//! The swarm-ui issue-report page's data source — repo listing plus the
//! two shapes of the report itself (all-repos default, single-repo
//! filtered). See [`crate::forge::Client::issue_report`] and
//! [`crate::forge::Client::issue_report_all`] for how a row's `blocked` /
//! `depended_on_by_count` fields are actually computed; this module is
//! just the HTTP surface over that logic, split out into its own file —
//! same shape [`crate::webhook`] already uses: business logic in
//! `crate::forge::Client`, the axum handlers next to their own routes.

use axum::{
    Json,
    extract::{Path, State},
};

use crate::forge;
use crate::routes::{AppState, StatusUnavailable, error_problem};

/// The 503 detail when the forge did not answer within
/// [`forge::FORGE_DEADLINE`].
const DEADLINE_DETAIL: &str = "the forge did not answer within the deadline";

/// Repos with at least one open issue, as `owner/name` full names — the
/// data source for swarm-ui's repo-filter dropdown. Not scoped to
/// `forge::CONFIG_ORG` the way `routes/config_prs.rs`'s `get_config_prs` is: this
/// report deliberately covers the whole forge instance, not one org, since
/// the report itself is a general-purpose browsing tool rather than
/// something agent-config-specific.
#[utoipa::path(
    get,
    path = "/api/repos",
    responses(
        (status = 200, description = "repos with at least one open issue, as owner/name", body = Vec<String>),
        (status = 503, description = "no forge is configured on this host, or the forge did not answer within two minutes", body = String),
    ),
    tag = "repos"
)]
pub async fn get_repos(
    State(state): State<AppState>,
) -> Result<Json<Vec<String>>, StatusUnavailable> {
    let Some(client) = state.forge.get() else {
        return Err(StatusUnavailable(
            "no forge is configured on this host".to_owned(),
        ));
    };
    let Some(listed) =
        forge::within_forge_deadline("issue repos", client.list_repos_with_open_issues()).await
    else {
        return Err(StatusUnavailable(DEADLINE_DETAIL.to_owned()));
    };
    match listed {
        Ok(repos) => Ok(Json(repos)),
        Err(e) => {
            let detail = format!("{e:#}");
            tracing::warn!(error = %detail, "listing repos failed");
            Err(StatusUnavailable(detail))
        }
    }
}

/// Every open issue across every repo with at least one — the default,
/// no-repo-filter view. See [`get_issue_report`] for the single-repo
/// counterpart (used once the dropdown's repo filter is set) and
/// [`forge::Client::issue_report_all`] for how the fan-out works.
#[utoipa::path(
    get,
    path = "/api/issue-report",
    responses(
        (status = 200, description = "every open issue across every repo with one, blocked/dependent-count pre-resolved", body = Vec<forge::IssueReportRow>),
        (status = 503, description = "no forge is configured on this host, the report could not be built, or the forge did not answer within two minutes", body = String),
    ),
    tag = "repos"
)]
pub async fn get_issue_report_all(
    State(state): State<AppState>,
) -> Result<Json<Vec<forge::IssueReportRow>>, StatusUnavailable> {
    let Some(client) = state.forge.get() else {
        return Err(StatusUnavailable(
            "no forge is configured on this host".to_owned(),
        ));
    };
    let Some(built) = forge::within_forge_deadline("issue report", client.issue_report_all()).await
    else {
        return Err(StatusUnavailable(DEADLINE_DETAIL.to_owned()));
    };
    match built {
        Ok(rows) => Ok(Json(rows)),
        Err(e) => {
            let detail = format!("{e:#}");
            tracing::warn!(error = %detail, "building the all-repos issue report failed");
            Err(StatusUnavailable(detail))
        }
    }
}

