<?php

declare(strict_types=1);

namespace Nih\CommandBuilder;

use InvalidArgumentException;
use Override;
use Stringable;

/**
 * Describes what to do with a standard I/O stream for a child process when
 * passed to the stdin, stdout, and stderr methods of {@see Command}.
 *
 * @psalm-suppress UnusedClass
 */
abstract class Stdio
{
    /**
     * The child inherits from the corresponding parent descriptor.
     */
    public static function inherit(): StdioInterface
    {
        return new class implements StdioInterface {
            #[Override]
            public function getDescriptionSpec(int $fd): mixed
            {
                return match ($fd) {
                    0 => STDIN,
                    1 => STDOUT,
                    2 => STDERR,
                    default => ['php://fd/' . $fd, 'w+'],
                };
            }
        };
    }

    /**
     * A new pipe should be arranged to connect the parent and child processes.
     */
    public static function piped(): StdioInterface
    {
        return new class implements StdioInterface {
            #[Override]
            public function getDescriptionSpec(int $fd): mixed
            {
                return match ($fd) {
                    0 => ['pipe', 'r'],
                    1, 2 => ['pipe', 'w'],
                    default => ['pipe', 'w+'],
                };
            }
        };
    }

    /**
     * This stream will be ignored. This is the equivalent of attaching the
     * stream to `/dev/null`.
     */
    public static function null(): StdioInterface
    {
        return new class implements StdioInterface {
            #[Override]
            public function getDescriptionSpec(int $fd): mixed
            {
                // TODO: Support windows (I think you just write to `nul` in any
                //       directory?)
                return match ($fd) {
                    0 => ['file', '/dev/null', 'r'],
                    1, 2 => ['file', '/dev/null', 'w'],
                    default => ['file', '/dev/null', 'w+'],
                };
            }
        };
    }

    /**
     * Like piped, but instead of capturing the stream into a handle, read
     * and/or write from/to a file.
     */
    public static function file(string|Stringable $filename, string $mode): StdioInterface
    {
        return new class((string) $filename, $mode) implements StdioInterface {
            public function __construct(
                private string $filename,
                private string $mode,
            ) {}

            #[Override]
            public function getDescriptionSpec(int $fd): mixed
            {
                return ['file', $this->filename, $this->mode];
            }
        };
    }

    /**
     * Like piped, but instead of capturing the stream into a handle, read
     * and/or write from/to a stream resource.
     *
     * @param resource $stream
     *
     * @throws InvalidArgumentException When stream is not a stream resource
     */
    public static function stream($stream): StdioInterface
    {
        if (get_resource_type($stream) !== 'stream') {
            throw new InvalidArgumentException('resource is not a stream');
        }

        return new class($stream) implements StdioInterface {
            public function __construct(private mixed $stream) {}

            #[Override]
            public function getDescriptionSpec(int $fd): mixed
            {
                return $this->stream;
            }
        };
    }
}