cratestack-parser 0.9.3

//! Collision detection between a bespoke `procedure` name and the
//! per-model CRUD handler idents `include_server_schema!` emits into the
//! same generated axum module.
//!
//! The two idents are formed independently and were never compared:
//!
//! - procedures → `handle_{to_snake_case(procedure.name)}` and
//!   `handle_{…}_dispatch` (`cratestack-macros/src/axum/procedure.rs`,
//!   `.../transport/rpc.rs`)
//! - models → `handle_{list,create}_{pluralize(to_snake_case(model.name))}`
//!   and `handle_{get,update,delete}_{to_snake_case(model.name)}`, each
//!   with a matching `_dispatch` twin
//!   (`cratestack-macros/src/axum/model/prep.rs`,
//!   `.../axum/model/routes.rs`, `.../transport/rpc/model_dispatch.rs`)
//!
//! So `model Order` + `procedure getOrder` both generate `handle_get_order`
//! (and `handle_get_order_dispatch`). `cratestack check` reported `schema
//! OK` and the only diagnostic was a raw rustc `error[E0428]: the name
//! `handle_get_order` is defined multiple times`, which names neither the
//! procedure, nor the model, nor the fix — the same opacity
//! [`super::snake_case_collisions::validate_model_name_collisions`] was
//! added to close for `FOO_MODEL`.
//!
//! `@@internal(...)` suppression is deliberately *not* an exemption:
//! `axum/model/routes.rs` only omits the `.route(...)` registration for a
//! suppressed verb, the handler and dispatch functions themselves are
//! emitted unconditionally, so the ident collides either way.
//!
//! Like [`super::route_collisions`], this is a schema-wide parser check
//! rather than a guard inside one codegen path. The colliding idents only
//! exist on the server path (`include_embedded_schema!` ignores procedures
//! entirely; `include_client_schema!` names its methods differently), but a
//! schema shaped this way is broken for *any* server consumption, and the
//! whole point of the report is that `cratestack check` should say so
//! instead of deferring to rustc.

use std::collections::BTreeMap;

use cratestack_core::Schema;
use cratestack_core::route_naming::{pluralize, to_snake_case};

use crate::diagnostics::{SchemaError, span_error};

/// The five generated CRUD operations, as `(operation, ident stem)` pairs
/// for one model — mirroring `cratestack-macros/src/axum/model/prep.rs`'s
/// `handle_*` / `handle_*_dispatch` construction exactly. `list`/`create`
/// key off the pluralized stem (they hang off the collection route),
/// `get`/`update`/`delete` off the singular one.
fn model_handler_stems(model_name: &str) -> [(&'static str, String); 5] {
    let snake = to_snake_case(model_name);
    let plural = pluralize(&snake);
    [
        ("list", format!("list_{plural}")),
        ("create", format!("create_{plural}")),
        ("get", format!("get_{snake}")),
        ("update", format!("update_{snake}")),
        ("delete", format!("delete_{snake}")),
    ]
}

/// Reject a `procedure` whose generated axum handler ident is already
/// taken by a model's generated CRUD handler, naming the procedure, the
/// model, the operation, the shared ident, and the fix.
///
/// Both of a procedure's generated idents are checked against both of each
/// model's — so `procedure getOrder` (`handle_get_order`) and `procedure
/// getOrderDispatch` (`handle_get_order_dispatch`) are caught alike,
/// rather than only the first.
pub(super) fn validate_procedure_model_handler_collisions(
    schema: &Schema,
) -> Result<(), SchemaError> {
    if schema.models.is_empty() || schema.procedures.is_empty() {
        return Ok(());
    }

    // ident -> (model name, operation). First writer wins: two models
    // generating the same handler ident is already rejected upstream by
    // `snake_case_collisions`/`route_collisions`, so the entry that lands
    // here is the only one a message would ever want to name.
    let mut generated: BTreeMap<String, (&str, &'static str)> = BTreeMap::new();
    for model in &schema.models {
        for (operation, stem) in model_handler_stems(&model.name) {
            generated
                .entry(format!("handle_{stem}"))
                .or_insert((model.name.as_str(), operation));
            generated
                .entry(format!("handle_{stem}_dispatch"))
                .or_insert((model.name.as_str(), operation));
        }
    }

    for procedure in &schema.procedures {
        let snake = to_snake_case(&procedure.name);
        for handler in [
            format!("handle_{snake}"),
            format!("handle_{snake}_dispatch"),
        ] {
            let Some((model_name, operation)) = generated.get(handler.as_str()) else {
                continue;
            };
            return Err(span_error(
                format!(
                    "procedure `{procedure}` collides with the generated `{operation}` CRUD \
                     handler for model `{model_name}` — both emit `{handler}` into the axum \
                     module generated by `include_server_schema!` (and the matching RPC \
                     dispatch arm), which fails to compile as `error[E0428]`; rename the \
                     procedure",
                    procedure = procedure.name,
                ),
                procedure.name_span,
            ));
        }
    }

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn model_stems_track_the_macro_naming_scheme() {
        let stems = model_handler_stems("SubOrder");
        let stems: Vec<&str> = stems.iter().map(|(_, stem)| stem.as_str()).collect();
        assert_eq!(
            stems,
            vec![
                "list_sub_orders",
                "create_sub_orders",
                "get_sub_order",
                "update_sub_order",
                "delete_sub_order",
            ]
        );
    }
}