/**
 * Converts HTML email to plain text, conservatively removing signatures
 * and quoted reply chains.
 *
 * Public API:
 *   htmlEmailToText(html, requesterName?)
 *
 * Important:
 * Email signature extraction is heuristic. Preserve the original HTML
 * separately; this output should not be the authoritative ticket record.
 */

const cheerio = require('cheerio');

const BLOCK_TAGS = new Set([
    'address', 'article', 'aside', 'blockquote', 'caption',
    'dd', 'div', 'dl', 'dt', 'fieldset', 'figcaption', 'figure',
    'footer', 'form', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6',
    'header', 'li', 'main', 'nav', 'ol', 'p', 'pre',
    'section', 'table', 'tr', 'ul',
]);

// Do not include divtagdefaultwrapper: it can wrap the entire message.
const SIGNATURE_MARKERS = [
    'signature',
    'gmail_signature',
    'email-signature',
    'mail-signature',
    'x_signature',
    'moz-signature',
];

const QUOTE_MARKERS = [
    'gmail_quote',
    'gmail_quote_container',
    'freshdesk_quote',
    'appendonsend',
    // divrplyfwdmsg deliberately excluded: often header-only.
    'yahoo_quoted',
    'protonmail_quote',
    'zmail_extra',
];


const ATTRIBUTION_RE =
    /^(?:on\b.{3,500}\bwrote|le\b.{3,500}\ba\s*[ée]crit|el\b.{3,500}\bescribi[óo]|am\b.{1,200}\bschrieb\b.{1,300}|il\b.{3,500}\bha\s+scritto|em\b.{3,500}\bescreveu)\s*:\s*$/i;

const ORIGINAL_MESSAGE_RE =
    /^[-–—]{2,}\s*(?:original message|forwarded message)\s*[-–—]{2,}\s*$/i;

const FORWARDED_MESSAGE_RE =
    /^begin forwarded message\s*:\s*$/i;

const UNDERSCORE_SEPARATOR_RE = /^_{5,}$/;

const HEADER_LINE_RE =
    /^(from|sent|date|to|subject|cc|reply-to|de|envoyé|envoye|à|a|objet|para|fecha|asunto|von|gesendet|an|betreff)\s*:\s*(.*)$/i;

const HEADER_NAMES = {
    from: 'from',
    de: 'from',
    von: 'from',

    sent: 'date',
    date: 'date',
    envoyé: 'date',
    envoye: 'date',
    fecha: 'date',
    gesendet: 'date',

    to: 'to',
    à: 'to',
    a: 'to',
    para: 'to',
    an: 'to',

    subject: 'subject',
    objet: 'subject',
    asunto: 'subject',
    betreff: 'subject',

    cc: 'cc',
    'reply-to': 'reply-to',
};

const SIGNOFF_RE =
    /^(?:thanks(?:\s+(?:(?:and|&)\s+)?regards)?|thank\s+you(?:\s+so\s+much)?|many\s+thanks|best(?:\s+(?:regards|wishes))?|kind\s+regards|warm\s+regards|regards|sincerely|cheers|yours(?:\s+(?:truly|sincerely))?|with\s+appreciation|cordially|respectfully)[,!.\s]*$/i;

const SIGNATURE_SEPARATOR_RE = /^--\s*$/;

const MOBILE_SIGNATURE_RE =
    /^(?:sent from (?:my|a) (?:iphone|ipad|ipod|android|samsung|galaxy|blackberry|mobile|phone)\b.*|sent from (?:outlook|mail) for (?:ios|android|windows)\b.*|get outlook for (?:ios|android)\b.*)$/i;

const DISCLAIMER_RE =
    /^(?:confidentiality\s+(?:notice|disclaimer)|(?:legal\s+)?disclaimer\s*:\s*(?:this|the|please|if|confidential|privileged)|privileged\s+(?:and\s+)?confidential|this\s+(?:e-?mail|message|communication)(?:\s+and\s+(?:any\s+)?attachments?)?\s+(?:is|are|may\s+be)\s+(?:confidential|privileged|intended)|the\s+information\s+contained\s+in\s+this\s+(?:e-?mail|message|communication)\s+is\s+(?:confidential|privileged|intended)|if\s+you\s+(?:are\s+not\s+the\s+intended\s+recipient|have\s+received\s+this\s+(?:e-?mail|message)\s+in\s+error)|please\s+consider\s+the\s+environment\s+before\s+printing)/i;

const LEGAL_CONTINUATION_RE =
    /(?:confidential|privileged|intended recipient|unauthori[sz]ed|disclos(?:e|ure)|distribution|dissemination|attachments?|received.{0,40}error|delete.{0,40}(?:message|email|e-mail)|notify.{0,40}sender|liability|virus|printing this|all rights reserved|copyright)/i;

