stremio/apps/master-api/src/openf1/circuit.ts

export type CircuitPoint = { x: number; y: number };

export type CircuitMap = {
  circuitKey: number | null;
  name: string | null;
  rotation: number;
  path: CircuitPoint[];
  corners: Array<{ number: number; letter?: string; x: number; y: number }>;
};

type RawCircuit = {
  circuitKey?: number;
  circuitName?: string;
  rotation?: number;
  x?: number[];
  y?: number[];
  corners?: Array<{ number?: number; letter?: string; x?: number; y?: number }>;
};

function rotate(x: number, y: number, deg: number): CircuitPoint {
  const rad = (deg * Math.PI) / 180;
  const cos = Math.cos(rad);
  const sin = Math.sin(rad);
  return { x: x * cos + y * sin, y: -x * sin + y * cos };
}

function bounds(points: CircuitPoint[]): { minX: number; maxX: number; minY: number; maxY: number } {
  let minX = Infinity;
  let maxX = -Infinity;
  let minY = Infinity;
  let maxY = -Infinity;
  for (const p of points) {
    if (p.x < minX) minX = p.x;
    if (p.x > maxX) maxX = p.x;
    if (p.y < minY) minY = p.y;
    if (p.y > maxY) maxY = p.y;
  }
  return { minX, maxX, minY, maxY };
}

function normalize(p: CircuitPoint, b: { minX: number; maxX: number; minY: number; maxY: number }): CircuitPoint {
  const dx = b.maxX - b.minX || 1;
  const dy = b.maxY - b.minY || 1;
  return {
    x: (p.x - b.minX) / dx,
    y: 1 - (p.y - b.minY) / dy,
  };
}

export function projectCircuit(raw: RawCircuit): CircuitMap {
  const rotation = Number(raw.rotation || 0);
  const xs = Array.isArray(raw.x) ? raw.x : [];
  const ys = Array.isArray(raw.y) ? raw.y : [];
  const n = Math.min(xs.length, ys.length);
  const rotated: CircuitPoint[] = [];
  for (let i = 0; i < n; i++) {
    const x = Number(xs[i]);
    const y = Number(ys[i]);
    if (!Number.isFinite(x) || !Number.isFinite(y)) continue;
    rotated.push(rotate(x, y, rotation));
  }
  const b = rotated.length ? bounds(rotated) : { minX: 0, maxX: 1, minY: 0, maxY: 1 };
  const path = rotated.map((p) => normalize(p, b));
  const corners: CircuitMap["corners"] = [];
  for (const c of raw.corners || []) {
    const x = Number(c.x);
    const y = Number(c.y);
    if (!Number.isFinite(x) || !Number.isFinite(y)) continue;
    const p = normalize(rotate(x, y, rotation), b);
    corners.push({ number: Number(c.number || 0), letter: c.letter, x: p.x, y: p.y });
  }

  return {
    circuitKey: raw.circuitKey ?? null,
    name: raw.circuitName ?? null,
    rotation,
    path,
    corners,
  };
}

export function projectCars(
  cars: Array<{ driverNumber: number; x: number; y: number }>,
  raw: RawCircuit
): Array<{ driverNumber: number; x: number; y: number }> {
  const rotation = Number(raw.rotation || 0);
  const xs = Array.isArray(raw.x) ? raw.x : [];
  const ys = Array.isArray(raw.y) ? raw.y : [];
  const n = Math.min(xs.length, ys.length);
  const track: CircuitPoint[] = [];
  for (let i = 0; i < n; i++) {
    const x = Number(xs[i]);
    const y = Number(ys[i]);
    if (!Number.isFinite(x) || !Number.isFinite(y)) continue;
    track.push(rotate(x, y, rotation));
  }
  const b = track.length ? bounds(track) : { minX: 0, maxX: 1, minY: 0, maxY: 1 };
  return cars
    .filter((c) => Number.isFinite(c.x) && Number.isFinite(c.y))
    .map((c) => {
      const p = normalize(rotate(c.x, c.y, rotation), b);
      return { driverNumber: c.driverNumber, x: p.x, y: p.y };
    });
}

const circuitCache = new Map<string, { at: number; map: CircuitMap; raw: RawCircuit }>();

export async function loadCircuitMap(circuitKey: number, year: number): Promise<{ map: CircuitMap; raw: RawCircuit } | null> {
  const cacheKey = `${circuitKey}:${year}`;
  const hit = circuitCache.get(cacheKey);
  if (hit && Date.now() - hit.at < 24 * 3600_000) return hit;
  const years = [year, year - 1, 2025, 2024, 2023, 2022];
  for (const y of [...new Set(years)]) {
    try {
      const res = await fetch(`https://api.multiviewer.app/api/v1/circuits/${circuitKey}/${y}`, {
        headers: { Accept: "application/json" },
        signal: AbortSignal.timeout(12_000),
      });
      if (!res.ok) continue;
      const raw = (await res.json()) as RawCircuit;
      const map = projectCircuit(raw);
      if (map.path.length < 20) continue;
      const packed = { at: Date.now(), map, raw };
      circuitCache.set(cacheKey, packed);
      return packed;
    } catch {
      /* try older year */
    }
  }
  return null;
}