cx-newsletter/templates/04-database_builder.php

<?php

namespace cx_newsletter;
use \wpdb;
use \cx_appengine\string_builder;

abstract class database_builder
extends database_worker
implements database_builder_interface {
    public function __construct(
        wpdb $database, 
        table_names $tables, 
        database_versions_manager $versions
    ) {
        parent::__construct($database, $tables);
        $this->versions = $versions;
    }

    protected function drop_table(string $name) : void {
        $query = $this->get_database()->prepare('drop table if exists '.$name);
        $this->get_database()->query($query);
    }

    protected function table_exists(string $name) : bool {
        $name = $this->get_database()->esc_like($name);
        $query = $this->get_database()->prepare('show tables like %s', $name);

        return $this->get_database()->get_var($query) === $name; 
    }
   
    protected function add_column(
        string $table, 
        string $column, 
        string $type
    ) : void {
        $query = (
            'alter table '.$table.' '.
            'add column '.$column.' '.$type
        );

        $this->get_database()->query($query);
    }

    protected function add_foreign_key(
        string $table,
        string $column,
        string $foreign_table,
        string $foreign_column
    ) : void {
        $query = (
            'alter table '.$table.' '.
            'add foreign key ('.$column.') '.
            'references '.$foreign_table.'('.$foreign_column.')'
        );

        $this->get_database()->query($query);
    }

    protected function create_table(string $name, array $structure) : void {
        $query = 'create table '.$name.' ';
        $query .= $this->string_from_structure($structure);

        $this->get_database()->query($query);
    }

    private function string_from_structure(array $structure) : string {
        $flat = [];

        foreach ($structure as $key => $type) {
            array_push($flat, $key.' '.$type);
        }

        $result = new string_builder($flat, ', ');
        $result->push(')');
        $result->push_start('(');

        return $result->get();
    }

    protected function get_versions() : database_versions_manager {
        return $this->versions;
    }

    private database_versions_manager $versions;
}