//! Forgejo webhook endpoints.
//!
//! - **`/webhook/config-pr`** — `pull_request` events on any `agent-configs/*`
//!   repo queue a [`hive_sh4re::approvals::ApprovalKind::MergeConfigPr`] approval row
//!   so the operator can review + approve the merge from the dashboard.
//!
//! There was a second endpoint here, `/webhook/knowledge`, which pulled the
//! local `internal/knowledge` clone on push. It is gone along with the
//! per-hive registration that fed it: a webhook has exactly one target URL,
//! so every hive registering one against the shared repository was
//! last-writer-wins. The swarm controller now holds the single registration
//! and addresses an event to each hive over the queue, which
//! [`crate::workers::knowledge`] documents.
//!
//! The endpoint is reached via the gateway (HTTPS, public domain URL) so
//! Forgejo's SSRF guard does not block delivery. Each delivery is verified
//! against the `X-Hub-Signature-256` HMAC header Forgejo attaches; the
//! shared secret is auto-generated at startup and persisted to
//! [`crate::paths::webhook_secret_file()`].

use axum::{
    body::Bytes,
    extract::State,
    http::{HeaderMap, StatusCode},
    response::{IntoResponse, Response},
};
use serde::Deserialize;

use super::AppState;

// ── HMAC helper ───────────────────────────────────────────────────────────────

/// Verify the `X-Hub-Signature-256` header on an incoming Forgejo webhook.
/// Returns `Err` (with a safe-to-log message) on mismatch, missing header,
/// or when the HMAC secret is unavailable (load failure at startup).
fn verify_hmac(state: &AppState, headers: &HeaderMap, body: &Bytes) -> Result<(), String> {
    let secret = state
        .webhook_secret
        .as_deref()
        .ok_or_else(|| "webhook HMAC secret unavailable; endpoint disabled".to_owned())?;
    let sig = headers
        .get("x-hub-signature-256")
        .and_then(|v| v.to_str().ok())
        .unwrap_or("");
    if sig.is_empty() {
        return Err("missing X-Hub-Signature-256 header".to_owned());
    }
    crate::webhook_secret::verify_signature(secret, body, sig).map_err(|e| e.to_string())
}

// ── config-PR webhook ──────────────────────────────────────────────────────────

/// Minimal Forgejo `pull_request`-webhook payload.
///
/// Forgejo fires this for actions: `opened`, `closed`, `reopened`,
/// `synchronized`, `assigned`, `unassigned`, `label_updated`,
/// `label_cleared`, `milestoned`, `demilestoned`, `review_requested`,
/// `review_request_removed`, `auto_merge_enabled`, `auto_merge_disabled`.
/// We only act on `opened` and `synchronized` (Forgejo spells the
/// push-update action past-tense, unlike GitHub's `synchronize`).
#[derive(Deserialize)]
pub(super) struct PrWebhookPayload {
    /// What triggered this event (`opened`, `closed`, `synchronized`, …).
    action: Option<String>,
    /// PR index on the repo.
    number: Option<u64>,
    pull_request: Option<PrWebhookPr>,
    repository: Option<PrWebhookRepo>,
}

