'use strict'
/**
 * legacy-reports.js — analytical reports that query the LEGACY MariaDB
 * (gestionclient) directly, read-only. Distinct from lib/reports.js which
 * targets the migrated ERPNext PostgreSQL data.
 *
 * Connection reuses cfg.LEGACY_DB_* (same vars as auth.js sync-legacy).
 * A small pool is kept alive across requests for snappy report loads.
 *
 * Routes:
 *   GET /reports/legacy/overpriced-internet?threshold=90&segment=residential&addons=1
 *       → service addresses whose net MONTHLY Internet bill exceeds a
 *         threshold, discounts included. Used by Ops to spot clients who
 *         could be moved to a better-fit plan.
 *   GET /reports/legacy/overpriced-internet.csv  (same params)
 *
 * Data model recap (validated 2026-06):
 *   account (commercial: 0=residential, 1=commercial)
 *     → delivery (account_id)              one row per service address
 *       → service (delivery_id, status=1)  active service line
 *         → product (category, price)      the plan; price<0 = recurring discount
 *
 *   Account-level filters (mirror the legacy recurring-billing logic in
 *   LEGACY-ACCOUNTING-ANALYSIS.md §6.1, which bills only when BOTH
 *   service.status=1 AND account.status=1):
 *     account.status = 1     → active account. status=4 is terminated
 *                              (8602 accounts, most with a terminate_date,
 *                              e.g. Or Viande Inc closed in 2014 but still
 *                              carrying an orphan service.status=1 line).
 *     account.group_id = 5   → "Client" per the account_group table. Excludes
 *                              6 Prospect, 7 Fournisseur, 8 Relais (network
 *                              infrastructure accounts like a tower-host),
 *                              10 Équipement motorisé — none are billable
 *                              residential/commercial customers.
 *     customer_id NOT LIKE   → 59 "PROPRIO*" accounts sit inside group 5 but
 *       'PROPRIO%'             are landowners hosting our relay/antenna gear
 *                              under a special arrangement (e.g. Denis
 *                              Henderson "PROPRIOH_STCHARLES"), not regular
 *                              paying customers. Excluded by their id prefix.
 *
 *   Effective monthly price of a service line:
 *     base   = service.hijack=1 ? service.hijack_price : product.price
 *     // product.price is ALREADY the monthly unit price regardless of the
 *     // service's billing frequency — a semestrial FTTH1500I has price
 *     // 109.95 (same as the monthly one) and is billed 6×109.95 every 6
 *     // months. Verified against the legacy billing logic (LEGACY-
 *     // ACCOUNTING-ANALYSIS.md §6.1: "prix = quantité × prix_unitaire").
 *     // So we do NOT divide by service.payment_recurrence.
 *     // The one exception: true annual plans (SKU ends in "ANN", e.g.
 *     // FTTH_ANN @ 480$/yr where price IS the yearly amount) → normalize /12.
 *     monthly = base / (sku LIKE '%ANN' ? 12 : 1)
 *
 *   Only recurring lines count: product.price_recurr_type = 1. Type 0 is
 *   one-time charges (equipment, installation) which don't belong on a
 *   recurring monthly bill.
 *
 *   Expired credits excluded: a discount line (price<0) whose service
 *   actif_until is in the past no longer reduces the real bill — counting
 *   it would understate what the client actually pays today. (Per
 *   LEGACY-ACCOUNTING-ANALYSIS.md §10: promo credits carry an actif_until
 *   end date.)
 *
 *   Internet product categories:
 *     monthly:   32 Mensualités fibre, 4 Mensualités sans-fil, 23 camping
 *     equipment: 26/29 équipement fibre, 7/8 équipement sans-fil
 *                (recurring modem/router rentals + Internet discounts that
 *                 live here, e.g. RAB_FTTH_URBA). One-time install charges
 *                 in these cats are dropped by the price_recurr_type=1 filter.
 *     add-ons:   16 Téléch. supp, 17 IP fixe, 21 Location point-à-point
 *   Excluded entirely: 9 Téléphonie, 33 Télévision, 34 Install télé
 */

const cfg = require('./config')
const { log, json } = require('./helpers')

