rust-webx-macros 0.6.0

use proc_macro::TokenStream;
use quote::{format_ident, quote};
use syn::{
    parse::{Parse, ParseStream},
    parse_macro_input,
    punctuated::Punctuated,
    Attribute, Expr, GenericArgument, ItemImpl, Lit, LitStr, Meta, PathArguments, Token, Type,
};

// =====================================================================
// Generic #[endpoint(HttpMethod, "/path")] — full form
// =====================================================================

pub fn endpoint_impl(attr: TokenStream, item: TokenStream) -> TokenStream {
    emit_endpoint(attr, item)
}

// =====================================================================
// Shortcut macros: #[get("/path")], #[post("/path")], etc.
// =====================================================================

pub fn shortcut_get(attr: TokenStream, item: TokenStream) -> TokenStream {
    let path = parse_shortcut_attr(&attr.to_string());
    let attr_str = format!("Get, \"{}\"", path);
    emit_endpoint(attr_str.parse().unwrap(), item)
}

pub fn shortcut_post(attr: TokenStream, item: TokenStream) -> TokenStream {
    let path = parse_shortcut_attr(&attr.to_string());
    let attr_str = format!("Post, \"{}\"", path);
    emit_endpoint(attr_str.parse().unwrap(), item)
}

pub fn shortcut_put(attr: TokenStream, item: TokenStream) -> TokenStream {
    let path = parse_shortcut_attr(&attr.to_string());
    let attr_str = format!("Put, \"{}\"", path);
    emit_endpoint(attr_str.parse().unwrap(), item)
}

pub fn shortcut_delete(attr: TokenStream, item: TokenStream) -> TokenStream {
    let path = parse_shortcut_attr(&attr.to_string());
    let attr_str = format!("Delete, \"{}\"", path);
    emit_endpoint(attr_str.parse().unwrap(), item)
}

// =====================================================================
// Internal helpers
// =====================================================================

fn parse_shortcut_attr(attr: &str) -> String {
    let s = attr.trim();
    if s.is_empty() {
        "/".to_string()
    } else {
        s.trim_matches('"').trim_matches('\'').to_string()
    }
}

/// Generate a RouteEntry AND a RouteDispatch from an `impl IRequest<Response> for Name` block.
fn emit_endpoint(attr: TokenStream, item: TokenStream) -> TokenStream {
    let item_impl = parse_macro_input!(item as ItemImpl);
    let (method_str, path_str) = parse_endpoint_attr(&attr.to_string());
    match expand_endpoint(&method_str, &path_str, &item_impl) {
        Ok(tokens) => tokens,
        Err(error) => error.to_compile_error().into(),
    }
}

fn expand_endpoint(
    method_str: &str,
    path_str: &str,
    item_impl: &ItemImpl,
) -> syn::Result<TokenStream> {
    let self_ty = &item_impl.self_ty;
    let req_type_name = extract_type_name(self_ty);
    let method_ident = format_ident!("{}", method_str);

    let rsp_type_str = extract_response_type(item_impl).unwrap_or_else(|| "()".to_string());

    // Text priority: `#[display]` / `#[description]` first, then the impl
    // block's `///` doc comment. The doc's first line is the name, the full
    // comment the description.
    let doc = extract_doc_comments(&item_impl.attrs);
    let name = localized_name(&item_impl.attrs, &doc, &req_type_name)?;
    let description = localized_description(&item_impl.attrs, &doc)?;
    let category = localized_category(&item_impl.attrs)?;
    let authorization = extract_authorization(&item_impl.attrs)?;

    // Parse response type back to a Type for use in generated code
    let rsp_type: syn::Type =
        syn::parse_str(&rsp_type_str).unwrap_or_else(|_| syn::parse_str("()").unwrap());

