//! `swarmctl agent permissions` — the permissions the swarm grants one
//! agent, through swarm-controller's `/api/agents/{name}/permissions` routes.
//!
//! The agent applies its tool permissions at its next turn; the hive running
//! it restarts it, after its current turn, when `manage_root_agent` changes.
//! Unset leaves the agent on the default set; an empty list grants nothing.
//!
//! The shape below mirrors the controller's `Permissions`, for the reason
//! [`crate::agent`]'s module doc gives. Permission names are checked by the
//! controller, which answers 422 for one it does not know.

use anyhow::{Context as _, Result};
use serde::{Deserialize, Serialize};

use crate::agent::{parse_ident, send};
use crate::remote::Target;

/// One agent's permissions; an absent field is not set at swarm level.
#[derive(Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
struct Permissions {
    #[serde(default, skip_serializing_if = "Option::is_none")]
    permissions: Option<Vec<String>>,
}

fn runtime() -> Result<tokio::runtime::Runtime> {
    tokio::runtime::Builder::new_current_thread()
        .enable_all()
        .build()
        .context("starting a tokio runtime for the controller request")
}

/// The agent's permissions path. The name is checked first, so it cannot
/// reshape the URI.
fn member(agent: &str) -> Result<String> {
    let agent = parse_ident(agent, "agent name")?;
    Ok(format!("/api/agents/{agent}/permissions"))
}

/// Run `swarmctl agent permissions get`.
pub(crate) fn get(target: &Target, agent: &str) -> Result<()> {
    let uri = member(agent)?;
    let stored: Permissions = runtime()?.block_on(send(
        target,
        hyper::Method::GET,
        &uri,
        None::<&()>,
        "permissions-get",
    ))?;
    print!("{}", render(&stored));
    Ok(())
}

/// Run `swarmctl agent permissions set`: store the given permissions, which
/// replace the agent's record whole.
pub(crate) fn set(target: &Target, agent: &str, permissions: Vec<String>) -> Result<()> {
    let uri = member(agent)?;
    let stored: Permissions = runtime()?.block_on(send(
        target,
        hyper::Method::PUT,
        &uri,
        Some(&with_permissions(permissions)),
        "permissions-set",
    ))?;
    print!("{}", render(&stored));
    Ok(())
}

/// The record granting `permissions`. An empty name, as `--permissions ''`
/// gives, is dropped, so that spelling grants nothing.
fn with_permissions(permissions: Vec<String>) -> Permissions {
    Permissions {
        permissions: Some(permissions.into_iter().filter(|c| !c.is_empty()).collect()),
    }
}

/// Run `swarmctl agent permissions clear`.
pub(crate) fn clear(target: &Target, agent: &str) -> Result<()> {
    let uri = member(agent)?;
    runtime()?.block_on(send::<(), ()>(
        target,
        hyper::Method::DELETE,
        &uri,
        None,
        "permissions-clear",
    ))?;
    println!("cleared; {agent} goes back to the default");
    Ok(())
}

fn render(p: &Permissions) -> String {
    let caps = match p.permissions.as_deref() {
        None => "(not set; the default)".to_owned(),
        Some([]) => "(none)".to_owned(),
        Some(caps) => caps.join(", "),
    };
    format!("permissions: {caps}\n")
}

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

    #[test]
    fn get_tells_unset_from_none() {
        let unset: Permissions = serde_json::from_str("{}").unwrap();
        assert_eq!(render(&unset), "permissions: (not set; the default)\n");
        let none: Permissions = serde_json::from_str(r#"{"permissions":[]}"#).unwrap();
        assert_eq!(render(&none), "permissions: (none)\n");
        let ruth: Permissions =
            serde_json::from_str(r#"{"permissions":["manage_root_agent"]}"#).unwrap();
        assert_eq!(render(&ruth), "permissions: manage_root_agent\n");
    }

    /// `--permissions ''` stores an empty list, not one empty name.
    #[test]
    fn an_empty_list_flag_grants_nothing() {
        let set = with_permissions(vec![String::new()]);
        assert_eq!(
            serde_json::to_string(&set).unwrap(),
            r#"{"permissions":[]}"#
        );
    }
}