// Used to prevent a disclaimer/sign-off from eating an obvious new request.
const REQUEST_LINE_RE =
    /^(?:p\.?\s*s\.?(?=\s|[:.]|$)\s*[:.]?|please\b|can you\b|could you\b|would you\b|i (?:need|want|have|am|cannot|can't)\b|we (?:need|want|have|are|cannot|can't)\b|also\b|however\b|but\b|the (?:issue|problem|error)\b|it (?:still|does|doesn't|is|isn't)\b)/i;

const FORM_FIELD_RE =
    /^(?:first\s*name|last\s*name|full\s*name|name|e-?mail|organization|organisation|company|products?|timezone|time\s*zone|phone|telephone|mobile|subject|message|comments?|description|department|account(?:\s+(?:id|number))?|ticket(?:\s+(?:id|number))?)\s*[:\t]/i;

const EMAIL_RE = /[\w.!#$%&'*+/=?^`{|}~-]+@[\w-]+(?:\.[\w-]+)+/i;

const EMAIL_LINE_RE =
    /^(?:(?:e-?mail|e)\s*[:|]\s*)?[^\s<>@]+@[^\s<>@]+\.[^\s<>@]+[.,;]?$/i;

const URL_LINE_RE =
    /^(?:(?:web(?:site)?|url|linkedin)\s*[:|]\s*)?(?:https?:\/\/|www\.)\S+$/i;

const PHONE_LINE_RE =
    /^(?:(?:tel(?:ephone)?|phone|mobile|cell|fax|direct|office|work|t|m|p|f)\s*[:.]?\s*)?(?:\+?\d|\(\d)[\d\s()./-]*(?:\s*(?:(?:internal|int\.?)\s*[:.]?\s*(?:ex\.?|ext\.?)?|ext\.?|extension|ex\.?|x)\s*[:.]?\s*\d+)?$/i;

const TITLE_LINE_RE =
    /^(?:(?:senior|junior|principal|staff|lead|chief|vice president|vp|head of|assistant|associate|regional|global|technical|customer success)\s+)?(?:software|systems?|network|support|sales|security|data|product|project|account|marketing|operations?|business|solutions?)?\s*(?:engineer|architect|developer|manager|director|specialist|consultant|coordinator|analyst|administrator|representative|officer|executive|president|founder|owner|ceo|cto|coo|cfo|designer)(?:\s+of\s+[A-Za-z][A-Za-z0-9&/ -]{1,40})?(?:\s*[,–-]\s*[A-Za-z0-9&/.-]{1,30})?$/i;

const CREDENTIALS_LINE_RE =
    /^[A-Z][A-Z0-9/&.-]{1,10}(?:\s+[IVX]{1,4})?(?:,\s*[A-Z][A-Z0-9/&.-]{1,10}(?:\s+[IVX]{1,4})?)+$/;

const SIGNATURE_BOOKING_LINE_RE =
    /^(?:(?:schedule|book)\s+(?:a\s+)?(?:meeting|time|call|appointment)(?:\s+with\s+me)?\s*:(?:\s*\S.*)?|calendar)$/i;

const SIGNATURE_STATUS_LINE_RE =
    /^(?:out\s+of\s+(?:the\s+)?office|ooo|upcoming\s+(?:pto|out\s+of\s+office|leave)|travel(?:l?ing)?(?:\s+for\s+work)?|working\s+hours)\s*:\s*\S.*$/i;

const COMPANY_LINE_RE =
    /(?:\b(?:inc|incorporated|llc|l\.?l\.?c|ltd|limited|corp|corporation|gmbh|plc|llp|p\.?c|s\.?a|b\.?v|pty\.?\s*ltd)\b\.?|\b(?:university|college|institute|hospital|foundation)\b)$/i;

