/**
 * Narrows a per-page insight's context data down to the period the user picked.
 *
 * The per-page AI Insight used to send the whole cycle to the model no matter
 * which timeframe was selected, and only changed a label in the prompt — so
 * "Harian" and "Mingguan" produced near-identical answers. This trims the data
 * itself, which is the only thing the model actually reads.
 */

export type InsightTimeframe = 'harian' | 'mingguan';

/**
 * Rows of a day-indexed history carry a day number and/or a date.
 *
 * Pages are inconsistent about the field name: the dashboard builds `day`/`date`
 * while the FCR and EEF pages build `hari`/`tanggal`. Recognising only the
 * English spelling meant those two pages' histories were never sliced at all —
 * their timeframe selector changed nothing.
 */
type DayRow = Record<string, unknown> & {
  day?: unknown;
  hari?: unknown;
  date?: unknown;
  tanggal?: unknown;
};

const DAY_KEYS = ['day', 'hari'] as const;
const DATE_KEYS = ['date', 'tanggal'] as const;

const isPlainObject = (value: unknown): value is Record<string, unknown> =>
  typeof value === 'object' && value !== null && !Array.isArray(value);

const dayOf = (row: DayRow): number | null => {
  for (const key of DAY_KEYS) {
    const value = row[key];
    if (typeof value === 'number' && Number.isFinite(value)) return value;
  }
  return null;
};

const hasDateField = (row: DayRow): boolean =>
  DATE_KEYS.some((key) => typeof row[key] === 'string');

/**
 * A history indexed by time, as opposed to a snapshot list (cameras, devices,
 * coops) that has no time dimension. Only the former may be sliced by period —
 * trimming a device list to "today" would silently hide devices.
 */
const isDayIndexedArray = (value: unknown[]): value is DayRow[] =>
  value.length > 0 &&
  value.every(
    (item) =>
      isPlainObject(item) && (dayOf(item as DayRow) !== null || hasDateField(item as DayRow))
  );

const sliceHistory = (
  rows: DayRow[],
  timeframe: InsightTimeframe,
  selectedDay: number | null = null
): DayRow[] => {
  const days = rows.map(dayOf).filter((day): day is number => day !== null);

  if (timeframe === 'harian') {
    if (days.length > 0) {
      // Picking a day means "the cycle so far, up to that day" — day 0 through
      // day N — not that day in isolation. A single row shows no trend and
      // cannot support a cumulative figure like mortality-to-date.
      if (selectedDay !== null)
        return rows.filter((row) => (dayOf(row) ?? Infinity) <= selectedDay);
      return rows.filter((row) => dayOf(row) === Math.max(...days));
    }
    // Date-only history: the array position is the only ordering we have.
    if (selectedDay !== null) return rows.slice(0, selectedDay + 1);
    return rows.slice(-1);
  }

  if (days.length > 0) {
    const latestDay = Math.max(...days);
    // The 7-day window ending today, matched on each row's own `day` so gaps in
    // the data do not shift the window.
    return rows.filter((row) => {
      const day = dayOf(row);
      return day !== null && day > latestDay - 7 && day <= latestDay;
    });
  }
  return rows.slice(-7);
};

/**
 * Returns a copy of `contextData` where every day-indexed history is trimmed to
 * `timeframe`. Snapshot lists, scalars, and nested objects are preserved.
 */
export const scopeContextToTimeframe = <T>(
  contextData: T,
  timeframe: InsightTimeframe,
  selectedDay: number | null = null
): T => {
  if (Array.isArray(contextData)) {
    const scoped = isDayIndexedArray(contextData)
      ? sliceHistory(contextData as DayRow[], timeframe, selectedDay)
      : contextData;
    return scoped.map((item) =>
      scopeContextToTimeframe(item, timeframe, selectedDay)
    ) as unknown as T;
  }

  if (isPlainObject(contextData)) {
    const scoped: Record<string, unknown> = {};
    for (const [key, value] of Object.entries(contextData)) {
      scoped[key] = scopeContextToTimeframe(value, timeframe, selectedDay);
    }
    return scoped as unknown as T;
  }

  return contextData;
};

export const UNAVAILABLE = 'tidak tersedia';

/**
 * How one page's summary scalars relate to its day-indexed history.
 *
 * `derive` maps an OUTPUT key — which must carry its unit, e.g.
 * `bobotRataRata_gram` — to the history field it is computed from and how to
 * aggregate it across the window. `drop` lists the original unitless keys the
 * derived ones replace; leaving them in would hand the model both the stale
 * figure and the period one and let it pick. `unavailable` names scalars with
 * no day-indexed source at all: they are marked rather than left showing a
 * value from a different period.
 */
export type ScalarScopeSpec = {
  historyKey: string;
  /**
   * `replaces` names the original key this derived value stands in for. The
   * prompt drops the original, but the card's summary grid still renders it —
   * without the link the grid kept showing cycle-to-date figures beside a
   * narrative scoped to one period, which reads as the toggle doing nothing.
   */
  derive: Record<
    string,
    {
      field: string;
      /**
       * `last` takes the final row verbatim. `lastValid` walks backwards past
       * zeros — use it for readings where 0 means "the sensor sent nothing",
       * not "the measurement was zero". The IoT scale stopped reporting at day
       * 38 and has written 0 every day since, so `last` handed the card
       * "Rata-rata Bobot 0 kg" while the page beside it showed the real figure.
       */
      agg: 'mean' | 'sum' | 'last' | 'lastValid';
      replaces?: string;
    }
  >;
  drop?: string[];
  unavailable?: string[];
};

