regex = null;
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/// <summary>
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/// The kernel function to invoke the resource template handler.
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/// </summary>
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private KernelFunction? _kernelFunction = null;
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/// <summary>
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/// Gets or sets the MCP resource template.
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/// </summary>
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public required ResourceTemplate ResourceTemplate { get; init; }
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/// <summary>
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/// Gets or sets the handler for the MCP resource template.
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/// </summary>
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public required Delegate Handler { get; init; }
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/// <summary>
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/// Gets or sets the kernel instance to invoke the resource template handler.
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/// If not provided, an instance registered in DI container will be used.
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/// </summary>
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public Kernel? Kernel { get; set; }
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/// <summary>
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/// Checks if the given Uri matches the resource template.
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/// </summary>
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/// <param name="uri">The Uri to check for match.</param>
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public bool IsMatch(string uri)
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{
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return this.GetRegex().IsMatch(uri);
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}
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/// <summary>
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/// Invokes the resource template handler.
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/// </summary>
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/// <param name="context">The MCP server context.</param>
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/// <param name="cancellationToken">The cancellation token.</param>
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/// <returns>The result of the invocation.</returns>
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public async ValueTask<ReadResourceResult> InvokeHandlerAsync(RequestContext<ReadResourceRequestParams> context, CancellationToken cancellationToken)
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{
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this._kernelFunction ??= KernelFunctionFactory.CreateFromMethod(this.Handler);
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this.Kernel
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??= context.Server.Services?.GetRequiredService<Kernel>()
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?? throw new InvalidOperationException("Kernel is not available.");
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KernelArguments args = new(source: this.GetArguments(context.Params!.Uri!))
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{
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{ "context", context },
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};
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FunctionResult result = await this._kernelFunction.InvokeAsync(kernel: this.Kernel, arguments: args, cancellationToken: cancellationToken);
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return result.GetValue<ReadResourceResult>() ?? throw new InvalidOperationException("The handler did not return a valid result.");
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}
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private Regex GetRegex()
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{
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if (this._regex != null)
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{
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return this._regex;
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}
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var pattern = "^" +
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Regex.Escape(this.ResourceTemplate.UriTemplate)
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.Replace("\\{", "(?<")
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.Replace("}", ">[^/]+)") +
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"$";
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return this._regex = new(pattern, RegexOptions.Compiled);
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}
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private Dictionary<string, object?> GetArguments(string uri)
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{
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var match = this.GetRegex().Match(uri);
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if (!match.Success)
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{
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throw new ArgumentException($"The uri '{uri}' does not match the template '{this.ResourceTemplate.UriTemplate}'.");
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}
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return match.Groups.Cast<Group>().Where(g => g.Name != "0").ToDictionary(g => g.Name, g => (object?)g.Value);
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}
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}
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