<?php
declare(strict_types=1);

namespace Database;


use Closure;
use Exception;
use Kiri\Abstracts\Component;

/**
 * Class Pagination
 * @package Database
 */
class Pagination extends Component
{

    /** @var ActiveQuery */
    private ActiveQuery $activeQuery;

    /** @var int 从第几个开始查 */
    private int $_offset = 0;

    /** @var int 每页数量 */
    private int $_limit = 100;

    /** @var int 最大查询数量 */
    private int $_max = 0;

    /** @var int 当前已查询数量 */
    private int $_length = 0;

    /** @var Closure */
    private Closure $_callback;


    /**
     * PaginationIteration constructor.
     * @param ActiveQuery $activeQuery
     * @param array $config
     * @throws
     */
    public function __construct(ActiveQuery $activeQuery, array $config = [])
    {
        parent::__construct();
        $this->activeQuery = $activeQuery;
    }


    /**
     * @return void
     */
    public function clean(): void
    {
        unset($this->activeQuery, $this->_callback, $this->_group);
        $this->_offset = 0;
        $this->_limit  = 100;
        $this->_max    = 0;
        $this->_length = 0;;
    }


    /**
     * recover class by clone
     */
    public function __clone()
    {
        $this->clean();
    }


    /**
     * @param array|Closure $callback
     * @throws
     */
    public function setCallback(array|Closure $callback): void
    {
        if (!is_callable($callback, true)) {
            throw new Exception('非法回调函数~');
        }
        $this->_callback = $callback;
    }


    /**
     * @param int $number
     * @return Pagination
     */
    public function setOffset(int $number): static
    {
        if ($number < 0) {
            $number = 0;
        }
        $this->_offset = $number;
        return $this;
    }


    /**
     * @param int $number
     * @return Pagination
     */
    public function setLimit(int $number): static
    {
        if ($number < 1) {
            $number = 100;
        } else if ($number > 5000) {
            $number = 5000;
        }
        $this->_limit = $number;
        return $this;
    }


    /**
     * @param int $number
     * @return Pagination
     */
    public function setMax(int $number): static
    {
        if ($number < 0) {
            return $this;
        }
        $this->_max = $number;
        return $this;
    }


    /**
     * @param array $param
     * @return void
     * @throws
     */
    public function plunk(array $param = []): void
    {
        $this->loop($param);
    }


    /**
     * 轮训
     * @param $param
     * @return array
     * @throws
     */
    public function loop($param): array
    {
        if ($this->_max > 0 && $this->_length >= $this->_max) {
            return $this->output();
        }
        [$length, $data] = $this->get();
        try {
            call_user_func($this->_callback, $data, $param);
        } catch (\Throwable $exception) {
            error($exception);
        } finally {
            $data = null;
        }
        if ($length < $this->_limit) {
            return $this->output();
        }
        return $this->loop($param);
    }


    /**
     * @return array
     */
    public function output(): array
    {
        return [];
    }


    /**
     * @param $data
     * @param $param
     * @throws
     */
    private function executed($data, $param): void
    {
        try {
            call_user_func($this->_callback, $data, $param);
        } catch (\Throwable $exception) {
            error($exception);
        }
    }


    /**
     * @return array|Collection
     * @throws
     */
    private function get(): Collection|array
    {
        if ($this->_max > 0 && $this->_length + $this->_limit > $this->_max) {
            $this->_limit = $this->_length + $this->_limit - $this->_max;
        }
        $data          = $this->activeQuery->offset($this->_offset)->limit($this->_limit)->get();
        $this->_offset += $this->_limit;
        $size          = $data->size();
        $this->_length += $size;
        return [$size, $data];
    }

}