<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006~2019 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <liu21st@gmail.com>
// +----------------------------------------------------------------------

namespace think\model\relation;

use Closure;
use think\db\exception\DbException as Exception;
use think\helper\Str;
use think\Model;
use think\model\Relation;

/**
 * 多态关联类
 */
class MorphTo extends Relation
{
    /**
     * 多态关联外键
     * @var string
     */
    protected $morphKey;

    /**
     * 多态字段
     * @var string
     */
    protected $morphType;

    /**
     * 多态别名
     * @var array
     */
    protected $alias = [];

    /**
     * 关联名
     * @var string
     */
    protected $relation;

    /**
     * 架构函数
     * @access public
     * @param  Model  $parent    上级模型对象
     * @param  string $morphType 多态字段名
     * @param  string $morphKey  外键名
     * @param  array  $alias     多态别名定义
     * @param  string $relation  关联名
     */
    public function __construct(Model $parent, string $morphType, string $morphKey, array $alias = [], string $relation = null)
    {
        $this->parent    = $parent;
        $this->morphType = $morphType;
        $this->morphKey  = $morphKey;
        $this->alias     = $alias;
        $this->relation  = $relation;
    }

    /**
     * 获取当前的关联模型类的实例
     * @access public
     * @return Model
     */
    public function getModel(): Model
    {
        $morphType = $this->morphType;
        $model     = $this->parseModel($this->parent->$morphType);

        return (new $model);
    }

    /**
     * 延迟获取关联数据
     * @access public
     * @param  array   $subRelation 子关联名
     * @param  Closure $closure     闭包查询条件
     * @return Model
     */
    public function getRelation(array $subRelation = [], Closure $closure = null)
    {
        $morphKey  = $this->morphKey;
        $morphType = $this->morphType;

        // 多态模型
        $model = $this->parseModel($this->parent->$morphType);

        // 主键数据
        $pk = $this->parent->$morphKey;

        $relationModel = (new $model)->relation($subRelation)->find($pk);

        if ($relationModel) {
            $relationModel->setParent(clone $this->parent);
        }

        return $relationModel;
    }

    /**
     * 根据关联条件查询当前模型
     * @access public
     * @param  string  $operator 比较操作符
     * @param  integer $count    个数
     * @param  string  $id       关联表的统计字段
     * @param  string  $joinType JOIN类型
     * @param  Query   $query    Query对象
     * @return Query
     */
    public function has(string $operator = '>=', int $count = 1, string $id = '*', string $joinType = '', Query $query = null)
    {
        return $this->parent;
    }

    /**
     * 根据关联条件查询当前模型
     * @access public
     * @param  mixed  $where 查询条件（数组或者闭包）
     * @param  mixed  $fields 字段
     * @param  string $joinType JOIN类型
     * @param  Query  $query    Query对象
     * @return Query
     */
    public function hasWhere($where = [], $fields = null, string $joinType = '', Query $query = null)
    {
        throw new Exception('relation not support: hasWhere');
    }

    /**
     * 解析模型的完整命名空间
     * @access protected
     * @param  string $model 模型名（或者完整类名）
     * @return string
     */
    protected function parseModel(string $model): string
    {
        if (isset($this->alias[$model])) {
            $model = $this->alias[$model];
        }

        if (false === strpos($model, '\\')) {
            $path = explode('\\', get_class($this->parent));
            array_pop($path);
            array_push($path, Str::studly($model));
            $model = implode('\\', $path);
        }

        return $model;
    }

    /**
     * 设置多态别名
     * @access public
     * @param  array $alias 别名定义
     * @return $this
     */
    public function setAlias(array $alias)
    {
        $this->alias = $alias;

        return $this;
    }

    /**
     * 移除关联查询参数
     * @access public
     * @return $this
     */
    public function removeOption()
    {
        return $this;
    }

