<?php
declare(strict_types=1);

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

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

    public function directAdminBinary(): string
    {
        return $this->daBinary;
    }

    /** @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'] ?? '');
        $payload = [
            'action' => $exists ? 'modify' : 'create',
            'domain' => $domain,
            'user' => $local,
            'text' => (string)($rule['body'] ?? ''),
            'subject' => $subjectPrefix,
            'reply_encoding' => 'UTF-8',
            'reply_content_type' => 'text/plain',
            'reply_once_time' => $this->replyOnceTime($rule),
            'starttime' => $startTime,
            'startyear' => $startYear,
            'startmonth' => $startMonth,
            'startday' => $startDay,
            'endtime' => $endTime,
            'endyear' => $endYear,
            'endmonth' => $endMonth,
            'endday' => $endDay,
        ];
        if (!$exists) {
            $payload['create'] = 'Create';
        }
        return $payload;
    }

    /** @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;
        $args = ['curl', '-sS', '-X', 'POST', '-w', "\n%{http_code}"];
        foreach ($payload as $key => $value) {
            $args[] = '--data-urlencode';
            $args[] = $key . '=' . $value;
        }
        $args[] = $url;
        return $this->parseHttpResponse($this->run($args, ''));
    }

    /** @param array<string,mixed> $rule */
    private function replyOnceTime(array $rule): string
    {
        if (!empty($rule['reply_every_message'])) {
            return '0';
        }
        return match ((int)($rule['repeat_minutes'] ?? 1440)) {
            30 => '30m',
            60 => '1h',
            120 => '2h',
            360 => '6h',
            720 => '12h',
            1440 => '1d',
            2880 => '2d',
            10080 => '1w',
            default => '1d',
        };
    }

    private function parseHttpResponse(string $output): string
    {
        if (!preg_match("/\n([0-9]{3})$/", $output, $m, PREG_OFFSET_CAPTURE)) {
            return $output;
        }
        $code = (int)$m[1][0];
        $body = substr($output, 0, (int)$m[0][1]);
        if ($code < 200 || $code >= 400) {
            throw new RuntimeException('DirectAdmin API HTTP ' . $code . ': ' . $this->compactBody($body));
        }
        $this->throwIfApiError($body);
        return $body;
    }

    private function throwIfApiError(string $body): void
    {
        $trimmed = trim($body);
        if ($trimmed === '') {
            return;
        }

        $json = json_decode($trimmed, true);
        if (is_array($json) && isset($json['error']) && $this->truthyError($json['error'])) {
            throw new RuntimeException('DirectAdmin API error: ' . $this->compactBody(implode(' ', array_filter([
                (string)($json['text'] ?? ''),
                (string)($json['details'] ?? ''),
                (string)($json['result'] ?? ''),
                (string)($json['error'] ?? ''),
            ]))));
        }

        $fields = [];
        parse_str($trimmed, $fields);
        if (isset($fields['error']) && $this->truthyError($fields['error'])) {
            throw new RuntimeException('DirectAdmin API error: ' . $this->compactBody(implode(' ', array_filter([
                is_scalar($fields['text'] ?? null) ? (string)$fields['text'] : '',
                is_scalar($fields['details'] ?? null) ? (string)$fields['details'] : '',
                is_scalar($fields['result'] ?? null) ? (string)$fields['result'] : '',
                is_scalar($fields['error'] ?? null) ? (string)$fields['error'] : '',
            ]))));
        }
    }

    private function truthyError(mixed $value): bool
    {
        return in_array(strtolower(trim((string)$value)), ['1', 'yes', 'true', 'error'], true);
    }

    private function compactBody(string $body): string
    {
        $body = trim(preg_replace('/[[:cntrl:]]+/', ' ', $body) ?? $body);
        if ($body === '') {
            return 'empty response body';
        }
        if (strlen($body) > 1200) {
            return substr($body, 0, 1200) . '...';
        }
        return $body;
    }

    private function apiUrl(string $owner): string
    {
        $output = $this->run([$this->resolveDirectAdminBinary(), '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;
    }

    private function resolveDirectAdminBinary(): string
    {
        $candidates = array_values(array_unique([
            $this->daBinary,
            '/usr/local/directadmin/directadmin',
            '/usr/bin/da',
        ]));
        foreach ($candidates as $candidate) {
            if ($candidate !== '' && is_executable($candidate)) {
                return $candidate;
            }
        }
        throw new RuntimeException('DirectAdmin binary is not executable. Checked: ' . implode(', ', $candidates));
    }

    /** @param string[] $args */
    private function run(array $args, string $stdin): string
    {
        if ($this->runner !== null) {
            $result = call_user_func($this->runner, $args, $stdin);
            return (string)$result;
        }
        if (($args[0] ?? '') !== '' && str_contains($args[0], '/') && !is_executable($args[0])) {
            throw new RuntimeException('DirectAdmin API command is not executable: ' . $args[0]);
        }
        $process = proc_open($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;
    }
}