// ── Shop origin ──────────────────────────────────────────────────────────────
export const SHOP_LAT = 41.2284
export const SHOP_LNG = -73.0590   // 554 Boston Post Rd, Milford CT

// ── Rates ─────────────────────────────────────────────────────────────────────
export type DeliveryTier = 'dropoff' | 'classic' | 'organic'

export type DeliveryRatesConfig = Record<DeliveryTier, { base: number; perMile: number; label: string }>

export const RATES: DeliveryRatesConfig = {
  dropoff: {
    base:    20_00,   // cents
    perMile: 1_60,
    label:   'Drop-off delivery',
  },
  classic: {
    base:    30_00,
    perMile: 2_90,
    label:   'Setup & strike (arches / columns)',
  },
  organic: {
    base:    50_00,
    perMile: 2_90,
    label:   'Organic setup & strike (with Chiara Wall)',
  },
}

// ── On-site job duration (minutes) per delivery tier ─────────────────────────
export const JOB_MINUTES: Record<DeliveryTier, number> = {
  dropoff:  60,   // 1 hr on-site window
  classic: 150,   // 2.5 hrs setup + strike
  organic: 240,   // 4 hrs setup + strike
}

/** Straight-line distance fallback (haversine) with road overhead factor */
function haversineMiles(lat1: number, lng1: number, lat2: number, lng2: number): number {
  const R   = 3958.8 // Earth radius in miles
  const dLat = ((lat2 - lat1) * Math.PI) / 180
  const dLng = ((lng2 - lng1) * Math.PI) / 180
  const a =
    Math.sin(dLat / 2) ** 2 +
    Math.cos((lat1 * Math.PI) / 180) *
    Math.cos((lat2 * Math.PI) / 180) *
    Math.sin(dLng / 2) ** 2
  return R * 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a))
}

/** Driving info via OSRM — uses self-hosted instance if OSRM_URL is set,
 *  falls back to the public demo server, retries 3×, then haversine if all fail */
export async function drivingInfo(
  lat1: number, lng1: number,
  lat2: number, lng2: number,
): Promise<{ miles: number; minutes: number }> {
  const base = (process.env.OSRM_URL ?? 'https://router.project-osrm.org').replace(/\/$/, '')
  const url  = `${base}/route/v1/driving/${lng1},${lat1};${lng2},${lat2}?overview=false`
  // Self-hosted gets a generous timeout; public demo gets a short one
  const timeoutMs = process.env.OSRM_URL ? 10_000 : 6_000

  for (let attempt = 0; attempt < 3; attempt++) {
    try {
      const controller = new AbortController()
      const timer = setTimeout(() => controller.abort(), timeoutMs)
      const res = await fetch(url, {
        headers: { 'User-Agent': 'BeachPartyBalloonsShop/1.0' },
        next:    { revalidate: 86400 },
        signal:  controller.signal,
      })
      clearTimeout(timer)
      if (!res.ok) throw new Error(`OSRM ${res.status}`)
      const data = await res.json()
      if (data.code !== 'Ok' || !data.routes?.length) throw new Error('No route found')
      const miles   = (data.routes[0].distance as number) / 1609.344
      const minutes = Math.ceil((data.routes[0].duration as number) / 60)
      return { miles, minutes }
    } catch {
      if (attempt < 2) await new Promise((r) => setTimeout(r, 500 * (attempt + 1)))
    }
  }

  // Fallback: straight-line distance × 1.3 road overhead, ~25 mph average
  console.warn('[delivery] OSRM unavailable — using haversine fallback')
  const miles   = haversineMiles(lat1, lng1, lat2, lng2) * 1.3
  const minutes = Math.ceil((miles / 25) * 60)
  return { miles, minutes }
}

/** Geocode an address string via Nominatim (no API key required) */
export async function geocode(address: string): Promise<{ lat: number; lng: number } | null> {
  const params = new URLSearchParams({ q: address, format: 'json', limit: '1', countrycodes: 'us' })
  const res = await fetch(`https://nominatim.openstreetmap.org/search?${params}`, {
    headers: { 'User-Agent': 'BeachPartyBalloonsShop/1.0' },
    next: { revalidate: 86400 },   // cache geocode results for 24h
  })
  if (!res.ok) return null
  const data = await res.json()
  if (!data.length) return null
  return { lat: parseFloat(data[0].lat), lng: parseFloat(data[0].lon) }
}

export interface DeliveryQuote {
  tier:         DeliveryTier
  miles:        number
  driveMinutes: number
  baseCents:    number
  mileCents:    number
  totalCents:   number
  label:        string
  lat:          number
  lng:          number
}

export async function calcDelivery(
  destLat: number,
  destLng: number,
  tier: DeliveryTier,
  rates?: DeliveryRatesConfig,
): Promise<DeliveryQuote> {
  const rate      = (rates ?? RATES)[tier]
  const { miles: rawMiles, minutes: driveMinutes } =
    await drivingInfo(SHOP_LAT, SHOP_LNG, destLat, destLng)
  const miles      = Math.ceil(rawMiles * 10) / 10
  const mileCents  = Math.ceil(miles) * rate.perMile
  const totalCents = rate.base + mileCents

  return {
    tier,
    miles,
    driveMinutes,
    baseCents:  rate.base,
    mileCents,
    totalCents,
    label:      rate.label,
    lat:        destLat,
    lng:        destLng,
  }
}

/**
 * Infer delivery tier from item names in the cart.
 * Rules (in priority order):
 *   organic items + "chiara wall" → organic
 *   arch or column               → classic
 *   anything else                → dropoff
 */
export function inferTier(itemNames: string[]): DeliveryTier {
  const names = itemNames.map((n) => n.toLowerCase())
  const hasOrganic  = names.some((n) => /organic|garland/.test(n))
  const hasBackdrop = names.some((n) => /chiara/.test(n))
  const hasClassic  = names.some((n) => /arch|column/.test(n))

  if (hasOrganic && hasBackdrop) return 'organic'
  if (hasClassic)                return 'classic'
  return 'dropoff'
}