server_less_macros/

lib.rs

//! Proc macros for server-less.
//!
//! This crate provides attribute macros that transform impl blocks into protocol handlers,
//! and derive macros for common patterns.

use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
#[cfg(feature = "graphql")]
use syn::ItemEnum;
#[cfg(feature = "graphql")]
use syn::ItemStruct;
use syn::{DeriveInput, ItemImpl, parse_macro_input};

/// Compute the Levenshtein edit distance between two strings.
#[allow(clippy::needless_range_loop)]
fn levenshtein(a: &str, b: &str) -> usize {
    let a: Vec<char> = a.chars().collect();
    let b: Vec<char> = b.chars().collect();
    let m = a.len();
    let n = b.len();
    let mut dp = vec![vec![0usize; n + 1]; m + 1];
    for i in 0..=m {
        dp[i][0] = i;
    }
    for j in 0..=n {
        dp[0][j] = j;
    }
    for i in 1..=m {
        for j in 1..=n {
            dp[i][j] = if a[i - 1] == b[j - 1] {
                dp[i - 1][j - 1]
            } else {
                1 + dp[i - 1][j - 1].min(dp[i - 1][j]).min(dp[i][j - 1])
            };
        }
    }
    dp[m][n]
}

/// Return the closest candidate to `input` within edit distance ≤ 2, or `None`.
pub(crate) fn did_you_mean<'a>(input: &str, candidates: &[&'a str]) -> Option<&'a str> {
    candidates
        .iter()
        .filter_map(|&c| {
            let d = levenshtein(input, c);
            if d <= 2 { Some((d, c)) } else { None }
        })
        .min_by_key(|&(d, _)| d)
        .map(|(_, c)| c)
}

/// When `SERVER_LESS_DEBUG=1` is set at build time, print the generated token
/// stream to stderr so implementors can inspect macro output without `cargo expand`.
fn debug_emit(macro_name: &str, type_name: &str, tokens: &TokenStream2) {
    if std::env::var("SERVER_LESS_DEBUG").as_deref() == Ok("1") {
        eprintln!("--- server-less: #[{macro_name}] on {type_name} ---");
        eprintln!("{tokens}");
        eprintln!("--- end #[{macro_name}] on {type_name} ---");
    }
}

fn type_name(ty: &syn::Type) -> String {
    quote::quote!(#ty).to_string()
}

/// Strip the first `impl` block from a token stream.
///
/// Preset macros call multiple expand functions, each of which emits the
/// original impl block followed by generated code. To avoid duplicate method
/// definitions, the preset emits the impl block from the first expand call
/// and strips it from subsequent calls.
fn strip_first_impl(tokens: TokenStream2) -> TokenStream2 {
    let file: syn::File = match syn::parse2(tokens.clone()) {
        Ok(file) => file,
        Err(err) => {
            // Emit the original tokens (so the user's code is preserved) plus
            // a compile_error! pointing at the parse failure.  This surfaces the
            // real problem instead of silently dropping generated impls.
            let msg = format!("server-less: preset macro failed to parse generated tokens: {err}");
            return quote::quote! {
                #tokens
                ::core::compile_error!(#msg);
            };
        }
    };

    let mut found_first = false;
    let remaining: Vec<_> = file
        .items
        .into_iter()
        .filter(|item| {
            if !found_first && matches!(item, syn::Item::Impl(_)) {
                found_first = true;
                return false;
            }
            true
        })
        .collect();

    quote::quote! { #(#remaining)* }
}

/// Priority-ordered list of protocol macro attribute names.
///
/// When multiple protocol macros are stacked on the same impl block, Rust expands
/// each independently (outputs are concatenated, not pipelined).  To avoid emitting
/// the impl block multiple times, exactly ONE macro — the one with the highest
/// priority that's present — takes responsibility for emitting it.
const PROTOCOL_PRIORITY: &[&str] = &[
    "cli", "http", "mcp", "jsonrpc", "ws", "graphql", "openapi", "openrpc",
];

/// Returns `true` if this protocol macro should emit the original impl block.
///
/// A macro emits the impl when no higher-priority protocol sibling is present on
/// the same impl block.  This ensures exactly one copy is emitted when macros are
/// stacked, preventing duplicate method definitions.
pub(crate) fn is_protocol_impl_emitter(impl_block: &ItemImpl, current: &str) -> bool {
    let current_pos = PROTOCOL_PRIORITY
        .iter()
        .position(|&p| p == current)
        .unwrap_or(usize::MAX);
    // Emit if no sibling with LOWER index (higher priority) is present.
    !impl_block.attrs.iter().any(|attr| {
        PROTOCOL_PRIORITY[..current_pos]
            .iter()
            .any(|name| attr.path().is_ident(name))
    })
}


#[cfg(feature = "asyncapi")]
mod asyncapi;
#[cfg(feature = "capnp")]
mod capnp;
#[cfg(feature = "cli")]
mod cli;
#[cfg(feature = "connect")]
mod connect;
mod context;
mod error;
#[cfg(feature = "graphql")]
mod graphql;
#[cfg(feature = "graphql")]
mod graphql_enum;
#[cfg(feature = "graphql")]
mod graphql_input;
#[cfg(feature = "grpc")]
mod grpc;
#[cfg(feature = "http")]
mod http;
#[cfg(feature = "jsonrpc")]
mod jsonrpc;
#[cfg(feature = "jsonschema")]
mod jsonschema;
#[cfg(feature = "markdown")]
mod markdown;
#[cfg(feature = "mcp")]
mod mcp;
#[cfg(any(feature = "http", feature = "openapi"))]
mod openapi;
#[cfg(any(feature = "http", feature = "openapi"))]
mod openapi_gen;
#[cfg(feature = "openrpc")]
mod openrpc;
#[cfg(feature = "smithy")]
mod smithy;
#[cfg(feature = "thrift")]
mod thrift;
#[cfg(feature = "ws")]
mod ws;

mod app;
#[cfg(feature = "config")]
mod config_cmd;
#[cfg(feature = "config")]
mod config_derive;
mod server_attrs;

// Blessed preset modules
#[cfg(feature = "cli")]
mod program;
#[cfg(feature = "jsonrpc")]
mod rpc_preset;
#[cfg(feature = "http")]
mod server;
#[cfg(feature = "mcp")]
mod tool;