// Corporate suffix followed by a short comma clause (contractor / division / client relationship).
// Example: "Infosys Limited, Contracted to Pfizer Business Technology"
const COMPANY_WITH_CLAUSE_RE =
    /\b(?:inc\.?|incorporated|llc|l\.?l\.?c\.?|ltd\.?|limited|corp\.?|corporation|gmbh|plc|llp|p\.?c\.?|s\.?a\.?|b\.?v\.?|pty\.?\s*ltd\.?)\b,\s*[\p{L}\d&/().' -]{2,70}$/iu;

// Title-cased org-unit / department line with a unit keyword, optional (ACRONYM).
// Example: "Cloud Transformation, Infrastructure and Enterprise Solutions(C-TIES)"
const ORG_UNIT_KEYWORD_RE =
    /\b(?:solutions?|services|technology|technologies|infrastructure|transformation|operations|engineering|department|division|group|team|practice|unit|cent(?:er|re)|office|business)\b/i;

const ADDRESS_RE =
    /^(?:\d{1,6}\s+.{1,70}\b(?:street|st|avenue|ave|road|rd|parkway|pkwy|boulevard|blvd|drive|dr|lane|ln|way|court|ct|suite|ste|floor|fl)\b.*|p\.?\s*o\.?\s*box\s+\d+.*|[\p{L} .'-]+,\s*[\p{L} .'-]+\s+\d{5}(?:-\d{4})?(?:[\s,]+(?:USA|U\.S\.A\.?|US|U\.S\.?|United States(?:\s+of\s+America)?|Canada|UK|U\.K\.?))?)$/iu;

const SIGNATURE_LOOKBACK = 15;

function normalizeLine(value) {
    return value
        .replace(/\u00a0/g, ' ')
        .replace(/[\u200b\u200e\u200f\ufeff]/g, '')
        .replace(/[^\S\t\r\n]+/g, ' ')
        .trim();
}

function normalizeName(value) {
    return normalizeLine(value || '')
        .normalize('NFKC')
        .toLowerCase()
        .replace(/\s+/g, ' ');
}

function attrHitsMarker(value, markers) {
    if (!value) return false;

    const lower = value.toLowerCase();

    return markers.some(marker => {
        const escaped = marker.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
        return new RegExp(
            `(?:^|[\\s_-])${escaped}(?:$|[\\s_-])`
        ).test(lower);
    });
}

function hasMarker($el, markers) {
    return (
        attrHitsMarker($el.attr('class'), markers) ||
        attrHitsMarker($el.attr('id'), markers)
    );
}

function isAttribution(text) {
    return ATTRIBUTION_RE.test(text);
}

const DATE_OR_TIME_EVIDENCE_RE =
    /(?:\b(?:mon(?:day)?|tue(?:sday)?|wed(?:nesday)?|thu(?:rsday)?|fri(?:day)?|sat(?:urday)?|sun(?:day)?)\b|\b(?:jan(?:uary)?|feb(?:ruary)?|mar(?:ch)?|apr(?:il)?|may|jun(?:e)?|jul(?:y)?|aug(?:ust)?|sep(?:tember)?|oct(?:ober)?|nov(?:ember)?|dec(?:ember)?)\b|\b\d{1,2}[/-]\d{1,2}(?:[/-]\d{2,4})?\b|\b\d{4}[/-]\d{1,2}[/-]\d{1,2}\b|\b\d{1,2}:\d{2}(?:\s*[ap]\.?m\.?)?\b)/i;

function isStrongAttribution(text) {
    if (!isAttribution(text)) return false;

    return (
        EMAIL_RE.test(text) ||
        DATE_OR_TIME_EVIDENCE_RE.test(text)
    );
}

function isExplicitTextBoundary(text) {
    return (
        ORIGINAL_MESSAGE_RE.test(text) ||
        FORWARDED_MESSAGE_RE.test(text) ||
        isStrongAttribution(text)
    );
}

