const fail = (message, status = 400, code = 'SITE_GEOMETRY_INVALID') => Object.assign(new Error(message), { status, code });
const R = 6371008.8;
// Product scope is an ordinary property/work site in Denmark. These guards keep
// the planar topology check and spherical area calculation in their intended
// local domain: longitude 7.5-15.5°E, latitude 54-58°N, <=5 km per bbox
// axis, <=12 km perimeter and <=5 km² ground area. They deliberately reject
// country/continent/polar input and similarly small out-of-region polygons.
const LOCAL_WORK_BOUNDS = Object.freeze({
  minLongitude: 7.5,
  maxLongitude: 15.5,
  minLatitude: 54,
  maxLatitude: 58,
  maxBboxWidthM: 5_000,
  maxBboxHeightM: 5_000,
  maxPerimeterM: 12_000,
  maxGroundAreaM2: 5_000_000
});
const rad = n => n * Math.PI / 180;
const distanceM = (a, b) => {
  const [lng1, lat1] = a.map(rad);
  const [lng2, lat2] = b.map(rad);
  const h = Math.sin((lat2-lat1)/2)**2 + Math.cos(lat1)*Math.cos(lat2)*Math.sin((lng2-lng1)/2)**2;
  return 2*R*Math.asin(Math.sqrt(Math.min(1,h)));
};
const same = (a, b) => a[0] === b[0] && a[1] === b[1];
const cross = (a, b, c) => (b[0]-a[0])*(c[1]-a[1])-(b[1]-a[1])*(c[0]-a[0]);
const on = (a,b,c) => cross(a,b,c) === 0 && c[0] >= Math.min(a[0],b[0]) && c[0] <= Math.max(a[0],b[0]) && c[1] >= Math.min(a[1],b[1]) && c[1] <= Math.max(a[1],b[1]);
const intersects = (a,b,c,d) => (cross(a,b,c)*cross(a,b,d) < 0 && cross(c,d,a)*cross(c,d,b) < 0) || on(a,b,c) || on(a,b,d) || on(c,d,a) || on(c,d,b);
function normalizeGeometry(payload) {
  const geometry = payload?.geometry;
  const inputRing = geometry?.coordinates?.[0];
  const invalid = () => { throw fail('Tegn en lukket polygon med mindst tre forskellige punkter uden selvskæring.'); };
  if (geometry?.type !== 'Polygon' || geometry.coordinates.length !== 1 || !Array.isArray(inputRing) || inputRing.length < 4 || inputRing.length > 501) invalid();
  if (inputRing.some(p => !Array.isArray(p) || p.length !== 2 || !p.every(Number.isFinite) || Math.abs(p[0]) > 180 || Math.abs(p[1]) > 90)) invalid();
  if (!same(inputRing[0],inputRing[inputRing.length-1])) invalid();
  let points = inputRing.slice(0,-1);
  if (new Set(points.map(p => JSON.stringify(p))).size !== points.length) invalid();
  // Midpoint handles create redundant collinear vertices; normalize those away.
  let changed = true;
  while (changed && points.length >= 3) {
    changed = false;
    const filtered = points.filter((point, index) => {
      const previous = points[(index - 1 + points.length) % points.length];
      const next = points[(index + 1) % points.length];
      const redundant = on(previous, next, point);
      if (redundant) changed = true;
      return !redundant;
    });
    points = filtered;
  }
  if (points.length < 3) invalid();
  const ring = [...points, [...points[0]]];
  // This local work-area editor deliberately excludes antimeridian/polar polygons.