/// Generate HTTP handlers from an impl block.
///
/// # Basic Usage
///
/// ```ignore
/// use server_less::http;
///
/// #[http]
/// impl UserService {
///     async fn create_user(&self, name: String) -> User { /* ... */ }
/// }
/// ```
///
/// # With URL Prefix
///
/// ```ignore
/// #[http(prefix = "/api/v1")]
/// impl UserService {
///     // POST /api/v1/users
///     async fn create_user(&self, name: String) -> User { /* ... */ }
/// }
/// ```
///
/// # Per-Method Route Overrides
///
/// ```ignore
/// #[http]
/// impl UserService {
///     // Override HTTP method: GET /data becomes POST /data
///     #[route(method = "POST")]
///     async fn get_data(&self, payload: String) -> String { /* ... */ }
///
///     // Override path: POST /users becomes POST /custom-endpoint
///     #[route(path = "/custom-endpoint")]
///     async fn create_user(&self, name: String) -> User { /* ... */ }
///
///     // Override both
///     #[route(method = "PUT", path = "/special/{id}")]
///     async fn do_something(&self, id: String) -> String { /* ... */ }
///
///     // Skip route generation (internal methods)
///     #[route(skip)]
///     fn internal_helper(&self) -> String { /* ... */ }
///
///     // Hide from OpenAPI but still generate route
///     #[route(hidden)]
///     fn secret_endpoint(&self) -> String { /* ... */ }
/// }
/// ```
///
/// # Parameter Handling
///
/// ```ignore
/// #[http]
/// impl BlogService {
///     // Path parameters (id, post_id, etc. go in URL)
///     async fn get_post(&self, post_id: u32) -> Post { /* ... */ }
///     // GET /posts/{post_id}
///
///     // Query parameters (GET methods use query string)
///     async fn search_posts(&self, query: String, tag: Option<String>) -> Vec<Post> {
///         /* ... */
///     }
///     // GET /posts?query=rust&tag=tutorial
///
///     // Body parameters (POST/PUT/PATCH use JSON body)
///     async fn create_post(&self, title: String, content: String) -> Post {
///         /* ... */
///     }
///     // POST /posts with body: {"title": "...", "content": "..."}
/// }
/// ```
///
/// # Error Handling
///
/// ```ignore
/// #[http]
/// impl UserService {
///     // Return Result for error handling
///     async fn get_user(&self, id: u32) -> Result<User, MyError> {
///         if id == 0 {
///             return Err(MyError::InvalidId);
///         }
///         Ok(User { id, name: "Alice".into() })
///     }
///
///     // Return Option - None becomes 404
///     async fn find_user(&self, email: String) -> Option<User> {
///         // Returns 200 with user or 404 if None
///         None
///     }
/// }
/// ```
///
/// # Server-Sent Events (SSE) Streaming
///
/// Return `impl Stream<Item = T>` to enable Server-Sent Events streaming.
///
/// **Important for Rust 2024:** You must add `+ use<>` to impl Trait return types
/// to explicitly capture all generic parameters in scope. This is required by the
/// Rust 2024 edition's stricter lifetime capture rules.
///
/// ```ignore
/// use futures::stream::{self, Stream};
///
/// #[http]
/// impl DataService {
///     // Simple stream - emits values immediately
///     // Note the `+ use<>` syntax for Rust 2024
///     fn stream_numbers(&self, count: u32) -> impl Stream<Item = u32> + use<> {
///         stream::iter(0..count)
///     }
///
///     // Async stream with delays
///     async fn stream_events(&self, n: u32) -> impl Stream<Item = Event> + use<> {
///         stream::unfold(0, move |count| async move {
///             if count >= n {
///                 return None;
///             }
///             tokio::time::sleep(Duration::from_secs(1)).await;
///             Some((Event { id: count }, count + 1))
///         })
///     }
/// }
/// ```
///
/// Clients receive data as SSE:
/// ```text
/// data: {"id": 0}
///
/// data: {"id": 1}
///
/// data: {"id": 2}
/// ```
///
/// **Why `+ use<>`?**
/// - Rust 2024 requires explicit capture of generic parameters in return position impl Trait
/// - `+ use<>` captures all type parameters and lifetimes from the function context
/// - Without it, you'll get compilation errors about uncaptured parameters
/// - See: examples/streaming_service.rs for a complete working example
///
/// # Real-World Example
///
/// ```ignore
/// #[http(prefix = "/api/v1")]
/// impl UserService {
///     // GET /api/v1/users?page=0&limit=10
///     async fn list_users(
///         &self,
///         #[param(default = 0)] page: u32,
///         #[param(default = 20)] limit: u32,
///     ) -> Vec<User> {
///         /* ... */
///     }
///
///     // GET /api/v1/users/{user_id}
///     async fn get_user(&self, user_id: u32) -> Result<User, ApiError> {
///         /* ... */
///     }
///
///     // POST /api/v1/users with body: {"name": "...", "email": "..."}
///     #[response(status = 201)]
///     #[response(header = "Location", value = "/api/v1/users/{id}")]
///     async fn create_user(&self, name: String, email: String) -> Result<User, ApiError> {
///         /* ... */
///     }
///
///     // PUT /api/v1/users/{user_id}
///     async fn update_user(
///         &self,
///         user_id: u32,
///         name: Option<String>,
///         email: Option<String>,
///     ) -> Result<User, ApiError> {
///         /* ... */
///     }
///
///     // DELETE /api/v1/users/{user_id}
///     #[response(status = 204)]
///     async fn delete_user(&self, user_id: u32) -> Result<(), ApiError> {
///         /* ... */
///     }
/// }
/// ```
///
/// # Generated Methods
/// - `http_router() -> axum::Router` - Complete router with all endpoints
/// - `http_routes() -> Vec<&'static str>` - List of route paths
/// - `openapi_spec() -> serde_json::Value` - OpenAPI 3.0 specification (unless `openapi = false`)
///
/// # OpenAPI Control
///
/// By default, `#[http]` generates both HTTP routes and OpenAPI specs. You can disable
/// OpenAPI generation:
///
/// ```ignore
/// #[http(openapi = false)]  // No openapi_spec() method generated
/// impl MyService { /* ... */ }
/// ```
///
/// For standalone OpenAPI generation without HTTP routing, see `#[openapi]`.
#[cfg(feature = "http")]
#[proc_macro_attribute]
pub fn http(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as http::HttpArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match http::expand_http(args, impl_block) {
        Ok(tokens) => {
            debug_emit("http", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate OpenAPI specification without HTTP routing.
///
/// Generates OpenAPI 3.0 specs using the same naming conventions as `#[http]`,
/// but without creating route handlers. Useful for:
/// - Schema-first development
/// - Documentation-only use cases
/// - Separate OpenAPI generation from HTTP routing
///
/// # Basic Usage
///
/// ```ignore
/// use server_less::openapi;
///
/// #[openapi]
/// impl UserService {
///     /// Create a new user
///     fn create_user(&self, name: String, email: String) -> User { /* ... */ }
///
///     /// Get user by ID
///     fn get_user(&self, id: String) -> Option<User> { /* ... */ }
/// }
///
/// // Generate spec:
/// let spec = UserService::openapi_spec();
/// ```
///
/// # With URL Prefix
///
/// ```ignore
/// #[openapi(prefix = "/api/v1")]
/// impl UserService { /* ... */ }
/// ```
///
/// # Generated Methods
///
/// - `openapi_spec() -> serde_json::Value` - OpenAPI 3.0 specification
///
/// # Combining with #[http]
///
/// If you want separate control over OpenAPI generation:
///
/// ```ignore
/// // Option 1: Disable OpenAPI in http, use standalone macro
/// #[http(openapi = false)]
/// #[openapi(prefix = "/api")]
/// impl MyService { /* ... */ }
///
/// // Option 2: Just use http with default (openapi = true)
/// #[http]
/// impl MyService { /* ... */ }
/// ```
#[cfg(any(feature = "http", feature = "openapi"))]
#[proc_macro_attribute]
pub fn openapi(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as openapi::OpenApiArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match openapi::expand_openapi(args, impl_block) {
        Ok(tokens) => {
            debug_emit("openapi", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate a CLI application from an impl block.
///
/// # Basic Usage
///
/// ```ignore
/// use server_less::cli;
///
/// #[cli]
/// impl MyApp {
///     fn create_user(&self, name: String) { /* ... */ }
/// }
/// ```
///
/// # With All Options
///
/// ```ignore
/// #[cli(
///     name = "myapp",
///     version = "1.0.0",
///     about = "My awesome application"
/// )]
/// impl MyApp {
///     /// Create a new user (becomes: myapp create-user <NAME>)
///     fn create_user(&self, name: String) { /* ... */ }
///
///     /// Optional flags use Option<T>
///     fn list_users(&self, limit: Option<usize>) { /* ... */ }
/// }
/// ```
///
/// # Generated Methods
/// - `cli_app() -> clap::Command` - Complete CLI application
/// - `cli_run(&self, matches: &ArgMatches)` - Execute matched command
#[cfg(feature = "cli")]
#[proc_macro_attribute]
pub fn cli(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as cli::CliArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match cli::expand_cli(args, impl_block) {
        Ok(tokens) => {
            debug_emit("cli", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate MCP (Model Context Protocol) tools from an impl block.
///
/// # Basic Usage
///
/// ```ignore
/// use server_less::mcp;
///
/// #[mcp]
/// impl FileTools {
///     fn read_file(&self, path: String) -> String { /* ... */ }
/// }
/// ```
///
/// # With Namespace
///
/// ```ignore
/// #[mcp(namespace = "file")]
/// impl FileTools {
///     // Exposed as "file_read_file" tool
///     fn read_file(&self, path: String) -> String { /* ... */ }
/// }
/// ```
///
/// # Streaming Support
///
/// Methods returning `impl Stream<Item = T>` are automatically collected into arrays:
///
/// ```ignore
/// use futures::stream::{self, Stream};
///
/// #[mcp]
/// impl DataService {
///     // Returns JSON array: [0, 1, 2, 3, 4]
///     fn stream_numbers(&self, count: u32) -> impl Stream<Item = u32> + use<> {
///         stream::iter(0..count)
///     }
/// }
///
/// // Call with:
/// service.mcp_call_async("stream_numbers", json!({"count": 5})).await
/// // Returns: [0, 1, 2, 3, 4]
/// ```
///
/// **Note:** Streaming methods require `mcp_call_async`, not `mcp_call`.
///
/// # Generated Methods
/// - `mcp_tools() -> Vec<serde_json::Value>` - Tool definitions
/// - `mcp_call(&self, name, args) -> Result<Value, String>` - Execute tool (sync only)
/// - `mcp_call_async(&self, name, args).await` - Execute tool (supports async & streams)
#[cfg(feature = "mcp")]
#[proc_macro_attribute]
pub fn mcp(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as mcp::McpArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match mcp::expand_mcp(args, impl_block) {
        Ok(tokens) => {
            debug_emit("mcp", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate WebSocket JSON-RPC handlers from an impl block.
///
/// Methods are exposed as JSON-RPC methods over WebSocket connections.
/// Supports both sync and async methods.
///
/// # Basic Usage
///
/// ```ignore
/// use server_less::ws;
///
/// #[ws(path = "/ws")]
/// impl ChatService {
///     fn send_message(&self, room: String, content: String) -> Message {
///         // ...
///     }
/// }
/// ```
///
/// # With Async Methods
///
/// ```ignore
/// #[ws(path = "/ws")]
/// impl ChatService {
///     // Async methods work seamlessly
///     async fn send_message(&self, room: String, content: String) -> Message {
///         // Can await database, network calls, etc.
///     }
///
///     // Mix sync and async
///     fn get_rooms(&self) -> Vec<String> {
///         // Synchronous method
///     }
/// }
/// ```
///
/// # Error Handling
///
/// ```ignore
/// #[ws(path = "/ws")]
/// impl ChatService {
///     fn send_message(&self, room: String, content: String) -> Result<Message, ChatError> {
///         if room.is_empty() {
///             return Err(ChatError::InvalidRoom);
///         }
///         Ok(Message::new(room, content))
///     }
/// }
/// ```
///
/// # Client Usage
///
/// Clients send JSON-RPC 2.0 messages over WebSocket:
///
/// ```json
/// // Request
/// {
///   "jsonrpc": "2.0",
///   "method": "send_message",
///   "params": {"room": "general", "content": "Hello!"},
///   "id": 1
/// }
///
/// // Response
/// {
///   "jsonrpc": "2.0",
///   "result": {"id": 123, "room": "general", "content": "Hello!"},
///   "id": 1
/// }
/// ```
///
/// # Generated Methods
/// - `ws_router() -> axum::Router` - Router with WebSocket endpoint
/// - `ws_handle_message(msg) -> String` - Sync message handler
/// - `ws_handle_message_async(msg) -> String` - Async message handler
/// - `ws_methods() -> Vec<&'static str>` - List of available methods
#[cfg(feature = "ws")]
#[proc_macro_attribute]
pub fn ws(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as ws::WsArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match ws::expand_ws(args, impl_block) {
        Ok(tokens) => {
            debug_emit("ws", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate JSON-RPC 2.0 handlers over HTTP.
///
/// # Example
///
/// ```ignore
/// use server_less::jsonrpc;
///
/// struct Calculator;
///
/// #[jsonrpc]
/// impl Calculator {
///     /// Add two numbers
///     fn add(&self, a: i32, b: i32) -> i32 {
///         a + b
///     }
///
///     /// Multiply two numbers
///     fn multiply(&self, a: i32, b: i32) -> i32 {
///         a * b
///     }
/// }
///
/// // POST /rpc with {"jsonrpc": "2.0", "method": "add", "params": {"a": 1, "b": 2}, "id": 1}
/// // Returns: {"jsonrpc": "2.0", "result": 3, "id": 1}
/// ```
///
/// This generates:
/// - `Calculator::jsonrpc_router()` returning an axum Router
/// - `Calculator::jsonrpc_handle(request)` to handle JSON-RPC requests
/// - `Calculator::jsonrpc_methods()` listing available methods
///
/// Supports JSON-RPC 2.0 features:
/// - Named and positional parameters
/// - Batch requests (array of requests)
/// - Notifications (requests without id)
#[cfg(feature = "jsonrpc")]
#[proc_macro_attribute]
pub fn jsonrpc(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as jsonrpc::JsonRpcArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match jsonrpc::expand_jsonrpc(args, impl_block) {
        Ok(tokens) => {
            debug_emit("jsonrpc", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate OpenRPC specification for JSON-RPC services.
///
/// OpenRPC is to JSON-RPC what OpenAPI is to REST APIs.
///
/// # Example
///
/// ```ignore
/// use server_less::openrpc;
///
/// struct Calculator;
///
/// #[openrpc(title = "Calculator API", version = "1.0.0")]
/// impl Calculator {
///     /// Add two numbers
///     fn add(&self, a: i32, b: i32) -> i32 { a + b }
/// }
///
/// // Get OpenRPC spec as JSON
/// let spec = Calculator::openrpc_spec();
/// let json = Calculator::openrpc_json();
///
/// // Write to file
/// Calculator::write_openrpc("openrpc.json")?;
/// ```
#[cfg(feature = "openrpc")]
#[proc_macro_attribute]
pub fn openrpc(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as openrpc::OpenRpcArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match openrpc::expand_openrpc(args, impl_block) {
        Ok(tokens) => {
            debug_emit("openrpc", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate Markdown API documentation from an impl block.
///
/// Creates human-readable documentation that can be used with
/// any static site generator (VitePress, Docusaurus, MkDocs, etc.).
///
/// # Example
///
/// ```ignore
/// use server_less::markdown;
///
/// struct UserService;
///
/// #[markdown(title = "User API")]
/// impl UserService {
///     /// Create a new user
///     fn create_user(&self, name: String, email: String) -> User { ... }
///
///     /// Get user by ID
///     fn get_user(&self, id: String) -> Option<User> { ... }
/// }
///
/// // Get markdown string
/// let docs = UserService::markdown_docs();
///
/// // Write to file
/// UserService::write_markdown("docs/api.md")?;
/// ```
#[cfg(feature = "markdown")]
#[proc_macro_attribute]
pub fn markdown(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as markdown::MarkdownArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match markdown::expand_markdown(args, impl_block) {
        Ok(tokens) => {
            debug_emit("markdown", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate AsyncAPI specification for event-driven services.
///
/// AsyncAPI is to WebSockets/messaging what OpenAPI is to REST.
///
/// # Example
///
/// ```ignore
/// use server_less::asyncapi;
///
/// struct ChatService;
///
/// #[asyncapi(title = "Chat API", server = "ws://localhost:8080")]
/// impl ChatService {
///     /// Send a message to a room
///     fn send_message(&self, room: String, content: String) -> bool { true }
///
///     /// Get message history
///     fn get_history(&self, room: String, limit: Option<u32>) -> Vec<String> { vec![] }
/// }
///
/// // Get AsyncAPI spec
/// let spec = ChatService::asyncapi_spec();
/// let json = ChatService::asyncapi_json();
///
/// // Write to file
/// ChatService::write_asyncapi("asyncapi.json")?;
/// ```
#[cfg(feature = "asyncapi")]
#[proc_macro_attribute]
pub fn asyncapi(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as asyncapi::AsyncApiArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match asyncapi::expand_asyncapi(args, impl_block) {
        Ok(tokens) => {
            debug_emit("asyncapi", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate Connect protocol schema from an impl block.
///
/// Connect is a modern RPC protocol from Buf that works over HTTP/1.1, HTTP/2, and HTTP/3.
/// The generated schema is compatible with connect-go, connect-es, connect-swift, etc.
///
/// # Example
///
/// ```ignore
/// use server_less::connect;
///
/// struct UserService;
///
/// #[connect(package = "users.v1")]
/// impl UserService {
///     fn get_user(&self, id: String) -> User { ... }
/// }
///
/// // Get schema and endpoint paths
/// let schema = UserService::connect_schema();
/// let paths = UserService::connect_paths(); // ["/users.v1.UserService/GetUser", ...]
/// ```
#[cfg(feature = "connect")]
#[proc_macro_attribute]
pub fn connect(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as connect::ConnectArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match connect::expand_connect(args, impl_block) {
        Ok(tokens) => {
            debug_emit("connect", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate Protocol Buffers schema from an impl block.
///
/// # Example
///
/// ```ignore
/// use server_less::grpc;
///
/// struct UserService;
///
/// #[grpc(package = "users")]
/// impl UserService {
///     /// Get user by ID
///     fn get_user(&self, id: String) -> User { ... }
///
///     /// Create a new user
///     fn create_user(&self, name: String, email: String) -> User { ... }
/// }
///
/// // Get the proto schema
/// let proto = UserService::proto_schema();
///
/// // Write to file for use with tonic-build
/// UserService::write_proto("proto/users.proto")?;
/// ```
///
/// The generated schema can be used with tonic-build in your build.rs
/// to generate the full gRPC client/server implementation.
#[cfg(feature = "grpc")]
#[proc_macro_attribute]
pub fn grpc(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as grpc::GrpcArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match grpc::expand_grpc(args, impl_block) {
        Ok(tokens) => {
            debug_emit("grpc", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate Cap'n Proto schema from an impl block.
///
/// # Example
///
/// ```ignore
/// use server_less::capnp;
///
/// struct UserService;
///
/// #[capnp(id = "0x85150b117366d14b")]
/// impl UserService {
///     /// Get user by ID
///     fn get_user(&self, id: String) -> String { ... }
///
///     /// Create a new user
///     fn create_user(&self, name: String, email: String) -> String { ... }
/// }
///
/// // Get the Cap'n Proto schema
/// let schema = UserService::capnp_schema();
///
/// // Write to file for use with capnpc
/// UserService::write_capnp("schema/users.capnp")?;
/// ```
///
/// The generated schema can be used with capnpc to generate
/// the full Cap'n Proto serialization code.
#[cfg(feature = "capnp")]
#[proc_macro_attribute]
pub fn capnp(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as capnp::CapnpArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match capnp::expand_capnp(args, impl_block) {
        Ok(tokens) => {
            debug_emit("capnp", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate Apache Thrift schema from an impl block.
///
/// # Example
///
/// ```ignore
/// use server_less::thrift;
///
/// struct UserService;
///
/// #[thrift(namespace = "users")]
/// impl UserService {
///     /// Get user by ID
///     fn get_user(&self, id: String) -> String { ... }
///
///     /// Create a new user
///     fn create_user(&self, name: String, email: String) -> String { ... }
/// }
///
/// // Get the Thrift schema
/// let schema = UserService::thrift_schema();
///
/// // Write to file for use with thrift compiler
/// UserService::write_thrift("idl/users.thrift")?;
/// ```
///
/// The generated schema can be used with the Thrift compiler to generate
/// client/server code in various languages.
#[cfg(feature = "thrift")]
#[proc_macro_attribute]
pub fn thrift(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as thrift::ThriftArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match thrift::expand_thrift(args, impl_block) {
        Ok(tokens) => {
            debug_emit("thrift", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate Smithy IDL schema from an impl block.
///
/// Smithy is AWS's open-source interface definition language for defining APIs.
/// The generated schema follows Smithy 2.0 specification.
///
/// # Example
///
/// ```ignore
/// use server_less::smithy;
///
/// struct UserService;
///
/// #[smithy(namespace = "com.example.users")]
/// impl UserService {
///     /// Get user by ID
///     fn get_user(&self, id: String) -> User { ... }
///
///     /// Create a new user
///     fn create_user(&self, name: String, email: String) -> User { ... }
/// }
///
/// // Get Smithy schema
/// let schema = UserService::smithy_schema();
/// // Write to file
/// UserService::write_smithy("service.smithy")?;
/// ```
///
/// The generated schema can be used with the Smithy toolchain for code generation.
#[cfg(feature = "smithy")]
#[proc_macro_attribute]
pub fn smithy(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as smithy::SmithyArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match smithy::expand_smithy(args, impl_block) {
        Ok(tokens) => {
            debug_emit("smithy", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate JSON Schema from an impl block.
///
/// Generates JSON Schema definitions for request/response types.
/// Useful for API validation, documentation, and tooling.
///
/// # Example
///
/// ```ignore
/// use server_less::jsonschema;
///
/// struct UserService;
///
/// #[jsonschema(title = "User API")]
/// impl UserService {
///     /// Get user by ID
///     fn get_user(&self, id: String) -> User { ... }
///
///     /// Create a new user
///     fn create_user(&self, name: String, email: String) -> User { ... }
/// }
///
/// // Get JSON Schema
/// let schema = UserService::json_schema();
/// // Write to file
/// UserService::write_json_schema("schema.json")?;
/// ```
#[cfg(feature = "jsonschema")]
#[proc_macro_attribute]
pub fn jsonschema(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as jsonschema::JsonSchemaArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match jsonschema::expand_jsonschema(args, impl_block) {
        Ok(tokens) => {
            debug_emit("jsonschema", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Generate GraphQL schema from an impl block using async-graphql.
///
/// Methods are automatically classified as Queries or Mutations based on naming:
/// - Queries: `get_*`, `list_*`, `find_*`, `search_*`, `fetch_*`, `query_*`
/// - Mutations: everything else (create, update, delete, etc.)
///
/// # Basic Usage
///
/// ```ignore
/// use server_less::graphql;
///
/// #[graphql]
/// impl UserService {
///     // Query: returns single user
///     async fn get_user(&self, id: String) -> Option<User> {
///         // ...
///     }
///
///     // Query: returns list of users
///     async fn list_users(&self) -> Vec<User> {
///         // ...
///     }
///
///     // Mutation: creates new user
///     async fn create_user(&self, name: String, email: String) -> User {
///         // ...
///     }
/// }
/// ```
///
/// # Type Mappings
///
/// - `String`, `i32`, `bool`, etc. → GraphQL scalars
/// - `Option<T>` → nullable GraphQL field
/// - `Vec<T>` → GraphQL list `[T]`
/// - Custom structs → GraphQL objects (must derive SimpleObject)
///
/// ```ignore
/// use async_graphql::SimpleObject;
///
/// #[derive(SimpleObject)]
/// struct User {
///     id: String,
///     name: String,
///     email: Option<String>,  // Nullable field
/// }
///
/// #[graphql]
/// impl UserService {
///     async fn get_user(&self, id: String) -> Option<User> {
///         // Returns User object with proper GraphQL schema
///     }
///
///     async fn list_users(&self) -> Vec<User> {
///         // Returns [User] in GraphQL
///     }
/// }
/// ```
///
/// # GraphQL Queries
///
/// ```graphql
/// # Query single user
/// query {
///   getUser(id: "123") {
///     id
///     name
///     email
///   }
/// }
///
/// # List all users
/// query {
///   listUsers {
///     id
///     name
///   }
/// }
///
/// # Mutation
/// mutation {
///   createUser(name: "Alice", email: "alice@example.com") {
///     id
///     name
///   }
/// }
/// ```
///
/// # Custom Scalars
///
/// Common custom scalar types are automatically supported:
///
/// ```ignore
/// use chrono::{DateTime, Utc};
/// use uuid::Uuid;
///
/// #[graphql]
/// impl EventService {
///     // UUID parameter
///     async fn get_event(&self, event_id: Uuid) -> Option<Event> { /* ... */ }
///
///     // DateTime parameter
///     async fn list_events(&self, since: DateTime<Utc>) -> Vec<Event> { /* ... */ }
///
///     // JSON parameter
///     async fn search_events(&self, filter: serde_json::Value) -> Vec<Event> { /* ... */ }
/// }
/// ```
///
/// Supported custom scalars:
/// - `chrono::DateTime<Utc>` → DateTime
/// - `uuid::Uuid` → UUID
/// - `url::Url` → Url
/// - `serde_json::Value` → JSON
///
/// # Generated Methods
/// - `graphql_schema() -> Schema` - async-graphql Schema
/// - `graphql_router() -> axum::Router` - Router with /graphql endpoint
/// - `graphql_sdl() -> String` - Schema Definition Language string
#[cfg(feature = "graphql")]
#[proc_macro_attribute]
pub fn graphql(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as graphql::GraphqlArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match graphql::expand_graphql(args, impl_block) {
        Ok(tokens) => {
            debug_emit("graphql", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Define a GraphQL enum type.
///
/// Generates a GraphQL Enum type definition from a Rust enum.
/// Only unit variants (no fields) are supported.
///
/// # Example
///
/// ```ignore
/// use server_less::graphql_enum;
///
/// #[graphql_enum]
/// #[derive(Clone, Debug)]
/// enum Status {
///     /// User is active
///     Active,
///     /// User is inactive
///     Inactive,
///     /// Awaiting approval
///     Pending,
/// }
///
/// // Then register with #[graphql]:
/// #[graphql(enums(Status))]
/// impl MyService {
///     pub fn get_status(&self) -> Status { Status::Active }
/// }
/// ```
///
/// # Generated Methods
///
/// - `__graphql_enum_type() -> async_graphql::dynamic::Enum` - Enum type definition
/// - `__to_graphql_value(&self) -> async_graphql::Value` - Convert to GraphQL value
///
/// # Variant Naming
///
/// Variant names are converted to SCREAMING_SNAKE_CASE for GraphQL:
/// - `Active` → `ACTIVE`
/// - `InProgress` → `IN_PROGRESS`
#[cfg(feature = "graphql")]
#[proc_macro_attribute]
pub fn graphql_enum(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let item_enum = parse_macro_input!(item as ItemEnum);
    let name = item_enum.ident.to_string();

