<?php

namespace cx_newsletter;

abstract class validator
implements validator_interface {
    public function __construct(\wpdb $database, table_names $tables) { 
        $this->database = $database;
        $this->target = null;
        $this->error = null;

        $this->prevalidate($database, $tables);
    }

    protected abstract function prevalidate(
        \wpdb $database, 
        table_names $tables
    ) : void;

    public function check() : self {
        $result = $this->validate();

        $this->error = null;
        
        if ($result !== null) {
            $this->make_error($result);
        }

        return $this;
    }

    protected abstract function validate() : ?string;

    protected function is_loaded() : bool {
        return $this->target !== null;
    }

    protected function get_target() : mixed {
        if (!$this->is_loaded()) {
            throw new \exception('Must load target before get it.');
        }

        return $this->target;
    }

    public function load(mixed $target) : self {
        $this->target = $target;

        return $this;
    }

    protected function make_error(string $content) : void {
        if (!$this->is_valid()) {
            throw new \exception('This validator has already error.');
        }

        $this->error = $content;
    }

    public function is_valid() : bool {
        return $this->error === null;
    }

    public function error_on() : string {
        if ($this->is_valid()) {
            throw new \exception('Trying to load error on valid object.');
        }

        return $this->error;
    }

    private mixed $target;
    private ?string $error;
}