const round2 = (value: number) => Math.round(value * 100) / 100;

const aggregate = (rows: DayRow[], field: string, agg: 'mean' | 'sum' | 'last' | 'lastValid') => {
  const values = rows
    .map((row) => row[field])
    .filter((value): value is number => typeof value === 'number' && Number.isFinite(value));
  if (values.length === 0) return null;
  if (agg === 'lastValid') {
    // Mirrors `getLatestValid` on the FCR/EEF pages, so the insight card and
    // the page it sits on cannot report different numbers. All-zero means the
    // reading is missing, which has to surface as "tidak tersedia" rather than
    // a confident 0.
    for (let i = values.length - 1; i >= 0; i--) {
      const value = values[i];
      if (value !== undefined && value !== 0) return value;
    }
    return null;
  }
  if (agg === 'last') return values[values.length - 1] ?? null;
  const total = values.reduce((sum, value) => sum + value, 0);
  return round2(agg === 'sum' ? total : total / values.length);
};

/**
 * Bring a per-page context's scalars into the same period as its history.
 *
 * Slicing the history alone is not enough: a "Mingguan" payload whose chart
 * covers days 42-48 while `averageWeight` still holds the day-48 figure lets
 * the model quote either, which is the exact contradiction already fixed on the
 * dashboard. Run this AFTER `scopeContextToTimeframe`, on the sliced context.
 */
export const scopeScalarsToTimeframe = (
  scopedContext: Record<string, unknown>,
  timeframe: InsightTimeframe,
  spec: ScalarScopeSpec
): Record<string, unknown> => {
  const history = scopedContext[spec.historyKey];
  if (!Array.isArray(history)) return scopedContext;
  const rows = history as DayRow[];

  const out: Record<string, unknown> = { ...scopedContext };
  for (const key of spec.drop ?? []) delete out[key];

  const days = rows.map(dayOf).filter((day): day is number => day !== null);
  // A window covering more than one day must be named as a range, or the model
  // reads "hari ke-30" and reports a 31-day cumulative figure as one day's.
  const label =
    days.length === 0
      ? UNAVAILABLE
      : Math.min(...days) === Math.max(...days)
        ? `hari ke-${Math.max(...days)}`
        : `hari ke-${Math.min(...days)} s/d ke-${Math.max(...days)}`;

  for (const [outKey, rule] of Object.entries(spec.derive)) {
    const value = aggregate(rows, rule.field, rule.agg);
    out[outKey] = value === null ? UNAVAILABLE : value;
  }
  for (const key of spec.unavailable ?? []) out[key] = UNAVAILABLE;

  out.periode = label;
  // Only the multi-day window needs the "not today" warning; saying it in daily
  // mode contradicts the label directly above it.
  // Only a window that is not today needs the "not today" warning; saying it in
  // a single-day-today report contradicts the label directly above it.
  const satuHariTerakhir =
    timeframe === 'harian' && days.length > 0 && Math.min(...days) === Math.max(...days);
  const bukanHariIni = satuHariTerakhir ? '' : 'BUKAN kondisi hari ini. ';
  out.catatan_periode =
    `Angka ringkas di objek ini dihitung dari periode ${label} (${rows.length} hari data), ` +
    `${bukanHariIni}Satuan setiap angka tertulis di akhir nama field ` +
    `(_gram, _persen, _rasio, _karung, _ekor, _kg) — pakai satuan itu persis. ` +
    `Field berisi "${UNAVAILABLE}" memang tidak ada datanya: tulis "data tidak tersedia" ` +
    `dan JANGAN mengarang angkanya.`;

  return out;
};

/** Human-readable description of the window, for the prompt and the UI. */
export const describeTimeframe = (
  timeframe: InsightTimeframe,
  currentDay?: number | null,
  selectedDay: number | null = null
) => {
  if (timeframe === 'harian') {
    // Daily now means "the cycle so far", so the label must state the range. A
    // past end-day must not be described as "hari ini" either — the model
    // repeats that phrasing back and claims the figures are today's.
    if (selectedDay !== null) {
      const ekor = `hari ke-0 sampai hari ke-${selectedDay} (kumulatif sejak awal siklus)`;
      return selectedDay === currentDay ? `${ekor}, berakhir hari ini` : `${ekor}, BUKAN hari ini`;
    }
    return currentDay ? `Hari ini saja (hari ke-${currentDay})` : 'Hari ini saja (hari terakhir)';
  }
  return currentDay
    ? `7 hari terakhir (hari ke-${Math.max(1, currentDay - 6)} sampai hari ke-${currentDay})`
    : '7 hari terakhir';
};