<?php

declare(strict_types=1);

namespace KTXM\ProviderImap\Client\Command;

use Generator;
use KTXM\ProviderImap\Client\FetchTarget;
use KTXM\ProviderImap\Client\FetchOptions;
use KTXM\ProviderImap\Client\ImapException;
use KTXM\ProviderImap\Client\Message;
use KTXM\ProviderImap\Client\Protocol\RequestFrame;
use KTXM\ProviderImap\Client\Protocol\ResponseStream;
use KTXM\ProviderImap\Client\SequenceSet;
use KTXM\ProviderImap\Client\SessionContext;
use KTXM\ProviderImap\Client\SessionState;

/**
 * @implements CommandInterface<Generator<int, Message>>
 */
final class FetchManyCommand implements CommandInterface
{
    private readonly FetchTarget $target;
    private readonly FetchOptions $options;

    public function __construct(FetchTarget|string|SequenceSet|null $target = null, ?FetchOptions $options = null)
    {
        $this->target = match (true) {
            $target instanceof FetchTarget => $target,
            $target instanceof SequenceSet => FetchTarget::sequence($target),
            is_string($target) => FetchTarget::sequence($target),
            default => FetchTarget::all(),
        };
        $this->options = $options ?? FetchOptions::default();
    }

    public function name(): string
    {
        return 'FETCH';
    }

    public function allowedStates(): array
    {
        return [SessionState::Selected];
    }

    public function encode(string $tag, SessionContext $context): RequestFrame
    {
        unset($tag, $context);

        return new RequestFrame(sprintf(
            '%s %s (%s)',
            $this->target->toCommand(),
            $this->target->sequenceSet()->toCommand(),
            $this->options->toCommand(),
        ));
    }

    public function handle(ResponseStream $responses, SessionContext $context): Generator
    {
        if ($context->selectedMailbox() === null) {
            throw new ImapException('FETCH requires a selected mailbox.');
        }

        return (new FetchResponseParser())->parseMany($responses);
    }
}