    // Parameter metadata for OpenAPI
    let mut params_tokens: Vec<proc_macro2::TokenStream> = extract_path_params(path_str)
        .into_iter()
        .map(|name| {
            quote! {
                ::webx::ParamMeta {
                    name: #name,
                    source: "path",
                    type_hint: "string",
                }
            }
        })
        .collect();

    let is_body_method = method_str == "Post" || method_str == "Put" || method_str == "Patch";
    if is_body_method {
        params_tokens.push(quote! {
            ::webx::ParamMeta {
                name: "body",
                source: "body",
                type_hint: "object",
            }
        });
    }

    // Generate FromHttpContext impl for the request type
    let path_params: Vec<String> = extract_path_params(path_str);

    // Generate dispatch function
    let is_raw_response = is_response_data(&rsp_type_str);
    let dispatch_fn = generate_dispatch_fn(
        self_ty,
        &rsp_type,
        &req_type_name,
        &path_params,
        is_body_method,
        rsp_type_str == "()",
        is_raw_response,
    );

    let dispatch_fn_name = format_ident!("__lrwf_dispatch_{}", req_type_name.replace("::", "_"));

    let expanded = quote! {
        #item_impl

        #dispatch_fn

        ::inventory::submit! {
            ::webx::RouteDispatch {
                handler_type: #req_type_name,
                dispatch: #dispatch_fn_name,
            }
        }

        ::inventory::submit! {
            ::webx::RouteEntry::new(
                ::webx::HttpMethod::#method_ident,
                #path_str,
                #req_type_name,
                #rsp_type_str,
                #name,
                #description,
                #category,
                &[#(#params_tokens),*],
                #authorization,
            )
        }
    };

    Ok(expanded.into())
}

/// Generate the dispatch function that runs the full request lifecycle.
///
/// The function receives the live [`IHttpContext`], so it can:
///
/// * bind a `multipart/form-data` body — including uploaded files — through
///   `bind_form_request`, which streams the body rather than buffering it;
/// * fall back to JSON body or route/query parameter binding;
/// * forward authentication claims to the handler.
///
/// When the response type is `ResponseData` the handler's value is used as the
/// response verbatim, which is how an endpoint streams a file or sets custom
/// headers. Otherwise the value is serialized as JSON.
fn generate_dispatch_fn(
    ty: &Type,
    rsp_type: &syn::Type,
    type_name: &str,
    path_params: &[String],
    is_body: bool,
    is_unit_response: bool,
    is_raw_response: bool,
) -> proc_macro2::TokenStream {
    let fn_name = format_ident!("__lrwf_dispatch_{}", type_name.replace("::", "_"));

    // Generate request construction code for the non-multipart path.
    let build_request = if is_body && !path_params.is_empty() {
        let overrides: Vec<proc_macro2::TokenStream> = path_params
            .iter()
            .map(|name| {
                let ident = format_ident!("{}", name);
                let name_str = name.as_str();
                quote! {
                    #ident: route_params.get(#name_str).cloned().unwrap_or(req.#ident),
                }
            })
            .collect();
        quote! {{
            let mut req: #ty = ::serde_json::from_slice(&body_bytes)
                .map_err(|e| ::webx::Error::Serialization(e))?;
            req = #ty { #(#overrides)* ..req };
            req
        }}
    } else if is_body {
        quote! {
            ::serde_json::from_slice(&body_bytes).map_err(|e| ::webx::Error::Serialization(e))?
        }
    } else if !path_params.is_empty() {
        let field_assignments: Vec<proc_macro2::TokenStream> = path_params
            .iter()
            .map(|name| {
                let ident = format_ident!("{}", name);
                let name_str = name.as_str();
                quote! {
                    #ident: route_params.get(#name_str).cloned().unwrap_or_default()
                }
            })
            .collect();
        quote! {
            {
                if let Some(req) = ::webx::try_deserialize_from_params::<#ty>(
                    &route_params,
                    &_query_params,
                ) {
                    req
                } else {
                    #ty { #(#field_assignments,)* ..::std::default::Default::default() }
                }
            }
        }
    } else {
        quote! {
            {
                if let Some(req) = ::webx::try_deserialize_from_params::<#ty>(
                    &route_params,
                    &_query_params,
                ) {
                    req
                } else {
                    <#ty as ::std::default::Default>::default()
                }
            }
        }
    };

