package io.trygvis.btree;

import org.junit.Test;

import java.io.File;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import static io.trygvis.btree.HeapTest.Person.randomPerson;
import static io.trygvis.btree.TestUtils.deleteFile;
import static org.junit.Assert.assertEquals;

public class HeapTest {

    @Test
    public void testHeap() throws Exception {
        List<Person> persons = new ArrayList<Person>();

        File f = new File("target/heapTest");

        HeapFile file = new HeapFile(128, deleteFile(f));

        HeapPage page = file.blankPage();

        int pageNo = 0;
        for (int i = 0; i < 10; i++) {
            Person p = randomPerson();
            persons.add(p);

            byte[] bytes = p.toBytes();

            System.out.println("p = " + p + ", size = " + bytes.length);

            if (page.bytesFree() < bytes.length) {
                System.out.println("Flushing page");
                long actualPageNo = file.writePage(page);
                assertEquals(pageNo++, actualPageNo);
                page = file.blankPage();
            }

            page.append(bytes);
        }

        long actualPageNo = file.writePage(page);
        assertEquals(pageNo, actualPageNo);
        file.close();

        System.out.println("-------------------------------------------------------");
        file = new HeapFile(128, f);

        System.out.println("file.pageCount() = " + file.pageCount());

        int counter = 0;
        for (int i = 0; i < file.pageCount(); i++) {
            System.out.println("page #" + i);
            page = file.loadPage(i);

            for (ByteBuffer buffer : page.items()) {
                Person p = Person.fromBytes(buffer);
                System.out.println("p = " + p);
                assertEquals(persons.get(counter++), p);
            }
        }
    }

    public static class Person {
        private final String name;
        private final int age;

        public Person(String name, int age) {
            this.name = name;
            this.age = age;
        }

        public byte[] toBytes() {
            byte[] s = name.getBytes();
            ByteBuffer buffer = ByteBuffer.allocate(s.length + 8);
            buffer.putInt(s.length);
            buffer.put(s);
            buffer.putInt(age);
            return buffer.array();
        }

        public static Person fromBytes(ByteBuffer buffer) {
            int stringSize = buffer.getInt();
            byte[] s = new byte[stringSize];
            buffer.get(s);
            return new Person(new String(s), buffer.getInt());
        }

        @Override
        public String toString() {
            return "Person{" +
                    "name='" + name + '\'' +
                    ", age=" + age +
                    '}';
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (!(o instanceof Person)) return false;

            Person person = (Person) o;

            return age == person.age && name.equals(person.name);
        }

        @Override
        public int hashCode() {
            int result = name.hashCode();
            result = 31 * result + age;
            return result;
        }

        private final static Random r = new Random(0);
        private final static String[] names = new String[]{
                "Lukas", "Emil", "Mathias", "Jonas", "Aleksander", "William", "Oskar", "Magnus", "Markus", "Oliver",
                "Nora", "Emma", "Sofie", "Linnea", "Sara", "Emilie", "Ingrid", "Thea", "Leah", "Sofia"};

        public static Person randomPerson() {
            return new Person(names[r.nextInt(names.length)], r.nextInt(80) + 20);
        }
    }
}