// Whole-network editing tools (관망 도구): pipe length recalculation from
// geometry and elevation filling from the nearest node. Pure functions; the
// UI wraps them with undo.
import type { NetworkModel, InpNode } from './inpModel';
import { calculateGeoAwareDistance, type CRS } from './crs.ts';
import { getUnitSystem } from './unitSystem.ts';

export interface Point {
  x: number;
  y: number;
}

/** Link ID -> intermediate vertices, read from the raw [VERTICES] section. */
export function parseVertices(model: NetworkModel): Record<string, Point[]> {
  if (model.vertices) return model.vertices;
  const out: Record<string, Point[]> = {};
  const r = model.sectionIndices['VERTICES'];
  if (!r) return out;
  for (let i = r.start + 1; i <= r.end; i++) {
    const body = model.rawLines[i]?.split(';')[0].trim();
    if (!body) continue;
    const [id, xs, ys] = body.split(/\s+/);
    const x = Number(xs);
    const y = Number(ys);
    if (id && Number.isFinite(x) && Number.isFinite(y)) (out[id] ??= []).push({ x, y });
  }
  return out;
}

/** Polyline length (node1 -> vertices -> node2) in the model's length units. */
export function linkGeometryLength(model: NetworkModel, node1: string, node2: string, vertices: Point[], crs: CRS): { length: number; isPhysical: boolean } | null {
  const a = model.nodes[node1];
  const b = model.nodes[node2];
  if (!a || !b) return null;
  const system = getUnitSystem(model.options.units);
  const pts: Point[] = [a, ...vertices, b];
  let total = 0;
  let isPhysical = true;
  for (let i = 1; i < pts.length; i++) {
    const d = calculateGeoAwareDistance(pts[i - 1], pts[i], crs, system);
    total += d.distance;
    isPhysical = isPhysical && d.isPhysical;
  }
  return { length: total, isPhysical };
}

export interface LengthChange {
  id: string;
  before: number;
  after: number;
}

/**
 * Recalculate pipe lengths from coordinates (and [VERTICES]); `ids` limits the
 * set. Lengths are rounded to 0.01 and a zero-length result keeps the old value.
 */
export function recalcPipeLengths(model: NetworkModel, crs: CRS, ids?: Iterable<string>): { model: NetworkModel; changes: LengthChange[]; isPhysical: boolean } {
  const vertices = parseVertices(model);
  const target = ids ? new Set(ids) : null;
  const pipes = { ...model.pipes };
  const changes: LengthChange[] = [];
  let isPhysical = true;
  for (const p of Object.values(model.pipes)) {
    if (target && !target.has(p.id)) continue;
    const g = linkGeometryLength(model, p.node1, p.node2, vertices[p.id] ?? [], crs);
    if (!g) continue;
    isPhysical = isPhysical && g.isPhysical;
    const after = Math.round(g.length * 100) / 100;
    if (after > 0 && Math.abs(after - p.length) >= 0.005) {
      pipes[p.id] = { ...p, length: after };
      changes.push({ id: p.id, before: p.length, after });
    }
  }
  return { model: changes.length ? { ...model, pipes } : model, changes, isPhysical };
}

/** Pipes touching a node (for re-measuring after the node moved). */
export function pipesAtNode(model: NetworkModel, nodeId: string): string[] {
  return Object.values(model.pipes)
    .filter((p) => p.node1 === nodeId || p.node2 === nodeId)
    .map((p) => p.id);
}

/** Elevation of the nearest other node (by planar coordinate distance), or null. */
export function nearestNodeElevation(model: NetworkModel, x: number, y: number, exclude?: Set<string>, onlyNonZero = false): number | null {
  let best: InpNode | null = null;
  let bestD = Infinity;
  for (const n of Object.values(model.nodes)) {
    if (exclude?.has(n.id)) continue;
    if (onlyNonZero && !n.elevation) continue;
    const d = (n.x - x) ** 2 + (n.y - y) ** 2;
    if (d < bestD) {
      bestD = d;
      best = n;
    }
  }
  return best ? best.elevation : null;
}

/** Junctions/tanks with elevation 0 take the nearest non-zero node's elevation. */
export function fillZeroElevations(model: NetworkModel): { model: NetworkModel; filled: string[] } {
  const zero = Object.values(model.nodes).filter((n) => n.type !== 'RESERVOIR' && !n.elevation);
  if (!zero.length) return { model, filled: [] };
  const nodes = { ...model.nodes };
  const filled: string[] = [];
  const zeroIds = new Set(zero.map((n) => n.id));
  for (const n of zero) {
    const e = nearestNodeElevation(model, n.x, n.y, zeroIds, true);
    if (e !== null) {
      nodes[n.id] = { ...n, elevation: e };
      filled.push(n.id);
    }
  }
  return { model: filled.length ? { ...model, nodes } : model, filled };
}

// ---- edit options (persisted per browser) ----

export interface EditOptions {
  /** Re-measure connected pipe lengths when a node moves (new pipes are always measured). */
  autoLength: boolean;
  /** New nodes take the nearest existing node's elevation instead of 0. */
  nearestElevation: boolean;
}

const EDIT_OPTIONS_KEY = 'spipe_edit_options';
export const DEFAULT_EDIT_OPTIONS: EditOptions = { autoLength: true, nearestElevation: true };

export function loadEditOptions(): EditOptions {
  try {
    return { ...DEFAULT_EDIT_OPTIONS, ...JSON.parse(localStorage.getItem(EDIT_OPTIONS_KEY) || '{}') };
  } catch {
    return DEFAULT_EDIT_OPTIONS;
  }
}

export function saveEditOptions(o: EditOptions): void {
  try {
    localStorage.setItem(EDIT_OPTIONS_KEY, JSON.stringify(o));
  } catch {
    // storage unavailable: options just won't persist
  }
}