use std::sync::Arc;

use axum::extract::{Query, State};
use axum::response::{IntoResponse, Json, Response};
use axum::Extension;
use serde::{Deserialize, Serialize};
use tracing::info;

use crate::auth::OptionalUser;
use crate::data::DevelopmentSite;
use crate::licensing::{check_license_bounds, resolve_share_code};
use crate::parsing::require_bounds;
use crate::state::SharedState;

/// Hard cap on sites returned per viewport. Biggest schemes (by dwelling count)
/// are kept when a dense viewport exceeds this; `truncated` flags the clamp.
const DEVELOPMENTS_LIMIT: usize = 4000;

#[derive(Deserialize)]
pub struct DevelopmentsParams {
    bounds: Option<String>,
    /// Share-link code; grants bbox-scoped access for unlicensed users.
    share: Option<String>,
}

#[derive(Serialize)]
pub struct DevelopmentsResponse {
    pub developments: Vec<DevelopmentSite>,
    pub total: usize,
    pub truncated: bool,
}

/// Forward-looking "where new homes are coming" layer: planned/pipeline
/// development sites (MHCLG Brownfield Land register + Homes England Land Hub),
/// served as points within a viewport. Public OGL data, but still gated by the
/// normal demo/licence bounds check so unlicensed users only see their free zone.
pub async fn get_developments(
    State(shared): State<Arc<SharedState>>,
    Extension(user): Extension<OptionalUser>,
    Extension(geo): Extension<crate::demo_zone::DemoZone>,
    Query(params): Query<DevelopmentsParams>,
) -> Result<Json<DevelopmentsResponse>, Response> {
    let state = shared.load_state();

    let (south, west, north, east) =
        require_bounds(params.bounds).map_err(IntoResponse::into_response)?;

    let share_bounds = resolve_share_code(&state, params.share.as_deref()).await;
    check_license_bounds(
        &user.0,
        (south, west, north, east),
        geo.free_zone,
        share_bounds,
    )?;

    let developments = state.developments.clone();
    let (sites, total, truncated) =
        developments.query_bounds(south, west, north, east, DEVELOPMENTS_LIMIT);

    info!(
        results = sites.len(),
        total, truncated, "GET /api/developments"
    );

    Ok(Json(DevelopmentsResponse {
        developments: sites,
        total,
        truncated,
    }))
}