    match graphql_enum::expand_graphql_enum(item_enum) {
        Ok(tokens) => {
            debug_emit("graphql_enum", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Define a GraphQL input type.
///
/// Generates a GraphQL InputObject type definition from a Rust struct.
/// The struct must implement `serde::Deserialize` for input parsing.
///
/// # Example
///
/// ```ignore
/// use server_less::graphql_input;
/// use serde::Deserialize;
///
/// #[graphql_input]
/// #[derive(Clone, Debug, Deserialize)]
/// struct CreateUserInput {
///     /// User's name
///     name: String,
///     /// User's email address
///     email: String,
///     /// Optional age
///     age: Option<i32>,
/// }
///
/// // Then register with #[graphql]:
/// #[graphql(inputs(CreateUserInput))]
/// impl UserService {
///     pub fn create_user(&self, input: CreateUserInput) -> User { /* ... */ }
/// }
/// ```
///
/// # Generated Methods
///
/// - `__graphql_input_type() -> async_graphql::dynamic::InputObject` - Input type definition
/// - `__from_graphql_value(value) -> Result<Self, String>` - Parse from GraphQL value
///
/// # Field Naming
///
/// Field names are converted to camelCase for GraphQL:
/// - `user_name` → `userName`
/// - `email_address` → `emailAddress`
#[cfg(feature = "graphql")]
#[proc_macro_attribute]
pub fn graphql_input(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let item_struct = parse_macro_input!(item as ItemStruct);
    let name = item_struct.ident.to_string();

