<?php
/**
 * This source file is part of the open source project
 * ExpressionEngine (https://expressionengine.com)
 *
 * @link      https://expressionengine.com/
 * @copyright Copyright (c) 2003-2022, Packet Tide, LLC (https://www.packettide.com)
 * @license   https://expressionengine.com/license Licensed under Apache License, Version 2.0
 */

namespace ExpressionEngine\Service\Model\Relation;

use ExpressionEngine\Service\Model\Model;
use ExpressionEngine\Service\Model\MetaDataReader;

/**
 * Relation
 *
 * Relations describe how two model classes are related. For distinct
 * instance connections, @see Associations.
 */
abstract class Relation
{
    protected $from;
    protected $to;
    protected $name;
    protected $is_weak;
    protected $inverse;
    protected $inverse_info;

    protected $to_table;
    protected $from_table;

    protected $from_key;
    protected $to_key;
    protected $key_tuple;

    protected $from_primary_key;
    protected $to_primary_key;

    protected $datastore;

    public function __construct(MetaDataReader $from, MetaDataReader $to, $name, $options)
    {
        $this->from = $from;
        $this->to = $to;
        $this->name = $name;

        $this->from_primary_key = $from->getPrimaryKey();
        $this->to_primary_key = $to->getPrimaryKey();

        $this->is_weak = false;
        $this->processOptions($options);
    }

    /**
     * Remove some variables to get cleaner var_dump
     *
     * @return array
     */
    public function __debugInfo()
    {
        $footprint = get_object_vars($this);
        unset($footprint['datastore']);
        return $footprint;
    }

    /**
     *
     */
    abstract public function createAssociation();

    /**
     *
     */
    abstract public function fillLinkIds(Model $source, Model $target);

    /**
     *
     */
    abstract public function linkIds(Model $source, Model $target);

    /**
     *
     */
    abstract public function unlinkIds(Model $source, Model $target);

    /**
     *
     */
    abstract public function markLinkAsClean(Model $source, Model $target);

    /**
     *
     */
    abstract public function canSaveAcross();

    /**
     * Insert a database link between the model and targets
     */
    abstract public function insert(Model $source, $targets);

    /**
     * Drop the database link between the model and targets, potentially
     * triggering a soft delete.
     */
    abstract public function drop(Model $source, $targets = null);

    /**
     * Set the relation. Should do the minimum viable sql modifications required
     * to maintain consistency.
     */
    abstract public function set(Model $source, $targets);

    /**
     *
     */
    abstract protected function deriveKeys();

    /**
     * Reverse this relation. This allows us to set both sides of an
     * association when those get set.
     *
     * @return Relation Inverse of this relation or NULL
     */
    public function getInverse()
    {
        if (! isset($this->inverse)) {
            if ($this->hasForeignInverse()) {
                $this->setInverse($this->datastore->getGraph()->makeForeignInverse($this));
            } else {
                $this->setInverse($this->datastore->getGraph()->getInverse($this));
            }
        }

        return $this->inverse;
    }

    public function setInverse(Relation $inverse)
    {
        if (! isset($this->inverse)) {
            $this->inverse = $inverse;
        }
    }

    public function hasInverse()
    {
        return isset($this->inverse);
    }

    public function hasForeignInverse()
    {
        return isset($this->inverse_info);
    }

    /**
     *
     */
    public function modifyEagerQuery($query, $from_alias, $to_alias)
    {
        list($from, $to) = $this->getKeys();

        $query->join(
            "{$this->to_table} AS {$to_alias}_{$this->to_table}",
            "{$to_alias}_{$this->to_table}.{$to} = {$from_alias}_{$this->from_table}.{$from}",
            'LEFT'
        );
    }

    /**
     *
     */
    public function modifyLazyQuery($query, $source, $to_alias)
    {
        list($from, $to) = $this->getKeys();

        $query->where("{$to_alias}_{$this->to_table}.{$to}", $source->$from);
    }

    /**
     *
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     *
     */
    public function getSourceModel()
    {
        return $this->from->getName();
    }

    /**
     *
     */
    public function getTargetModel()
    {
        return $this->to->getName();
    }

    public function isWeak()
    {
        return $this->is_weak;
    }

    /**
     *
     */
    public function setDataStore($datastore)
    {
        $this->datastore = $datastore;
    }

    /**
     *
     */
    public function getKeys()
    {
        return $this->key_tuple;
    }

    public function getPivot()
    {
        return array();
    }

    public function getInverseOptions()
    {
        return array(
            'type' => $this->inverse_info['type'],
            'name' => $this->inverse_info['name'],

            'model' => $this->getSourceModel(),

            'from_key' => $this->to_key,
            'from_primary_key' => $this->to_primary_key,

            'to_key' => $this->from_key,
            'to_primary_key' => $this->from_primary_key,

            'weak' => $this->is_weak
        );
    }

    /**
     *
     */
    protected function processOptions($options)
    {
        if (isset($options['weak'])) {
            $this->is_weak = (bool) $options['weak'];
        }

        if (isset($options['from_key'])) {
            $this->from_key = $options['from_key'];
        }

        if (isset($options['to_key'])) {
            $this->to_key = $options['to_key'];
        }

        if (isset($options['inverse'])) {
            $this->inverse_info = $options['inverse'];
        }

        $this->key_tuple = $this->deriveKeys();
        list($from, $to) = $this->key_tuple;

        $this->from_key = $from;
        $this->to_key = $to;

        $this->from_table = $this->from->getTableForField($from);
        $this->to_table = $this->to->getTableForField($to);

        if (! $this->from_table) {
            throw new \Exception('Cannot find table for field ' . $from . ' on ' . $this->from->getClass());
        }

        if (! $this->to_table) {
            throw new \Exception('Cannot find table for field ' . $to . ' on ' . $this->to->getClass() . ' from ' . $this->from->getClass());
        }
    }
}

// EOF
