# Define tools for AI models to use
server = FastMcp::Server.new(name: 'popular-users', version: '1.0.0')

# Define a tool by inheriting from FastMcp::Tool
class CreateUserTool < FastMcp::Tool
  description "Create a user"
    # These arguments will generate the needed JSON to be presented to the MCP Client
    # And they will be validated at run time.
    # The validation is based off Dry-Schema, with the addition of the description.
  arguments do
    required(:first_name).filled(:string).description("First name of the user")
    optional(:age).filled(:integer).description("Age of the user")
    required(:address).description("The shipping address").hash do
      required(:street).filled(:string).description("Street address")
      optional(:city).filled(:string).description("City name")
      optional(:zipcode).maybe(:string).description("Postal code")
    end
  end

  def call(first_name:, age: nil, address: {})
    User.create!(first_name:, age:, address:)
  end
end

# Register the tool with the server
server.register_tool(CreateUserTool)

# Share data resources with AI models by inheriting from FastMcp::Resource
class PopularUsers < FastMcp::Resource
  uri "myapp:///users/popular"
  resource_name "Popular Users"
  mime_type "application/json"

  def content
    JSON.generate(User.popular.limit(5).as_json)
  end
end

class User < FastMcp::Resource
  uri "myapp:///users/{id}" # This is a resource template
  resource_name "user"
  mime_type "application/json"

  def content
    id = params[:id] # params are computed from the uri pattern

    JSON.generate(User.find(id).as_json)
  end
end

# Register the resource with the server
server.register_resources(PopularUsers, User)

# Accessing the resource through the server
server.read_resource(PopularUsers.uri)

# Notify the resource content has been updated to clients
server.notify_resource_updated(PopularUsers.variabilized_uri)

# Notifiy the content of a resource from a template has been updated to clients
server.notify_resource_updated(User.variabilized_uri(id: 1))

# Tag your tools for easy filtering
class AdminTool < FastMcp::Tool
  tags :admin, :dangerous
  description "Perform admin operations"

  def call
    # Admin only functionality
  end
end

# Filter tools based on user permissions
server.filter_tools do |request, tools|
  user_role = request.params['role']

  case user_role
  when 'admin'
    tools # Admins see all tools
  when 'user'
    tools.reject { |t| t.tags.include?(:admin) }
  else
    tools.select { |t| t.tags.include?(:public) }
  end
end

require 'fast_mcp'

FastMcp.mount_in_rails(
  Rails.application,
  name: Rails.application.class.module_parent_name.underscore.dasherize,
  version: '1.0.0',
  path_prefix: '/mcp', # This is the default path prefix
  messages_route: 'messages', # This is the default route for the messages endpoint
  sse_route: 'sse', # This is the default route for the SSE endpoint
  # Add allowed origins below, it defaults to Rails.application.config.hosts
  # allowed_origins: ['localhost', '127.0.0.1', 'example.com', /.*\.example\.com/],
  # localhost_only: true, # Set to false to allow connections from other hosts
  # whitelist specific ips to if you want to run on localhost and allow connections from other IPs
  # allowed_ips: ['127.0.0.1', '::1']
  # authenticate: true,       # Uncomment to enable authentication
  # auth_token: 'your-token' # Required if authenticate: true
) do |server|
  Rails.application.config.after_initialize do
    # FastMcp will automatically discover and register:
    # - All classes that inherit from ApplicationTool (which uses ActionTool::Base)
    # - All classes that inherit from ApplicationResource (which uses ActionResource::Base)
    server.register_tools(*ApplicationTool.descendants)
    server.register_resources(*ApplicationResource.descendants)
    # alternatively, you can register tools and resources manually:
    # server.register_tool(MyTool)
    # server.register_resource(MyResource)
  end
end

# Using Rails-style naming:
class MyTool < ActionTool::Base
  description "My awesome tool"

  arguments do
    required(:input).filled(:string)
  end

  def call(input:)
    # Your implementation
  end
end

# Using standard FastMcp naming:
class AnotherTool < FastMcp::Tool
  # Both styles work interchangeably in Rails apps
end

# app/tools/application_tool.rb
class ApplicationTool < ActionTool::Base
  # Base methods for all tools
end

# app/resources/application_resource.rb
class ApplicationResource < ActionResource::Base
  # Base methods for all resources
end

require 'fast_mcp'