    match graphql_input::expand_graphql_input(item_struct) {
        Ok(tokens) => {
            debug_emit("graphql_input", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Coordinate multiple protocol handlers into a single server.
///
/// # Example
///
/// ```ignore
/// use server_less::{http, ws, jsonrpc, serve};
///
/// struct MyService;
///
/// #[http]
/// #[ws]
/// #[jsonrpc]
/// #[serve(http, ws, jsonrpc)]
/// impl MyService {
///     fn list_items(&self) -> Vec<String> { vec![] }
/// }
///
/// // Now you can:
/// // - service.serve("0.0.0.0:3000").await  // start server
/// // - service.router()                     // get combined router
/// ```
///
/// # Arguments
///
/// - `http` - Include the HTTP router (REST API)
/// - `ws` - Include the WebSocket router (WS JSON-RPC)
/// - `jsonrpc` - Include the JSON-RPC HTTP router
/// - `graphql` - Include the GraphQL router
/// - `health = "/path"` - Custom health check path (default: `/health`)
#[cfg(feature = "http")]
#[proc_macro_attribute]
pub fn serve(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as http::ServeArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match http::expand_serve(args, impl_block) {
        Ok(tokens) => {
            debug_emit("serve", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Helper attribute for method-level HTTP route customization.
///
/// This attribute is used within `#[http]` impl blocks to customize
/// individual method routing. It is a no-op on its own.
///
/// # Example
///
/// ```ignore
/// #[http(prefix = "/api")]
/// impl MyService {
///     #[route(method = "POST", path = "/custom")]
///     fn my_method(&self) { }
///
///     #[route(skip)]
///     fn internal_method(&self) { }
///
///     #[route(hidden)]  // Hidden from OpenAPI but still routed
///     fn secret(&self) { }
/// }
/// ```
#[cfg(feature = "http")]
#[proc_macro_attribute]
pub fn route(_attr: TokenStream, item: TokenStream) -> TokenStream {
    // Pass through unchanged - the #[http] macro parses these attributes
    item
}

