<?php
// XArray.php
// Created: 2022-02-02
// Updated: 2023-11-09

namespace Index;

use stdClass;
use InvalidArgumentException;
use Countable;
use Iterator;
use IteratorAggregate;

/**
 * Provides various helper methods for collections.
 */
final class XArray {
    /**
     * Compare items normally without type casting for uniqueness.
     *
     * @var int
     */
    const UNIQUE_VALUE = SORT_REGULAR;

    /**
     * Compare items items as numbers.
     *
     * @var int
     */
    const UNIQUE_NUMBER = SORT_NUMERIC;

    /**
     * Compare items as strings.
     *
     * @var int
     */
    const UNIQUE_STRING = SORT_STRING;

    /**
     * Retrieves the amount of items in a collection.
     *
     * @return int
     */
    public static function count(iterable $iterable): int {
        if(is_array($iterable) || $iterable instanceof Countable)
            return count($iterable);

        $count = 0;

        foreach($iterable as $item)
            ++$count;

        return $count;
    }

    /**
     * Checks if a collection has no items.
     *
     * @return bool
     */
    public static function empty(iterable $iterable): bool {
        if(is_array($iterable))
            return empty($iterable);
        if($iterable instanceof Countable)
            return $iterable->count() < 1;

        $iterator = self::extractIterator($iterable);
        $iterator->rewind();

        return !$iterator->valid();
    }

    /**
     * Checks if an item occurs in a collection
     *
     * @param iterable $iterable
     * @param mixed $value
     * @param bool $strict
     * @return bool
     */
    public static function contains(iterable $iterable, mixed $value, bool $strict = false): bool {
        if(is_array($iterable))
            return in_array($value, $iterable, $strict);

        if($strict) {
            foreach($iterable as $item)
                if($item === $value)
                    return true;
        } else {
            foreach($iterable as $item)
                if($item == $value)
                    return true;
        }

        return false;
    }

    /**
     * Checks if a key occurs in a collection.
     *
     * @param iterable $iterable
     * @param mixed $key
     * @return bool
     */
    public static function containsKey(iterable $iterable, mixed $key): bool {
        if(is_array($iterable))
            return array_key_exists($key, $iterable);

        foreach($iterable as $k => $_)
            if($k === $key)
                return true;

        return false;
    }

    /**
     * Retrieves the first key in a collection.
     *
     * @param iterable $iterable
     * @return int|string|null
     */
    public static function firstKey(iterable $iterable): int|string|null {
        if(is_array($iterable))
            return array_key_first($iterable);

        foreach($iterable as $key => $_)
            return $key;

        return null;
    }

    /**
     * Retrieves the last key in a collection.
     *
     * @param iterable $iterable
     * @return int|string|null
     */
    public static function lastKey(iterable $iterable): int|string|null {
        if(is_array($iterable))
            return array_key_last($iterable);

        $key = null;
        foreach($iterable as $key => $_);

        return $key;
    }

    /**
     * Gets the index of a value in a collection.
     *
     * @param iterable $iterable
     * @param mixed $value
     * @param bool $strict
     * @return int|string|false
     */
    public static function indexOf(
        iterable $iterable,
        mixed $value,
        bool $strict = false
    ): int|string|false {
        if(is_array($iterable))
            return array_search($value, $iterable, $strict);

        if($strict) {
            foreach($iterable as $key => $item)
                if($item === $value)
                    return $key;
        } else {
            foreach($iterable as $key => $item)
                if($item == $value)
                    return $key;
        }

        return false;
    }

    /**
     * Extracts unique values from a collection.
     *
     * @param iterable $iterable
     * @param int $type
     * @return array
     */
    public static function unique(iterable $iterable, int $type = self::UNIQUE_VALUE): array {
        if(is_array($iterable))
            return array_unique($iterable, $type);

        // can probably be replicated better than this
        $items = [];

        foreach($iterable as $key => $item)
            $items[$key] = $item;

        return array_unique($items, $type);
    }

    /**
     * Takes values from a collection and discards the keys.
     *
     * @param iterable $iterable
     * @return array
     */
    public static function reflow(iterable $iterable): array {
        if(is_array($iterable))
            return array_values($iterable);

        $items = [];

        foreach($iterable as $item)
            $items[] = $item;

        return $items;
    }

    /**
     * Puts a collection in reverse order.
     *
     * @param iterable $iterable
     * @return array
     */
    public static function reverse(iterable $iterable): array {
        if(is_array($iterable))
            return array_reverse($iterable);

        $items = [];

        foreach($iterable as $key => $item)
            $items[$key] = $item;

        return array_reverse($items);
    }

    /**
     * Merges two collections.
     *
     * @param iterable $iterable1
     * @param iterable $iterable2
     * @return array
     */
    public static function merge(iterable $iterable1, iterable $iterable2): array {
        return array_merge(self::toArray($iterable1), self::toArray($iterable2));
    }

    /**
     * Sorts a collection according to a comparer.
     *
     * @param iterable $iterable
     * @param callable $comparer
     * @return array
     */
    public static function sort(iterable $iterable, callable $comparer): array {
        if(is_array($iterable)) {
            usort($iterable, $comparer);
            return $iterable;
        }

