package com.scalefocus;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.HashMap;
import java.util.IntSummaryStatistics;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class StreamsExamples {

    public static void main(String[] args) throws IOException {
        /*// 1. Integer Stream
                IntStream
                    .range(1, 10)
                    .forEach(System.out::print);
                System.out.println();

                // 2. Integer Stream with skip
                IntStream
                    .range(1, 10)
                    .skip(5)
                    .forEach(x -> System.out.println(x));
                System.out.println();

                // 3. Integer Stream with sum
                System.out.println(
                IntStream
                    .range(1, 5)
                    .sum());
                System.out.println();*/

                // 4. Stream.of, sorted and findFirst
                Stream.of("Ava", "Aneri", "Alberto")
                    .sorted()
                    .findFirst()
                    .ifPresent(System.out::println);

            /*  // 5. Stream from Array, sort, filter and print
                String[] names = {"Al", "Ankit", "Kushal", "Brent", "Sarika", "amanda", "Hans", "Shivika", "Sarah"};
                Arrays.stream(names)    // same as Stream.of(names)
                    .filter(x -> x.startsWith("S"))
                    .sorted()
                    .forEach(System.out::println);

                // 6. average of squares of an int array
                Arrays.stream(new int[] {2, 4, 6, 8, 10})
                    .map(x -> x * x)
                    .average()
                    .ifPresent(System.out::println);

                // 7. Stream from List, filter and print
                List<String> people = Arrays.asList("Al", "Ankit", "Brent", "Sarika", "amanda", "Hans", "Shivika", "Sarah");
                people
                    .stream()
                    .map(String::toLowerCase)
                    .filter(x -> x.startsWith("a"))
                    .forEach(System.out::println);

                // 8. Stream rows from text file, sort, filter, and print
                Stream<String> bands = Files.lines(Paths.get("bands.txt"));
                bands
                    .sorted()
                    .filter(x -> x.length() > 13)
                    .forEach(System.out::println);
                bands.close();

                // 9. Stream rows from text file and save to List
                List<String> bands2 = Files.lines(Paths.get("bands.txt"))
                    .filter(x -> x.contains("jit"))
                    .collect(Collectors.toList());
                bands2.forEach(x -> System.out.println(x));

                // 10. Stream rows from CSV file and count
                Stream<String> rows1 = Files.lines(Paths.get("data.txt"));
                int rowCount = (int)rows1
                    .map(x -> x.split(","))
                    .filter(x -> x.length == 3)
                    .count();
                System.out.println(rowCount + " rows.");
                rows1.close();

                // 11. Stream rows from CSV file, parse data from rows
                Stream<String> rows2 = Files.lines(Paths.get("data.txt"));
                rows2
                    .map(x -> x.split(","))
                    .filter(x -> x.length == 3)
                    .filter(x -> Integer.parseInt(x[1]) > 15)
                    .forEach(x -> System.out.println(x[0] + "  " + x[1] + "  " + x[2]));
                rows2.close();

                // 12. Stream rows from CSV file, store fields in HashMap
                Stream<String> rows3 = Files.lines(Paths.get("data.txt"));
                Map<String, Integer> map = new HashMap<>();
                map = rows3
                    .map(x -> x.split(","))
                    .filter(x -> x.length == 3)
                    .filter(x -> Integer.parseInt(x[1]) > 15)
                    .collect(Collectors.toMap(
                        x -> x[0],
                        x -> Integer.parseInt(x[1])));
                rows3.close();
                for (String key : map.keySet()) {
                    System.out.println(key + "  " + map.get(key));
                }

                // 13. Reduction - sum
                double total = Stream.of(7.3, 1.5, 4.8)
                    .reduce(0.0, (Double a, Double b) -> a + b);
                System.out.println("Total = " + total);

                // 14. Reduction - summary statistics
                IntSummaryStatistics summary = IntStream.of(7, 2, 19, 88, 73, 4, 10)
                    .summaryStatistics();
                System.out.println(summary);
        */
    }

}