# Create an MCP server
server = FastMcp::Server.new(name: 'my-ai-server', version: '1.0.0')

# Define a tool by inheriting from FastMcp::Tool
class SummarizeTool < FastMcp::Tool
  description "Summarize a given text"

  arguments do
    required(:text).filled(:string).description("Text to summarize")
    optional(:max_length).filled(:integer).description("Maximum length of summary")
  end

  def call(text:, max_length: 100)
    # Your summarization logic here
    text.split('.').first(3).join('.') + '...'
  end
end

# Register the tool with the server
server.register_tool(SummarizeTool)

# Create a resource by inheriting from FastMcp::Resource
class StatisticsResource < FastMcp::Resource
  uri "data/statistics"
  resource_name "Usage Statistics"
  description "Current system statistics"
  mime_type "application/json"

  def content
    JSON.generate({
      users_online: 120,
      queries_per_minute: 250,
      popular_topics: ["Ruby", "AI", "WebDev"]
    })
  end
end

# Register the resource with the server
server.register_resource(StatisticsResource)

# Start the server
server.start

# app.rb
require 'sinatra'
require 'fast_mcp'

use FastMcp::RackMiddleware.new(name: 'my-ai-server', version: '1.0.0') do |server|
  # Register tools and resources here
  server.register_tool(SummarizeTool)
end

get '/' do
  'Hello World!'
end

# Configure allowed origins (defaults to ['localhost', '127.0.0.1'])
FastMcp.rack_middleware(app,
  allowed_origins: ['localhost', '127.0.0.1', 'your-domain.com', /.*\.your-domain\.com/],
  localhost_only: false,
  allowed_ips: ['192.168.1.1', '10.0.0.1'],
  # other options...
)

# Enable authentication
FastMcp.authenticated_rack_middleware(app,
  auth_token: 'your-secret-token',
  # other options...
)

# OAuth-protected MCP server
transport = FastMcp::Transports::OAuthStreamableHttpTransport.new(
  app, mcp_server,

  # OAuth Resource Server Configuration
  oauth_enabled: true,
  require_https: true, # Enforced in production
  resource_identifier: 'https://your-api.com/mcp', # Must match token audience

  # Authorization Servers (for RFC 9728 metadata endpoint)
  authorization_servers: [
    'https://your-auth-server.com'
  ],

  # Token Validation (choose one)

  # Option 1: JWT tokens with JWKS
  jwks_uri: 'https://your-auth-server.com/.well-known/jwks.json',
  audience: 'https://your-api.com/mcp',

  # Option 2: Opaque tokens with custom validator
  opaque_token_validator: lambda do |token|
    user = User.find_by(api_token: token)
    {
      valid: user&.active?,
      scopes: user&.mcp_scopes || [],
      subject: user&.id
    }
  end,

  # Scope Configuration
  tools_scope: 'mcp:tools',      # Required to execute tools
  resources_scope: 'mcp:resources', # Required to read resources
  admin_scope: 'mcp:admin',      # Required for admin operations

  # Security Features
  resource_identifier: 'https://your-api.com/mcp' # Audience binding
)

# config/initializers/fast_mcp.rb
FastMcp.mount_in_rails(
  Rails.application,
  transport: :oauth,

  # OAuth Resource Server Configuration
  oauth_enabled: true,
  require_https: Rails.env.production?,
  resource_identifier: ENV['MCP_RESOURCE_IDENTIFIER'],
  authorization_servers: ENV['OAUTH_AUTHORIZATION_SERVERS'].split(','),

  # JWT Token Validation
  jwks_uri: ENV['OAUTH_JWKS_URI'],
  audience: ENV['MCP_JWT_AUDIENCE'],

  # Scope-based Authorization
  tools_scope: 'mcp:tools',
  resources_scope: 'mcp:resources',
  admin_scope: 'mcp:admin'
)

# No configuration needed - automatically detected!
# Supports hundreds/thousands of concurrent SSE connections with minimal memory
bundle add falcon async async-io
falcon serve

# Just works with your existing Puma/Unicorn setup
bundle exec puma

# Force async mode
transport = FastMcp::Transports::StreamableHttpTransport.new(
  app, server, async_mode: :enabled
)

# Force threaded mode
transport = FastMcp::Transports::StreamableHttpTransport.new(
  app, server, async_mode: :disabled
)

# Auto-detect (default)
transport = FastMcp::Transports::StreamableHttpTransport.new(
  app, server, async_mode: :auto
)