<?php
declare(strict_types=1);

namespace App\Dto;

/**
 * 数据集合传输对象
 */
class CollectionDto extends BaseDto
{
    private array $items = [];

    private int $count = 0;

    private array $meta = [];

    public function __construct(array $items = [])
    {
        $this->items = $items;
        $this->count = count($items);
    }

    public function getItems(): array
    {
        return $this->items;
    }

    public function setItems(array $items): self
    {
        $this->items = $items;
        $this->count = count($items);
        return $this;
    }

    public function getCount(): int
    {
        return $this->count;
    }

    public function getMeta(): array
    {
        return $this->meta;
    }

    public function setMeta(array $meta): self
    {
        $this->meta = $meta;
        return $this;
    }

    /**
     * 添加项目
     */
    public function add(mixed $item): self
    {
        $this->items[] = $item;
        $this->count++;
        return $this;
    }

    /**
     * 添加元数据
     */
    public function addMeta(string $key, mixed $value): self
    {
        $this->meta[$key] = $value;
        return $this;
    }

    /**
     * 检查是否为空
     */
    public function isEmpty(): bool
    {
        return $this->count === 0;
    }

    /**
     * 检查是否不为空
     */
    public function isNotEmpty(): bool
    {
        return $this->count > 0;
    }

    /**
     * 获取第一个项目
     */
    public function first(): mixed
    {
        return $this->items[0] ?? null;
    }

    /**
     * 获取最后一个项目
     */
    public function last(): mixed
    {
        return $this->items[$this->count - 1] ?? null;
    }

    /**
     * 获取指定索引的项目
     */
    public function get(int $index): mixed
    {
        return $this->items[$index] ?? null;
    }

    /**
     * 映射集合
     */
    public function map(callable $callback): self
    {
        $new = clone $this;
        $new->items = array_map($callback, $this->items);
        return $new;
    }

    /**
     * 过滤集合
     */
    public function filter(callable $callback): self
    {
        $new = clone $this;
        $new->items = array_filter($this->items, $callback);
        $new->count = count($new->items);
        return $new;
    }

    /**
     * 排序集合
     */
    public function sort(callable $callback): self
    {
        $new = clone $this;
        $items = $this->items;
        usort($items, $callback);
        $new->items = $items;
        return $new;
    }

    /**
     * 反转集合
     */
    public function reverse(): self
    {
        $new = clone $this;
        $new->items = array_reverse($this->items);
        return $new;
    }

    /**
     * 获取唯一的集合
     */
    public function unique(): self
    {
        $new = clone $this;
        $new->items = array_unique($this->items);
        $new->count = count($new->items);
        return $new;
    }

    /**
     * 切片集合
     */
    public function slice(int $offset, ?int $length = null): self
    {
        $new = clone $this;
        $new->items = array_slice($this->items, $offset, $length);
        $new->count = count($new->items);
        return $new;
    }

    /**
     * 限制集合大小
     */
    public function take(int $limit): self
    {
        return $this->slice(0, $limit);
    }

    /**
     * 跳过指定数量
     */
    public function skip(int $count): self
    {
        return $this->slice($count);
    }

    /**
     * 分块集合
     */
    public function chunk(int $size): array
    {
        return array_chunk($this->items, $size);
    }

    /**
     * 求和
     */
    public function sum(callable|string $key = null): float
    {
        if ($key === null) {
            return array_sum($this->items);
        }

        if (is_callable($key)) {
            return array_sum(array_map($key, $this->items));
        }

        return array_sum(array_column($this->items, $key));
    }

    /**
     * 求平均值
     */
    public function avg(callable|string $key = null): float
    {
        if ($this->isEmpty()) {
            return 0;
        }

        return $this->sum($key) / $this->count;
    }

    /**
     * 求最大值
     */
    public function max(callable|string $key = null): mixed
    {
        if ($this->isEmpty()) {
            return null;
        }

        if ($key === null) {
            return max($this->items);
        }

        if (is_callable($key)) {
            $values = array_map($key, $this->items);
            return max($values);
        }

        return max(array_column($this->items, $key));
    }

    /**
     * 求最小值
     */
    public function min(callable|string $key = null): mixed
    {
        if ($this->isEmpty()) {
            return null;
        }

        if ($key === null) {
            return min($this->items);
        }

        if (is_callable($key)) {
            $values = array_map($key, $this->items);
            return min($values);
        }

        return min(array_column($this->items, $key));
    }

    /**
     * 查找项目
     */
    public function find(callable $callback): mixed
    {
        foreach ($this->items as $item) {
            if ($callback($item)) {
                return $item;
            }
        }
        return null;
    }

    /**
     * 检查是否存在项目
     */
    public function contains(mixed $item): bool
    {
        return in_array($item, $this->items, true);
    }

    /**
     * 检查是否包含满足条件的项目
     */
    public function containsWhere(callable $callback): bool
    {
        return $this->find($callback) !== null;
    }

    /**
     * 获取所有键
     */
    public function keys(): array
    {
        return array_keys($this->items);
    }

    /**
     * 获取所有值
     */
    public function values(): array
    {
        return array_values($this->items);
    }

    /**
     * 合并其他集合
     */
    public function merge(self $other): self
    {
        $new = clone $this;
        $new->items = array_merge($this->items, $other->getItems());
        $new->count = count($new->items);
        return $new;
    }

    /**
     * 转换为分页对象
     */
    public function toPagination(int $page = 1, int $pageSize = 10): PaginationDto
    {
        $offset = ($page - 1) * $pageSize;
        $items = array_slice($this->items, $offset, $pageSize);
        
        return PaginationDto::create($items, $this->count, $page, $pageSize);
    }

    /**
     * 创建空集合
     */
    public static function empty(): self
    {
        return new self([]);
    }

    /**
     * 从数组创建集合
     */
    public static function fromArray(array $items): self
    {
        return new self($items);
    }

    /**
     * 创建包含单个项目的集合
     */
    public static function of(mixed $item): self
    {
        return new self([$item]);
    }

    /**
     * 创建范围集合
     */
    public static function range(int $start, int $end): self
    {
        return new self(range($start, $end));
    }

    /**
     * 转换为数组
     */
    public function toArray(): array
    {
        return [
            'items' => $this->items,
            'count' => $this->count,
            'meta' => empty($this->meta) ? null : $this->meta,
        ];
    }

    /**
     * 转换为JSON
     */
    public function toJson(): string
    {
        return json_encode($this->toArray(), JSON_UNESCAPED_UNICODE);
    }

    /**
     * 实现ArrayAccess接口
     */
    public function offsetExists(mixed $offset): bool
    {
        return isset($this->items[$offset]);
    }

    public function offsetGet(mixed $offset): mixed
    {
        return $this->items[$offset] ?? null;
    }

    public function offsetSet(mixed $offset, mixed $value): void
    {
        if ($offset === null) {
            $this->items[] = $value;
        } else {
            $this->items[$offset] = $value;
        }
        $this->count = count($this->items);
    }

    public function offsetUnset(mixed $offset): void
    {
        unset($this->items[$offset]);
        $this->count = count($this->items);
    }

    /**
     * 实现Countable接口
     */
    public function count(): int
    {
        return $this->count;
    }

    /**
     * 实现IteratorAggregate接口
     */
    public function getIterator(): \ArrayIterator
    {
        return new \ArrayIterator($this->items);
    }

    /**
     * 实现JsonSerializable接口
     */
    public function jsonSerialize(): array
    {
        return $this->toArray();
    }
}