<?php

declare(strict_types=1);

/*
 * This file is part of the TYPO3 CMS project.
 *
 * It is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, either version 2
 * of the License, or any later version.
 *
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 *
 * The TYPO3 project - inspiring people to share!
 */

namespace TYPO3\CMS\Core\Utility;

use Symfony\Component\Mime\Address;
use Symfony\Component\Mime\Exception\ExceptionInterface;

/**
 * Class to handle mail specific functionality
 */
class MailUtility
{
    /**
     * Gets a valid "from" for mail messages (email and name).
     *
     * Ready to be passed to $mail->setFrom()
     *
     * This method can return three different variants:
     * 1. An assoc. array: key => Valid email address which can be used as sender; value => Valid name which can be used as a sender
     * 2. A numeric array with one entry: Valid email address which can be used as sender
     * 3. Null, if no address is configured
     *
     * @return array<string|int, string>|null
     */
    public static function getSystemFrom(): ?array
    {
        $address = self::getSystemFromAddress();
        $name = self::getSystemFromName();
        if (!$address) {
            return null;
        }
        if ($name) {
            return [$address => $name];
        }
        return [$address];
    }

    /**
     * Creates a valid "from" name for mail messages.
     *
     * As configured in Install Tool.
     *
     * @return string|null The name (unquoted, unformatted). NULL if none is set or an invalid non-string value.
     */
    public static function getSystemFromName(): ?string
    {
        $name = $GLOBALS['TYPO3_CONF_VARS']['MAIL']['defaultMailFromName'] ?? null;

        return (!empty($name) && is_string($name)) ? $name : null;
    }

    /**
     * Creates a valid email address for the sender of mail messages.
     *
     * Uses a fallback chain:
     * $TYPO3_CONF_VARS['MAIL']['defaultMailFromAddress'] ->
     * no-reply@FirstDomainRecordFound ->
     * no-reply@php_uname('n') ->
     * no-reply@example.com
     *
     * Ready to be passed to $mail->setFrom()
     *
     * @return string An email address
     */
    public static function getSystemFromAddress(): string
    {
        $address = $GLOBALS['TYPO3_CONF_VARS']['MAIL']['defaultMailFromAddress'] ?? null;

        if (!is_string($address) || !GeneralUtility::validEmail($address)) {
            // still nothing, get host name from server
            $address = 'no-reply@' . php_uname('n');
            if (!GeneralUtility::validEmail($address)) {
                // if everything fails use a dummy address
                $address = 'no-reply@example.com';
            }
        }
        return $address;
    }

    /**
     * Gets a default "reply-to" for mail messages (email and name).
     *
     * Ready to be passed to $mail->setReplyTo()
     *
     * This method returns a list of email addresses, but depending on the existence of "defaultMailReplyToName"
     * the array can have a different shape:
     *
     * 1. An assoc. array: key => a valid reply-to address which can be used as sender; value => a valid reply-to name which can be used as a sender
     * 2. A numeric array with one entry: a valid reply-to address which can be used as sender
     *
     * @return array<string|int, string>
     */
    public static function getSystemReplyTo(): array
    {
        $mailConfiguration = $GLOBALS['TYPO3_CONF_VARS']['MAIL'] ?? [];
        $replyToAddress = $mailConfiguration['defaultMailReplyToAddress'] ?? null;
        if (empty($replyToAddress) || !GeneralUtility::validEmail($replyToAddress)) {
            return [];
        }

        if (!empty($mailConfiguration['defaultMailReplyToName'])) {
            $replyTo = [$replyToAddress => $mailConfiguration['defaultMailReplyToName']];
        } else {
            $replyTo = [$replyToAddress];
        }

        return $replyTo;
    }

    /**
     * Breaks up a single line of text for emails
     * Words - longer than $lineWidth - will not be split into parts
     *
     * @param string $str The string to break up
     * @param string $newlineChar The string to implode the broken lines with (default/typically \n)
     * @param int $lineWidth The line width
     * @return string Reformatted text
     */
    public static function breakLinesForEmail(string $str, string $newlineChar = LF, int $lineWidth = 76): string
    {
        $lines = [];
        $substrStart = 0;
        while (strlen($str) > $substrStart) {
            $substr = substr($str, $substrStart, $lineWidth);
            // has line exceeded (reached) the maximum width?
            if (strlen($substr) === $lineWidth) {
                // find last space-char
                $spacePos = strrpos(rtrim($substr), ' ');
                // space-char found?
                if ($spacePos !== false) {
                    // take everything up to last space-char
                    $theLine = substr($substr, 0, $spacePos);
                    $substrStart++;
                } else {
                    // search for space-char in remaining text
                    // makes this line longer than $lineWidth!
                    $afterParts = explode(' ', substr($str, $lineWidth + $substrStart), 2);
                    $theLine = $substr . $afterParts[0];
                }
                if ($theLine === '') {
                    // prevent endless loop because of empty line
                    break;
                }
            } else {
                $theLine = $substr;
            }
            $lines[] = trim($theLine);
            $substrStart += strlen($theLine);
            if (trim(substr($str, $substrStart, $lineWidth)) === '') {
                // no more text
                break;
            }
        }
        return implode($newlineChar, $lines);
    }