/// Every open issue in `{org}/{repo}` specifically — the filtered view once
/// swarm-ui's repo dropdown (populated by [`get_repos`]) has a selection.
/// See [`forge::Client::issue_report`] for how `blocked` /
/// `depended_on_by_count` are computed and why this has to be a
/// server-side pass rather than something swarm-ui resolves itself per row.
///
/// Unlike [`get_repos`] / [`get_issue_report_all`], a failure here isn't
/// automatically 503: `issue_report` calls `issue_list_issues(org, repo,
/// ...)` first, and a Forgejo 404 there — a typo'd or deleted repo — means
/// "this will never work", not "try again later". See
/// [`issue_report_error_status`] for how that's told apart from a genuine
/// forge failure, which does stay 503.
#[utoipa::path(
    get,
    path = "/api/repos/{org}/{repo}/issue-report",
    params(
        ("org" = String, Path, description = "repo owner (user or org)"),
        ("repo" = String, Path, description = "repo name"),
    ),
    responses(
        (status = 200, description = "every open issue in this repo, blocked/dependent-count pre-resolved", body = Vec<forge::IssueReportRow>),
        (status = 404, description = "no such repo (problem+json)", body = String),
        (status = 503, description = "no forge is configured on this host, the report could not be built, or the forge did not answer within two minutes", body = String),
    ),
    tag = "repos"
)]
pub async fn get_issue_report(
    State(state): State<AppState>,
    Path((org, repo)): Path<(String, String)>,
) -> Result<Json<Vec<forge::IssueReportRow>>, problem_details::ProblemDetails> {
    let Some(client) = state.forge.get() else {
        return Err(error_problem(
            axum::http::StatusCode::SERVICE_UNAVAILABLE,
            "no forge is configured on this host",
        ));
    };
    let Some(built) =
        forge::within_forge_deadline("repo issue report", client.issue_report(&org, &repo)).await
    else {
        return Err(error_problem(
            axum::http::StatusCode::SERVICE_UNAVAILABLE,
            DEADLINE_DETAIL,
        ));
    };
    match built {
        Ok(rows) => Ok(Json(rows)),
        Err(e) => {
            let status = issue_report_error_status(&e);
            if status == axum::http::StatusCode::NOT_FOUND {
                tracing::info!(%org, %repo, "issue report requested for a repo that doesn't exist");
                Err(error_problem(status, &format!("{org}/{repo} not found")))
            } else {
                let detail = format!("{e:#}");
                tracing::warn!(error = %detail, %org, %repo, "building issue report failed");
                Err(error_problem(status, &detail))
            }
        }
    }
}

/// The status [`get_issue_report`]'s forge error should answer with.
///
/// `Client::issue_report` propagates through `anyhow`, so the concrete
/// [`forgejo_api::ForgejoError`] survives underneath but is not the type in
/// hand — downcasting back to it, same pattern `routes`'s
/// `wanted_error_status` uses for `swarm_queue_client::Error`. A 404 there
/// (`forge::is_repo_not_found`) means the repo itself doesn't exist;
/// anything else — including a 404 on some *other* call this function
/// doesn't cover, an outage, auth failure, etc. — stays 503, same as before
/// this existed.
pub(crate) fn issue_report_error_status(e: &anyhow::Error) -> axum::http::StatusCode {
    match e.downcast_ref::<forgejo_api::ForgejoError>() {
        Some(fe) if forge::is_repo_not_found(fe) => axum::http::StatusCode::NOT_FOUND,
        _ => axum::http::StatusCode::SERVICE_UNAVAILABLE,
    }
}

#[cfg(test)]
mod tests {
    use crate::forge;
    use forgejo_api::{ApiErrorKind, ForgejoError};

    // ── a repo-not-found forge error maps to 404, everything else stays
    //    503 ───────────────────────────────────────────────────────────

    /// `issue_report_error_status` as a pure function first: build the
    /// exact `ForgejoError` a 404 from `issue_list_issues` decodes to (see
    /// `forge::is_repo_not_found`'s doc comment for the trace through
    /// forgejo-api's generated client), wrap it the same way `?` inside
    /// `Client::issue_report`'s `.with_context(...)` does, and confirm it
    /// downcasts back to the status the route is meant to answer.
    #[test]
    fn repo_not_found_maps_to_404() {
        let e: anyhow::Error =
            ForgejoError::ApiError(ApiErrorKind::NotFound { errors: None }.into()).into();
        let e = e.context("list open issues in some-org/some-repo");
        assert_eq!(
            super::issue_report_error_status(&e),
            axum::http::StatusCode::NOT_FOUND
        );
    }