/// Helper attribute for method-level HTTP response customization.
///
/// This attribute is used within `#[http]` impl blocks to customize
/// individual method responses. It is a no-op on its own.
///
/// # Supported Options
///
/// - `status = <code>` - Custom HTTP status code (e.g., 201, 204)
/// - `content_type = "<type>"` - Custom content type
/// - `header = "<name>", value = "<value>"` - Add custom response header
///
/// Multiple `#[response(...)]` attributes can be combined on a single method.
///
/// # Examples
///
/// ```ignore
/// #[http(prefix = "/api")]
/// impl MyService {
///     // Custom status code for creation
///     #[response(status = 201)]
///     fn create_item(&self, name: String) -> Item { /* ... */ }
///
///     // No content response
///     #[response(status = 204)]
///     fn delete_item(&self, id: String) { /* ... */ }
///
///     // Binary response with custom content type
///     #[response(content_type = "application/octet-stream")]
///     fn download(&self, id: String) -> Vec<u8> { /* ... */ }
///
///     // Add custom headers
///     #[response(header = "X-Custom", value = "foo")]
///     fn with_header(&self) -> String { /* ... */ }
///
///     // Combine multiple response attributes
///     #[response(status = 201)]
///     #[response(header = "Location", value = "/api/items/123")]
///     #[response(header = "X-Request-Id", value = "abc")]
///     fn create_with_headers(&self, name: String) -> Item { /* ... */ }
/// }
/// ```
#[cfg(feature = "http")]
#[proc_macro_attribute]
pub fn response(_attr: TokenStream, item: TokenStream) -> TokenStream {
    // Pass through unchanged - the #[http] macro parses these attributes
    item
}

