Looks up how many UK companies exist for all 2-permutations of a given list of words.

boxdrive.swift

import Foundation

func boxdrive() {

  let words = ["drop", "box", "live", "drive"]
  let template = "https://beta.companieshouse.gov.uk/search?q={name}"

  let permutations = blended(words: words)
  let results = fetchResults(for: permutations, template: template)
  print(results)
}

func blended(words: [String]) -> [String] {
  return words.flatMap { first in
    words.flatMap { second in
      guard first != second else { return nil }
      return "\(first)\(second)"
    }
  }
}

func fetchResults(for words: [String], template: String) -> [(String, Int?)] {
  return words.map { word in
    guard let url = makeURL(for: word, template: template) else { return (word, nil) }
    let result = fetchResult(from: url)
    return (word, result)
  }
}

func makeURL(for word: String, template: String) -> URL? {
  let prepared = template.replacingOccurrences(of: "{name}", with: word)
  return URL(string: prepared)
}

func fetchResult(from url: URL) -> Int? {
  let request = makeRequest(for: url)
  guard let data = data(for: request) else { return nil }
  return extractTotalResults(from: data)
}

func makeRequest(for url: URL) -> URLRequest {
  var request = URLRequest(url: url)
  request.setValue("application/json", forHTTPHeaderField: "Accept")
  return request
}

func data(for request: URLRequest) -> Data? {
  let semaphore = DispatchSemaphore(value: 0)
  var returnData: Data?
  let task = URLSession.shared.dataTask(with: request) { data, _, _ in
    returnData = data
    semaphore.signal()
  }
  task.resume()
  semaphore.wait()
  return returnData
}

func extractTotalResults(from data: Data) -> Int? {
  do {
    let json = try JSONSerialization.jsonObject(with: data) as? [String: Any]
    let totalResults = json?["total_results"]
    return totalResults as? Int
  } catch {
    return nil
  }
}

func print(_ results: [(String, Int?)]) {
  results.forEach { (name, count) in
    let count = count?.description ?? "error"
    print("\(name): \(count)")
  }
}