// API-key-gated routes for other stack apps (currently `reports`, for the
// Directors' report) — not JWT/cookie auth. Mirrors the forecasting <-> reports
// internal API pattern (X-API-Key header, static key from env).
import { pool } from '../db.js'
import {
  getPeriodConsumption, getTariffForMeter, getRateWindows, computeCost,
  getTrailingDailyRate, resolvePeriod, daysInclusive, daysBetween,
} from '../lib/cost-calc.js'

async function requireApiKey(req, reply) {
  const key = req.headers['x-api-key']
  if (!process.env.UTILITIES_API_KEY || key !== process.env.UTILITIES_API_KEY) {
    return reply.status(401).send({ error: 'Invalid or missing API key' })
  }
}

async function resolveCategoryFilter(category) {
  if (!category) return null
  const { rows } = await pool.query(
    'SELECT id FROM meter_categories WHERE key = $1 OR id::text = $1',
    [category]
  )
  return rows[0]?.id ?? null
}

export async function internalRoutes(app) {
  app.addHook('preHandler', requireApiKey)

  // GET /api/internal/readings?period=YYYY-MM&category= — raw reading summary
  app.get('/api/internal/readings', async (req) => {
    const { start, end } = resolvePeriod(req.query.period)
    const categoryId = await resolveCategoryFilter(req.query.category)

    const conditions = ['m.active = TRUE']
    const params = []
    if (categoryId) { params.push(categoryId); conditions.push(`m.category_id = $${params.length}`) }

    const { rows: meters } = await pool.query(
      `SELECT m.id, m.name, m.category_id, c.key AS category_key, c.name AS category_name, c.unit_label
       FROM meters m JOIN meter_categories c ON c.id = m.category_id
       WHERE ${conditions.join(' AND ')}
       ORDER BY c.sort_order, m.name`,
      params
    )

    const readings = []
    for (const m of meters) {
      const { consumption, first, last, has_data } = await getPeriodConsumption(m.id, start, end)
      readings.push({
        meter_id: m.id, meter_name: m.name,
        category: m.category_key, category_name: m.category_name, unit_label: m.unit_label,
        first_reading: first, last_reading: last, consumption, has_data,
      })
    }

    return { period: { start, end }, readings }
  })

  // GET /api/internal/costs?period=YYYY-MM — cost breakdown by category
  app.get('/api/internal/costs', async (req) => {
    const { start, end } = resolvePeriod(req.query.period)
    const daysInPeriod = daysInclusive(start, end)

    const { rows: categories } = await pool.query('SELECT * FROM meter_categories WHERE active = TRUE ORDER BY sort_order')
    const breakdown = []
    const totals = { usage_cost_pence: 0, standing_cost_pence: 0, ccl_cost_pence: 0, vat_pence: 0, total_pence: 0, consumption: 0 }

    for (const cat of categories) {
      const { rows: meters } = await pool.query('SELECT id FROM meters WHERE category_id = $1 AND active = TRUE', [cat.id])
      const catTotals = { usage_cost_pence: 0, standing_cost_pence: 0, ccl_cost_pence: 0, vat_pence: 0, total_pence: 0, consumption: 0 }

      for (const m of meters) {
        const { consumption, has_data } = await getPeriodConsumption(m.id, start, end)
        const tariff = await getTariffForMeter(m.id, end)
        const windows = tariff ? await getRateWindows(tariff.id) : []
        const cost = computeCost({ tariff, windows, consumption, daysInPeriod })
        if (has_data) catTotals.consumption += consumption
        catTotals.usage_cost_pence += cost.usage_cost_pence
        catTotals.standing_cost_pence += cost.standing_cost_pence
        catTotals.ccl_cost_pence += cost.ccl_cost_pence
        catTotals.vat_pence += cost.vat_pence
        catTotals.total_pence += cost.total_pence
      }

      breakdown.push({ category: cat.key, category_name: cat.name, unit_label: cat.unit_label, ...catTotals })
      for (const k of Object.keys(totals)) totals[k] += catTotals[k]
    }

    return { period: { start, end, days_in_period: daysInPeriod }, categories: breakdown, totals }
  })

  // GET /api/internal/estimate?period=current — projected cost for the open period
  app.get('/api/internal/estimate', async (req) => {
    const { start, end, year, month } = resolvePeriod(req.query.period)
    const today = new Date().toISOString().slice(0, 10)
    const asOfDate = today < end ? today : end
    const daysInPeriod = daysInclusive(start, end)
    const remainingDays = Math.max(daysBetween(asOfDate, end), 0)

    const { rows: config } = await pool.query("SELECT value FROM config WHERE key = 'estimate_trailing_days'")
    const globalDefault = config[0]?.value ?? 30

    const { rows: categories } = await pool.query('SELECT * FROM meter_categories WHERE active = TRUE ORDER BY sort_order')
    const breakdown = []
    const totals = { total_pence: 0, projected_consumption: 0 }

    for (const cat of categories) {
      const windowDays = cat.estimate_trailing_days || globalDefault
      const { rows: meters } = await pool.query('SELECT id FROM meters WHERE category_id = $1 AND active = TRUE', [cat.id])
      let catConsumption = 0
      let catTotalPence = 0

      for (const m of meters) {
        const { daily_rate } = await getTrailingDailyRate(m.id, windowDays)
        const { consumption: actualToDate, has_data } = await getPeriodConsumption(m.id, start, asOfDate)
        let projected = null
        if (daily_rate != null) projected = (has_data ? actualToDate : 0) + daily_rate * remainingDays
        else if (has_data) projected = actualToDate

        const tariff = await getTariffForMeter(m.id, asOfDate)
        const windows = tariff ? await getRateWindows(tariff.id) : []
        const cost = computeCost({ tariff, windows, consumption: projected, daysInPeriod })

        if (projected != null) catConsumption += projected
        catTotalPence += cost.total_pence
      }

      breakdown.push({ category: cat.key, category_name: cat.name, unit_label: cat.unit_label, projected_consumption: catConsumption, total_pence: catTotalPence })
      totals.projected_consumption += catConsumption
      totals.total_pence += catTotalPence
    }

    return { period: { year, month, start, end, remaining_days: remainingDays }, categories: breakdown, totals }
  })
}