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Functional Programming Library for Java
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/*
 * Copyright (c) 2018-2024, Antonio Gabriel Muñoz Conejo 
 * Distributed under the terms of the MIT License
 */
package com.github.tonivade.purefun.data;

import static com.github.tonivade.purefun.core.Precondition.checkNonNull;
import static java.util.stream.Collectors.collectingAndThen;
import java.io.Serial;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import org.pcollections.PVector;
import org.pcollections.TreePVector;

import com.github.tonivade.purefun.Kind;
import com.github.tonivade.purefun.core.Equal;
import com.github.tonivade.purefun.core.Function1;
import com.github.tonivade.purefun.core.Matcher1;

/**
 * Similar to a ArrayList
 * @param  the type of elements in this array
 */
public interface ImmutableArray extends Sequence {

  List toList();

  @Override
  ImmutableArray append(E element);
  @Override
  ImmutableArray remove(E element);
  @Override
  ImmutableArray appendAll(Sequence other);
  @Override
  ImmutableArray removeAll(Sequence other);

  @Override
  ImmutableArray reverse();
  ImmutableArray sort(Comparator comparator);

  E get(int position);
  ImmutableArray remove(int position);
  ImmutableArray replace(int position, E element);
  ImmutableArray insert(int position, E element);
  ImmutableArray insertAll(int position, Sequence elements);

  ImmutableArray drop(int n);

  @Override
  default  ImmutableArray map(Function1 mapper) {
    return ImmutableArray.from(stream().map(mapper::apply));
  }

  @Override
  default  ImmutableArray flatMap(Function1, ? extends R>> mapper) {
    return ImmutableArray.from(stream().flatMap(mapper.andThen(SequenceOf::toSequence).andThen(Sequence::stream)::apply));
  }

  @Override
  default ImmutableArray filter(Matcher1 matcher) {
    return ImmutableArray.from(stream().filter(matcher::match));
  }

  @Override
  default ImmutableArray filterNot(Matcher1 matcher) {
    return filter(matcher.negate());
  }

  static  ImmutableArray from(Iterable iterable) {
    return from(Sequence.asStream(iterable.iterator()));
  }

  static  ImmutableArray from(Stream stream) {
    ArrayList collect = stream.collect(Collectors.toCollection(ArrayList::new));
    return new PImmutableArray<>(collect);
  }

  @SafeVarargs
  static  ImmutableArray of(T... elements) {
    return from(Arrays.stream(elements));
  }

  @SuppressWarnings("unchecked")
  static  ImmutableArray empty() {
    return (ImmutableArray) PImmutableArray.EMPTY;
  }

  static  Collector> toImmutableArray() {
    return collectingAndThen(Collectors.toCollection(ArrayList::new), PImmutableArray::new);
  }

  final class PImmutableArray implements ImmutableArray, Serializable {

    private static final ImmutableArray EMPTY = new PImmutableArray<>(TreePVector.empty());

    private static final Equal> EQUAL = Equal.>of().comparing(a -> a.backend);

    @Serial
    private static final long serialVersionUID = -6967820945086954257L;

    private final PVector backend;

    private PImmutableArray(Collection collection) {
      this(TreePVector.from(collection));
    }

    private PImmutableArray(PVector backend) {
      this.backend = checkNonNull(backend);
    }

    @Override
    public int size() {
      return backend.size();
    }

    @Override
    public boolean contains(Object element) {
      return backend.contains(element);
    }

    @Override
    public Iterator iterator() {
      return backend.iterator();
    }

    @Override
    public List toList() {
      return new ArrayList<>(backend);
    }

    @Override
    public ImmutableArray append(E element) {
      return new PImmutableArray<>(backend.plus(element));
    }

    @Override
    public ImmutableArray remove(E element) {
      return new PImmutableArray<>(backend.minus(element));
    }

    @Override
    public ImmutableArray appendAll(Sequence other) {
      return new PImmutableArray<>(backend.plusAll(other.toCollection()));
    }

    @Override
    public ImmutableArray removeAll(Sequence other) {
      return new PImmutableArray<>(backend.minusAll(other.toCollection()));
    }

    @Override
    public ImmutableArray drop(int n) {
      if (n >= backend.size()) {
        return empty();
      }
      return new PImmutableArray<>(backend.subList(n, backend.size()));
    }

    @Override
    public ImmutableArray reverse() {
      return new PImmutableArray<>(backend.reversed());
    }

    @Override
    public ImmutableArray sort(Comparator comparator) {
      var copy = new ArrayList<>(backend);
      copy.sort(comparator);
      return new PImmutableArray<>(copy);
    }

    @Override
    public E get(int position) {
      return backend.get(position);
    }

    @Override
    public ImmutableArray remove(int position) {
      return new PImmutableArray<>(backend.minus(position));
    }

    @Override
    public ImmutableArray replace(int position, E element) {
      return new PImmutableArray<>(backend.with(position, element));
    }

    @Override
    public ImmutableArray insert(int position, E element) {
      return new PImmutableArray<>(backend.plus(position, element));
    }

    @Override
    public ImmutableArray insertAll(int position, Sequence elements) {
      return new PImmutableArray<>(backend.plusAll(position, elements.toCollection()));
    }

    @Override
    public int hashCode() {
      return Objects.hash(backend);
    }

    @Override
    public boolean equals(Object obj) {
      return EQUAL.applyTo(this, obj);
    }

    @Override
    public String toString() {
      return "ImmutableArray(" + backend + ")";
    }

    @Serial
    private Object readResolve() {
      if (backend.isEmpty()) {
        return EMPTY;
      }
      return this;
    }
  }
}