//! `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 body comes from `swarm-controller-api`, which the controller imports
//! too. A name that is not a permission fails before the request.

use anyhow::{Context as _, Result};
use hive_types::Permission;
use swarm_controller_api::permissions::Permissions;

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

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: &[String]) -> Result<()> {
    let uri = member(agent)?;
    let wanted = with_permissions(permissions)?;
    let stored: Permissions = runtime()?.block_on(send(
        target,
        hyper::Method::PUT,
        &uri,
        Some(&wanted),
        "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: &[String]) -> Result<Permissions> {
    let granted = permissions
        .iter()
        .filter(|name| !name.is_empty())
        .map(|name| parse_permission(name))
        .collect::<Result<Vec<_>>>()?;
    Ok(Permissions {
        permissions: Some(granted),
    })
}

/// The permission `name` spells, or an error listing the names that would
/// have been accepted.
fn parse_permission(name: &str) -> Result<Permission> {
    Permission::ALL
        .iter()
        .copied()
        .find(|p| <&str>::from(*p) == name)
        .ok_or_else(|| {
            let known: Vec<&str> = Permission::ALL.iter().map(|p| <&str>::from(*p)).collect();
            anyhow::anyhow!(
                "invalid permission {name:?}: expected one of {}",
                known.join(", ")
            )
        })
}

/// 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(perms) => perms
            .iter()
            .map(|p| <&str>::from(*p))
            .collect::<Vec<_>>()
            .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(&[String::new()]).unwrap();
        assert_eq!(
            serde_json::to_string(&set).unwrap(),
            r#"{"permissions":[]}"#
        );
    }

    /// A name that is not a permission fails locally and lists the valid ones.
    #[test]
    fn an_unknown_permission_is_refused() {
        let err = with_permissions(&["messaging".to_owned(), "fly".to_owned()]).unwrap_err();
        let text = err.to_string();
        assert!(text.contains("invalid permission \"fly\""), "{text}");
        assert!(text.contains("manage_root_agent"), "{text}");
        let ok = with_permissions(&["web_tools".to_owned()]).unwrap();
        assert_eq!(
            serde_json::to_string(&ok).unwrap(),
            r#"{"permissions":["web_tools"]}"#
        );
    }
}