<?php

declare(strict_types=1);

namespace Psl\Collection;

use Closure;

/**
 * The base interface implemented for a collection type that you are able to access its values.
 *
 * Every concrete class indirectly implements this interface.
 *
 * @template Tk of array-key
 * @template Tv
 *
 * @extends CollectionInterface<Tk, Tv>
 * @extends IndexAccessInterface<Tk, Tv>
 */
interface AccessibleCollectionInterface extends CollectionInterface, IndexAccessInterface
{
    /**
     * Returns a `AccessibleCollectionInterface` containing the values of the current
     * `AccessibleCollectionInterface`.
     *
     * @return AccessibleCollectionInterface<int<0, max>, Tv>
     *
     * @psalm-mutation-free
     */
    public function values(): AccessibleCollectionInterface;

    /**
     * Returns a `AccessibleCollectionInterface` containing the keys of the current `AccessibleCollectionInterface`.
     *
     * @return AccessibleCollectionInterface<int<0, max>, Tk>
     *
     * @psalm-mutation-free
     */
    public function keys(): AccessibleCollectionInterface;

    /**
     * Returns a `AccessibleCollectionInterface` containing the values of the current `AccessibleCollectionInterface`
     * that meet a supplied condition.
     *
     * Only values that meet a certain criteria are affected by a call to
     * `filter()`.
     *
     * The keys associated with the current `AccessibleCollectionInterface` remain unchanged in the
     * returned `AccessibleCollectionInterface`.
     *
     * @param (Closure(Tv): bool) $fn The callback containing the condition to apply to the current
     *                                `AccessibleCollectionInterface` values.
     *
     * @return AccessibleCollectionInterface<Tk, Tv> A `AccessibleCollectionInterface` containing the values
     *                                               after a user-specified condition is applied.
     */
    public function filter(Closure $fn): AccessibleCollectionInterface;

    /**
     * Returns a `AccessibleCollectionInterface` containing the values of the current `AccessibleCollectionInterface`
     * that meet a supplied condition applied to its keys and values.
     *
     * Only keys and values that meet a certain criteria are affected by a call
     * to `filterWithKey()`.
     *
     * The keys associated with the current `AccessibleCollectionInterface` remain unchanged in the
     * returned `AccessibleCollectionInterface`; the keys will be used in the filtering process only.
     *
     * @param (Closure(Tk, Tv): bool) $fn The callback containing the condition to apply to the current
     *                                    `AccessibleCollectionInterface` keys and values.
     *
     * @return AccessibleCollectionInterface<Tk, Tv> A `AccessibleCollectionInterface` containing the values
     *                                               after a user-specified condition is applied to the keys and values
     *                                               of the current `AccessibleCollectionInterface`.
     */
    public function filterWithKey(Closure $fn): AccessibleCollectionInterface;

    /**
     * Returns the first value in the current `AccessibleCollectionInterface`.
     *
     * @return Tv|null The first value in the current `AccessibleCollectionInterface`, or `null` if the
     *                 current `AccessibleCollectionInterface` is empty.
     *
     * @psalm-mutation-free
     */
    public function first(): mixed;

    /**
     * Returns the first key in the current `AccessibleCollectionInterface`.
     *
     * @return Tk|null The first key in the current `AccessibleCollectionInterface`, or `null` if the
     *                 current `AccessibleCollectionInterface` is empty.
     *
     * @psalm-mutation-free
     */
    public function firstKey(): int|string|null;

    /**
     * Returns the last value in the current `AccessibleCollectionInterface`.
     *
     * @return Tv|null The last value in the current `AccessibleCollectionInterface`, or `null` if the
     *                 current `AccessibleCollectionInterface` is empty.
     *
     * @psalm-mutation-free
     */
    public function last(): mixed;

    /**
     * Returns the last key in the current `AccessibleCollectionInterface`.
     *
     * @return Tk|null The last key in the current `AccessibleCollectionInterface`, or `null` if the
     *                 current `AccessibleCollectionInterface` is empty.
     *
     * @psalm-mutation-free
     */
    public function lastKey(): int|string|null;

    /**
     * Returns the index of the first element that matches the search value.
     *
     * If no element matches the search value, this function returns null.
     *
     * @param Tv $search_value The value that will be search for in the current
     *                         `AccessibleCollectionInterface`.
     *
     * @return Tk|null The key (index) where that value is found; null if it is not found.
     *
     * @psalm-mutation-free
     */
    public function linearSearch(mixed $search_value): int|string|null;

    /**
     * Returns a `AccessibleCollectionInterface` where each element is a `array{0: Tv, 1: Tu}` that combines the
     * element of the current `AccessibleCollectionInterface` and the provided elements array.
     *
     * If the number of elements of the `AccessibleCollectionInterface` are not equal to the
     * number of elements in `$elements`, then only the combined elements
     * up to and including the final element of the one with the least number of
     * elements is included.
     *
     * @template Tu
     *
     * @param array<array-key, Tu> $elements The elements to use to combine with the elements of this `AccessibleCollectionInterface`.
     *
     * @return AccessibleCollectionInterface<Tk, array{0: Tv, 1: Tu}> The `AccessibleCollectionInterface` that combines the values of the current
     *                                                                `AccessibleCollectionInterface` with the provided elements.
     *
     * @psalm-mutation-free
     */
    public function zip(array $elements): AccessibleCollectionInterface;

