<?php

namespace Egulias\EmailValidator\Parser;

use Doctrine\Common\Lexer\Token;
use Egulias\EmailValidator\EmailLexer;
use Egulias\EmailValidator\Warning\TLD;
use Egulias\EmailValidator\Result\Result;
use Egulias\EmailValidator\Result\ValidEmail;
use Egulias\EmailValidator\Result\InvalidEmail;
use Egulias\EmailValidator\Result\Reason\DotAtEnd;
use Egulias\EmailValidator\Result\Reason\DotAtStart;
use Egulias\EmailValidator\Warning\DeprecatedComment;
use Egulias\EmailValidator\Result\Reason\CRLFAtTheEnd;
use Egulias\EmailValidator\Result\Reason\LabelTooLong;
use Egulias\EmailValidator\Result\Reason\NoDomainPart;
use Egulias\EmailValidator\Result\Reason\ConsecutiveAt;
use Egulias\EmailValidator\Result\Reason\DomainTooLong;
use Egulias\EmailValidator\Result\Reason\CharNotAllowed;
use Egulias\EmailValidator\Result\Reason\DomainHyphened;
use Egulias\EmailValidator\Result\Reason\ExpectingATEXT;
use Egulias\EmailValidator\Parser\CommentStrategy\DomainComment;
use Egulias\EmailValidator\Result\Reason\ExpectingDomainLiteralClose;
use Egulias\EmailValidator\Parser\DomainLiteral as DomainLiteralParser;

class DomainPart extends PartParser
{
    public const DOMAIN_MAX_LENGTH = 253;
    public const LABEL_MAX_LENGTH = 63;

    /**
     * @var string
     */
    protected $domainPart = '';

    /**
     * @var string
     */
    protected $label = '';

    public function parse(): Result
    {
        $this->lexer->clearRecorded();
        $this->lexer->startRecording();

        $this->lexer->moveNext();

        $domainChecks = $this->performDomainStartChecks();
        if ($domainChecks->isInvalid()) {
            return $domainChecks;
        }

        if ($this->lexer->current->isA(EmailLexer::S_AT)) {
            return new InvalidEmail(new ConsecutiveAt(), $this->lexer->current->value);
        }

        $result = $this->doParseDomainPart();
        if ($result->isInvalid()) {
            return $result;
        }

        $end = $this->checkEndOfDomain();
        if ($end->isInvalid()) {
            return $end;
        }

        $this->lexer->stopRecording();
        $this->domainPart = $this->lexer->getAccumulatedValues();

        $length = strlen($this->domainPart);
        if ($length > self::DOMAIN_MAX_LENGTH) {
            return new InvalidEmail(new DomainTooLong(), $this->lexer->current->value);
        }

        return new ValidEmail();
    }

    private function checkEndOfDomain(): Result
    {
        $prev = $this->lexer->getPrevious();
        if ($prev->isA(EmailLexer::S_DOT)) {
            return new InvalidEmail(new DotAtEnd(), $this->lexer->current->value);
        }
        if ($prev->isA(EmailLexer::S_HYPHEN)) {
            return new InvalidEmail(new DomainHyphened('Hypen found at the end of the domain'), $prev->value);
        }

        if ($this->lexer->current->isA(EmailLexer::S_SP)) {
            return new InvalidEmail(new CRLFAtTheEnd(), $prev->value);
        }
        return new ValidEmail();
    }

    private function performDomainStartChecks(): Result
    {
        $invalidTokens = $this->checkInvalidTokensAfterAT();
        if ($invalidTokens->isInvalid()) {
            return $invalidTokens;
        }

        $missingDomain = $this->checkEmptyDomain();
        if ($missingDomain->isInvalid()) {
            return $missingDomain;
        }

        if ($this->lexer->current->isA(EmailLexer::S_OPENPARENTHESIS)) {
            $this->warnings[DeprecatedComment::CODE] = new DeprecatedComment();
        }
        return new ValidEmail();
    }

    private function checkEmptyDomain(): Result
    {
        $thereIsNoDomain = $this->lexer->current->isA(EmailLexer::S_EMPTY) ||
            ($this->lexer->current->isA(EmailLexer::S_SP) &&
                !$this->lexer->isNextToken(EmailLexer::GENERIC));

        if ($thereIsNoDomain) {
            return new InvalidEmail(new NoDomainPart(), $this->lexer->current->value);
        }

        return new ValidEmail();
    }

    private function checkInvalidTokensAfterAT(): Result
    {
        if ($this->lexer->current->isA(EmailLexer::S_DOT)) {
            return new InvalidEmail(new DotAtStart(), $this->lexer->current->value);
        }
        if ($this->lexer->current->isA(EmailLexer::S_HYPHEN)) {
            return new InvalidEmail(new DomainHyphened('After AT'), $this->lexer->current->value);
        }
        return new ValidEmail();
    }

    protected function parseComments(): Result
    {
        $commentParser = new Comment($this->lexer, new DomainComment());
        $result = $commentParser->parse();
        $this->warnings = array_merge($this->warnings, $commentParser->getWarnings());

        return $result;
    }

    protected function doParseDomainPart(): Result
    {
        $tldMissing = true;
        $hasComments = false;
        $domain = '';
        do {
            $prev = $this->lexer->getPrevious();

            $notAllowedChars = $this->checkNotAllowedChars($this->lexer->current);
            if ($notAllowedChars->isInvalid()) {
                return $notAllowedChars;
            }

            if (
                $this->lexer->current->isA(EmailLexer::S_OPENPARENTHESIS) ||
                $this->lexer->current->isA(EmailLexer::S_CLOSEPARENTHESIS)
            ) {
                $hasComments = true;
                $commentsResult = $this->parseComments();