/// Helper attribute for parameter-level HTTP customization.
///
/// This attribute is used on function parameters within `#[http]` impl blocks
/// to customize parameter extraction and naming. It is a no-op on its own.
///
/// **Note:** Requires nightly Rust with `#![feature(register_tool)]` and
/// `#![register_tool(param)]` at the crate root.
///
/// # Supported Options
///
/// - `name = "<wire_name>"` - Use a different name on the wire (e.g., `q` instead of `query`)
/// - `default = <value>` - Provide a default value for optional parameters
/// - `query` - Force parameter to come from query string
/// - `path` - Force parameter to come from URL path
/// - `body` - Force parameter to come from request body
/// - `header` - Extract parameter from HTTP header
///
/// # Location Inference
///
/// When no location is specified, parameters are inferred based on conventions:
/// - Parameters named `id` or ending in `_id` → path parameters
/// - POST/PUT/PATCH methods → body parameters
/// - GET/DELETE methods → query parameters
///
/// # Examples
///
/// ```ignore
/// #![feature(register_tool)]
/// #![register_tool(param)]
///
/// #[http(prefix = "/api")]
/// impl SearchService {
///     // Rename parameter: code uses `query`, API accepts `q`
///     fn search(&self, #[param(name = "q")] query: String) -> Vec<Result> {
///         /* ... */
///     }
///
///     // Default value for pagination
///     fn list_items(
///         &self,
///         #[param(default = 0)] offset: u32,
///         #[param(default = 10)] limit: u32,
///     ) -> Vec<Item> {
///         /* ... */
///     }
///
///     // Extract API key from header
///     fn protected_endpoint(
///         &self,
///         #[param(header, name = "X-API-Key")] api_key: String,
///         data: String,
///     ) -> String {
///         /* ... */
///     }
///
///     // Override location inference: force to query even though method is POST
///     fn search_posts(
///         &self,
///         #[param(query)] filter: String,
///         #[param(body)] content: String,
///     ) -> Vec<Post> {
///         /* ... */
///     }
///
///     // Combine multiple options
///     fn advanced(
///         &self,
///         #[param(query, name = "page", default = 1)] page_num: u32,
///     ) -> Vec<Item> {
///         /* ... */
///     }
/// }
/// ```
///
/// # OpenAPI Integration
///
/// - Parameters with `name` are documented with their wire names
/// - Parameters with `default` are marked as not required
/// - Location overrides are reflected in OpenAPI specs
#[cfg(feature = "http")]
#[proc_macro_attribute]
pub fn param(_attr: TokenStream, item: TokenStream) -> TokenStream {
    // Pass through unchanged - the #[http] macro parses these attributes
    item
}