    let response_expr = if is_raw_response {
        quote! { ::std::result::Result::Ok(result) }
    } else if is_unit_response {
        quote! { ::std::result::Result::Ok(::webx::ResponseData::no_content()) }
    } else {
        quote! { ::webx::ResponseData::json(&result) }
    };

    quote! {
        #[allow(clippy::needless_update)]
        fn #fn_name<'__webx_dispatch>(
            ctx: &'__webx_dispatch mut dyn ::webx::IHttpContext,
        ) -> ::std::pin::Pin<
            Box<
                dyn ::std::future::Future<
                        Output = ::webx::Result<::webx::ResponseData>,
                    > + Send
                    + '__webx_dispatch,
            >,
        > {
            Box::pin(async move {
                // A multipart body must be bound before anything else touches it,
                // because binding consumes the live request stream.
                let bound: ::std::option::Option<#ty> =
                    ::webx::bind_form_request::<#ty>(&mut *ctx).await?;

                let mut request: #ty = match bound {
                    ::std::option::Option::Some(request) => request,
                    ::std::option::Option::None => {
                        #[allow(unused_variables)]
                        let route_params = ctx.request().route_params().clone();
                        #[allow(unused_variables)]
                        let _query_params = ctx.request().query().clone();
                        #[allow(unused_variables)]
                        let body_bytes: Vec<u8> = if #is_body {
                            ctx.request_mut().body_bytes().await?
                        } else {
                            Vec::new()
                        };
                        #build_request
                    }
                };

                let claims: ::std::option::Option<Box<dyn ::webx::IClaims>> =
                    ctx.claims().map(|c| c.clone_box());
                let operator_id = claims.as_ref().map(|c| c.subject().to_string());

                // Inject claims into the request *before* dispatch (no-op if the
                // request type has no inherent `set_claims`).
                {
                    use ::webx::IClaimsCarrier;
                    request.set_claims(claims);
                }

                ::webx::RequestContext::run(operator_id, async move {
                    // HTTP adapter: construct request, then dispatch via IMediator
                    // (same path as in-process calls).
                    let mediator = ::webx::Mediator::new(::webx::dispatch_provider());
                    let result: #rsp_type = mediator.send(request).await?;
                    #response_expr
                })
                .await
            })
        }
    }
}

/// Whether the declared response type is the framework's raw response envelope.
///
/// Matches `ResponseData` and any qualified path ending in `ResponseData`, so
/// `webx::ResponseData` and `::webx::ResponseData` both work.
fn is_response_data(rsp_type: &str) -> bool {
    rsp_type
        .rsplit("::")
        .next()
        .map(|segment| segment.trim() == "ResponseData")
        .unwrap_or(false)
}

/// Extract the response type from `impl IRequest<UserModel> for GetUserRequest`.
///
/// ItemImpl::trait_ is `Option<(T![!], Path, T![for])>`.
/// We reach the Path (index 1) and examine its first generic argument.
fn extract_response_type(item_impl: &ItemImpl) -> Option<String> {
    let (_bang, path, _for_token) = item_impl.trait_.as_ref()?;
    let last_seg = path.segments.last()?;
    match &last_seg.arguments {
        PathArguments::AngleBracketed(args) => {
            let gen_arg = args.args.first()?;
            match gen_arg {
                GenericArgument::Type(ty) => Some(type_to_string(ty)),
                _ => None,
            }
        }
        _ => None,
    }
}

fn type_to_string(ty: &Type) -> String {
    match ty {
        Type::Path(tp) => {
            let mut result = String::new();
            let segments: Vec<String> = tp
                .path
                .segments
                .iter()
                .map(|s| s.ident.to_string())
                .collect();
            result.push_str(&segments.join("::"));

