import { newError } from '../error.js'
import WBK from '../get_instance_wikibase_sdk.js'
import { getJson } from '../request/get_json.js'
import { validatePropertyId } from '../validate.js'
import type { AbsoluteUrl } from '../types/common.js'
import type { SerializedConfig } from '../types/config.js'
import type { Datatype, Property, PropertyId, WbGetEntitiesResponse } from 'wikibase-sdk'

export type PropertiesDatatypes = Record<PropertyId, Datatype>

const propertiesByInstance: Record<AbsoluteUrl, PropertiesDatatypes> = {}

export async function fetchPropertiesDatatypes (config: SerializedConfig, propertyIds: PropertyId[] = []) {
  let { instance, properties } = config

  propertyIds.forEach(validatePropertyId)

  if (!properties) {
    propertiesByInstance[instance] = propertiesByInstance[instance] || {}
    config.properties = properties = propertiesByInstance[instance]
  }

  const missingPropertyIds = propertyIds.filter(notIn(properties))

  if (missingPropertyIds.length === 0) return

  const urls = WBK(instance).getManyEntities({ ids: missingPropertyIds, props: 'info' })

  const headers = { 'user-agent': config.userAgent }
  const responses: WbGetEntitiesResponse[] = await Promise.all(urls.map(url => getJson(url, { headers })))
  const responsesEntities = responses.map(parseResponse)
  const allEntities = Object.assign({}, ...responsesEntities)
  missingPropertyIds.forEach(addMissingPropertyFactory(allEntities, properties, instance))
}

const notIn = object => key => object[key] == null

type PropertiesByIds = Record<PropertyId, Property>

function parseResponse ({ entities, error }: WbGetEntitiesResponse) {
  if (error) throw newError(error.info, 400, error)
  return entities as PropertiesByIds
}

function addMissingPropertyFactory (entities: PropertiesByIds, properties: PropertiesDatatypes, instance: AbsoluteUrl) {
  return function addMissingProperty (propertyId: PropertyId) {
    const property = entities[propertyId]
    if (!(property?.datatype)) throw newError('property not found', { propertyId, instance })
    properties[propertyId] = property.datatype
  }
}