<?php
declare(strict_types=1);

class DirectAdminVacationApi
{
    /** @var callable|null */
    private $request;
    private string $daBinary = '/usr/local/bin/da';

    public function __construct(string $daBinary = '/usr/local/bin/da', ?callable $request = null)
    {
        $this->daBinary = $daBinary;
        $this->request = $request;
    }

    /** @param array<string,mixed> $rule @return array<string,string> */
    public function buildSavePayload(string $email, array $rule, bool $exists = true): array
    {
        if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
            throw new InvalidArgumentException('Invalid mailbox email');
        }
        [$local, $domain] = explode('@', strtolower($email), 2);
        [$startDate, $startTime] = $this->splitPeriod((string)($rule['start_value'] ?? ''));
        [$endDate, $endTime] = $this->splitPeriod((string)($rule['end_value'] ?? ''));
        [$startYear, $startMonth, $startDay] = explode('-', $startDate);
        [$endYear, $endMonth, $endDay] = explode('-', $endDate);
        $subjectPrefix = (string)($rule['subject_prefix'] ?? $rule['subject'] ?? '');
        $replyFrequency = !empty($rule['reply_every_message']) ? '0' : (string)max(0, (int)($rule['repeat_minutes'] ?? 1440));
        return [
            'action' => $exists ? 'modify' : 'create',
            'domain' => $domain,
            'user' => $local,
            'email' => $email,
            'text' => (string)($rule['body'] ?? ''),
            'subject_prefix' => $subjectPrefix,
            'subject' => $subjectPrefix,
            'reply_frequency' => $replyFrequency,
            'reply_once_time' => $replyFrequency,
            'starttime' => $startTime,
            'startyear' => $startYear,
            'startmonth' => $startMonth,
            'startday' => $startDay,
            'endtime' => $endTime,
            'endyear' => $endYear,
            'endmonth' => $endMonth,
            'endday' => $endDay,
            'create' => $exists ? '' : 'Create',
        ];
    }

    /** @param array<string,mixed> $rule */
    public function saveVacation(string $owner, string $email, array $rule, bool $exists): void
    {
        $this->requestAsUser($owner, 'CMD_API_EMAIL_VACATION', $this->buildSavePayload($email, $rule, $exists));
    }

    public function vacationExists(string $owner, string $email): bool
    {
        if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
            throw new InvalidArgumentException('Invalid mailbox email');
        }
        [$local, $domain] = explode('@', strtolower($email), 2);
        return in_array($local, $this->listVacations($owner, $domain), true);
    }

    /** @return string[] */
    public function listVacations(string $owner, string $domain): array
    {
        if (!preg_match('/^[A-Za-z0-9.-]+$/', $domain)) {
            throw new InvalidArgumentException('Invalid domain');
        }
        $response = $this->requestAsUser($owner, 'CMD_API_EMAIL_VACATION', ['domain' => strtolower($domain)]);
        $users = [];
        foreach (explode('&', trim($response)) as $pair) {
            if ($pair === '' || !str_contains($pair, '=')) {
                continue;
            }
            [$key] = explode('=', $pair, 2);
            $local = strtolower(urldecode($key));
            if (preg_match('/^[A-Za-z0-9._+-]+$/', $local)) {
                $users[] = $local;
            }
        }
        sort($users);
        return array_values(array_unique($users));
    }

    public function deleteVacation(string $owner, string $email): void
    {
        if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
            throw new InvalidArgumentException('Invalid mailbox email');
        }
        [$local, $domain] = explode('@', strtolower($email), 2);
        $this->requestAsUser($owner, 'CMD_API_EMAIL_VACATION', [
            'action' => 'delete',
            'domain' => $domain,
            'select0' => $local,
        ]);
    }

    /** @return array{0:string,1:string} */
    private function splitPeriod(string $value): array
    {
        if (!preg_match('/^([0-9]{4}-[0-9]{2}-[0-9]{2})\|(morning|afternoon|evening)$/', $value, $m)) {
            throw new InvalidArgumentException('DirectAdmin API backend requires directadmin_period values');
        }
        return [$m[1], $m[2]];
    }

    /** @param array<string,string> $payload */
    private function requestAsUser(string $owner, string $endpoint, array $payload): string
    {
        if (!preg_match('/^[A-Za-z0-9._-]+$/', $owner)) {
            throw new InvalidArgumentException('Invalid DirectAdmin owner');
        }
        if ($this->request !== null) {
            $result = call_user_func($this->request, $owner, $endpoint, $payload);
            if ($result === false) {
                throw new RuntimeException('DirectAdmin API request failed');
            }
            return (string)$result;
        }
        $baseUrl = $this->apiUrl($owner);
        $url = rtrim($baseUrl, '/') . '/' . $endpoint;
        $args = ['curl', '-fsS', '-X', 'POST'];
        foreach ($payload as $key => $value) {
            $args[] = '--data-urlencode';
            $args[] = $key . '=' . $value;
        }
        $args[] = $url;
        return $this->run($args, '');
    }

    private function apiUrl(string $owner): string
    {
        $output = $this->run([$this->daBinary, 'api-url', '--user=' . $owner], '');
        $url = trim($output);
        if ($url === '' || !preg_match('#^https?://#', $url)) {
            throw new RuntimeException('Cannot determine DirectAdmin API URL for user');
        }
        return $url;
    }

    /** @param string[] $args */
    private function run(array $args, string $stdin): string
    {
        $process = proc_open($args, [['pipe', 'r'], ['pipe', 'w'], ['pipe', 'w']], $pipes);
        if (!is_resource($process)) {
            throw new RuntimeException('Cannot start DirectAdmin API command');
        }
        fwrite($pipes[0], $stdin);
        fclose($pipes[0]);
        $stdout = stream_get_contents($pipes[1]) ?: '';
        $stderr = stream_get_contents($pipes[2]) ?: '';
        fclose($pipes[1]);
        fclose($pipes[2]);
        $code = proc_close($process);
        if ($code !== 0) {
            throw new RuntimeException('DirectAdmin API command failed: ' . trim($stderr));
        }
        return $stdout;
    }
}