//! Topology (set-parent) endpoints for the dashboard.
//!
//! Operator-driven agent reparenting — single (`/api/topology/set-parent`,
//! form-encoded) and bulk (`/api/topology/set-parent-bulk`, JSON array →
//! one git commit). Both submit a `NodeKind::Reparent` DAG to the job
//! queue (fire-and-forget, like every other queue-backed op — the
//! dashboard tree repaints off the queue's own snapshot/rescan once the
//! commit lands, same as a rebuild or restart). The executor delegates to
//! `Coordinator::reparent_bulk_with_notify`, which wraps
//! `crate::meta::bulk_commit_topology` with the move-notification messages
//! and the `ContainerView` rescan.

use axum::{
    extract::{Form, State},
    http::StatusCode,
    response::{IntoResponse, Response},
};
use serde::Deserialize;
use utoipa::ToSchema;

use problem_details::ProblemDetails;

use super::{AppState, error_problem};
use crate::job_queue::{Source, submit};

/// `POST /api/topology/set-parent` body. `child` is required.
/// `new_parent` may be:
/// - absent or empty / whitespace-only → promote to root,
/// - non-empty → new parent's logical name.
///
/// (The CLI surface gates "no parent specified" behind an explicit
/// `--root` flag for safety; the HTTP surface is permissive
/// because the dashboard form encodes "no value" as the empty
/// string for the optional radio-group input.)
#[derive(Deserialize, ToSchema)]
pub(super) struct SetParentForm {
    child: String,
    new_parent: Option<String>,
}

/// One entry in a `POST /api/topology/set-parent-bulk` JSON array.
/// `new_parent`: absent/null/empty-string all mean "promote to root".
#[derive(Deserialize, ToSchema)]
pub(super) struct SetParentBulkEntry {
    child: String,
    #[serde(default)]
    new_parent: Option<String>,
}

/// `POST /api/topology/set-parent` — operator-driven parent move.
/// Form fields: `child` (required, agent name), `new_parent`
/// (optional — empty / absent string ⇒ promote to root). Refuses
/// cycles and unknown agents (surfaced async on the job view — this
/// handler only validates the identifiers, not the move itself). The
/// manager is reparentable like any other agent — its privileges come
/// from the privileged MCP socket, not its tree position. Submitting
/// re-emits the queue snapshot immediately so the dashboard shows the
/// queued move without a refresh; the tree itself repaints once the
/// commit lands.
#[utoipa::path(
    post,
    path = "/api/topology/set-parent",
    responses(
        (status = 200, description = "reparent queued", body = String),
        (status = 400, description = "missing/invalid child or new_parent identifier"),
    ),
    tag = "topology"
)]
pub(super) async fn post_set_parent(
    State(state): State<AppState>,
    Form(form): Form<SetParentForm>,
) -> Result<Response, ProblemDetails> {
    let child = form.child.trim().to_owned();
    if child.is_empty() {
        return Err(ProblemDetails::from_status_code(StatusCode::BAD_REQUEST)
            .with_detail("set-parent: `child` required"));
    }
    let child = hive_types::Ident::parse(&child)
        .map_err(|e| error_problem(&format!("set-parent: `child` {e}")))?;
    // Empty / whitespace-only `new_parent` ⇒ promote to root. Web
    // forms submit the empty string for a "no value" radio button,
    // so this is the ergonomic encoding.
    let new_parent = form
        .new_parent
        .as_deref()
        .map(str::trim)
        .filter(|s| !s.is_empty())
        .map(hive_types::Ident::parse)
        .transpose()
        .map_err(|e| error_problem(&format!("set-parent: `new_parent` {e}")))?;
    tracing::info!(
        child = %child,
        new_parent = ?new_parent,
        "operator: set-parent via dashboard"
    );
    submit::reparent(
        &state.coord,
        vec![(child, new_parent)],
        Source::Manual,
        "manual set-parent via dashboard".to_owned(),
    );
    Ok((StatusCode::OK, "ok").into_response())
}

/// `POST /api/topology/set-parent-bulk` — move multiple agents in a single
/// request, producing **one** git commit. JSON body: `[{"child":"name",
/// "new_parent":"target-or-null"}, ...]`. Empty array is a no-op (200 OK).
/// First identifier that fails to parse aborts the whole batch before
/// anything is submitted — a partially-invalid bulk move never reaches
/// the queue.
#[utoipa::path(
    post,
    path = "/api/topology/set-parent-bulk",
    responses(
        (status = 200, description = "reparents queued", body = String),
        (status = 400, description = "an invalid child identifier in the batch"),
    ),
    tag = "topology"
)]
pub(super) async fn post_set_parent_bulk(
    State(state): State<AppState>,
    axum::Json(body): axum::Json<Vec<SetParentBulkEntry>>,
) -> Result<Response, ProblemDetails> {
    if body.is_empty() {
        return Ok((StatusCode::OK, "ok").into_response());
    }
    // Collect into `Result<_, String>` first, not `ProblemDetails` directly —
    // clippy::result_large_err flags a ~232-byte `Err` variant threaded
    // through this closure's `?`. `String` is small enough to satisfy the
    // lint; the single `map_err` below promotes it to a `ProblemDetails`
    // once, after the fallible collect.
    let moves = body
        .iter()
        .map(|e| {
            let child = hive_types::Ident::parse(e.child.trim())
                .map_err(|err| format!("set-parent-bulk: `{}` {err}", e.child))?;
            let new_parent = e
                .new_parent
                .as_deref()
                .map(str::trim)
                .filter(|s| !s.is_empty())
                .map(hive_types::Ident::parse)
                .transpose()
                .map_err(|err| format!("set-parent-bulk: `{}` {err}", e.child))?;
            Ok((child, new_parent))
        })
        .collect::<Result<Vec<_>, String>>()
        .map_err(|e| error_problem(&e))?;
    let names: Vec<&str> = body.iter().map(|e| e.child.as_str()).collect();
    tracing::info!(agents = ?names, "operator: set-parent-bulk via dashboard");
    submit::reparent(
        &state.coord,
        moves,
        Source::Manual,
        "manual set-parent-bulk via dashboard".to_owned(),
    );
    Ok((StatusCode::OK, "ok").into_response())
}