    /**
     * 预载入关联查询
     * @access public
     * @param  array   $resultSet   数据集
     * @param  string  $relation    当前关联名
     * @param  array   $subRelation 子关联名
     * @param  Closure $closure     闭包
     * @param  array   $cache       关联缓存
     * @return void
     * @throws Exception
     */
    public function eagerlyResultSet(array &$resultSet, string $relation, array $subRelation, Closure $closure = null, array $cache = []): void
    {
        $morphKey  = $this->morphKey;
        $morphType = $this->morphType;
        $range     = [];

        foreach ($resultSet as $result) {
            // 获取关联外键列表
            if (!empty($result->$morphKey)) {
                $range[$result->$morphType][] = $result->$morphKey;
            }
        }

        if (!empty($range)) {

            foreach ($range as $key => $val) {
                // 多态类型映射
                $model = $this->parseModel($key);
                $obj   = new $model;
                if (!\is_null($closure)) {
                    $obj = $closure($obj);
                }
                $pk    = $obj->getPk();
                $list  = $obj->with($subRelation)
                    ->cache($cache[0] ?? false, $cache[1] ?? null, $cache[2] ?? null)
                    ->select($val);
                $data = [];

                foreach ($list as $k => $vo) {
                    $data[$vo->$pk] = $vo;
                }

                foreach ($resultSet as $result) {
                    if ($key == $result->$morphType) {
                        // 关联模型
                        if (!isset($data[$result->$morphKey])) {
                            $relationModel = null;
                        } else {
                            $relationModel = $data[$result->$morphKey];
                            $relationModel->setParent(clone $result);
                            $relationModel->exists(true);
                        }

                        $result->setRelation($relation, $relationModel);
                    }
                }
            }
        }
    }

    /**
     * 预载入关联查询
     * @access public
     * @param  Model   $result      数据对象
     * @param  string  $relation    当前关联名
     * @param  array   $subRelation 子关联名
     * @param  Closure $closure     闭包
     * @param  array   $cache       关联缓存
     * @return void
     */
    public function eagerlyResult(Model $result, string $relation, array $subRelation = [], Closure $closure = null, array $cache = []): void
    {
        // 多态类型映射
        $model = $this->parseModel($result->{$this->morphType});

        $this->eagerlyMorphToOne($model, $relation, $result, $subRelation, $cache);
    }

    /**
     * 关联统计
     * @access public
     * @param  Model   $result  数据对象
     * @param  Closure $closure 闭包
     * @param  string  $aggregate 聚合查询方法
     * @param  string  $field 字段
     * @return integer
     */
    public function relationCount(Model $result, Closure $closure = null, string $aggregate = 'count', string $field = '*')
    {}

    /**
     * 多态MorphTo 关联模型预查询
     * @access protected
     * @param  string $model       关联模型对象
     * @param  string $relation    关联名
     * @param  Model  $result
     * @param  array  $subRelation 子关联
     * @param  array  $cache       关联缓存
     * @return void
     */
    protected function eagerlyMorphToOne(string $model, string $relation, Model $result, array $subRelation = [], array $cache = []): void
    {
        // 预载入关联查询 支持嵌套预载入
        $pk   = $this->parent->{$this->morphKey};
        $data = (new $model)->with($subRelation)
            ->cache($cache[0] ?? false, $cache[1] ?? null, $cache[2] ?? null)
            ->find($pk);

        if ($data) {
            $data->setParent(clone $result);
            $data->exists(true);
        }

        $result->setRelation($relation, $data ?: null);
    }

    /**
     * 添加关联数据
     * @access public
     * @param  Model  $model  关联模型对象
     * @param  string $type   多态类型
     * @return Model
     */
    public function associate(Model $model, string $type = ''): Model
    {
        $morphKey  = $this->morphKey;
        $morphType = $this->morphType;
        $pk        = $model->getPk();

        $this->parent->setAttr($morphKey, $model->$pk);
        $this->parent->setAttr($morphType, $type ?: get_class($model));
        $this->parent->save();

        return $this->parent->setRelation($this->relation, $model);
    }

    /**
     * 注销关联数据
     * @access public
     * @return Model
     */
    public function dissociate(): Model
    {
        $morphKey  = $this->morphKey;
        $morphType = $this->morphType;

        $this->parent->setAttr($morphKey, null);
        $this->parent->setAttr($morphType, null);
        $this->parent->save();

        return $this->parent->setRelation($this->relation, null);
    }

}