<?php

namespace App\Xapi\Fake;

use App\Xapi\Xva;

/**
 * The demo pool's HTTP handlers for XVA files (part of FakeXapi): GET /export?session_id=…&ref=<vm>&task_id=…&use_compression=…
 * streams a small XVA (a tar: ova.xml + the disks in 1 MiB members), PUT /import?session_id=…&sr_id=…&task_id=… reads one and
 * makes a halted VM of it, its ref in the task's result as XAPI writes it. task.create makes the task the client follows.
 */
trait XvaOps
{
    /** @var list<FakeHttpStream> */
    private array $httpStreams = [];
    /** the size of each fake disk in an export (tests make it smaller or bigger) */
    public int $xvaDiskBytes = 2097152;

    /** @return array{0: \Closure(): object, 1: string} how to open a stream of one's own to this server (HttpStreamTransfer), and its Host */
    public function connector(): array
    {
        return [function (): object {
            $stream = new FakeHttpStream(fn (FakeHttpStream $s, string $what) => $this->onHttp($s, $what));
            $this->httpStreams[] = $stream;
            return $stream;
        }, $this->address];
    }

    private function pollXva(float $dt): void
    {
        foreach ($this->httpStreams as $i => $stream) {
            $stream->poll();
            $task = (string)($stream->context['task'] ?? '');
            if ($task !== '' && $stream->method === 'GET' && isset($stream->context['size']) && ($this->db['task'][$task]['status'] ?? '') === 'pending') {
                $progress = round(min(0.99, $stream->sent / max(1.0, (float)$stream->context['size'])), 2);
                if (abs($progress - (float)$this->db['task'][$task]['progress']) >= 0.1) {
                    $this->set('task', $task, ['progress' => $progress]);
                }
                if ($stream->isClosed()) {
                    $this->set('task', $task, ['status' => 'success', 'progress' => 1.0, 'finished' => $this->date()]);
                }
            }
            if ($stream->isClosed()) {
                unset($this->httpStreams[$i]);
            }
        }
        $this->httpStreams = array_values($this->httpStreams);
    }

    /** @return array{0: float, 1: \Closure, 2: string, 3: string}|null */
    private function xvaOperation(string $class, string $method, array $p): ?array
    {
        if ($class === 'task' && $method === 'create') {
            return [0.0, fn (): string => $this->add('task', ['name_label' => (string)($p[0] ?? ''), 'name_description' => (string)($p[1] ?? ''), 'status' => 'pending',
                'progress' => 0.0, 'created' => $this->date(), 'finished' => '19700101T00:00:00Z', 'result' => '', 'error_info' => [],
                'resident_on' => array_key_first($this->db['host']), 'allowed_operations' => ['cancel'], 'other_config' => []]), 'Creating a task', ''];
        }
        return null;
    }

    /** task.cancel of a task an HTTP handler works for: the handler stops and closes its connection, as XAPI's do. */
    private function cancelHttp(string $task): void
    {
        foreach ($this->httpStreams as $stream) {
            if (($stream->context['task'] ?? '') === $task && !$stream->isClosed()) {
                $this->set('task', $task, ['status' => 'cancelled', 'finished' => $this->date()]);
                $stream->close();
            }
        }
    }