  if (Math.max(...points.map(p => p[0])) - Math.min(...points.map(p => p[0])) >= 180) invalid();
  const minLng = Math.min(...points.map(p => p[0]));
  const maxLng = Math.max(...points.map(p => p[0]));
  const minLat = Math.min(...points.map(p => p[1]));
  const maxLat = Math.max(...points.map(p => p[1]));
  const middleLat = (minLat + maxLat) / 2;
  const bboxWidthM = distanceM([minLng, middleLat], [maxLng, middleLat]);
  const bboxHeightM = distanceM([minLng, minLat], [minLng, maxLat]);
  let perimeterM = 0;
  for (let i=0;i<points.length;i++) perimeterM += distanceM(ring[i], ring[i+1]);
  if (minLng < LOCAL_WORK_BOUNDS.minLongitude || maxLng > LOCAL_WORK_BOUNDS.maxLongitude
      || minLat < LOCAL_WORK_BOUNDS.minLatitude || maxLat > LOCAL_WORK_BOUNDS.maxLatitude
      || bboxWidthM > LOCAL_WORK_BOUNDS.maxBboxWidthM
      || bboxHeightM > LOCAL_WORK_BOUNDS.maxBboxHeightM
      || perimeterM > LOCAL_WORK_BOUNDS.maxPerimeterM) {
    throw fail('Området skal være en lokal dansk arbejdsgrund inden for de understøttede størrelsesgrænser.', 400, 'SITE_GEOMETRY_OUT_OF_BOUNDS');
  }
  for (let i=0;i<points.length;i++) {
    for (let j=i+2;j<points.length;j++) {
      if (i === 0 && j === points.length-1) continue;
      if (intersects(ring[i],ring[i+1],ring[j],ring[j+1])) invalid();
    }
  }
  let area = 0;
  for (let i=0;i<points.length;i++) {
    const [lng1,lat1] = ring[i].map(rad);
    const [lng2,lat2] = ring[i+1].map(rad);
    area += (lng2-lng1)*(2+Math.sin(lat1)+Math.sin(lat2));
  }
  const groundAreaM2 = Math.abs(area)*R*R/2;
  if (!Number.isFinite(groundAreaM2) || groundAreaM2 < 0.01) invalid();
  if (groundAreaM2 > LOCAL_WORK_BOUNDS.maxGroundAreaM2) {
    throw fail('Området skal være en lokal dansk arbejdsgrund inden for de understøttede størrelsesgrænser.', 400, 'SITE_GEOMETRY_OUT_OF_BOUNDS');
  }
  const normalized = points.map(p => [...p]);
  if (area > 0) normalized.reverse();
  const first = normalized.reduce((best,p,i) => p[0] < normalized[best][0] || (p[0] === normalized[best][0] && p[1] < normalized[best][1]) ? i : best,0);
  const ordered = [...normalized.slice(first),...normalized.slice(0,first)];
  ordered.push([...ordered[0]]);
  return {
    schema: 'site_geometry_v1', crs: 'EPSG:4326',
    areas: [{ id: 'area-1', kind: 'work_area', label: 'Område 1', geometry: { type: 'Polygon', coordinates: [ordered] }, groundAreaM2, perimeterM,
      source: { type: 'user_drawn', provider: 'openstreetmap' }, quality: { grade: 'unverified', reasonCodes: ['USER_DRAWN_NOT_FIELD_MEASURED'] } }],
    totals: { groundAreaM2, perimeterM, roofSlopedAreaM2: null },
    calculation: { engine: 'siteGeometry', version: 1, areaAlgorithm: 'server_geodesic_sphere_v1' }
  };
}
module.exports = { normalizeGeometry, fail, LOCAL_WORK_BOUNDS };

const { createHash } = require('crypto');
const parse = row => row ? (typeof row.geometry_json === 'string' ? JSON.parse(row.geometry_json) : row.geometry_json) : null;
const validRevision = value => Number.isSafeInteger(value) && value >= 0 && value < 2147483647;
const isTombstone = value => value?.schema === 'site_geometry_tombstone_v1' && value.deleted === true;
class SiteGeometryService {
  constructor(db) { this.db = db; }
  async getState(projectId) {
    const projects = await this.db.query('SELECT id FROM customer_projects WHERE id=?', [projectId]);
    if (!projects.length) throw fail('Projekt ikke fundet', 404, 'PROJECT_NOT_FOUND');
    const rows = await this.db.query('SELECT revision, geometry_json FROM project_site_geometry WHERE project_id=?', [projectId]);
    const stored = parse(rows[0]);
    if (!stored) return { geometry: null, revision: 0 };
    if (isTombstone(stored)) return { geometry: null, revision: Number(rows[0].revision), deleted: true };
    return { geometry: stored, revision: Number(rows[0].revision) };
  }
  async get(projectId) {
    return (await this.getState(projectId)).geometry;
  }
  async save(projectId, payload, operator) {
    if (!validRevision(payload?.expectedRevision) || !operator) throw fail('Revision og operatør skal angives');
    const canonical = normalizeGeometry(payload);
    const connection = await this.db.pool.getConnection();
    try {
      await connection.beginTransaction();
      // Lock the parent even before the first geometry row exists.
