<?php

class mysql {

    protected ?mysqli $link = null;

    function __construct(
        protected string $host,
        protected string $user,
        protected string $password,
        protected string $database) {}

    protected function prepareQuery(string $sql, ...$args): string {
        global $config;
        if (!empty($args)) {
            $mark_count = substr_count($sql, '?');
            $positions = array();
            $last_pos = -1;
            for ($i = 0; $i < $mark_count; $i++) {
                $last_pos = strpos($sql, '?', $last_pos + 1);
                $positions[] = $last_pos;
            }
            for ($i = $mark_count - 1; $i >= 0; $i--) {
                $arg_val = $args[$i];
                if (is_null($arg_val)) {
                    $v = 'NULL';
                } else {
                    $v = '\''.$this->escape($arg_val) . '\'';
                }
                $sql = substr_replace($sql, $v, $positions[$i], 1);
            }
        }
        if (!empty($config['mysql']['log']))
            logDebug(__METHOD__.': ', $sql);
        return $sql;
    }

    function insert(string $table, array $fields) {
        return $this->performInsert('INSERT', $table, $fields);
    }

    function replace(string $table, array $fields) {
        return $this->performInsert('REPLACE', $table, $fields);
    }

    protected function performInsert(string $command, string $table, array $fields) {
        $names = [];
        $values = [];
        $count = 0;
        foreach ($fields as $k => $v) {
            $names[] = $k;
            $values[] = $v;
            $count++;
        }

        $sql = "{$command} INTO `{$table}` (`" . implode('`, `', $names) . "`) VALUES (" . implode(', ', array_fill(0, $count, '?')) . ")";
        array_unshift($values, $sql);

        return $this->query(...$values);
    }

    function update(string $table, array $rows, ...$cond) {
        $fields = [];
        $args = [];
        foreach ($rows as $row_name => $row_value) {
            $fields[] = "`{$row_name}`=?";
            $args[] = $row_value;
        }
        $sql = "UPDATE `$table` SET ".implode(', ', $fields);
        if (!empty($cond)) {
            $sql .= " WHERE ".$cond[0];
            if (count($cond) > 1)
                $args = array_merge($args, array_slice($cond, 1));
        }
        return $this->query($sql, ...$args);
    }

    function multipleInsert(string $table, array $rows) {
        list($names, $values) = $this->getMultipleInsertValues($rows);
        $sql = "INSERT INTO `{$table}` (`".implode('`, `', $names)."`) VALUES ".$values;
        return $this->query($sql);
    }

    function multipleReplace(string $table, array $rows) {
        list($names, $values) = $this->getMultipleInsertValues($rows);
        $sql = "REPLACE INTO `{$table}` (`".implode('`, `', $names)."`) VALUES ".$values;
        return $this->query($sql);
    }

    protected function getMultipleInsertValues(array $rows): array {
        $names = [];
        $sql_rows = [];
        foreach ($rows as $i => $fields) {
            $row_values = [];
            foreach ($fields as $field_name => $field_val) {
                if ($i == 0) {
                    $names[] = $field_name;
                }
                $row_values[] = $this->escape($field_val);
            }
            $sql_rows[] = "('".implode("', '", $row_values)."')";
        }
        return [$names, implode(', ', $sql_rows)];
    }

    function __destruct() {
        if ($this->link)
            $this->link->close();
    }

    function connect(): bool {
        $this->link = new mysqli();
        $result = $this->link->real_connect($this->host, $this->user, $this->password, $this->database);
        if ($result)
            $this->link->set_charset('utf8mb4');
        return !!$result;
    }

    function query(string $sql, ...$args): mysqli_result|bool {
        $sql = $this->prepareQuery($sql, ...$args);
        $q = $this->link->query($sql);
        if (!$q)
            logError(__METHOD__.': '.$this->link->error."\n$sql\n".backtrace_as_string(1));
        return $q;
    }

    function fetch($q): ?array {
        $row = $q->fetch_assoc();
        if (!$row) {
            $q->free();
            return null;
        }
        return $row;
    }

    function fetchAll($q): ?array {
        if (!$q)
            return null;
        $list = [];
        while ($f = $q->fetch_assoc()) {
            $list[] = $f;
        }
        $q->free();
        return $list;
    }

    function fetchRow($q): ?array {
        return $q?->fetch_row();
    }

    function result($q, $field = 0) {
        return $q?->fetch_row()[$field];
    }

    function insertId(): int {
        return $this->link->insert_id;
    }

    function numRows($q): ?int {
        return $q?->num_rows;
    }

    function affectedRows(): ?int {
        return $this->link?->affected_rows;
    }

    function foundRows(): int {
        return (int)$this->fetch($this->query("SELECT FOUND_ROWS() AS `count`"))['count'];
    }

    function escape(string $s): string {
        return $this->link->real_escape_string($s);
    }

}

class mysql_bitfield {

    private GMP $value;
    private int $size;

    public function __construct($value, int $size = 64) {
        $this->value = gmp_init($value);
        $this->size = $size;
    }

    public function has(int $bit): bool {
        $this->validateBit($bit);
        return gmp_testbit($this->value, $bit);
    }

    public function set(int $bit): void {
        $this->validateBit($bit);
        gmp_setbit($this->value, $bit);
    }

    public function clear(int $bit): void {
        $this->validateBit($bit);
        gmp_clrbit($this->value, $bit);
    }

    public function isEmpty(): bool {
        return !gmp_cmp($this->value, 0);
    }

    public function __toString(): string {
        $buf = '';
        for ($bit = $this->size-1; $bit >= 0; --$bit)
            $buf .= gmp_testbit($this->value, $bit) ? '1' : '0';
        if (($pos = strpos($buf, '1')) !== false) {
            $buf = substr($buf, $pos);
        } else {
            $buf = '0';
        }
        return $buf;
    }

    private function validateBit(int $bit): void {
        if ($bit < 0 || $bit >= $this->size)
            throw new Exception('invalid bit '.$bit.', allowed range: [0..'.$this->size.')');
    }


}

function DB(): mysql|null {
    global $config;

    /** @var ?mysql $link */
    static $link = null;
    if (!is_null($link))
        return $link;

    $link = new mysql(
        $config['mysql']['host'],
        $config['mysql']['user'],
        $config['mysql']['password'],
        $config['mysql']['database']);
    if (!$link->connect()) {
        if (!is_cli()) {
            header('HTTP/1.1 503 Service Temporarily Unavailable');
            header('Status: 503 Service Temporarily Unavailable');
            header('Retry-After: 300');
            die('database connection failed');
        } else {
            fwrite(STDERR, 'database connection failed');
            exit(1);
        }
    }

    return $link;
}

function MC(): Memcached {
    static $mc = null;
    if ($mc === null) {
        $mc = new Memcached();
        $mc->addServer("127.0.0.1", 11211);
    }
    return $mc;
}