/**
 * Plain-text rendering used to inspect a possible signature card.
 * Includes the root node and handles text nodes, blocks, and <br>.
 */
function visibleText(node) {
    if (!node) return '';
    if (node.type === 'text') return node.data || '';

    const tag = (node.tagName || '').toLowerCase();
    if (tag === 'script' || tag === 'style') return '';
    if (tag === 'br') return '\n';

    const text = (node.children || []).map(visibleText).join('');

    if (tag === 'td' || tag === 'th') return `${text}\t`;
    return BLOCK_TAGS.has(tag) ? `\n${text}\n` : text;
}

function isPhoneLine(line) {
    if (!PHONE_LINE_RE.test(line)) return false;

    const digits = line.replace(/\D/g, '');
    return digits.length >= 7 && digits.length <= 18;
}

function isContactLine(line) {
    return EMAIL_LINE_RE.test(line) || URL_LINE_RE.test(line) || isPhoneLine(line);
}

function looksLikeName(line, requesterName) {
    if (requesterName && normalizeName(line) === normalizeName(requesterName)) {
        return true;
    }

    if (line.length > 70 || REQUEST_LINE_RE.test(line)) return false;
    if (isTitleLine(line) || isCompanyLine(line)) return false;

    // Deliberately conservative without a known sender name.
    // Lowercase/non-Latin display names still work through requesterName.
    return /^(?:\p{Lu}[\p{L}'’.-]*)(?:\s+(?:(?:de|del|van|von|da|di|la)\s+)?\p{Lu}[\p{L}'’.-]*){1,3}$/u.test(line);
}

function isTitleLine(line) {
    return (
        line.length <= 90 &&
        !/[?!]/.test(line) &&
        !/[.]\s*$/.test(line) &&
        !REQUEST_LINE_RE.test(line) &&
        !/\b(?:i(?!\.)|we|you|your|our|need|please|escalate|send|contact|call|update|fix|change)\b/i.test(line) &&
        TITLE_LINE_RE.test(line)
    );
}

function isCompanyLine(line) {
    return (
        line.length <= 90 &&
        !/[?!]/.test(line) &&
        !REQUEST_LINE_RE.test(line) &&
        !/\b(?:i(?!\.)|we|you|your|our|need|please|escalate|send|contact|call|update|fix|change)\b/i.test(line) &&
        (COMPANY_LINE_RE.test(line) || COMPANY_WITH_CLAUSE_RE.test(line))
    );
}

function isOrgUnitLine(line) {
    if (line.length > 90 || /[?!]/.test(line) || /[.]\s*$/.test(line)) return false;
    if (REQUEST_LINE_RE.test(line)) return false;
    if (/\b(?:i(?!\.)|we|you|your|our|need|please|escalate|send|contact|call|update|fix|change|is|are|was|has|have|will)\b/i.test(line)) return false;
    if (!ORG_UNIT_KEYWORD_RE.test(line)) return false;

    // Strip an optional trailing "(C-TIES)" acronym, then require Title Case
    // words (small connectors like "and"/"of"/"for" allowed).
    const body = line.replace(/\s*\([A-Z][A-Z0-9&/-]{1,12}\)\s*$/, '');
    const words = body.split(/[\s,/&-]+/).filter(Boolean);
    return words.length >= 2 && words.every(w =>
        /^(?:and|of|for|the|to|in|on)$/i.test(w) ||
        /^\p{Lu}[\p{L}\d'’.-]*$/u.test(w)
    );
}

function isSignatureDetail(line, requesterName) {
    return (
        looksLikeName(line, requesterName) ||
        isTitleLine(line) ||
        isCompanyLine(line) ||
        isOrgUnitLine(line) ||
        isContactLine(line) ||
        ADDRESS_RE.test(line) ||
        MOBILE_SIGNATURE_RE.test(line) ||
        SIGNATURE_SEPARATOR_RE.test(line) ||
        SIGNOFF_RE.test(line) ||
        CREDENTIALS_LINE_RE.test(line) ||
        SIGNATURE_BOOKING_LINE_RE.test(line) ||
        SIGNATURE_STATUS_LINE_RE.test(line)
    );
}

// Examples:
//   DPC, Donnelly 115
//   MIT, Building 32
//
// Deliberately requires an uppercase campus/site code, a comma,
// a capitalized building name, and a room/building number.
const CAMPUS_LOCATION_RE =
    /^[A-Z][A-Z0-9&.-]{1,11},\s*(?:\p{Lu}[\p{L}.'’-]*\s+){1,4}\d{1,5}[A-Za-z]?$/u;