// ============================================================================
// Blessed Presets
// ============================================================================

/// Blessed preset: HTTP server with OpenAPI and serve.
///
/// Combines `#[http]` + `#[serve(http)]` into a single attribute.
///
/// # Example
///
/// ```ignore
/// use server_less::server;
///
/// #[derive(Clone)]
/// struct MyApi;
///
/// #[server]
/// impl MyApi {
///     pub fn list_items(&self) -> Vec<String> { vec![] }
///     pub fn create_item(&self, name: String) -> String { name }
/// }
///
/// // Equivalent to:
/// // #[http]
/// // #[serve(http)]
/// // impl MyApi { ... }
/// ```
///
/// # Options
///
/// - `prefix` - URL prefix (e.g., `#[server(prefix = "/api")]`)
/// - `openapi` - Toggle OpenAPI generation (default: true)
/// - `health` - Custom health check path (default: `/health`)
/// - `config` - Config struct type for config subcommand wiring (e.g., `#[server(config = MyConfig)]`)
/// - `config_cmd` - Config subcommand name override or `false` to disable (default: `"config"`)
/// - `name` - App name (forwarded from `#[app]`; default: kebab-case struct name)
/// - `description` - App description for CLI help and OpenAPI info
/// - `version` - Version string; `false` disables `--version` (default: `CARGO_PKG_VERSION`)
/// - `homepage` - URL used in OpenAPI and OpenRPC info fields
#[cfg(feature = "http")]
#[proc_macro_attribute]
pub fn server(attr: TokenStream, item: TokenStream) -> TokenStream {
    // When applied to a method inside an impl block (e.g. `#[server(skip)]`),
    // pass through unchanged.  The enclosing protocol macro reads these
    // attributes from the ItemImpl tokens; `#[server]` just needs to not error.
    let item2: proc_macro2::TokenStream = item.clone().into();
    if syn::parse2::<ItemImpl>(item2).is_err() {
        return item;
    }
    let args = parse_macro_input!(attr as server::ServerArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match server::expand_server(args, impl_block) {
        Ok(tokens) => {
            debug_emit("server", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Blessed preset: JSON-RPC server with OpenRPC spec and serve.
///
/// Combines `#[jsonrpc]` + `#[openrpc]` + `#[serve(jsonrpc)]` into a single attribute.
/// OpenRPC and serve are included when their features are enabled, and gracefully
/// omitted otherwise.
///
/// # Example
///
/// ```ignore
/// use server_less::rpc;
///
/// #[derive(Clone)]
/// struct Calculator;
///
/// #[rpc]
/// impl Calculator {
///     pub fn add(&self, a: i32, b: i32) -> i32 { a + b }
///     pub fn multiply(&self, a: i32, b: i32) -> i32 { a * b }
/// }
/// ```
///
/// # Options
///
/// - `path` - JSON-RPC endpoint path (e.g., `#[rpc(path = "/api")]`)
/// - `openrpc` - Toggle OpenRPC spec generation (default: true)
/// - `health` - Custom health check path (default: `/health`)
#[cfg(feature = "jsonrpc")]
#[proc_macro_attribute]
pub fn rpc(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as rpc_preset::RpcArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match rpc_preset::expand_rpc(args, impl_block) {
        Ok(tokens) => {
            debug_emit("rpc", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Blessed preset: MCP tools with JSON Schema.
///
/// Combines `#[mcp]` + `#[jsonschema]` into a single attribute.
/// JSON Schema is included when the feature is enabled, and gracefully
/// omitted otherwise.
///
/// # Example
///
/// ```ignore
/// use server_less::tool;
///
/// struct FileTools;
///
/// #[tool(namespace = "file")]
/// impl FileTools {
///     pub fn read_file(&self, path: String) -> String { String::new() }
///     pub fn write_file(&self, path: String, content: String) -> bool { true }
/// }
/// ```
///
/// # Options
///
/// - `namespace` - MCP tool namespace prefix
/// - `jsonschema` - Toggle JSON Schema generation (default: true)
#[cfg(feature = "mcp")]
#[proc_macro_attribute]
pub fn tool(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as tool::ToolArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match tool::expand_tool(args, impl_block) {
        Ok(tokens) => {
            debug_emit("tool", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Blessed preset: CLI application with Markdown docs.
///
/// Combines `#[cli]` + `#[markdown]` into a single attribute.
/// Markdown docs are included when the feature is enabled, and gracefully
/// omitted otherwise.
///
/// Named `program` instead of `cli` to avoid collision with the existing
/// `#[cli]` attribute macro.
///
/// # Example
///
/// ```ignore
/// use server_less::program;
///
/// struct MyApp;
///
/// #[program(name = "myctl", version = "1.0.0")]
/// impl MyApp {
///     pub fn create_user(&self, name: String) { println!("Created {}", name); }
///     pub fn list_users(&self) { println!("Listing users..."); }
/// }
/// ```
///
/// # Options
///
/// - `name` - CLI application name
/// - `version` - CLI version string
/// - `about` - CLI description
/// - `markdown` - Toggle Markdown docs generation (default: true)
#[cfg(feature = "cli")]
#[proc_macro_attribute]
pub fn program(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = parse_macro_input!(attr as program::ProgramArgs);
    let impl_block = parse_macro_input!(item as ItemImpl);
    let name = type_name(&impl_block.self_ty);