    /**
     * Parses mailbox headers and turns them into an array.
     *
     * Mailbox headers are a comma separated list of 'name <email@example.org>' combinations
     * or plain email addresses (or a mix of these).
     * The resulting array has key-value pairs where the key is either a number
     * (no display name in the mailbox header) and the value is the email address,
     * or the key is the email address and the value is the display name.
     *
     * Groups (RFC 5322 section 3.4) are flattened to their members and their display
     * name is discarded, comments are removed, and invalid addresses are silently skipped.
     *
     * @param string $rawAddresses Comma separated list of email addresses (optionally with display name)
     * @return array Parsed list of addresses.
     */
    public static function parseAddresses(string $rawAddresses): array
    {
        $addressList = [];
        foreach (self::splitAddressList($rawAddresses) as $rawMailbox) {
            $address = self::parseMailbox($rawMailbox);
            if ($address === null) {
                continue;
            }
            if ($address->getName() !== '') {
                // item with name found ( name <email@example.org> )
                $addressList[$address->getAddress()] = $address->getName();
            } else {
                // item without name found ( email@example.org )
                $addressList[] = $address->getAddress();
            }
        }
        return $addressList;
    }

    /**
     * Splits a raw address-list header value into its individual mailboxes, while
     * honoring quoted strings ( "last, first" <email@example.org> ), comments
     * (which are removed), domain literals ( user@[IPv6:2001:db8::1] ) and
     * angle-addr parts. Group members are flattened into the list, the display
     * name of a group is discarded.
     *
     * @return string[]
     */
    private static function splitAddressList(string $rawAddresses): array
    {
        $mailboxes = [];
        $buffer = '';
        $inQuotes = false;
        $inAngleAddr = false;
        $inDomainLiteral = false;
        $commentDepth = 0;
        $length = strlen($rawAddresses);
        for ($i = 0; $i < $length; $i++) {
            $char = $rawAddresses[$i];
            if ($commentDepth > 0) {
                if ($char === '\\') {
                    $i++;
                } elseif ($char === '(') {
                    $commentDepth++;
                } elseif ($char === ')') {
                    $commentDepth--;
                    if ($commentDepth === 0) {
                        // a comment is equivalent to folding white space (RFC 5322, section 3.2.2)
                        $buffer .= ' ';
                    }
                }
                continue;
            }
            if ($inQuotes) {
                if ($char === '\\' && $i + 1 < $length) {
                    $buffer .= $char . $rawAddresses[++$i];
                    continue;
                }
                if ($char === '"') {
                    $inQuotes = false;
                }
                $buffer .= $char;
                continue;
            }
            switch ($char) {
                case '"':
                    $inQuotes = true;
                    $buffer .= $char;
                    break;
                case '(':
                    $commentDepth++;
                    break;
                case '[':
                case ']':
                    $inDomainLiteral = $char === '[';
                    $buffer .= $char;
                    break;
                case '<':
                case '>':
                    $inAngleAddr = $char === '<';
                    $buffer .= $char;
                    break;
                case ',':
                case ';':
                    if ($inAngleAddr || $inDomainLiteral) {
                        $buffer .= $char;
                        break;
                    }
                    $mailboxes[] = $buffer;
                    $buffer = '';
                    break;
                case ':':
                    if ($inAngleAddr || $inDomainLiteral) {
                        $buffer .= $char;
                        break;
                    }
                    // a colon ends the display name of a group ( groupname: member@example.org; )
                    $buffer = '';
                    break;
                default:
                    $buffer .= $char;
            }
        }
        $mailboxes[] = $buffer;
        return $mailboxes;
    }

    private static function parseMailbox(string $rawMailbox): ?Address
    {
        $rawMailbox = trim($rawMailbox);
        // NUL is invalid anywhere, even in the obsolete syntax (RFC 5322, section 4.1)
        if ($rawMailbox === '' || str_contains($rawMailbox, "\0")) {
            return null;
        }
        $displayName = '';
        $addrSpec = $rawMailbox;
        $angleStart = self::findAngleAddrStart($rawMailbox);
        if ($angleStart !== null) {
            $angleEnd = strrpos($rawMailbox, '>');
            if ($angleEnd === false || $angleEnd < $angleStart) {
                return null;
            }
            $displayName = self::normalizeDisplayName(substr($rawMailbox, 0, $angleStart));
            $addrSpec = substr($rawMailbox, $angleStart + 1, $angleEnd - $angleStart - 1);
            if (str_starts_with($addrSpec, '@')) {
                // an obsolete route ( <@relay.example.org:user@example.org> ) is ignored (RFC 5322, section 4.4)
                $routeEnd = strpos($addrSpec, ':');
                if ($routeEnd !== false) {
                    $addrSpec = substr($addrSpec, $routeEnd + 1);
                }
            }
        }
        try {
            return new Address($addrSpec, $displayName);
        } catch (ExceptionInterface) {
            return null;
        }
    }

    /**
     * Finds the position of the '<' starting an angle-addr, ignoring any '<'
     * inside a quoted display name ( "Contact <va@example.org>" <real@example.org> ).
     */
    private static function findAngleAddrStart(string $rawMailbox): ?int
    {
        $inQuotes = false;
        $length = strlen($rawMailbox);
        for ($i = 0; $i < $length; $i++) {
            $char = $rawMailbox[$i];
            if ($inQuotes && $char === '\\') {
                $i++;
            } elseif ($char === '"') {
                $inQuotes = !$inQuotes;
            } elseif ($char === '<' && !$inQuotes) {
                return $i;
            }
        }
        return null;
    }

    /**
     * Resolves a quoted display name ( "last, first" ) and contained
     * quoted-pairs ( \" ) to the plain text it represents.
     */
    private static function normalizeDisplayName(string $displayName): string
    {
        $displayName = trim($displayName);
        if (strlen($displayName) > 1 && str_starts_with($displayName, '"') && str_ends_with($displayName, '"')) {
            $displayName = stripslashes(substr($displayName, 1, -1));
        }
        return $displayName;
    }
}