class Headers

final class Headers {
    private const UNIQUE_HEADERS = [
        'date',
        'from',
        'sender',
        'reply-to',
        'to',
        'cc',
        'bcc',
        'message-id',
        'in-reply-to',
        'references',
        'subject',
    ];
    private const HEADER_CLASS_MAP = [
        'date' => DateHeader::class,
        'from' => MailboxListHeader::class,
        'sender' => MailboxHeader::class,
        'reply-to' => MailboxListHeader::class,
        'to' => MailboxListHeader::class,
        'cc' => MailboxListHeader::class,
        'bcc' => MailboxListHeader::class,
        'message-id' => IdentificationHeader::class,
        'in-reply-to' => [
            UnstructuredHeader::class,
            IdentificationHeader::class,
        ],
        // `In-Reply-To` and `References` are less strict than RFC 2822 (3.6.4) to allow users entering the original email's ...
'references' => [
            UnstructuredHeader::class,
            IdentificationHeader::class,
        ],
        // ... `Message-ID`, even if that is no valid `msg-id`
'return-path' => PathHeader::class,
    ];
    
    /**
     * @var HeaderInterface[][]
     */
    private array $headers = [];
    private int $lineLength = 76;
    public function __construct(HeaderInterface ...$headers) {
        foreach ($headers as $header) {
            $this->add($header);
        }
    }
    public function __clone() {
        foreach ($this->headers as $name => $collection) {
            foreach ($collection as $i => $header) {
                $this->headers[$name][$i] = clone $header;
            }
        }
    }
    public function setMaxLineLength(int $lineLength) : void {
        $this->lineLength = $lineLength;
        foreach ($this->all() as $header) {
            $header->setMaxLineLength($lineLength);
        }
    }
    public function getMaxLineLength() : int {
        return $this->lineLength;
    }
    
    /**
     * @param array<Address|string> $addresses
     *
     * @return $this
     */
    public function addMailboxListHeader(string $name, array $addresses) : static {
        return $this->add(new MailboxListHeader($name, Address::createArray($addresses)));
    }
    
    /**
     * @return $this
     */
    public function addMailboxHeader(string $name, Address|string $address) : static {
        return $this->add(new MailboxHeader($name, Address::create($address)));
    }
    
    /**
     * @return $this
     */
    public function addIdHeader(string $name, string|array $ids) : static {
        return $this->add(new IdentificationHeader($name, $ids));
    }
    
    /**
     * @return $this
     */
    public function addPathHeader(string $name, Address|string $path) : static {
        return $this->add(new PathHeader($name, $path instanceof Address ? $path : new Address($path)));
    }
    
    /**
     * @return $this
     */
    public function addDateHeader(string $name, \DateTimeInterface $dateTime) : static {
        return $this->add(new DateHeader($name, $dateTime));
    }
    
    /**
     * @return $this
     */
    public function addTextHeader(string $name, string $value) : static {
        return $this->add(new UnstructuredHeader($name, $value));
    }
    
    /**
     * @return $this
     */
    public function addParameterizedHeader(string $name, string $value, array $params = []) : static {
        return $this->add(new ParameterizedHeader($name, $value, $params));
    }
    
    /**
     * @return $this
     */
    public function addHeader(string $name, mixed $argument, array $more = []) : static {
        $headerClass = self::HEADER_CLASS_MAP[strtolower($name)] ?? UnstructuredHeader::class;
        if (\is_array($headerClass)) {
            $headerClass = $headerClass[0];
        }
        $parts = explode('\\', $headerClass);
        $method = 'add' . ucfirst(array_pop($parts));
        if ('addUnstructuredHeader' === $method) {
            $method = 'addTextHeader';
        }
        elseif ('addIdentificationHeader' === $method) {
            $method = 'addIdHeader';
        }
        elseif ('addMailboxListHeader' === $method && !\is_array($argument)) {
            $argument = [
                $argument,
            ];
        }
        return $this->{$method}($name, $argument, $more);
    }
    public function has(string $name) : bool {
        return isset($this->headers[strtolower($name)]);
    }
    