#[derive(Deserialize)]
struct PrWebhookPr {
    head: Option<PrWebhookHead>,
}

#[derive(Deserialize)]
struct PrWebhookHead {
    sha: Option<String>,
}

#[derive(Deserialize)]
struct PrWebhookRepo {
    full_name: Option<String>,
}

/// POST `/webhook/config-pr` — Forgejo `pull_request` webhook for
/// `agent-configs/*` repos.
///
/// On `opened` or `synchronized` for an `agent-configs/<agent>` PR:
/// fetches the current PR head sha, queues a `MergeConfigPr` approval row,
/// and emits the `ApprovalAdded` event so the dashboard card appears
/// immediately.
///
/// All other actions (closed, label changes, etc.) are silently ignored —
/// the operator can deny a pending approval if the PR is later closed.
///
/// Always returns HTTP 200 (even on queue failure) so Forgejo does not
/// retry the delivery. Failures are logged at `warn` level.
///
/// Expected Forgejo webhook configuration:
/// - URL: `https://<HYPERHIVE_HIVE_DOMAIN>/webhook/config-pr`
/// - Content type: `application/json`
/// - Events: "Pull Request" only
/// - Secret: auto-generated HMAC key (see [`crate::webhook_secret`])
/// - Organisation: `agent-configs` (org-level hook covers all config repos)
///
/// hive-c0re registers this hook automatically at startup via
/// [`crate::forge::ensure_config_pr_webhook`].
#[utoipa::path(
    post,
    path = "/webhook/config-pr",
    request_body(
        content = String,
        content_type = "application/json",
        description = "Forgejo pull_request-webhook payload, taken as raw \
                        bytes (not a typed extractor) so HMAC verification \
                        runs over the exact wire bytes before any JSON \
                        parsing"
    ),
    responses(
        (status = 200, description = "processed (approval queued or ignored)", body = String),
        (status = 400, description = "invalid JSON payload"),
        (status = 401, description = "bad or missing HMAC signature"),
        (status = 503, description = "HMAC secret unavailable at startup"),
    ),
    tag = "webhook"
)]
pub(super) async fn post_webhook_config_pr(
    State(state): State<AppState>,
    headers: HeaderMap,
    body: Bytes,
) -> Response {
    if let Err(e) = verify_hmac(&state, &headers, &body) {
        tracing::warn!("webhook/config-pr: HMAC verification failed: {e}");
        let status = if e.contains("unavailable") {
            StatusCode::SERVICE_UNAVAILABLE
        } else {
            StatusCode::UNAUTHORIZED
        };
        return (status, e).into_response();
    }

    let payload = match serde_json::from_slice::<PrWebhookPayload>(&body) {
        Ok(p) => p,
        Err(e) => {
            tracing::warn!("webhook/config-pr: JSON parse error: {e}");
            return (StatusCode::BAD_REQUEST, "invalid JSON").into_response();
        }
    };

    let action = payload.action.as_deref().unwrap_or("");
    // Only act on a newly-opened PR or a new push to its branch. Forgejo's
    // webhook payload spells the push-update action `synchronized` (past
    // tense), NOT GitHub's `synchronize` — matching only the GitHub spelling
    // silently dropped every PR-update delivery (the whole reason updates were
    // "only found by poll"). Accept both so the handler is correct against
    // Forgejo and stays GitHub-compatible.
    if action != "opened" && action != "synchronize" && action != "synchronized" {
        tracing::debug!(action, "webhook/config-pr: ignoring action");
        return (StatusCode::OK, "ignored").into_response();
    }

    let full_name = payload
        .repository
        .as_ref()
        .and_then(|r| r.full_name.as_deref())
        .unwrap_or("");

    // Expect `agent-configs/<agent>`.
    let agent = match full_name.strip_prefix(&format!("{}/", crate::forge::CONFIG_ORG)) {
        Some(name) if !name.is_empty() && !name.contains('/') => name,
        _ => {
            tracing::debug!(
                full_name,
                "webhook/config-pr: ignoring non-config-repo event"
            );
            return (StatusCode::OK, "ignored").into_response();
        }
    };

    let pr_number = match payload.number {
        Some(n) if n > 0 => n,
        _ => {
            tracing::warn!(full_name, "webhook/config-pr: missing or zero PR number");
            return (StatusCode::OK, "ignored").into_response();
        }
    };

    // The payload already carries the head sha — use it as an early hint for
    // logging, but the canonical sha comes from `submit_merge_config_pr`'s
    // fresh forge API call so we don't trust a potentially-stale payload sha.
    let payload_sha = payload
        .pull_request
        .as_ref()
        .and_then(|pr| pr.head.as_ref())
        .and_then(|h| h.sha.as_deref())
        .unwrap_or("<unknown>");

    tracing::info!(
        %full_name, %agent, %pr_number, %payload_sha, %action,
        "webhook/config-pr: queuing MergeConfigPr approval"
    );

    // Queue the approval. The description surfaces the action and PR number
    // on the dashboard card so the operator has context without opening the
    // forge PR.
    let description = format!("PR #{pr_number} on {full_name} ({action})");
    if let Err(e) = crate::socket_server::submit_merge_config_pr(
        &state.coord,
        agent,
        pr_number,
        Some(&description),
        "forge", // submitter — identifies the webhook path in the audit trail
    )
    .await
    {
        tracing::warn!(
            %agent, %pr_number, error = ?e,
            "webhook/config-pr: failed to queue MergeConfigPr approval"
        );
    }

    (StatusCode::OK, "ok").into_response()
}