let mysql
try { mysql = require('mysql2/promise') } catch { /* optional dep */ }

// Internet category sets. CORE = monthly plans + Internet equipment.
// The equipment categories (26/29 fibre, 7/8 wireless) carry recurring
// modem/router rentals (FTTH_LOCMOD +10, LOC_TPL +5) AND recurring Internet
// discounts (RAB_FTTH_URBA), which are part of the real Internet bill — a
// client's net Internet cost is wrong without them. Example: Claude Bergeron
// shows 94.95 from cat 32 alone, but a -60$ RAB_FTTH_URBA discount lives in
// cat 26, so his true net is 44.95 (and he correctly drops off the report).
// The price_recurr_type=1 filter still excludes one-time install charges
// (INSTFIBRE -199, etc.) that share these equipment categories.
const CAT_INTERNET_CORE = [32, 4, 23, 26, 29, 7, 8]
const CAT_INTERNET_ADDONS = [16, 17, 21]   // extra download, static IP, point-to-point
// Always excluded: 9 Téléphonie, 33 Télévision, 34 Installation/équip télé.

// Monthly-normalized effective price expression (see header comment).
const EFF = `((CASE WHEN s.hijack=1 THEN s.hijack_price ELSE p.price END) / (CASE WHEN p.sku LIKE '%ANN' THEN 12 ELSE 1 END))`

let _pool = null
function getPool () {
  if (!mysql) return null
  if (!_pool) {
    _pool = mysql.createPool({
      host: cfg.LEGACY_DB_HOST, user: cfg.LEGACY_DB_USER,
      password: cfg.LEGACY_DB_PASS, database: cfg.LEGACY_DB_NAME,
      connectionLimit: 3, waitForConnections: true, queueLimit: 0,
      idleTimeout: 60000, enableKeepAlive: true,
    })
  }
  return _pool
}

// Build the shared SQL + params from the request's query string. Used by
// both the JSON and CSV handlers so the two never drift apart.
function buildQuery (url) {
  const threshold = Math.max(0, parseFloat(url.searchParams.get('threshold') || '90'))
  const segment = url.searchParams.get('segment') || 'residential'   // residential | commercial | all
  const includeAddons = url.searchParams.get('addons') !== '0'
  const limit = Math.min(5000, parseInt(url.searchParams.get('limit') || '2000', 10))

  const cats = includeAddons ? [...CAT_INTERNET_CORE, ...CAT_INTERNET_ADDONS] : CAT_INTERNET_CORE
  const catPlaceholders = cats.map(() => '?').join(',')

  let commercialClause = ''
  if (segment === 'residential') commercialClause = 'AND a.commercial = 0'
  else if (segment === 'commercial') commercialClause = 'AND a.commercial = 1'

  const sql = `
    SELECT
      a.id            AS account_id,
      a.customer_id   AS customer_id,
      TRIM(CONCAT(COALESCE(a.first_name,''),' ',COALESCE(a.last_name,''))) AS client_name,
      a.company       AS company,
      a.email         AS email,
      a.cell          AS cell,
      a.tel_home      AS tel_home,
      a.commercial    AS commercial,
      d.id            AS delivery_id,
      d.address1      AS address1,
      d.city          AS city,
      d.zip           AS zip,
      ROUND(SUM(${EFF}), 2)                                          AS net_internet,
      ROUND(SUM(CASE WHEN (${EFF}) > 0 THEN (${EFF}) ELSE 0 END), 2) AS gross,
      ROUND(SUM(CASE WHEN (${EFF}) < 0 THEN (${EFF}) ELSE 0 END), 2) AS discounts,
      COUNT(*)        AS n_lines,
      SUBSTRING(GROUP_CONCAT(
        CONCAT(p.sku, '=', FORMAT(${EFF}, 2))
        ORDER BY (${EFF}) DESC SEPARATOR ' · '
      ), 1, 500)      AS detail,
      -- Recently-expired discounts on this address: deactivated credit
      -- lines (status=0, price<0) whose actif_until fell in the last 180
      -- days. Explains a sudden bill jump (e.g. Julie Dupuis lost
      -- RAB24M -15 + RAB_X -35 on 2026-03-01 → bill went 103→145$). The
      -- prime retention signal — these clients are about to see the
      -- increase and may shop around.
      (SELECT ROUND(SUM(CASE WHEN s2.hijack=1 THEN s2.hijack_price ELSE p2.price END), 2)
         FROM service s2 JOIN product p2 ON p2.id = s2.product_id
        WHERE s2.delivery_id = d.id AND s2.status = 0 AND p2.price < 0
          AND s2.actif_until IS NOT NULL
          AND s2.actif_until < UNIX_TIMESTAMP()
          AND s2.actif_until > (UNIX_TIMESTAMP() - 15552000)
      ) AS recent_expired_discount
    FROM account a
    JOIN delivery d ON d.account_id = a.id
    JOIN service  s ON s.delivery_id = d.id AND s.status = 1
    JOIN product  p ON p.id = s.product_id
    WHERE p.category IN (${catPlaceholders})
      AND a.status = 1
      AND a.group_id = 5
      AND a.customer_id NOT LIKE 'PROPRIO%'
      AND p.price_recurr_type = 1
      AND NOT (p.price < 0 AND s.actif_until IS NOT NULL AND s.actif_until > 0 AND s.actif_until < UNIX_TIMESTAMP())
      ${commercialClause}
    GROUP BY d.id
    HAVING net_internet > ?
    ORDER BY net_internet DESC
    LIMIT ?`

