// scripts/lib/webexBulk.js
//
// Shared utilities for bulk Webex admin scripts driven off Control Hub
// CSV exports (reclaimWebexHosts.js, removeAdvancedMessaging.js, etc.).
// Kept intentionally dependency-free — everything the operator needs is
// already in the repo (WebexClient, logger). No dev deps to install.
//
// Contents:
//   CSV
//     parseCsvLine(line)         → string[]
//     readCsv(path)              → { header, rows }
//     detectFormat(header)       → 'meetings-inactive' | 'users-export' | null
//     FORMAT_* constants
//
//   Concurrency + retry
//     runPool(items, limit, worker) → results[] with { ok, value? , error? }
//     callWithRetry(fn, opts)      → retries 429/503 with Retry-After
//
//   Webex helpers
//     fetchAllLicenses()           → all org licenses
//     fetchSiteLicenses(siteUrl)   → subset with siteUrl matching (case-insensitive)
//     seatsFree(license)           → number
//     explainWebexError(err)       → concise `${apiMsg} (HTTP ${status})`
//
// All Webex calls go through the shared WebexClient singleton which
// handles service-app token refresh; nothing to configure per-script.

import fs from 'node:fs';
import webex from '../../integrations/webex/WebexClient.js';

// ─────────────────────────────────────────────────────────────────────────────
// CSV parsing (RFC 4180-ish; handles quoted fields, escaped "")
// ─────────────────────────────────────────────────────────────────────────────

export function parseCsvLine(line) {
  const cells = [];
  let cur = '';
  let inQ = false;
  for (let i = 0; i < line.length; i++) {
    const c = line[i];
    if (inQ) {
      if (c === '"' && line[i + 1] === '"') { cur += '"'; i++; }
      else if (c === '"') inQ = false;
      else cur += c;
    } else {
      if (c === '"') inQ = true;
      else if (c === ',') { cells.push(cur); cur = ''; }
      else cur += c;
    }
  }
  cells.push(cur);
  return cells;
}

export function readCsv(filePath) {
  const raw = fs.readFileSync(filePath, 'utf8').replace(/^\uFEFF/, '');
  const lines = raw.split(/\r?\n/).filter((l) => l.length > 0);
  if (lines.length === 0) return { header: [], rows: [] };
  // Preserve original header text — Control Hub exports vary between
  // UPPER_SNAKE and Title Case With Punctuation, and Users Export
  // license columns are literally "aeo2go.webex.com - WebEx Meetings
  // Free [Sub601269]". Case-preserving avoids ambiguity.
  const header = parseCsvLine(lines[0]).map((h) => h.trim());
  const rows = lines.slice(1).map((l) => {
    const cells = parseCsvLine(l);
    const row = {};
    for (let i = 0; i < header.length; i++) row[header[i]] = cells[i] ?? '';
    return row;
  });
  return { header, rows };
}

// ─────────────────────────────────────────────────────────────────────────────
// Format detection
// ─────────────────────────────────────────────────────────────────────────────

export const FORMAT_MEETINGS_INACTIVE = 'meetings-inactive';
export const FORMAT_USERS_EXPORT = 'users-export';

export function detectFormat(header) {
  const set = new Set(header);
  if (set.has('EMAIL') && set.has('IS_HOST') && set.has('DAYS_SINCE_LAST_ACTIVE')) {
    return FORMAT_MEETINGS_INACTIVE;
  }
  if (set.has('User ID/Email (Required)') && set.has('Days since Last Service Accessed')) {
    return FORMAT_USERS_EXPORT;
  }
  return null;
}

// ─────────────────────────────────────────────────────────────────────────────
// Bounded-concurrency worker pool
// ─────────────────────────────────────────────────────────────────────────────
// Runs `worker(item, idx)` across `items` with at most `limit` in flight.
// Never throws — each slot in the result array is either `{ok: true, value}`
// or `{ok: false, error}` so the caller can accumulate a per-item report.

export async function runPool(items, limit, worker) {
  const results = new Array(items.length);
  let idx = 0;
  const workers = new Array(Math.min(limit, items.length)).fill(null).map(async () => {
    while (true) {
      const i = idx++;
      if (i >= items.length) return;
      try {
        results[i] = { ok: true, value: await worker(items[i], i) };
      } catch (err) {
        results[i] = { ok: false, error: err };
      }
    }
  });
  await Promise.all(workers);
  return results;
}

