/**
 * useMapProvider.js — resolve the active map engine ("provider").
 *
 * Resolution order (first defined wins):
 *   1. profile-config `provider`   — per-map, set in the profile-config JSON
 *   2. window.MAP_PROVIDER          — runtime override (e.g. a host reads ?provider=…)
 *   3. 'mapbox'                     — default; existing behaviour, never regresses
 *
 * Valid values: 'mapbox' | 'maplibre'. Anything else falls back to the default.
 */

import { inject } from 'vue'

export const MAP_PROVIDERS   = ['mapbox', 'maplibre']
export const DEFAULT_PROVIDER = 'mapbox'

/** Unwrap a ref/computed to its config object; pass plain objects through. */
function unwrapConfig(profileConfig) {
  if (profileConfig && typeof profileConfig === 'object'
      && 'value' in profileConfig && !('provider' in profileConfig) && !('profile' in profileConfig)) {
    return profileConfig.value
  }
  return profileConfig
}

/**
 * Resolve the provider from a profile-config (object or ref) + window fallback.
 * Pure — safe to call outside a Vue setup().
 */
export function resolveMapProvider(profileConfig) {
  const cfg        = unwrapConfig(profileConfig)
  const fromConfig = cfg?.provider
  const fromUrl    = typeof location !== 'undefined'
    ? new URLSearchParams(location.search).get('provider') : undefined
  const fromWindow = typeof window !== 'undefined' ? window.MAP_PROVIDER : undefined
  const raw = String(fromConfig || fromUrl || fromWindow || DEFAULT_PROVIDER).toLowerCase().trim()
  return MAP_PROVIDERS.includes(raw) ? raw : DEFAULT_PROVIDER
}

/** Human-readable engine label for a badge / UI. */
export function providerLabel(provider) {
  return provider === 'maplibre' ? 'MapLibre' : 'Mapbox'
}

/** Convenience for use inside a Vue setup() — injects the provided profileConfig. */
export function useMapProvider() {
  const profileConfig = inject('profileConfig', null)
  return resolveMapProvider(profileConfig)
}

/** True when this map instance is a Mapbox GL map (vs MapLibre). Per-instance runtime
 *  sniff — works even on dual-engine pages where both globals are loaded. */
export function isMapboxMap(map) {
  return typeof window !== 'undefined' && !!window.mapboxgl && map instanceof window.mapboxgl.Map
}

/** Mapbox-Standard-only lighting paint props, per engine. MapLibre rejects layers whose
 *  paint carries unknown properties (the whole layer is dropped → invisible pins), so
 *  spread this instead of writing 'circle-emissive-strength' literally. */
export function emissivePaint(map) {
  return isMapboxMap(map) ? { 'circle-emissive-strength': 1 } : {}
}