//! The `claude` child's environment: an allowlist, not the daemon's.
//!
//! `hive-claude` sets its variables on top of the parent's environment, and
//! the daemon's holds the store identity paths and the queue coordinates. So
//! `claude` is spawned as this same binary with [`EXEC_CLAUDE`] naming the
//! real one: [`exec_if_requested`] runs first in `main`, clears the
//! environment down to [`ALLOWED`] and execs `claude` with the same
//! arguments, in the same process.

use std::ffi::OsString;
use std::os::unix::process::CommandExt as _;
use std::process::Command;

/// Set on the child only: the `claude` binary to exec.
pub const EXEC_CLAUDE: &str = "SWARM_REVIEW_CLASSIFIER_EXEC_CLAUDE";

/// Every variable `claude` keeps: the key, what it needs to run, and its
/// telemetry settings.
const ALLOWED: &[&str] = &[
    "ANTHROPIC_API_KEY",
    "PATH",
    "HOME",
    "CLAUDE_CONFIG_DIR",
    "CLAUDE_CODE_ENABLE_TELEMETRY",
    "OTEL_METRICS_EXPORTER",
    "OTEL_EXPORTER_OTLP_ENDPOINT",
    "OTEL_EXPORTER_OTLP_PROTOCOL",
    "OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE",
    "OTEL_RESOURCE_ATTRIBUTES",
];

/// The variables of `vars` on [`ALLOWED`].
pub fn allowed(vars: impl IntoIterator<Item = (OsString, OsString)>) -> Vec<(OsString, OsString)> {
    vars.into_iter()
        .filter(|(name, _)| ALLOWED.iter().any(|a| name == a))
        .collect()
}

/// When this process is the trampoline, exec `claude` and never return.
pub fn exec_if_requested() {
    let Some(claude) = std::env::var_os(EXEC_CLAUDE) else {
        return;
    };
    let error = Command::new(&claude)
        .args(std::env::args_os().skip(1))
        .env_clear()
        .envs(allowed(std::env::vars_os()))
        .exec();
    eprintln!("exec {}: {error}", claude.to_string_lossy());
    std::process::exit(127);
}

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

    #[test]
    fn only_the_allowlist_reaches_claude() {
        let daemon = [
            ("ANTHROPIC_API_KEY", "k"),
            ("HOME", "/tmp/run"),
            ("OTEL_RESOURCE_ATTRIBUTES", "repo=o/r,pr=7"),
            (
                "BAO_CLIENT_KEY",
                "/run/credentials/x/review-classifier-bao-key",
            ),
            ("BAO_ADDR", "https://bao.example:8200"),
            ("CREDENTIALS_DIRECTORY", "/run/credentials/x"),
            (
                "SWARM_REVIEW_CLASSIFIER_NATS_URL",
                "tls://nats.example:4222",
            ),
            (EXEC_CLAUDE, "/bin/claude"),
        ]
        .map(|(n, v)| (OsString::from(n), OsString::from(v)));
        let kept: Vec<String> = allowed(daemon)
            .into_iter()
            .map(|(n, _)| n.to_string_lossy().into_owned())
            .collect();
        assert_eq!(
            kept,
            ["ANTHROPIC_API_KEY", "HOME", "OTEL_RESOURCE_ATTRIBUTES"]
        );
    }
}