    /**
     * @return $this
     */
    public function add(HeaderInterface $header) : static {
        self::checkHeaderClass($header);
        $header->setMaxLineLength($this->lineLength);
        $name = strtolower($header->getName());
        if (\in_array($name, self::UNIQUE_HEADERS, true) && isset($this->headers[$name]) && \count($this->headers[$name]) > 0) {
            throw new LogicException(\sprintf('Impossible to set header "%s" as it\'s already defined and must be unique.', $header->getName()));
        }
        $this->headers[$name][] = $header;
        return $this;
    }
    public function get(string $name) : ?HeaderInterface {
        $name = strtolower($name);
        if (!isset($this->headers[$name])) {
            return null;
        }
        $values = array_values($this->headers[$name]);
        return array_shift($values);
    }
    public function all(?string $name = null) : iterable {
        if (null === $name) {
            foreach ($this->headers as $name => $collection) {
                foreach ($collection as $header) {
                    (yield $name => $header);
                }
            }
        }
        elseif (isset($this->headers[strtolower($name)])) {
            foreach ($this->headers[strtolower($name)] as $header) {
                (yield $header);
            }
        }
    }
    public function getNames() : array {
        return array_keys($this->headers);
    }
    public function remove(string $name) : void {
        unset($this->headers[strtolower($name)]);
    }
    public static function isUniqueHeader(string $name) : bool {
        return \in_array(strtolower($name), self::UNIQUE_HEADERS, true);
    }
    
    /**
     * @throws LogicException if the header name and class are not compatible
     */
    public static function checkHeaderClass(HeaderInterface $header) : void {
        $name = strtolower($header->getName());
        $headerClasses = self::HEADER_CLASS_MAP[$name] ?? [];
        if (!\is_array($headerClasses)) {
            $headerClasses = [
                $headerClasses,
            ];
        }
        if (!$headerClasses) {
            return;
        }
        foreach ($headerClasses as $c) {
            if ($header instanceof $c) {
                return;
            }
        }
        throw new LogicException(\sprintf('The "%s" header must be an instance of "%s" (got "%s").', $header->getName(), implode('" or "', $headerClasses), get_debug_type($header)));
    }
    public function toString() : string {
        $string = '';
        foreach ($this->toArray() as $str) {
            $string .= $str . "\r\n";
        }
        return $string;
    }
    public function toArray() : array {
        $arr = [];
        foreach ($this->all() as $header) {
            if ('' !== $header->getBodyAsString()) {
                $arr[] = $header->toString();
            }
        }
        return $arr;
    }
    public function getHeaderBody(string $name) : mixed {
        return $this->has($name) ? $this->get($name)
            ->getBody() : null;
    }
    
    /**
     * @internal
     */
    public function setHeaderBody(string $type, string $name, mixed $body) : void {
        if ($this->has($name)) {
            $this->get($name)
                ->setBody($body);
        }
        else {
            $this->{'add' . $type . 'Header'}($name, $body);
        }
    }
    public function getHeaderParameter(string $name, string $parameter) : ?string {
        if (!$this->has($name)) {
            return null;
        }
        $header = $this->get($name);
        if (!$header instanceof ParameterizedHeader) {
            throw new LogicException(\sprintf('Unable to get parameter "%s" on header "%s" as the header is not of class "%s".', $parameter, $name, ParameterizedHeader::class));
        }
        return $header->getParameter($parameter);
    }
    
    /**
     * @internal
     */
    public function setHeaderParameter(string $name, string $parameter, ?string $value) : void {
        if (!$this->has($name)) {
            throw new LogicException(\sprintf('Unable to set parameter "%s" on header "%s" as the header is not defined.', $parameter, $name));
        }
        $header = $this->get($name);
        if (!$header instanceof ParameterizedHeader) {
            throw new LogicException(\sprintf('Unable to set parameter "%s" on header "%s" as the header is not of class "%s".', $parameter, $name, ParameterizedHeader::class));
        }
        $header->setParameter($parameter, $value);
    }

}