  const params = [...cats, threshold, limit]
  return { sql, params, meta: { threshold, segment, includeAddons, cats, limit } }
}

// Freshness probe — the most recent invoice date in the legacy copy tells
// us how stale the data is. The copy is a one-shot snapshot (no auto-sync),
// so the report must advertise its as-of date to avoid misleading the
// operator into acting on month-old prices (a re-negotiated client like
// Julie Dupuis won't show their new discount until the copy is refreshed).
async function fetchDataAsOf (pool) {
  try {
    const [r] = await pool.execute('SELECT MAX(date_orig) AS max_ts FROM invoice')
    const ts = r?.[0]?.max_ts
    return ts ? new Date(ts * 1000).toISOString() : null
  } catch { return null }
}

async function handleJson (req, res, url) {
  const pool = getPool()
  if (!pool) return json(res, 503, { error: 'mysql2 not installed on hub' })
  const { sql, params, meta } = buildQuery(url)
  try {
    const t0 = Date.now()
    const [rows] = await pool.execute(sql, params)
    const dataAsOf = await fetchDataAsOf(pool)
    log(`legacy report overpriced-internet: ${rows.length} rows in ${Date.now() - t0}ms (threshold=${meta.threshold}, segment=${meta.segment}, addons=${meta.includeAddons})`)
    return json(res, 200, {
      threshold: meta.threshold, segment: meta.segment,
      include_addons: meta.includeAddons, categories: meta.cats,
      data_as_of: dataAsOf,
      count: rows.length, rows,
    })
  } catch (e) {
    log(`legacy report error: ${e.message}`)
    return json(res, 500, { error: 'legacy query failed: ' + e.message })
  }
}

async function handleCsv (req, res, url) {
  const pool = getPool()
  if (!pool) return json(res, 503, { error: 'mysql2 not installed on hub' })
  const { sql, params, meta } = buildQuery(url)
  try {
    const [rows] = await pool.execute(sql, params)
    const headers = ['account_id', 'customer_id', 'client_name', 'company', 'email', 'cell', 'tel_home',
      'address1', 'city', 'zip', 'net_internet', 'gross', 'discounts', 'recent_expired_discount', 'n_lines', 'detail']
    const esc = (v) => {
      if (v == null) return ''
      const s = String(v)
      return /[",\r\n]/.test(s) ? '"' + s.replace(/"/g, '""') + '"' : s
    }
    const lines = [headers.join(',')]
    for (const r of rows) lines.push(headers.map(h => esc(r[h])).join(','))
    const csv = '' + lines.join('\r\n') + '\r\n'
    res.writeHead(200, {
      'Content-Type': 'text/csv; charset=utf-8',
      'Content-Disposition': `attachment; filename="internet-cher-${meta.segment}-${meta.threshold}.csv"`,
      'Cache-Control': 'no-store',
    })
    return res.end(csv)
  } catch (e) {
    return json(res, 500, { error: 'legacy query failed: ' + e.message })
  }
}

async function handle (req, res, method, path, url) {
  if (path === '/reports/legacy/overpriced-internet' && method === 'GET') return handleJson(req, res, url)
  if (path === '/reports/legacy/overpriced-internet.csv' && method === 'GET') return handleCsv(req, res, url)
  return json(res, 404, { error: 'legacy report not found' })
}

module.exports = { handle }