            // Handle generic type arguments (e.g., Vec<UserModel>)
            if let Some(last_seg) = tp.path.segments.last() {
                if let PathArguments::AngleBracketed(args) = &last_seg.arguments {
                    let gen_args: Vec<String> = args
                        .args
                        .iter()
                        .filter_map(|a| match a {
                            GenericArgument::Type(t) => Some(type_to_string(t)),
                            _ => None,
                        })
                        .collect();
                    if !gen_args.is_empty() {
                        result.push('<');
                        result.push_str(&gen_args.join(", "));
                        result.push('>');
                    }
                }
            }

            result
        }
        Type::Tuple(t) if t.elems.is_empty() => "()".to_string(),
        Type::Reference(r) => {
            format!("&{}", type_to_string(&r.elem))
        }
        _ => format!("{}", quote! { #ty }),
    }
}

fn map_method_name(attr_name: &str) -> &str {
    match attr_name {
        "HttpGet" | "http_get" => "Get",
        "HttpPost" | "http_post" => "Post",
        "HttpPut" | "http_put" => "Put",
        "HttpDelete" | "http_delete" => "Delete",
        "HttpPatch" | "http_patch" => "Patch",
        other => other,
    }
}

fn parse_endpoint_attr(attr: &str) -> (String, String) {
    let s = attr.trim();
    if let Some(idx) = s.find(',') {
        let raw_method = s[..idx].trim();
        let method = map_method_name(raw_method).to_string();
        let path = s[idx + 1..]
            .trim()
            .trim_matches('"')
            .trim_matches('\'')
            .to_string();
        (method, path)
    } else {
        ("Get".to_string(), "/".to_string())
    }
}

fn extract_type_name(ty: &Type) -> String {
    match ty {
        Type::Path(type_path) => type_path
            .path
            .segments
            .iter()
            .map(|seg| seg.ident.to_string())
            .collect::<Vec<_>>()
            .join("::"),
        _ => "UnknownType".to_string(),
    }
}

/// Extract path parameter names from a route pattern like "/users/{id}".
///
/// Wildcard segments `{*rest}` yield the field name `rest` (asterisk stripped),
/// matching matchit's param key and the docs convention.
fn extract_path_params(path: &str) -> Vec<String> {
    let mut params = Vec::new();
    let bytes = path.as_bytes();
    let mut i = 0;
    while i < bytes.len() {
        if bytes[i] == b'{' {
            let start = i + 1;
            i += 1;
            while i < bytes.len() && bytes[i] != b'}' {
                i += 1;
            }
            if i < bytes.len() {
                let name = path[start..i].trim_start_matches('*');
                if !name.is_empty() {
                    params.push(name.to_string());
                }
            }
        }
        i = i.saturating_add(1);
    }
    params
}

/// Generate a fallback name when the endpoint has neither `#[display]` nor a
/// doc comment. "GetUserRequest" → "Get user", "ListUsersRequest" → "List users".
fn generate_name(type_name: &str) -> String {
    let name = type_name.strip_suffix("Request").unwrap_or(type_name);
    let mut result = String::new();
    for c in name.chars() {
        if c.is_ascii_uppercase() && !result.is_empty() {
            result.push(' ');
        }
        result.push(c.to_ascii_lowercase());
    }
    result
}

/// One `#[display]` / `#[description]` declaration: a resource key and/or a
/// literal text.
#[derive(Default)]
struct TextAttr {
    key: String,
    text: String,
}

impl Parse for TextAttr {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        if input.is_empty() {
            return Err(syn::Error::new(
                proc_macro2::Span::call_site(),
                "expected a string, `key = \"...\"`, or `text = \"...\"`",
            ));
        }

        let mut value = Self::default();

        // Positional form: `#[display("literal")]`.
        if input.peek(LitStr) {
            let text: LitStr = input.parse()?;
            value.text = text.value();
            if input.peek(Token![,]) {
                input.parse::<Token![,]>()?;
            }
        }

