<?php
namespace DatabaseHelper;

use DatabaseHelper\enums\Propagation;
use DatabaseHelper\enums\Type;
use InvalidArgumentException;

class Migration
{
    protected Schema $schema;
    protected array $columnsToAdd = [];
    protected array $columnsToModify = [];
    protected array $columnsToDrop = [];
    protected array $primaryKey = null;
    protected array $foreignKeysToAdd = [];
    protected array $foreignKeysToDrop = [];

    public function __construct(Schema $table) {
        $this->schema = $table->copy();
    }

    public function add(string $name, Type $type, mixed $default = null, bool $isNullable = false, bool $isUnique = false): Migration {
        if ($this->schema->existsColumn($name))
            throw new InvalidArgumentException("Column '$name' already exists.");
        $this->schema->columns[$name] = [
            'name' => $name,
            'type' => $type,
            'default' => $default,
            'isNullable' => $isNullable,
            'isUnique' => $isUnique
        ];
        $this->columnsToAdd[] = $name;
        return $this;
    }

    public function modify(string $name, Type $type, mixed $default = null, bool $isNullable = false, bool $isUnique = false): Migration {
        $this->schema->requireColumn($name);
        $this->schema->columns[$name] = [
            'name' => $name,
            'type' => $type,
            'default' => $default,
            'isNullable' => $isNullable,
            'isUnique' => $isUnique
        ];
        $this->columnsToModify[] = $name;
        return $this;
    }

    public function delete(string $name): Migration {
        $this->schema->requireColumn($name);
        unset($this->schema->columns[$name]);
        $this->columnsToDrop[] = $name;
        return $this;
    }

    public function reference(Schema $foreignTable, Propagation $onDelete = Propagation::CASCADE, Propagation $onUpdate = Propagation::CASCADE): Migration {

    }

    public function dereference(Schema $foreignTable): Migration {

    }

    public function toSql(): string {

    }

    public function drop(): null {
        global $wpdb;

    }

    public function migrate(): Schema {
        global $wpdb;
        $sql = $this->toSql();
        $wpdb->query($sql);
        return $this->schema;
    }
}