<?php

namespace Amp\Process\Internal\Windows;

use Amp\Deferred;
use Amp\Loop;
use Amp\Process\Internal\ProcessHandle;
use Amp\Process\Internal\ProcessRunner;
use Amp\Process\Internal\ProcessStatus;
use Amp\Process\ProcessException;
use Amp\Process\ProcessInputStream;
use Amp\Process\ProcessOutputStream;
use Amp\Promise;
use const Amp\Process\BIN_DIR;

/**
 * @internal
 * @codeCoverageIgnore Windows only.
 */
final class Runner implements ProcessRunner {
    const FD_SPEC = [
        ["pipe", "r"], // stdin
        ["pipe", "w"], // stdout
        ["pipe", "w"], // stderr
        ["pipe", "w"], // exit code pipe
    ];

    const WRAPPER_EXE_PATH = PHP_INT_SIZE === 8
        ? BIN_DIR . '\\windows\\ProcessWrapper64.exe'
        : BIN_DIR . '\\windows\\ProcessWrapper.exe';

    private $socketConnector;

    private function makeCommand(string $workingDirectory): string {
        $result = \sprintf(
            '%s --address=%s --port=%d --token-size=%d',
            \escapeshellarg(self::WRAPPER_EXE_PATH),
            $this->socketConnector->address,
            $this->socketConnector->port,
            SocketConnector::SECURITY_TOKEN_SIZE
        );

        if ($workingDirectory !== '') {
            $result .= ' ' . \escapeshellarg('--cwd=' . \rtrim($workingDirectory, '\\'));
        }

        return $result;
    }

    public function __construct() {
        $this->socketConnector = new SocketConnector;
    }

    /** @inheritdoc */
    public function start(string $command, string $cwd = null, array $env = [], array $options = []): ProcessHandle {
        if (\strpos($command, "\0") !== false) {
            throw new ProcessException("Can't execute commands that contain null bytes.");
        }

        $options['bypass_shell'] = true;

        $handle = new Handle;
        $handle->proc = @\proc_open($this->makeCommand($cwd ?? ''), self::FD_SPEC, $pipes, $cwd ?: null, $env ?: null, $options);

        if (!\is_resource($handle->proc)) {
            $message = "Could not start process";
            if ($error = \error_get_last()) {
                $message .= \sprintf(" Errno: %d; %s", $error["type"], $error["message"]);
            }
            throw new ProcessException($message);
        }

        $status = \proc_get_status($handle->proc);

        if (!$status) {
            \proc_close($handle->proc);
            throw new ProcessException("Could not get process status");
        }

        $securityTokens = \random_bytes(SocketConnector::SECURITY_TOKEN_SIZE * 6);
        $written = \fwrite($pipes[0], $securityTokens . "\0" . $command . "\0");

        \fclose($pipes[0]);
        \fclose($pipes[1]);

        if ($written !== SocketConnector::SECURITY_TOKEN_SIZE * 6 + \strlen($command) + 2) {
            \fclose($pipes[2]);
            \proc_close($handle->proc);

            throw new ProcessException("Could not send security tokens / command to process wrapper");
        }

        $handle->securityTokens = \str_split($securityTokens, SocketConnector::SECURITY_TOKEN_SIZE);
        $handle->wrapperPid = $status['pid'];
        $handle->wrapperStderrPipe = $pipes[2];

        $stdinDeferred = new Deferred;
        $handle->stdioDeferreds[] = $stdinDeferred;
        $handle->stdin = new ProcessOutputStream($stdinDeferred->promise());

        $stdoutDeferred = new Deferred;
        $handle->stdioDeferreds[] = $stdoutDeferred;
        $handle->stdout = new ProcessInputStream($stdoutDeferred->promise());

        $stderrDeferred = new Deferred;
        $handle->stdioDeferreds[] = $stderrDeferred;
        $handle->stderr = new ProcessInputStream($stderrDeferred->promise());

        $this->socketConnector->registerPendingProcess($handle);

        return $handle;
    }

    /** @inheritdoc */
    public function join(ProcessHandle $handle): Promise {
        /** @var Handle $handle */
        $handle->exitCodeRequested = true;

        if ($handle->exitCodeWatcher !== null) {
            Loop::reference($handle->exitCodeWatcher);
        }

        return $handle->joinDeferred->promise();
    }

    /** @inheritdoc */
    public function kill(ProcessHandle $handle) {
        /** @var Handle $handle */
        // todo: send a signal to the wrapper to kill the child instead?
        if (!\proc_terminate($handle->proc)) {
            throw new ProcessException("Terminating process failed");
        }

        $failStart = false;

        if ($handle->childPidWatcher !== null) {
            Loop::cancel($handle->childPidWatcher);
            $handle->childPidWatcher = null;
            $handle->pidDeferred->fail(new ProcessException("The process was killed"));
            $failStart = true;
        }

        if ($handle->exitCodeWatcher !== null) {
            Loop::cancel($handle->exitCodeWatcher);
            $handle->exitCodeWatcher = null;
            $handle->joinDeferred->fail(new ProcessException("The process was killed"));
        }

        $handle->status = ProcessStatus::ENDED;

        if ($failStart || $handle->stdioDeferreds) {
            $this->socketConnector->failHandleStart($handle, "The process was killed");
        }

        $this->free($handle);
    }

    /** @inheritdoc */
    public function signal(ProcessHandle $handle, int $signo) {
        throw new ProcessException('Signals are not supported on Windows');
    }

    /** @inheritdoc */
    public function destroy(ProcessHandle $handle) {
        /** @var Handle $handle */
        if ($handle->status < ProcessStatus::ENDED && \is_resource($handle->proc)) {
            try {
                $this->kill($handle);
            } catch (ProcessException $e) {
                // ignore
            }
        }

        $this->free($handle);
    }

    private function free(Handle $handle) {
        if ($handle->childPidWatcher !== null) {
            Loop::cancel($handle->childPidWatcher);
            $handle->childPidWatcher = null;
        }

        if ($handle->exitCodeWatcher !== null) {
            Loop::cancel($handle->exitCodeWatcher);
            $handle->exitCodeWatcher = null;
        }

        $handle->stdin->close();
        $handle->stdout->close();
        $handle->stderr->close();

        for ($i = 0; $i < 4; $i++) {
            if (\is_resource($handle->sockets[$i] ?? null)) {
                \fclose($handle->sockets[$i]);
            }
        }

        @\stream_get_contents($handle->wrapperStderrPipe);
        @\fclose($handle->wrapperStderrPipe);

        if (\is_resource($handle->proc)) {
            \proc_close($handle->proc);
        }
    }
}