build.rs

use std::env;
use std::fs;
use std::path::Path;

fn to_pascal_case(s: &str) -> String {
    s.split('_')
        .map(|word| {
            if word.is_empty() {
                return String::new();
            }
            let mut chars = word.chars();
            let first = chars.next().unwrap();
            first.to_uppercase().to_string() + &chars.as_str().to_lowercase()
        })
        .collect()
}

fn main() {
    let binding = env::var("CARGO_MANIFEST_DIR").unwrap();
    let manifest_dir = Path::new(&binding);
    let agents_dir = manifest_dir.join("src/agents");

    let mut agents: Vec<(String, String, String)> = Vec::new();

    if let Ok(entries) = fs::read_dir(&agents_dir) {
        for entry in entries.flatten() {
            let path = entry.path();
            if path.extension().map(|e| e == "rs").unwrap_or(false) {
                let filename = path.file_stem().unwrap().to_str().unwrap();
                if filename == "mod" || filename == "mod_template" {
                    continue;
                }

                let content = fs::read_to_string(&path).unwrap_or_default();

                let cli_name = if let Some(pos) = content.find("pub const NORMALIZED_NAME:") {
                    let rest = &content[pos..];
                    rest.find('"').and_then(|start| {
                        let after_start = &rest[start + 1..];
                        after_start
                            .find('"')
                            .map(|end| after_start[..end].to_string())
                    })
                } else {
                    None
                }
                .unwrap_or_else(|| filename.to_string());

                let module_name = filename.to_string();
                let variant_name = to_pascal_case(filename);

                agents.push((variant_name, module_name, cli_name));
            }
        }
    }

    agents.sort_by(|a, b| a.2.cmp(&b.2));

    let mut mod_content = String::new();
    mod_content.push_str("// This file is auto-generated by build.rs. DO NOT EDIT.\n\n");

    for (_, module_name, _) in &agents {
        mod_content.push_str(&format!("mod {};\n", module_name));
    }

    mod_content.push_str("\nuse std::fmt;\n\n");

    mod_content.push_str("/// Auto-generated agent registry.\n");
    mod_content.push_str("/// To add a new agent: create src/agents/<name>.rs and run build.\n");
    mod_content.push_str("#[macro_export]\n");
    mod_content.push_str("macro_rules! for_each_agent {\n");
    mod_content.push_str("    ($callback:ident) => {\n");
    mod_content.push_str("        $callback! {\n");
    for (variant, module, cli_name) in &agents {
        mod_content.push_str(&format!(
            "            ({}, {}, \"{}\"),\n",
            variant, module, cli_name
        ));
    }
    mod_content.push_str("        }\n");
    mod_content.push_str("    };\n");
    mod_content.push_str("}\n\n");

    let template_path = manifest_dir.join("src/agents/mod_template.rs");
    if template_path.exists() {
        mod_content.push_str(&fs::read_to_string(&template_path).unwrap_or_default());
    }

    let out_dir = env::var("OUT_DIR").unwrap();
    let dest_path = Path::new(&out_dir).join("agents_mod.rs");
    fs::write(&dest_path, &mod_content).expect("Failed to write generated agents_mod.rs");

    fs::write("src/agents/mod.rs", &mod_content).expect("Failed to write src/agents/mod.rs");

    println!("cargo:rerun-if-changed=src/agents/");
}