<?php
namespace Relay\Database;

use Relay\Files\Fs;
use Relay\Support\RelayError;

final class FileSink implements SqlSink
{
    /** @var resource|null */
    private $handle;
    private bool $gzip;
    private int $bytes = 0;

    public function __construct(string $path, bool $gzip)
    {
        $this->gzip = $gzip;
        $handle = $gzip ? (Fs::writable($path) ? gzopen($path, 'ab6') : false) : Fs::open($path, 'ab');
        if ($handle === false) {
            throw new RelayError('export.open_failed', esc_html__('Could not open the export file for writing.', 'siterelay'), esc_html__('Check that wp-content/uploads is writable.', 'siterelay'));
        }
        $this->handle = $handle;
    }

    public function statement(string $sql): void
    {
        $this->write($sql . ";\n");
    }

    public function write(string $text): void
    {
        if ($text === '') {
            return;
        }
        $written = $this->gzip ? gzwrite($this->handle, $text) : Fs::write($this->handle, $text);
        if ($written === false || $written < strlen($text)) {
            throw new RelayError('export.write_failed', esc_html__('Could not write to the export file. The disk may be full.', 'siterelay'));
        }
        $this->bytes += strlen($text);
    }

    public function bytes(): int { return $this->bytes; }

    public function close(): void
    {
        if ($this->handle !== null) {
            $this->gzip ? gzclose($this->handle) : Fs::close($this->handle);
            $this->handle = null;
        }
    }

    /** Cut a file back to a previously saved size (each gzip session is its own member, so this stays valid). */
    public static function truncate(string $path, int $size): void
    {
        clearstatcache(true, $path);
        if (is_file($path) && filesize($path) > $size) {
            $h = Fs::open($path, 'r+');
            ftruncate($h, $size);
            Fs::close($h);
        }
    }

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