import { toNumber } from "@/lib/weather-utils";
import type { ImgwCurrentWeather, RawImgwHybridWeatherResponse, RawImgwHybridWeatherRow } from "@/types/imgw-current";

const STALE_TEN_MINUTE_THRESHOLD_MS = 2 * 60 * 60 * 1000;

interface NormalizedHybridRow {
  row: RawImgwHybridWeatherRow;
  measuredAt: string;
  timestamp: number;
}

function toCelsius(value: unknown) {
  const temperature = toNumber(value);
  if (temperature === null) return null;
  return temperature > 150 ? temperature - 273.15 : temperature;
}

function toHectopascals(value: unknown) {
  const pressure = toNumber(value);
  if (pressure === null) return null;
  return pressure > 2_000 ? pressure / 100 : pressure;
}

function normalizeDate(value: unknown) {
  if (typeof value !== "string") return null;
  const date = new Date(value);
  return Number.isNaN(date.getTime()) ? null : date.toISOString();
}

function normalizeHybridRow(candidate: RawImgwHybridWeatherRow): NormalizedHybridRow | null {
  const measuredAt = normalizeDate(candidate.Date);
  if (!measuredAt) return null;
  const timestamp = new Date(measuredAt).getTime();
  return Number.isNaN(timestamp) ? null : { row: candidate, measuredAt, timestamp };
}

function getWeatherCode(iconCode: unknown) {
  if (typeof iconCode !== "string") return null;
  const match = iconCode.match(/z(\d{2})/i);
  return match ? Number(match[1]) : null;
}

function getCondition(weatherCode: number | null, rainfall10m: number | null, snowfall10m: number | null) {
  if (weatherCode !== null && weatherCode >= 95) return "thunderstorm" as const;
  if ((snowfall10m ?? 0) > 0) return "snow" as const;
  if ((rainfall10m ?? 0) > 0) return "rain" as const;
  return null;
}

function hasNumericValue(value: unknown) {
  return toNumber(value) !== null;
}

function isFullWeatherRow(candidate: RawImgwHybridWeatherRow) {
  return hasNumericValue(candidate.Temperature)
    && hasNumericValue(candidate.Chill)
    && hasNumericValue(candidate.Humidity)
    && hasNumericValue(candidate.Wind_Speed)
    && hasNumericValue(candidate.PressureMSL);
}

function hasPrecipitationValue(candidate: RawImgwHybridWeatherRow) {
  return hasNumericValue(candidate.Precipitation10m) || hasNumericValue(candidate.Rain10m) || hasNumericValue(candidate.Snow10m);
}

function pickFullWeatherRow(rows: NormalizedHybridRow[]) {
  const tenMinuteRow = rows.find((candidate) => candidate.row.Type === "Type_Ten_Minutes" && isFullWeatherRow(candidate.row));
  const hourlyRow = rows.find((candidate) => candidate.row.Type === "Type_Hour" && isFullWeatherRow(candidate.row));
  if (!tenMinuteRow) return hourlyRow ?? null;
  if (!hourlyRow) return tenMinuteRow;
  return hourlyRow.timestamp - tenMinuteRow.timestamp > STALE_TEN_MINUTE_THRESHOLD_MS ? hourlyRow : tenMinuteRow;
}

function pickPrecipitationRow(rows: NormalizedHybridRow[], fullRow: NormalizedHybridRow | null) {
  if (fullRow && hasPrecipitationValue(fullRow.row)) return fullRow;
  const precipitationRows = rows.filter((candidate) => candidate.row.Type === "Type_Ten_Minutes" && hasPrecipitationValue(candidate.row));
  if (!precipitationRows.length) return null;
  if (!fullRow) return precipitationRows[0];
  return precipitationRows.reduce((best, candidate) => (
    Math.abs(candidate.timestamp - fullRow.timestamp) < Math.abs(best.timestamp - fullRow.timestamp) ? candidate : best
  ));
}

export function normalizeImgwCurrentWeather(payload: RawImgwHybridWeatherResponse): ImgwCurrentWeather | null {
  if (!payload.data?.Valid || !Array.isArray(payload.data.Data)) return null;

  const rows = payload.data.Data
    .flatMap((candidate): NormalizedHybridRow[] => {
      if (!candidate || typeof candidate !== "object") return [];
      const row = candidate as RawImgwHybridWeatherRow;
      if (row.Type !== "Type_Ten_Minutes" && row.Type !== "Type_Hour") return [];
      const normalizedRow = normalizeHybridRow(row);
      return normalizedRow ? [normalizedRow] : [];
    });
  const fullRow = pickFullWeatherRow(rows);
  const precipitationRow = pickPrecipitationRow(rows, fullRow);
  const row = fullRow ?? precipitationRow;
  if (!row) return null;

  const precipitationSource = precipitationRow?.row ?? row.row;
  const rainfall10m = toNumber(precipitationSource.Rain10m);
  const snowfall10m = toNumber(precipitationSource.Snow10m);
  const weatherCode = getWeatherCode(row.row.Icon10);

  return {
    coverage: fullRow?.row.Type === "Type_Ten_Minutes" ? "full" : fullRow ? "hourly" : "precipitation-only",
    measuredAt: row.measuredAt,
    temperature: toCelsius(row.row.Temperature),
    feelsLike: toCelsius(row.row.Chill),
    windSpeed: toNumber(row.row.Wind_Speed),
    windDirection: toNumber(row.row.Wind_Dir),
    humidity: toNumber(row.row.Humidity),
    pressure: toHectopascals(row.row.PressureMSL),
    precipitation10m: toNumber(precipitationSource.Precipitation10m),
    rainfall10m,
    snowfall10m,
    cloudCover: toNumber(row.row.Cloud),
    weatherCode,
    condition: getCondition(weatherCode, rainfall10m, snowfall10m),
  };
}

export async function fetchImgwCurrentWeather(latitude: number, longitude: number, signal?: AbortSignal) {
  const params = new URLSearchParams({ latitude: String(latitude), longitude: String(longitude) });
  const response = await fetch(`/api/imgw-current?${params}`, { signal });
  if (!response.ok) throw new Error("Nie udało się pobrać bieżącej analizy IMGW Hybrid.");
  return normalizeImgwCurrentWeather(await response.json() as RawImgwHybridWeatherResponse);
}