import { fetchTile, TileRequestError, TileUpstreamError } from './tiles.js';
import { handleFeatureQuery } from './features.js';
import { handlePlan } from './planner.js';
import { handleSprite } from './sprites.js';
import {
  anthropicConfigured,
  mapillaryToken,
  plannerModel,
  QUERY_MAX_TILES,
  FEATURE_TILE_ZOOM,
} from './constants.js';

function sendJson(res, status, payload) {
  res.statusCode = status;
  res.setHeader('Content-Type', 'application/json; charset=utf-8');
  res.setHeader('Cache-Control', 'no-store');
  res.end(JSON.stringify(payload));
}

/** GET /api/mapillary/status — what this install can do, never a value. */
function handleStatus(req, res) {
  if (req.method !== 'GET')
    return sendJson(res, 405, { error: 'Method not allowed' });
  sendJson(res, 200, {
    configured: Boolean(mapillaryToken()),
    planner: anthropicConfigured(),
    plannerModel: anthropicConfigured() ? plannerModel() : null,
    limits: { maxTiles: QUERY_MAX_TILES, featureZoom: FEATURE_TILE_ZOOM },
  });
}

/** GET /api/mapillary/tiles/{layer}/{z}/{x}/{y} — cached protobuf tile. */
async function handleTile(req, res) {
  if (req.method !== 'GET')
    return sendJson(res, 405, { error: 'Method not allowed' });
  const match =
    /^\/(coverage|points|signs)\/(\d{1,2})\/(\d{1,6})\/(\d{1,6})$/.exec(
      (req.url || '').split('?')[0],
    );
  if (!match)
    return sendJson(res, 400, {
      error: 'Tile path must be /{layer}/{z}/{x}/{y}',
    });
  if (!mapillaryToken())
    return sendJson(res, 503, { error: 'no_key', keyRequired: true });
  const abandoned = new AbortController();
  req.on?.('aborted', () => abandoned.abort());
  res.on?.('close', () => abandoned.abort());
  try {
    const { bytes, source } = await fetchTile(
      { layer: match[1], z: match[2], x: match[3], y: match[4] },
      { signal: abandoned.signal },
    );
    if (res.writableEnded) return;
    res.statusCode = bytes.length ? 200 : 204;
    res.setHeader('Content-Type', 'application/x-protobuf');
    res.setHeader('Cache-Control', 'public, max-age=3600');
    res.setHeader('X-Gev-Cache', source);
    res.end(bytes.length ? bytes : undefined);
  } catch (error) {
    if (res.writableEnded || abandoned.signal.aborted) return;
    if (error instanceof TileRequestError)
      return sendJson(res, error.status, { error: error.message });
    if (error instanceof TileUpstreamError)
      return sendJson(res, error.status >= 500 ? 502 : error.status, {
        error: error.message,
      });
    sendJson(res, 502, { error: error?.message || 'Tile fetch failed' });
  }
}

/** Attach every Mapillary route to a connect-style middleware stack. */
export function installMapillaryRoutes(middlewares) {
  middlewares.use('/api/mapillary/status', handleStatus);
  middlewares.use('/api/mapillary/tiles', handleTile);
  middlewares.use('/api/mapillary/features', handleFeatureQuery);
  middlewares.use('/api/mapillary/plan', handlePlan);
  middlewares.use('/api/mapillary/sprite', handleSprite);
}