// services/voiceReport/businessWindow.js
// Store-local business-hour windows for /voicereport (default 9am–9pm).

import { DateTime } from 'luxon';
import { DISPLAY_TIMEZONE } from '../../utils/time.js';

const TWELVE_HOURS_MS = 12 * 60 * 60 * 1000;

function envInt(name, fallback) {
  const v = Number(process.env[name]);
  return Number.isFinite(v) ? v : fallback;
}

export function getBusinessHourConfig() {
  return {
    startHour: envInt('VOICEREPORT_BUSINESS_START_HOUR', 9),
    endHour: envInt('VOICEREPORT_BUSINESS_END_HOUR', 21),
    apiLagMs: envInt('VOICEREPORT_API_LAG_MS', 5 * 60 * 1000),
  };
}

/**
 * Parse user date arg into a mode + calendar date in store TZ.
 * @param {string|null|undefined} raw
 * @param {string} timeZone IANA zone
 * @param {Date} [now] injectable for tests
 */
export function parseReportDateArg(raw, timeZone, now = new Date()) {
  const zone = timeZone || DISPLAY_TIMEZONE;
  const nowLocal = DateTime.fromJSDate(now, { zone });
  const token = String(raw || 'yesterday').trim().toLowerCase();

  if (!token || token === 'yesterday') {
    const day = nowLocal.minus({ days: 1 }).startOf('day');
    return { mode: 'fullDay', day, label: day.toISODate() };
  }
  if (token === 'today') {
    return { mode: 'today', day: nowLocal.startOf('day'), label: nowLocal.toISODate() };
  }
  const parsed = DateTime.fromISO(token, { zone });
  if (parsed.isValid) {
    return { mode: 'fullDay', day: parsed.startOf('day'), label: parsed.toISODate() };
  }
  return { error: `Unrecognised date "${raw}". Use yesterday, today, or YYYY-MM-DD.` };
}

/**
 * Compute UTC ISO window for cdr_feed / Prisma queries.
 * @returns {{ startTime: string, endTime: string, timeZone: string, label: string, mode: string, ready: boolean, reason?: string }}
 */
export function computeBusinessWindow({ timeZone, dateArg, now = new Date() }) {
  const zone = timeZone || DISPLAY_TIMEZONE;
  const cfg = getBusinessHourConfig();
  const parsed = parseReportDateArg(dateArg, zone, now);
  if (parsed.error) {
    return { ready: false, reason: parsed.error, timeZone: zone };
  }

  const startLocal = parsed.day.set({
    hour: cfg.startHour,
    minute: 0,
    second: 0,
    millisecond: 0,
  });

  let endLocal;
  const nowLocal = DateTime.fromJSDate(now, { zone });

  if (parsed.mode === 'today') {
    const businessEnd = parsed.day.set({
      hour: cfg.endHour,
      minute: 0,
      second: 0,
      millisecond: 0,
    });
    const lagEnd = nowLocal.minus({ milliseconds: cfg.apiLagMs });
    if (lagEnd < startLocal.plus({ minutes: 1 })) {
      return {
        ready: false,
        reason: 'Business window has not started yet, or insufficient data after the 5-minute API lag.',
        timeZone: zone,
        label: parsed.label,
        mode: parsed.mode,
      };
    }
    endLocal = DateTime.min(lagEnd, businessEnd);
  } else {
    endLocal = parsed.day.set({
      hour: cfg.endHour,
      minute: 0,
      second: 0,
      millisecond: 0,
    });
  }

  if (endLocal <= startLocal) {
    return {
      ready: false,
      reason: 'Computed window is empty (end is not after start).',
      timeZone: zone,
      label: parsed.label,
      mode: parsed.mode,
    };
  }

  let startMs = startLocal.toUTC().toMillis();
  let endMs = endLocal.toUTC().toMillis();

  const latestAllowedEnd = now.getTime() - cfg.apiLagMs;
  if (endMs > latestAllowedEnd) endMs = latestAllowedEnd;
  if (endMs - startMs > TWELVE_HOURS_MS) startMs = endMs - TWELVE_HOURS_MS;

  if (startMs >= endMs) {
    return {
      ready: false,
      reason: 'Window invalid after API lag clamp.',
      timeZone: zone,
      label: parsed.label,
      mode: parsed.mode,
    };
  }

  return {
    ready: true,
    timeZone: zone,
    label: parsed.label,
    mode: parsed.mode,
    startTime: new Date(startMs).toISOString(),
    endTime: new Date(endMs).toISOString(),
    startLocal: startLocal.toISO(),
    endLocal: endLocal.toISO(),
  };
}

/**
 * True when a timestamp (ISO or ms) falls inside the business window.
 */
export function isWithinWindow(isoOrMs, window) {
  if (!window?.startTime || !window?.endTime) return false;
  const t = new Date(isoOrMs).getTime();
  const s = new Date(window.startTime).getTime();
  const e = new Date(window.endTime).getTime();
  return t >= s && t <= e;
}