<?php

namespace cx_newsletter;
use \wpdb;

abstract class database_worker {
    public function __construct(
        wpdb $database, 
        table_names $tables, 
    ) {
        $this->database = $database;
        $this->tables = $tables;
    }

    protected function parse_limit(?int $limit) : string {
        if ($limit === null) {
            return '';
        }

        return 'limit '.strval($limit).' ';
    }

    protected function parse_filters(
        array $filters,
        filter_type $type = filter_type::equal,
        filter_glue $glue = filter_glue::all
    ) : string {
        if (empty($filters)) {
            return '';
        }

        $result = new \cx_appengine\string_builder('where ');
        
        foreach ($filters as $name => $content) {
            $result->push($name);

            if ($content === null) {
                $result->push(' is null');
            } elseif (is_numeric($content)) {
                $result->push($type->value.strval($content));
            } elseif (is_string($content)) {
                $result->push($type->value.'"'.$content.'"');
            } else {
                throw $this->get_exception('parse_filters');
            }

            $result->push($glue->value);
        }       

        return $result->cut(strlen($glue->value))->push(' ')->get();
    }

    protected function get_exception(string $operation) : \exception {
        $exception = "\n\n";
        $exception .= 'Can not make operation on database in class: ';
        $exception .= get_class($this).'. Trying to make: '.$operation.'.'; 
        $exception .= "\n\n";

        return new \exception($exception);
    }

    protected function get_has_id_exception() : \exception {
        $exception = "\n\n";
        $exception .= 'Can not make operation on database in class: ';
        $exception .= get_class($this).'. Trying to insert item with ID.'; 
        $exception .= "\n\n";

        return new \exception($exception);
    }

    protected function get_blank_id_exception() : \exception {
        $exception = "\n\n";
        $exception .= 'Can not make operation on database in class: ';
        $exception .= get_class($this).'. Trying to load target without ID.';
        $exception .= "\n\n";

        return new \exception($exception);
    }

    protected function get_tables() : table_names {
        return $this->tables;
    }

    protected function get_database() : wpdb {
        return $this->database;
    }

    private table_names $tables;
    private wpdb $database;
}