        // Named form: `key = "..."` / `text = "..."`.
        while !input.is_empty() {
            let name: syn::Ident = input.parse()?;
            input.parse::<Token![=]>()?;
            let lit: LitStr = input.parse()?;
            match name.to_string().as_str() {
                "key" => {
                    if !value.key.is_empty() {
                        return Err(syn::Error::new(name.span(), "duplicate `key`"));
                    }
                    value.key = lit.value();
                }
                "text" => {
                    if !value.text.is_empty() {
                        return Err(syn::Error::new(name.span(), "duplicate `text`"));
                    }
                    value.text = lit.value();
                }
                other => {
                    return Err(syn::Error::new(
                        name.span(),
                        format!("unknown key `{other}`; expected `key` or `text`"),
                    ))
                }
            }
            if input.peek(Token![,]) {
                input.parse::<Token![,]>()?;
            }
        }

        Ok(value)
    }
}

/// Parse the single `#[display]` / `#[description]` declaration on the impl.
///
/// Localized text is a resource lookup, not a set of per-language attributes:
/// declare the key once and keep translations in resource files.
fn text_attr(attrs: &[Attribute], names: &[&str]) -> syn::Result<Option<TextAttr>> {
    let attr_name = names.first().copied().unwrap_or("display");
    let mut found = None;
    for attr in attrs {
        let matches = attr
            .path()
            .segments
            .last()
            .map(|segment| names.iter().any(|name| segment.ident == *name))
            .unwrap_or(false);
        if !matches {
            continue;
        }
        if found.is_some() {
            return Err(syn::Error::new_spanned(
                attr,
                format!(
                    "declare `#[{attr_name}]` at most once; use `key` + `text`, \
                     not one attribute per language"
                ),
            ));
        }
        found = Some(match &attr.meta {
            Meta::List(list) => syn::parse2::<TextAttr>(list.tokens.clone())?,
            Meta::NameValue(meta) => match &meta.value {
                Expr::Lit(expr) => match &expr.lit {
                    Lit::Str(text) => TextAttr {
                        key: String::new(),
                        text: text.value(),
                    },
                    _ => {
                        return Err(syn::Error::new_spanned(
                            expr,
                            format!("`#[{attr_name}]` expects a string or `key = \"...\"`"),
                        ))
                    }
                },
                _ => {
                    return Err(syn::Error::new_spanned(
                        meta,
                        format!("`#[{attr_name}]` expects a string or `key = \"...\"`"),
                    ))
                }
            },
            Meta::Path(path) => {
                return Err(syn::Error::new_spanned(
                    path,
                    format!("`#[{attr_name}]` expects a string or `key = \"...\"`"),
                ))
            }
        });
    }
    Ok(found)
}

/// Render a `TextRef` literal for the generated code.
fn text_ref_tokens(key: String, text: String) -> proc_macro2::TokenStream {
    quote! {
        ::webx::TextRef {
            key: #key,
            text: #text,
        }
    }
}

fn localized_name(
    attrs: &[Attribute],
    doc: &str,
    req_type_name: &str,
) -> syn::Result<proc_macro2::TokenStream> {
    let (key, text) = match text_attr(attrs, &["display", "__webx_display"])? {
        // `#[display]` was declared: its `text` is the only literal fallback.
        Some(attr) => (attr.key, attr.text),
        None => (
            String::new(),
            doc_first_line(doc).unwrap_or_else(|| generate_name(req_type_name)),
        ),
    };
    Ok(text_ref_tokens(key, text))
}

fn localized_description(attrs: &[Attribute], doc: &str) -> syn::Result<proc_macro2::TokenStream> {
    let (key, text) = match text_attr(attrs, &["description", "__webx_description"])? {
        Some(attr) => (attr.key, attr.text),
        None => (String::new(), doc.to_string()),
    };
    Ok(text_ref_tokens(key, text))
}

fn localized_category(attrs: &[Attribute]) -> syn::Result<proc_macro2::TokenStream> {
    let (key, text) = match text_attr(attrs, &["category", "__webx_category"])? {
        Some(attr) => (attr.key, attr.text),
        None => (String::new(), String::new()),
    };
    Ok(text_ref_tokens(key, text))
}