                //Invalid comment parsing
                if ($commentsResult->isInvalid()) {
                    return $commentsResult;
                }
            }

            $dotsResult = $this->checkConsecutiveDots();
            if ($dotsResult->isInvalid()) {
                return $dotsResult;
            }

            if ($this->lexer->current->isA(EmailLexer::S_OPENBRACKET)) {
                $literalResult = $this->parseDomainLiteral();

                $this->addTLDWarnings($tldMissing);
                return $literalResult;
            }

            $labelCheck = $this->checkLabelLength();
            if ($labelCheck->isInvalid()) {
                return $labelCheck;
            }

            $FwsResult = $this->parseFWS();
            if ($FwsResult->isInvalid()) {
                return $FwsResult;
            }

            $domain .= $this->lexer->current->value;

            if ($this->lexer->current->isA(EmailLexer::S_DOT) && $this->lexer->isNextToken(EmailLexer::GENERIC)) {
                $tldMissing = false;
            }

            $exceptionsResult = $this->checkDomainPartExceptions($prev, $hasComments);
            if ($exceptionsResult->isInvalid()) {
                return $exceptionsResult;
            }
            $this->lexer->moveNext();
        } while (!$this->lexer->current->isA(EmailLexer::S_EMPTY));

        $labelCheck = $this->checkLabelLength(true);
        if ($labelCheck->isInvalid()) {
            return $labelCheck;
        }
        $this->addTLDWarnings($tldMissing);

        $this->domainPart = $domain;
        return new ValidEmail();
    }

     /** 
     * @param Token<int, string> $token
     * 
     * @return Result
     */
    private function checkNotAllowedChars(Token $token): Result
    {
        $notAllowed = [EmailLexer::S_BACKSLASH => true, EmailLexer::S_SLASH => true];
        if (isset($notAllowed[$token->type])) {
            return new InvalidEmail(new CharNotAllowed(), $token->value);
        }
        return new ValidEmail();
    }

    /**
     * @return Result
     */
    protected function parseDomainLiteral(): Result
    {
        try {
            $this->lexer->find(EmailLexer::S_CLOSEBRACKET);
        } catch (\RuntimeException $e) {
            return new InvalidEmail(new ExpectingDomainLiteralClose(), $this->lexer->current->value);
        }

        $domainLiteralParser = new DomainLiteralParser($this->lexer);
        $result = $domainLiteralParser->parse();
        $this->warnings = array_merge($this->warnings, $domainLiteralParser->getWarnings());
        return $result;
    }

    /**
     * @param Token<int, string> $prev
     * @param bool $hasComments
     * 
     * @return Result
     */
    protected function checkDomainPartExceptions(Token $prev, bool $hasComments): Result
    {
        if ($this->lexer->current->isA(EmailLexer::S_OPENBRACKET) && $prev->type !== EmailLexer::S_AT) {
            return new InvalidEmail(new ExpectingATEXT('OPENBRACKET not after AT'), $this->lexer->current->value);
        }

        if ($this->lexer->current->isA(EmailLexer::S_HYPHEN) && $this->lexer->isNextToken(EmailLexer::S_DOT)) {
            return new InvalidEmail(new DomainHyphened('Hypen found near DOT'), $this->lexer->current->value);
        }

        if (
            $this->lexer->current->isA(EmailLexer::S_BACKSLASH)
            && $this->lexer->isNextToken(EmailLexer::GENERIC)
        ) {
            return new InvalidEmail(new ExpectingATEXT('Escaping following "ATOM"'), $this->lexer->current->value);
        }

        return $this->validateTokens($hasComments);
    }

    protected function validateTokens(bool $hasComments): Result
    {
        $validDomainTokens = array(
            EmailLexer::GENERIC => true,
            EmailLexer::S_HYPHEN => true,
            EmailLexer::S_DOT => true,
        );

        if ($hasComments) {
            $validDomainTokens[EmailLexer::S_OPENPARENTHESIS] = true;
            $validDomainTokens[EmailLexer::S_CLOSEPARENTHESIS] = true;
        }

        if (!isset($validDomainTokens[$this->lexer->current->type])) {
            return new InvalidEmail(new ExpectingATEXT('Invalid token in domain: ' . $this->lexer->current->value), $this->lexer->current->value);
        }

        return new ValidEmail();
    }

    private function checkLabelLength(bool $isEndOfDomain = false): Result
    {
        if ($this->lexer->current->isA(EmailLexer::S_DOT) || $isEndOfDomain) {
            if ($this->isLabelTooLong($this->label)) {
                return new InvalidEmail(new LabelTooLong(), $this->lexer->current->value);
            }
            $this->label = '';
        }
        $this->label .= $this->lexer->current->value;
        return new ValidEmail();
    }


    private function isLabelTooLong(string $label): bool
    {
        if (preg_match('/[^\x00-\x7F]/', $label)) {
            idn_to_ascii($label, IDNA_DEFAULT, INTL_IDNA_VARIANT_UTS46, $idnaInfo);
            return (bool) ($idnaInfo['errors'] & IDNA_ERROR_LABEL_TOO_LONG);
        }
        return strlen($label) > self::LABEL_MAX_LENGTH;
    }

    private function addTLDWarnings(bool $isTLDMissing): void
    {
        if ($isTLDMissing) {
            $this->warnings[TLD::CODE] = new TLD();
        }
    }

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