'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
 *
 *   Effective monthly price of a service line:
 *     base   = service.hijack=1 ? service.hijack_price : product.price
 *     // Annual plans (SKU ends in "ANN", e.g. FTTH_ANN @ 480$/yr) are
 *     // normalized to a monthly equivalent so the threshold compares apples
 *     // to apples — otherwise a $480/yr (=$40/mo) plan falsely shows as $480.
 *     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.
 *
 *   Internet product categories:
 *     32 Mensualités fibre, 4 Mensualités sans-fil, 23 Internet camping
 *     (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 */ }

const CAT_INTERNET_CORE = [32, 4, 23]      // fibre, wireless, camping
const CAT_INTERNET_ADDONS = [16, 17, 21]   // extra download, static IP, point-to-point

// 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 (${EFF}) DESC SEPARATOR ' · '
      ), 1, 500)      AS detail
    FROM account a
    JOIN delivery d ON d.account_id = a.id
    JOIN service  s ON s.delivery_id = d.id AND s.status = 1
    JOIN product  p ON p.id = s.product_id
    WHERE p.category IN (${catPlaceholders})
      AND p.price_recurr_type = 1
      ${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 } }
}

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)
    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,
      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', '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 }