    /**
     * Returns a `AccessibleCollectionInterface` containing the first `n` values of the current
     * `AccessibleCollectionInterface`.
     *
     * The returned `AccessibleCollectionInterface` will always be a proper subset of the current
     * `AccessibleCollectionInterface`.
     *
     * `$n` is 1-based. So the first element is 1, the second 2, etc.
     *
     * @param int<0, max> $n The last element that will be included in the returned
     *                       `AccessibleCollectionInterface`.
     *
     * @return AccessibleCollectionInterface<Tk, Tv> A `AccessibleCollectionInterface` that is a proper
     *                                               subset of the current `AccessibleCollectionInterface` up
     *                                               to `n` elements.
     *
     * @psalm-mutation-free
     */
    public function take(int $n): AccessibleCollectionInterface;

    /**
     * Returns a `AccessibleCollectionInterface` containing the values of the current `AccessibleCollectionInterface`
     * up to but not including the first value that produces `false` when passed
     * to the specified callback.
     *
     * The returned `AccessibleCollectionInterface` will always be a proper subset of the current
     * `AccessibleCollectionInterface`.
     *
     * @param (Closure(Tv): bool) $fn The callback that is used to determine the stopping
     *                                condition.
     *
     * @return AccessibleCollectionInterface<Tk, Tv> A `AccessibleCollectionInterface` that is a proper subset
     *                                               of the current `AccessibleCollectionInterface` up until
     *                                               the callback returns `false`.
     */
    public function takeWhile(Closure $fn): AccessibleCollectionInterface;

    /**
     * Returns a `AccessibleCollectionInterface` containing the values after the `n`-th element of
     * the current `AccessibleCollectionInterface`.
     *
     * The returned `AccessibleCollectionInterface` will always be a proper subset of the current
     * `AccessibleCollectionInterface`.
     *
     * `$n` is 1-based. So the first element is 1, the second 2, etc.
     *
     * @param int<0, max> $n The last element to be skipped; the $n+1 element will be the
     *                       first one in the returned `AccessibleCollectionInterface`.
     *
     * @return AccessibleCollectionInterface<Tk, Tv> A `AccessibleCollectionInterface` that is a proper subset
     *                                               of the current `AccessibleCollectionInterface` containing values
     *                                               after the specified `n`-th element.
     *
     * @psalm-mutation-free
     */
    public function drop(int $n): AccessibleCollectionInterface;

    /**
     * Returns a `AccessibleCollectionInterface` containing the values of the current `AccessibleCollectionInterface`
     * starting after and including the first value that produces `true` when
     * passed to the specified callback.
     *
     * The returned `AccessibleCollectionInterface` will always be a proper subset of the current
     * `AccessibleCollectionInterface`.
     *
     * @param (Closure(Tv): bool) $fn The callback used to determine the starting element for the
     *                                returned `AccessibleCollectionInterface`.
     *
     * @return AccessibleCollectionInterface<Tk, Tv> A `AccessibleCollectionInterface` that is a proper subset
     *                                               of the current `AccessibleCollectionInterface` starting after
     *                                               the callback returns `true`.
     */
    public function dropWhile(Closure $fn): AccessibleCollectionInterface;

    /**
     * Returns a subset of the current `AccessibleCollectionInterface` starting from a given key up
     * to, but not including, the element at the provided length from the starting
     * key.
     *
     * `$start` is 0-based. $len is 1-based. So `slice(0, 2)` would return the
     * elements at key 0 and 1.
     *
     * The returned `AccessibleCollectionInterface` will always be a proper subset of this
     * `AccessibleCollectionInterface`.
     *
     * @param int<0, max> $start The starting key of this Vector to begin the returned
     *                           `AccessibleCollectionInterface`
     * @param null|int<0, max> $length The length of the returned `AccessibleCollectionInterface`
     *
     * @return AccessibleCollectionInterface<Tk, Tv> A `AccessibleCollectionInterface` that is a proper subset
     *                                               of the current `AccessibleCollectionInterface` starting at `$start`
     *                                               up to but not including the element `$start + $length`.
     *
     * @psalm-mutation-free
     */
    public function slice(int $start, null|int $length = null): AccessibleCollectionInterface;

    /**
     * Returns a `AccessibleCollectionInterface` containing the original `AccessibleCollectionInterface` split into
     * chunks of the given size.
     *
     * If the original `AccessibleCollectionInterface` doesn't divide evenly, the final chunk will be
     * smaller.
     *
     * @param positive-int $size The size of each chunk.
     *
     * @return AccessibleCollectionInterface<int<0, max>, static<Tk, Tv>> A `AccessibleCollectionInterface` containing the original
     *                                                                    `AccessibleCollectionInterface` split into chunks of the given size.
     *
     * @psalm-mutation-free
     */
    public function chunk(int $size): AccessibleCollectionInterface;
}