        $items = [];

        foreach($iterable as $key => $item)
            $items[$key] = $item;

        usort($items, $comparer);

        return $items;
    }

    /**
     * Takes a subsection of a collection.
     *
     * @param iterable $iterable
     * @param int $offset
     * @param int|null $length
     * @return array
     */
    public static function slice(iterable $iterable, int $offset, int|null $length = null): array {
        if(is_array($iterable))
            return array_slice($iterable, $offset, $length);

        $items = [];

        foreach($iterable as $key => $item)
            $items[$key] = $item;

        return array_slice($items, $offset, $length);
    }

    public static function toArray(iterable $iterable): array {
        if(is_array($iterable))
            return $iterable;

        $items = [];

        foreach($iterable as $key => $item)
            $items[$key] = $item;

        return $items;
    }

    /**
     * Checks if any value in the collection matches a given predicate.
     *
     * @param iterable $iterable
     * @param callable $predicate
     * @return bool
     */
    public static function any(iterable $iterable, callable $predicate): bool {
        foreach($iterable as $value)
            if($predicate($value))
                return true;

        return false;
    }

    /**
     * Checks if all values in the collection match a given predicate.
     *
     * @param iterable $iterable
     * @param callable $predicate
     * @return bool
     */
    public static function all(iterable $iterable, callable $predicate): bool {
        foreach($iterable as $value)
            if(!$predicate($value))
                return false;

        return true;
    }

    /**
     * Gets a subset of a collection based on a given predicate.
     *
     * @param iterable $iterable
     * @param callable $predicate
     * @return array
     */
    public static function where(iterable $iterable, callable $predicate): array {
        $array = [];

        foreach($iterable as $value)
            if($predicate($value))
                $array[] = $value;

        return $array;
    }

    /**
     * Gets the first item in a collection that matches a given predicate.
     *
     * @param iterable $iterable
     * @param callable|null $predicate
     * @return mixed
     */
    public static function first(iterable $iterable, ?callable $predicate = null): mixed {
        if($predicate === null) {
            if(is_array($iterable)) {
                if(empty($iterable))
                    return null;

                return $iterable[array_key_first($iterable)];
            }

            foreach($iterable as $value)
                return $value;

            return null;
        }

        foreach($iterable as $value)
            if($predicate($value))
                return $value;

        return null;
    }

    /**
     * Gets the last item in a collection that matches a given predicate.
     *
     * @param iterable $iterable
     * @param callable|null $predicate
     * @return mixed
     */
    public static function last(iterable $iterable, ?callable $predicate = null): mixed {
        if($predicate === null) {
            if(is_array($iterable)) {
                if(empty($iterable))
                    return null;

                return $iterable[array_key_last($iterable)];
            }

            $value = null;

            foreach($iterable as $value);

            return $value;
        }

        $iterable = self::reverse($iterable);
        foreach($iterable as $value)
            if($predicate($value))
                return $value;

        return null;
    }

    /**
     * Applies a modifier on a collection.
     *
     * @param iterable $iterable
     * @param callable $selector
     * @return array
     */
    public static function select(iterable $iterable, callable $selector): array {
        if(is_array($iterable))
            return array_map($selector, $iterable);

        $array = [];

        foreach($iterable as $key => $value)
            $array[] = $selector($value, $key);

        return $array;
    }

    /**
     * Tries to extract an instance of Iterator from any iterable type.
     *
     * @param iterable $iterable
     * @return Iterator
     */
    public static function extractIterator(iterable &$iterable): Iterator {
        if($iterable instanceof Iterator)
            return $iterable;
        if($iterable instanceof IteratorAggregate)
            return $iterable->getIterator(); // @phpstan-ignore-line
        if(is_array($iterable))
            return new ArrayIterator($iterable);

        throw new InvalidArgumentException('$iterable wasn\'t Iterator, IteratorAggregate or array.');
    }

    /**
     * Checks if two collections are equal in both keys and values.
     *
     * @param iterable $iterable1
     * @param iterable $iterable2
     * @return bool
     */
    public static function sequenceEquals(iterable $iterable1, iterable $iterable2): bool {
        if(count($iterable1) !== count($iterable2))
            return false;

        $iterator1 = self::extractIterator($iterable1);
        $iterator2 = self::extractIterator($iterable2);

        $iterator1->rewind();
        $iterator2->rewind();
        if(($valid = $iterator1->valid()) !== $iterator2->valid())
            return false;

        while($valid) {
            if($iterator1->key() !== $iterator2->key())
                return false;

            $c1 = $iterator1->current();
            $c2 = $iterator2->current();

            if($c1 instanceof IEquatable) {
                if(!$c1->equals($c2))
                    return false;
            } elseif($c2 instanceof IEquatable) {
                if(!$c2->equals($c1))
                    return false;
            } elseif($c1 !== $c2)
                return false;

            $iterator1->next();
            $iterator2->next();
            if(($valid = $iterator1->valid()) !== $iterator2->valid())
                return false;
        }

        return true;
    }
}