    /// Belt-and-braces case: a 404 that arrives as `UnexpectedStatusCode`
    /// rather than the parsed `ApiErrorKind::NotFound` shape (the body
    /// didn't decode as forgejo's not-found JSON) still maps to 404 — see
    /// `forge::is_repo_not_found`'s dual check.
    #[test]
    fn unparsed_404_still_maps_to_404() {
        let e: anyhow::Error =
            ForgejoError::UnexpectedStatusCode(axum::http::StatusCode::NOT_FOUND).into();
        assert_eq!(
            super::issue_report_error_status(&e),
            axum::http::StatusCode::NOT_FOUND
        );
    }

    /// A *different* `ForgejoError` variant — a real forge failure, not
    /// "repo doesn't exist" — stays 503. Proves the match looks at which
    /// kind of forge error this is, not just "was `ForgejoError` involved
    /// at all".
    #[test]
    fn a_different_forge_error_stays_503() {
        let e: anyhow::Error = ForgejoError::ApiError(ApiErrorKind::Forbidden.into()).into();
        assert_eq!(
            super::issue_report_error_status(&e),
            axum::http::StatusCode::SERVICE_UNAVAILABLE
        );
    }

    /// Invert-proof for the 404 cases above: an `anyhow::Error` that does
    /// not wrap a `ForgejoError` at all (the shape a genuine non-forge
    /// failure takes) must NOT downcast to it, and must stay 503. Without
    /// this, an `issue_report_error_status` that answered 404
    /// unconditionally would still pass the tests above. This is also the
    /// status quo this change preserves — before this change, *every*
    /// error on this route (including the 404 case above) answered 503
    /// unconditionally; this test alone can't distinguish "old
    /// unconditional 503" from "new, correctly-scoped 503", the 404 tests
    /// above do that.
    #[test]
    fn a_non_forge_error_stays_503() {
        let e = anyhow::anyhow!("list open issues in some-org/some-repo");
        assert_eq!(
            super::issue_report_error_status(&e),
            axum::http::StatusCode::SERVICE_UNAVAILABLE
        );
    }

    /// Each route against a forge that accepts the connection and never
    /// answers: 503 at the deadline. The paused clock jumps to the deadline
    /// once nothing else can run, so this takes no wall time.
    #[tokio::test(start_paused = true)]
    async fn every_route_is_503_when_the_forge_never_answers() {
        use axum::body::Body;
        use axum::http::{Request, StatusCode};
        use tower::ServiceExt as _;

        // Bound but never accepted: the handshake completes, no response comes.
        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
        let url = url::Url::parse(&format!("http://{}/", listener.local_addr().unwrap())).unwrap();
        for uri in [
            "/api/repos",
            "/api/issue-report",
            "/api/repos/o/r/issue-report",
        ] {
            let (state, _) = crate::routes::tests::state_with_roster();
            assert!(
                state
                    .forge
                    .set(std::sync::Arc::new(forge::Client::for_test_forge(
                        url.clone()
                    )))
                    .is_ok()
            );
            let start = tokio::time::Instant::now();
            let req = Request::get(uri).body(Body::empty()).expect("a request");
            let res = crate::startup::build_app(state)
                .oneshot(req)
                .await
                .expect("infallible");
            assert_eq!(res.status(), StatusCode::SERVICE_UNAVAILABLE, "{uri}");
            let bytes = axum::body::to_bytes(res.into_body(), usize::MAX)
                .await
                .unwrap();
            let body = String::from_utf8_lossy(&bytes);
            assert!(body.contains(super::DEADLINE_DETAIL), "{uri}: {body}");
            assert_eq!(start.elapsed(), forge::FORGE_DEADLINE, "{uri}");
        }
    }
}