const candidates = [
  "https://raw.githubusercontent.com/richaude/blue-book/master/scrubbed.csv",
  "https://raw.githubusercontent.com/alecfirrincieli/UFO-sightings/main/ufo-sightings.csv",
];

let csvText = null;
for (const url of candidates) {
  try {
    const response = await fetch(url);
    if (!response.ok) continue;
    const text = await response.text();
    if (text && text.includes("datetime,city,state")) {
      csvText = text;
      break;
    }
  } catch {}
}

if (!csvText) {
  throw new Error("Unable to fetch UFO sightings dataset from public mirrors.");
}

const { csvParse } = await import("d3-dsv");
const rows = csvParse(csvText);

const normalizeKey = (value) =>
  String(value ?? "")
    .trim()
    .toLowerCase();

function readField(row, key) {
  const target = normalizeKey(key);
  for (const [field, value] of Object.entries(row)) {
    if (normalizeKey(field) === target) return value;
  }
  return undefined;
}

function parseNumber(value) {
  const parsed = Number(value);
  return Number.isFinite(parsed) ? parsed : null;
}

const ufo = rows
  .map((row, index) => {
    const state = String(readField(row, "state") ?? "")
      .trim()
      .toLowerCase();
    const country = String(readField(row, "country") ?? "")
      .trim()
      .toLowerCase();
    const latitude = parseNumber(readField(row, "latitude"));
    const longitude = parseNumber(readField(row, "longitude"));

    if (state !== "ca" || country !== "us") return null;
    if (latitude === null || longitude === null) return null;

    const inCaliforniaBounds =
      latitude >= 32 &&
      latitude <= 42.5 &&
      longitude >= -125 &&
      longitude <= -114;

    if (!inCaliforniaBounds) return null;

    const durationSeconds =
      parseNumber(readField(row, "duration (seconds)")) ?? 0;

    return {
      id: `ufo/${index}`,
      datetime: readField(row, "datetime") ?? null,
      city: readField(row, "city") ?? "Unknown",
      state,
      shape: String(readField(row, "shape") ?? "unknown").toLowerCase(),
      durationSeconds,
      comments: readField(row, "comments") ?? "",
      latitude,
      longitude,
    };
  })
  .filter(Boolean);

process.stdout.write(JSON.stringify(ufo));