arcature-cli 2026.2.0

//! `arc make event <name> --module <module>` — generate an event struct.
//!
//! Creates `src/<module>/<name>_event.rs` with a `#[derive(Event)]` struct,
//! and appends `pub mod <name>_event;` to the module's `mod.rs`. The event
//! name is PascalCase (e.g. `UserRegistered`).

use std::path::Path;

use super::naming::{
    append_mod_declaration, mod_declaration, module_file_path, snake_case, validate_module_name,
    validate_type_name,
};
use super::write::{GeneratedFile, module_mod_rs};

pub(crate) fn generate(
    root: &Path,
    raw_name: &str,
    raw_module: &str,
) -> Result<(GeneratedFile, String), String> {
    let name = validate_type_name(raw_name)?;
    let module = validate_module_name(raw_module)?;
    let event_name = name.clone();
    let stem = format!("{}_event", snake_case(&name));
    let path = module_file_path(root, &module, &format!("{stem}.rs"))?;
    let content = render(&event_name, &module);
    let file = GeneratedFile {
        path: path.clone(),
        content,
    };
    let mod_rs = module_mod_rs(root, &module);
    let declaration = mod_declaration(&stem)?;
    let mod_msg = append_mod_declaration(&mod_rs, &declaration)?;
    Ok((file, mod_msg))
}

fn render(event_name: &str, module: &str) -> String {
    format!(
        "//! `{event_name}` — event for the `{module}` module.\n\
         \n\
         /// A typed application event. `#[derive(Event)]` generates `DxComponent`\n\
         /// and `Event`. Add the fields your listeners need; events are\n\
         /// type-erased via `serde_json::Value` at dispatch time.\n\
         #[derive(Debug, Clone, serde::Serialize, serde::Deserialize, arcature::Event)]\n\
         pub struct {event_name} {{\n\
         \x20   // Add event payload fields here.\n\
         }}\n"
    )
}