<?php
namespace Relay\Database;

final class RowEncoder
{
    // Ported from WP Migrate 2.7.11 (GPL) Table::process_row value encoding. Changes: NULL ints stay NULL
    // (the original substituted the column default), bit values are written in binary (decbin), and pseudo
    // columns (__hex/__bit) are never emitted because only schema columns are iterated.
    public static function values(object $row, TableSchema $s, ?callable $transform = null): string
    {
        $out = [];
        foreach ($s->columns as $col) {
            $value = property_exists($row, $col) ? $row->$col : null;
            if ($value === null) {
                $out[] = 'NULL';
                continue;
            }
            if (isset($s->ints[$col])) {
                $out[] = is_numeric($value) ? (string) $value : "'" . self::escape((string) $value) . "'";
                continue;
            }
            if (isset($s->bins[$col])) {
                $hex = strtolower($col) . '__hex';
                $out[] = "UNHEX('" . preg_replace('/[^0-9A-Fa-f]/', '', (string) ($row->$hex ?? '')) . "')";
                continue;
            }
            if (isset($s->bits[$col])) {
                $bit = strtolower($col) . '__bit';
                $out[] = "b'" . decbin((int) ($row->$bit ?? 0)) . "'";
                continue;
            }
            if (isset($s->points[$col])) {
                $p = strlen((string) $value) >= 25 ? unpack('x4/corder/Ltype/dlon/dlat', (string) $value) : false;
                $out[] = is_array($p) && isset($p['lon'], $p['lat'])
                    ? "ST_GeomFromText('POINT(" . self::num($p['lon']) . ' ' . self::num($p['lat']) . ")')"
                    : 'NULL';
                continue;
            }
            $value = (string) $value;
            if ($transform !== null) {
                $value = $transform($col, $value);
            }
            $out[] = "'" . self::escape($value) . "'";
        }
        return '(' . implode(',', $out) . ')';
    }

    /** Backslash-escape for MySQL string literals; never leaves a raw newline, CR, NUL or ^Z. */
    public static function escape(string $value): string
    {
        $value = str_replace('\\', '\\\\', $value);
        $value = str_replace("'", "\\'", $value);
        return str_replace(["\x00", "\x0a", "\x0d", "\x1a"], ['\\0', '\\n', '\\r', '\\Z'], $value);
    }

    public static function columns(TableSchema $s): string
    {
        return '(' . implode(',', array_map([Db::class, 'ident'], $s->columns)) . ')';
    }

    /** Shortest-safe decimal that converts back to the exact same double. */
    private static function num(float $f): string
    {
        return sprintf('%.17G', $f);
    }
}