      const [projects] = await connection.execute('SELECT id FROM customer_projects WHERE id=? FOR UPDATE', [projectId]);
      if (!projects.length) throw fail('Projekt ikke fundet', 404, 'PROJECT_NOT_FOUND');
      const [rows] = await connection.execute('SELECT revision, geometry_json FROM project_site_geometry WHERE project_id=? FOR UPDATE', [projectId]);
      if (Number(rows[0]?.revision || 0) !== payload.expectedRevision) throw fail('Området er ændret i en anden session. Genåbn kortet for at hente seneste version.', 409, 'GEOMETRY_REVISION_CONFLICT');
      const previous = parse(rows[0]);
      const now = new Date().toISOString();
      canonical.revision = payload.expectedRevision + 1;
      canonical.audit = { createdAt: previous?.audit?.createdAt || now, createdBy: previous?.audit?.createdBy || operator, updatedAt: now, updatedBy: operator, editMethod: 'polygon_handles' };
      canonical.signature = createHash('sha256').update(JSON.stringify(canonical)).digest('hex');
      const json = JSON.stringify(canonical);
      await connection.execute('INSERT INTO project_site_geometry (project_id, revision, geometry_json) VALUES (?, ?, ?) ON DUPLICATE KEY UPDATE revision=VALUES(revision), geometry_json=VALUES(geometry_json)', [projectId, canonical.revision, json]);
      await connection.execute('INSERT INTO project_site_geometry_audit (project_id, revision, actor_id, event_type, occurred_at, before_signature, after_signature, geometry_json) VALUES (?, ?, ?, ?, ?, ?, ?, ?)', [projectId, canonical.revision, operator, isTombstone(previous) ? 'restored' : previous ? 'edited' : 'created', new Date(now), previous?.signature || null, canonical.signature, json]);
      await connection.commit();
      return canonical;
    } catch (error) {
      await connection.rollback();
      throw error;
    } finally { connection.release(); }
  }
  async delete(projectId, payload, operator) {
    if (!validRevision(payload?.expectedRevision) || !operator) throw fail('Revision og operatør skal angives');
    const connection = await this.db.pool.getConnection();
    try {
      await connection.beginTransaction();
      const [projects] = await connection.execute('SELECT id FROM customer_projects WHERE id=? FOR UPDATE', [projectId]);
      if (!projects.length) throw fail('Projekt ikke fundet', 404, 'PROJECT_NOT_FOUND');
      const [rows] = await connection.execute('SELECT revision, geometry_json FROM project_site_geometry WHERE project_id=? FOR UPDATE', [projectId]);
      const currentRevision = Number(rows[0]?.revision || 0);
      const previous = parse(rows[0]);
      if (!previous || isTombstone(previous)) {
        if (currentRevision !== payload.expectedRevision) throw fail('Området er ændret i en anden session. Genåbn kortet for at hente seneste version.', 409, 'GEOMETRY_REVISION_CONFLICT');
        throw fail('Der er ikke et gemt kortområde at slette.', 404, 'SITE_GEOMETRY_NOT_FOUND');
      }
      if (currentRevision !== payload.expectedRevision) throw fail('Området er ændret i en anden session. Genåbn kortet for at hente seneste version.', 409, 'GEOMETRY_REVISION_CONFLICT');
      const now = new Date().toISOString();
      const tombstone = {
        schema: 'site_geometry_tombstone_v1',
        revision: currentRevision + 1,
        deleted: true,
        audit: {
          createdAt: previous.audit?.createdAt || now,
          createdBy: previous.audit?.createdBy || operator,
          deletedAt: now,
          deletedBy: operator
        }
      };
      tombstone.signature = createHash('sha256').update(JSON.stringify(tombstone)).digest('hex');
      const json = JSON.stringify(tombstone);
      await connection.execute('INSERT INTO project_site_geometry (project_id, revision, geometry_json) VALUES (?, ?, ?) ON DUPLICATE KEY UPDATE revision=VALUES(revision), geometry_json=VALUES(geometry_json)', [projectId, tombstone.revision, json]);
      await connection.execute('INSERT INTO project_site_geometry_audit (project_id, revision, actor_id, event_type, occurred_at, before_signature, after_signature, geometry_json) VALUES (?, ?, ?, ?, ?, ?, ?, ?)', [projectId, tombstone.revision, operator, 'deleted', new Date(now), previous.signature || null, tombstone.signature, json]);
      await connection.commit();
      return { geometry: null, revision: tombstone.revision, deleted: true };
    } catch (error) {
      await connection.rollback();
      throw error;
    } finally { connection.release(); }
  }
}
module.exports.SiteGeometryService = SiteGeometryService;