// ─────────────────────────────────────────────────────────────────────────────
// 429/503-aware retry helper. Honors Retry-After (seconds).
// ─────────────────────────────────────────────────────────────────────────────

export async function callWithRetry(fn, { tries = 4, baseDelayMs = 500 } = {}) {
  let lastErr;
  for (let attempt = 0; attempt < tries; attempt++) {
    try {
      return await fn();
    } catch (err) {
      lastErr = err;
      const status = err?.response?.status;
      if (status !== 429 && status !== 503) throw err;
      const retryAfter = Number(err?.response?.headers?.['retry-after']);
      const wait = Number.isFinite(retryAfter) && retryAfter > 0
        ? retryAfter * 1000
        : baseDelayMs * Math.pow(2, attempt);
      await new Promise((r) => setTimeout(r, wait));
    }
  }
  throw lastErr;
}

// ─────────────────────────────────────────────────────────────────────────────
// Webex license helpers
// ─────────────────────────────────────────────────────────────────────────────

export async function fetchAllLicenses() {
  const data = await webex.listLicenses();
  return Array.isArray(data?.items) ? data.items : [];
}

export async function fetchSiteLicenses(siteUrl) {
  const items = await fetchAllLicenses();
  const want = (siteUrl || '').toLowerCase();
  return items.filter((l) => (l.siteUrl || '').toLowerCase() === want);
}

export function seatsFree(l) {
  const total = Number(l.totalUnits ?? 0);
  const used = Number(l.consumedUnits ?? 0);
  return Math.max(0, total - used);
}

// Generic paginated fetch that follows the Webex `Link: <…>; rel="next"`
// header cursor. Accumulates every item in the response's `arrayKey` field
// (defaults to 'items' — the shape most Webex list endpoints use). Some
// endpoints use a different key (e.g. /telephony/config/numbers returns
// `phoneNumbers`); pass `arrayKey` in that case.
//
// Uses WebexClient.requestRaw() directly so we can read headers. First
// call is relative (`endpoint`); subsequent calls follow the absolute
// URLs from the Link header, which carry the cursor query string.
export async function fetchAllPaginated(endpoint, opts = {}) {
  return fetchAllPaginatedWithClient(webex, endpoint, opts);
}

/**
 * Paginated fetch using any client with requestRaw() (WebexClient or
 * createTokenClient()).
 */
export async function fetchAllPaginatedWithClient(client, endpoint, {
  params = null,
  arrayKey = 'items',
  pageSize = 1000,
  retry = { tries: 6, baseDelayMs: 2000 },
} = {}) {
  const firstParams = { max: pageSize, ...(params || {}) };
  let { data, headers } = await callWithRetry(
    () => client.requestRaw('GET', endpoint, null, firstParams),
    retry,
  );
  const all = [];
  const pickArray = (d) => {
    const arr = d?.[arrayKey];
    return Array.isArray(arr) ? arr : [];
  };
  all.push(...pickArray(data));

  let nextUrl = parseLinkNext(headers?.link || headers?.Link);
  while (nextUrl) {
    ({ data, headers } = await callWithRetry(
      () => client.requestRaw('GET', nextUrl),
      retry,
    ));
    all.push(...pickArray(data));
    nextUrl = parseLinkNext(headers?.link || headers?.Link);
  }
  return all;
}

/** @returns {Promise<Array<{ id: string, name: string }>>} */
export async function fetchAllTelephonyLocations(client) {
  const rows = await fetchAllPaginatedWithClient(client, 'telephony/config/locations', {
    arrayKey: 'locations',
    pageSize: 1000,
  });
  return rows
    .map((loc) => ({
      id: loc?.id || loc?.locationId || '',
      name: loc?.name || '',
    }))
    .filter((loc) => loc.id);
}

/** @returns {Promise<object[]>} */
export async function fetchDevicesForLocation(client, locationId) {
  if (!locationId) return [];
  return callWithRetry(
    () => fetchAllPaginatedWithClient(client, 'devices', {
      params: { locationId },
      arrayKey: 'items',
      pageSize: 100,
      retry: { tries: 6, baseDelayMs: 2000 },
    }),
    { tries: 3, baseDelayMs: 3000 },
  );
}

function parseLinkNext(linkHeader) {
  if (!linkHeader || typeof linkHeader !== 'string') return null;
  // Tolerate multiple entries (comma-separated); grab the first `rel="next"`.
  const entries = linkHeader.split(/,\s*(?=<)/);
  for (const e of entries) {
    const m = e.match(/^\s*<([^>]+)>\s*;\s*rel\s*=\s*"?next"?/i);
    if (m) return m[1];
  }
  return null;
}

export function explainWebexError(err) {
  const status = err?.response?.status;
  const apiMsg =
    err?.response?.data?.message ||
    err?.response?.data?.errors?.[0]?.description ||
    err?.message ||
    String(err);
  return status ? `${apiMsg} (HTTP ${status})` : apiMsg;
}