    private function onHttp(FakeHttpStream $s, string $what): void
    {
        parse_str((string)parse_url($s->path, PHP_URL_QUERY), $q);
        $route = (string)parse_url($s->path, PHP_URL_PATH);
        $task = (string)($q['task_id'] ?? '');
        if ($what === 'head') {
            $s->context['task'] = isset($this->db['task'][$task]) ? $task : '';
            if (!isset($this->sessions[(string)($q['session_id'] ?? '')])) {
                $s->reply(403, 'Forbidden', ['Content-Length' => '0']);
                return;
            }
            if ($route === '/export' && $s->method === 'GET') {
                $this->httpExport($s, (string)($q['ref'] ?? ''), ($q['use_compression'] ?? '') === 'true');
            } elseif ($route === '/import' && $s->method === 'PUT') {
                $sr = (string)($q['sr_id'] ?? '');
                if (!isset($this->db['sr'][$sr])) {
                    $this->failTask($s, ['HANDLE_INVALID', 'SR', $sr]);
                    return;
                }
                $s->context['sr'] = $sr;
                $s->context['length'] = (float)($s->headers['content-length'] ?? 0);
                if ($s->context['length'] <= 0) {
                    $this->failTask($s, ['IMPORT_ERROR', 'No Content-Length']);
                }
            } else {
                $s->reply(404, 'Not Found', ['Content-Length' => '0']);
            }
            return;
        }
        // a part of an upload arrived
        if ($route !== '/import' || !isset($s->context['sr']) || !empty($s->context['answered'])) {
            return;
        }
        $length = (float)$s->context['length'];
        $task = (string)$s->context['task'];
        if ($task !== '') {
            $progress = round(min(0.99, $s->received / max(1.0, $length)), 2);
            if (abs($progress - (float)$this->db['task'][$task]['progress']) >= 0.1) {
                $this->set('task', $task, ['progress' => $progress]);
            }
        }
        if ($s->received < $length) {
            return;
        }
        $s->context['answered'] = true;
        $info = Xva::readHeader($s->bodyHead);
        if ($info === null) {
            $this->failTask($s, ['IMPORT_ERROR', 'The file is not an XVA export (no ova.xml at its start).']);
            return;
        }
        $disk = 0;
        foreach ($info['disks'] as [, $size]) {
            $disk = max($disk, (int)ceil($size / self::GIB));
        }
        $network = (string)array_key_first($this->db['network']);
        $vm = $this->addVm(['name_label' => (string)$info['name_label'], 'description' => (string)$info['name_description'], 'power_state' => 'Halted',
            'memory' => max(256 * self::MIB, (float)$info['memory_static_max']), 'vcpus' => max(1, (int)$info['VCPUs_max']), 'disk' => max(1, $disk),
            'sr' => (string)$s->context['sr'], 'networks' => [$network], 'index' => count($this->db['vm'])]);
        if ($task !== '') {
            $this->set('task', $task, ['status' => 'success', 'progress' => 1.0, 'finished' => $this->date(),
                'result' => '<value><array><data><value>' . $vm . '</value></data></array></value>']);
        }
        $s->reply(200, 'OK', ['Content-Length' => '0']);
    }

    private function httpExport(FakeHttpStream $s, string $vm, bool $compress): void
    {
        $record = $this->db['vm'][$vm] ?? null;
        if ($record === null) {
            $this->failTask($s, ['HANDLE_INVALID', 'VM', $vm]);
            return;
        }
        if ($record['power_state'] !== 'Halted' && empty($record['is_a_snapshot'])) {
            $this->failTask($s, ['VM_BAD_POWER_STATE', $vm, 'halted', strtolower((string)$record['power_state'])]);
            return;
        }
        $disks = [];
        foreach ((array)$record['VBDs'] as $vbd) {
            $vdi = (string)($this->db['vbd'][$vbd]['VDI'] ?? '');
            if (($this->db['vbd'][$vbd]['type'] ?? '') === 'Disk' && isset($this->db['vdi'][$vdi])) {
                $disks[] = ['id' => 'Ref:' . (count($disks) + 1), 'name' => (string)$this->db['vdi'][$vdi]['name_label'], 'size' => (float)$this->db['vdi'][$vdi]['virtual_size']];
            }
        }
        $parts = [Xva::member('ova.xml', Xva::ovaXml($record, $disks), $this->now)];
        foreach ($disks as $disk) {
            // the disks' blocks: 1 MiB members and their checksums (a pattern here, not the VM's data)
            for ($at = 0, $n = 0; $at < $this->xvaDiskBytes; $at += 1048576, $n++) {
                $block = str_repeat(substr(md5($disk['id'] . $n), 0, 16), (int)(min(1048576, $this->xvaDiskBytes - $at) / 16));
                $name = $disk['id'] . '/' . sprintf('%08d', $n);
                $parts[] = Xva::member($name, $block, $this->now);
                $parts[] = Xva::member($name . '.checksum', sha1($block), $this->now);
            }
        }
        $parts[] = Xva::end();
        if ($compress && function_exists('gzencode')) {
            // XAPI's use_compression: the whole tar gzipped, sent until the connection closes (no length)
            $parts = [(string)gzencode(implode('', $parts), 1)];
            $s->context['size'] = (float)strlen($parts[0]);
            $s->reply(200, 'OK', ['Content-Type' => 'application/octet-stream'], str_split($parts[0], 262144));
            return;
        }
        $size = 0;
        foreach ($parts as $part) {
            $size += strlen($part);
        }
        $s->context['size'] = (float)$size;
        $s->reply(200, 'OK', ['Content-Type' => 'application/octet-stream', 'Content-Length' => (string)$size], $parts);
    }

    /** @param list<string> $failure the task fails with it, the HTTP answer is a 500 */
    private function failTask(FakeHttpStream $s, array $failure): void
    {
        $task = (string)($s->context['task'] ?? '');
        if ($task !== '') {
            $this->set('task', $task, ['status' => 'failure', 'progress' => 1.0, 'finished' => $this->date(), 'error_info' => $failure]);
        }
        $s->context['answered'] = true;
        $s->reply(500, 'Internal Error', ['Content-Type' => 'text/plain', 'Content-Length' => (string)strlen(implode(' ', $failure))], implode(' ', $failure));
    }
}