/// The first non-empty line of the doc comment — the endpoint name fallback.
fn doc_first_line(doc: &str) -> Option<String> {
    doc.lines()
        .map(str::trim)
        .find(|line| !line.is_empty())
        .map(str::to_string)
}

// ---------------------------------------------------------------------------
// Authorization rules
// ---------------------------------------------------------------------------

#[derive(Default)]
struct AuthorizeArgs {
    roles: Vec<String>,
    permissions: Vec<String>,
}

impl Parse for AuthorizeArgs {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        let mut args = Self::default();
        while !input.is_empty() {
            let key: syn::Ident = input.parse()?;
            input.parse::<Token![=]>()?;
            match key.to_string().as_str() {
                "role" | "roles" => parse_string_list(input, &mut args.roles)?,
                "permission" | "permissions" => parse_string_list(input, &mut args.permissions)?,
                other => {
                    return Err(syn::Error::new(
                        key.span(),
                        format!(
                        "unknown `#[authorize]` key `{other}`; expected role(s) or permission(s)"
                    ),
                    ))
                }
            }
            if input.peek(Token![,]) {
                input.parse::<Token![,]>()?;
            }
        }
        Ok(args)
    }
}

/// A quoted string or an array of quoted strings.
fn parse_string_list(input: ParseStream, out: &mut Vec<String>) -> syn::Result<()> {
    if input.peek(syn::token::Bracket) {
        let content;
        syn::bracketed!(content in input);
        let values: Punctuated<LitStr, Token![,]> = Punctuated::parse_terminated(&content)?;
        out.extend(values.iter().map(LitStr::value));
    } else {
        let value: LitStr = input.parse()?;
        out.push(value.value());
    }
    Ok(())
}

/// Render the `&[AuthorizeRule]` literal for the generated code.
fn extract_authorization(attrs: &[Attribute]) -> syn::Result<proc_macro2::TokenStream> {
    let mut rules = Vec::new();
    for attr in attrs {
        if !attr.path().is_ident("authorize") {
            continue;
        }
        match &attr.meta {
            // Bare `#[authorize]`: any authenticated principal.
            Meta::Path(_) => rules.push(AuthorizeArgs::default()),
            Meta::List(list) => rules.push(syn::parse2::<AuthorizeArgs>(list.tokens.clone())?),
            Meta::NameValue(meta) => {
                return Err(syn::Error::new_spanned(
                    meta,
                    "use `#[authorize]` or `#[authorize(role = \"...\", permission = \"...\")]`",
                ))
            }
        }
    }

    let rendered = rules.iter().map(|rule| {
        let roles = &rule.roles;
        let permissions = &rule.permissions;
        quote! {
            ::webx::AuthorizeRule {
                roles: &[#(#roles),*],
                permissions: &[#(#permissions),*],
            }
        }
    });

    Ok(quote! { &[#(#rendered),*] })
}

/// Extract `///` doc comments from a list of attributes.
///
/// Rust converts each `///` line into a separate `#[doc = "..."]` attribute.
/// This function collects all such attributes, trims whitespace from each line,
/// and joins them with newlines so the first line can serve as the endpoint name.
///
/// Returns the joined text, or an empty string if no doc comments exist.
fn extract_doc_comments(attrs: &[Attribute]) -> String {
    let lines: Vec<String> = attrs
        .iter()
        .filter(|attr| attr.path().is_ident("doc"))
        .filter_map(|attr| match &attr.meta {
            Meta::NameValue(nv) => {
                if let Expr::Lit(el) = &nv.value {
                    if let Lit::Str(ls) = &el.lit {
                        return Some(ls.value().trim().to_string());
                    }
                }
                None
            }
            _ => None,
        })
        .collect();

    lines.join("\n")
}