    match program::expand_program(args, impl_block) {
        Ok(tokens) => {
            debug_emit("program", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Derive macro for error types that implement `IntoErrorCode`.
///
/// # Example
///
/// ```ignore
/// use server_less::ServerlessError;
///
/// #[derive(ServerlessError)]
/// enum MyError {
///     #[error(code = NotFound, message = "User not found")]
///     UserNotFound,
///     #[error(code = 400)]  // HTTP status also works
///     InvalidInput(String),
///     // Code inferred from variant name
///     Unauthorized,
/// }
/// ```
///
/// This generates:
/// - `impl IntoErrorCode for MyError`
/// - `impl Display for MyError`
/// - `impl Error for MyError`
///
/// # Attributes
///
/// - `#[error(code = X)]` - Set error code (ErrorCode variant or HTTP status)
/// - `#[error(message = "...")]` - Set custom message
///
/// Without attributes, the error code is inferred from the variant name.
#[proc_macro_derive(ServerlessError, attributes(error))]
pub fn serverless_error(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let name = input.ident.to_string();

    match error::expand_serverless_error(input) {
        Ok(tokens) => {
            debug_emit("ServerlessError", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}

/// Attach protocol-neutral application metadata to an impl block.
///
/// `#[app]` is consumed by all protocol macros on the same impl block
/// (`#[server]`, `#[cli]`, `#[http]`, `#[program]`, etc.).  It does not
/// generate code itself — it passes metadata downstream via an internal
/// `#[__app_meta]` helper attribute that the consuming macro removes.
///
/// # Fields
///
/// | Field | Default | Effect |
/// |-------|---------|--------|
/// | `name` | inferred from struct name (kebab-case) | App name used in config file path, CLI header, spec titles |
/// | `description` | none | Human-readable description for CLI `--help`, OpenAPI info, etc. |
/// | `version` | `env!("CARGO_PKG_VERSION")` | Version string; powers `--version`; `false` disables version entirely |
/// | `homepage` | none | URL used in OpenAPI `info.contact.url`, OpenRPC info, etc. |
///
/// # Example
///
/// ```ignore
/// #[app(
///     name = "myapp",
///     description = "Does the thing",
///     version = "2.1.0",
///     homepage = "https://myapp.example.com",
/// )]
/// #[server]
/// impl MyApi {
///     fn list_items(&self) -> Vec<Item> { ... }
/// }
/// ```
///
/// All preset macros also accept these fields inline as a shorthand:
///
/// ```ignore
/// #[server(name = "myapp", description = "Does the thing")]
/// impl MyApi { ... }
/// ```
#[proc_macro_attribute]
pub fn app(args: TokenStream, item: TokenStream) -> TokenStream {
    let args = proc_macro2::TokenStream::from(args);
    let input = parse_macro_input!(item as ItemImpl);
    match app::expand_app(args, input) {
        Ok(tokens) => tokens.into(),
        Err(err) => err.to_compile_error().into(),
    }
}

/// Internal helper attribute — do not use directly.
///
/// `#[__app_meta]` is injected by `#[app]` and consumed by downstream
/// protocol macros.  If it reaches the final compile step unconsumed
/// (e.g. you wrote `#[app(...)]` without any protocol macro), it is a
/// no-op that strips itself from the item.
#[proc_macro_attribute]
pub fn __app_meta(args: TokenStream, item: TokenStream) -> TokenStream {
    let args = proc_macro2::TokenStream::from(args);
    let input = parse_macro_input!(item as ItemImpl);
    app::expand_app_meta_passthrough(args, input).into()
}

/// Derive config loading from multiple sources for a struct.
///
/// `#[derive(Config)]` generates a [`server_less_core::config::Config`]
/// implementation that loads values from defaults, TOML files, and environment
/// variables, with a configurable precedence order.
///
/// # Example
///
/// ```rust,ignore
/// use server_less::Config;
///
/// #[derive(Config)]
/// struct AppConfig {
///     #[param(default = "localhost")]
///     host: String,
///     #[param(default = 8080)]
///     port: u16,
///     #[param(env = "DATABASE_URL")]
///     database_url: String,
///     timeout_secs: Option<u64>,
/// }
///
/// let cfg = AppConfig::load(&[
///     ConfigSource::Defaults,
///     ConfigSource::File("app.toml".into()),
///     ConfigSource::Env { prefix: Some("APP".into()) },
/// ])?;
/// ```
///
/// # Field attributes
///
/// - `#[param(default = value)]` — compile-time default; field becomes optional in sources
/// - `#[param(env = "VAR")]` — exact env var name (overrides `{PREFIX}_{FIELD}` generation)
/// - `#[param(file_key = "a.b.c")]` — dotted TOML key override (default: field name)
/// - `#[param(help = "...")]` — description used by `config show --schema` and doc generators
#[cfg(feature = "config")]
#[proc_macro_derive(Config, attributes(param))]
pub fn derive_config(input: TokenStream) -> TokenStream {
    let input = parse_macro_input!(input as DeriveInput);
    let name = input.ident.to_string();
    match config_derive::expand_config(input) {
        Ok(tokens) => {
            debug_emit("Config", &name, &tokens);
            tokens.into()
        }
        Err(err) => err.to_compile_error().into(),
    }
}