package streams;

import java.io.IOException;
import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class CreatingStreams
{
   public static <T> void show(String title, Stream<T> stream)
   {
      final int SIZE = 10;
      List<T> firstElements = stream
            .limit(SIZE + 1)
            .collect(Collectors.toList());
      System.out.print(title + ": ");
      for (int i = 0; i < firstElements.size(); i++)
      {
         if (i > 0) System.out.print(", ");
         if (i < SIZE) System.out.print(firstElements.get(i));
         else System.out.print("...");
      }
      System.out.println();
   }

   public static void main(String[] args) throws IOException
   {
      Path path = Paths.get("../gutenberg/alice30.txt");
      String contents = new String(Files.readAllBytes(path),
            StandardCharsets.UTF_8);

      Stream<String> words = Stream.of(contents.split("\\PL+"));
      show("words", words);
      Stream<String> song = Stream.of("gently", "down", "the", "stream");
      show("song", song);
      Stream<String> silence = Stream.empty();
      show("silence", silence);

      Stream<String> echos = Stream.generate(() -> "Echo");
      show("echos", echos);

      Stream<Double> randoms = Stream.generate(Math::random);
      show("randoms", randoms);

      Stream<BigInteger> integers = Stream.iterate(BigInteger.ONE,
            n -> n.add(BigInteger.ONE));
      show("integers", integers);

      Stream<String> wordsAnotherWay = Pattern.compile("\\PL+").splitAsStream(
            contents);
      show("wordsAnotherWay", wordsAnotherWay);

      try (Stream<String> lines = Files.lines(path, StandardCharsets.UTF_8))
      {
         show("lines", lines);
      }
   }
}