<?php

/**
 * Wrapper around PHP's Prepared Statements.
 *
 * 2018
 *
 * More info: http://php.net/manual/en/mysqli.quickstart.prepared-statements.php
 */
class Database {

    /**
     * Change the below variables to match your host name, database name, user
     * name, and password respectively.
     */
    private $host = "localhost";
    private $name = "<redacted>";
    private $user = "<redacted>";
    private $pass = "<redacted>";

    /**
     * Other variables
     */
    private $connection = NULL;
    public $connected = false;
    public $error = "";

    /**
     * Tries to connect and returns whether the attempt was succesful
     */
    function connect() {
        if ($this->connected === true) {
            $this->error = "";
            return true;
        }


        $this->connection = new mysqli($this->host, $this->user, $this->pass, $this->name);

        // has the connection failed
        if ($this->connection->connect_errno !== 0) {
            // connection failed, so set the error and connection
            // status
            $this->error = $this->connection->connect_error;
            $this->connected = false;
            $this->connection->close();
        } else {
            // successful, so unset the error and set the connected
            // flag
            $this->error = "";
            $this->connected = true;
        }

        return $this->connected;
    }

    /**
     * Returns false on failure
     */
    function disconnect() {
        $this->connection = null;
        // $this->connection->close();
        $this->connected = false;
        $this->error = "";
        return true;
    }

    /**
     * Performs a query with types and returns the result or false on
     * failure.
     * See
     *
     * Ex. $db->query("SELECT * FROM things WHERE id = ?", "i", $id);
     */
    function query(string $query, string $types = null, ...$params) {
        $this->error = "";

        if (!$this->connected) {
            return false;
        }

        if (is_null($types) || count($params) === 0) {
            $result = $this->connection->query($query);
        } else {
            // prepare query
            $statement = $this->connection->prepare($query);

            if (!$statement) {
                return false;
            }

            // bind params
            if (!$statement->bind_param($types, ...$params)) {
                return false;
            }

            // execute
            if (!$statement->execute()) {
                return false;
            }

            $result = $this->get_result($statement);
        }

        if (!$result) {
            return false;
        }

        return $result;
    }

    function get_result($statement) {
        $ret = new fake_mysqli_result($statement);
        if (!$ret)
            return null;

        return $ret;
    }
}

/**    EXPLANATION:
 * We are creating a fake "result" structure to enable us to have
 * source-level equivalent syntax to a query executed via
 * mysqli_query().
 **/
class fake_mysqli_result {
    public $statement, $field_count;

    function __construct($statement) {
        $this->statement = $statement;

        $metadata = $statement->result_metadata();

        if ($metadata === false) {
            return null;
        }

        $this->field_count = $metadata->field_count;
        $metadata->free_result();
    }

    function fetch_array() {
        $ret = array_fill(0, $this->field_count, null);

        if (!$this->statement->bind_result(...$ret)) {
            return null;
        }

        // This should advance the "$this->statement" cursor.
        if (!$this->statement->fetch()) {
            return null;
        }

        // Return the array we built.
        return $ret;
    }
}