<?php
namespace DatabaseHelper;

use Exception;
use InvalidArgumentException;

class Deletion
{
    use Conditionable;

    protected Schema $table;

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

    /**
     * Generates the SQL statement.
     * @return string SQL query.
     * @throws InvalidArgumentException
     */
    public function toSql(): string {
        $table = $this->table->name;
        $whereClause = $this->combineConditions();

        if (!$this->isConditioned())
            throw new InvalidArgumentException("Deletions need to be conditioned.");

        return "DELETE FROM $table WHERE $whereClause";
    }

    /**
     * Executes the DELETE query.
     * @return int Number of affected rows.
     * @throws Exception
     */
    public function delete(): int {
        global $wpdb;
        $query = $this->toSql();
        $result = $wpdb->query($query);

        if ($result === false)
            throw new Exception("Deletion failed: " . $wpdb->last_error . ".");
        return intval($result);
    }

    /**
     * Clears all entries from the table.
     * @return int Number of affected rows.
     * @throws Exception
     */
    public function truncate(): int {
        global $wpdb;
        $table = $this->table->name;
        $query = esc_sql("TRUNCATE TABLE $table");
        $result = $wpdb->query($query);

        if ($result === false)
            throw new Exception("Truncation failed: " . $wpdb->last_error . ".");
        return intval($result);
    }
}