// Examples:
//   Room 115
//   Office: B-204
//   Suite 300
//   Building 32
//
// Does not accept arbitrary text after the room identifier.
const LABELED_ROOM_RE =
    /^(?:room|rm\.?|office|suite|ste\.?|building|bldg\.?)\s*:?\s*(?:[A-Za-z]{1,3}[- ]?)?\d{1,5}[A-Za-z]?(?:[-/]\d{1,5}[A-Za-z]?)?$/i;

function isSignatureLocationLine(line) {
    return (
        line.length <= 80 &&
        !REQUEST_LINE_RE.test(line) &&
        (
            CAMPUS_LOCATION_RE.test(line) ||
            LABELED_ROOM_RE.test(line)
        )
    );
}

/**
 * Validate a complete signature tail.
 *
 * A building/room line is allowed only when:
 * - the tail contains a recognizable contact line;
 * - it also contains a title or company line;
 * - at most one line needs the location exception.
 *
 * Every other line must satisfy the existing signature-detail rules.
 * Unknown prose is never silently accepted.
 */
function isSignatureTail(lines, requesterName) {
    if (hasStructuredForm(lines)) return false;

    const hasContact = lines.some(isContactLine);
    const hasProfessionalContext = lines.some(line =>
        isTitleLine(line) || isCompanyLine(line) || isOrgUnitLine(line)
    );

    let locationExceptions = 0;

    for (const line of lines) {
        if (isSignatureDetail(line, requesterName)) continue;

        if (
            hasContact &&
            hasProfessionalContext &&
            locationExceptions === 0 &&
            isSignatureLocationLine(line)
        ) {
            locationExceptions++;
            continue;
        }

        return false;
    }

    return true;
}

/**
 * A logo + website alone is not enough: it could be a real message card.
 * Require a compact contact card with a person/title signal and a direct
 * contact link, and never classify a leading layout table as a signature.
 */
function isSignatureCard($, el, requesterName, hasPrecedingText) {
    if (!hasPrecedingText) return false;

    const tag = (el.tagName || '').toLowerCase();
    if (!['table', 'div', 'section'].includes(tag)) return false;

    const $el = $(el);
    if (!$el.find('img').length) return false;

    const hasDirectContact = $el.find('a[href]').toArray().some(a =>
        /^(?:mailto|tel):/i.test(($(a).attr('href') || '').trim())
    );

    const lines = visibleText(el)
        .split(/\r\n?|\n|\t/)
        .map(normalizeLine)
        .filter(Boolean);

    const hasVisibleContact = lines.some(isContactLine);

    if (!hasDirectContact && !hasVisibleContact) return false;

    if (lines.length < 2 || lines.length > 8) return false;
    if (lines.join(' ').length > 500) return false;

    return (
        lines.some(line =>
            looksLikeName(line, requesterName) || isTitleLine(line)
        ) &&
        isSignatureTail(lines, requesterName)
    );
}

/**
 * Render into structured lines rather than injecting magic text tokens.
 *
 * A removed quote remains represented as { kind: 'quote' }, allowing:
 *
 *   On ... wrote:
 *   <blockquote type="cite">old message</blockquote>
 *   My response below the quote.
 *
 * to retain the response rather than truncating at the attribution.
 */
function renderEmailLines($, root, requesterName, options = {}) {
    const keepQuotes = options.keepQuotes === true;
    const keepSignatures = options.keepSignatures === true;
    const lines = [];
    let buffer = '';
    let hasPrecedingText = false;

    function flush() {
        for (const part of buffer.split(/\r\n?|\n/)) {
            const text = normalizeLine(part);
            if (!text) continue;

            lines.push({ kind: 'text', text });
            hasPrecedingText = true;
        }
        buffer = '';
    }

    function marker(kind) {
        flush();
        lines.push({ kind });
    }

    function walk(node) {
        if (node.type === 'text') {
            buffer += node.data || '';
            return;
        }

        const tag = (node.tagName || '').toLowerCase();

        // Also traverse document/root nodes.
        if (!tag) {
            (node.children || []).forEach(walk);
            return;
        }

        if (['script', 'style', 'head', 'template'].includes(tag)) return;

        const $el = $(node);
        const style = $el.attr('style') || '';

        if (
            $el.attr('hidden') !== undefined ||
            /(?:^|;)\s*display\s*:\s*none\b/i.test(style) ||
            /(?:^|;)\s*visibility\s*:\s*hidden\b/i.test(style)
        ) {
            return;
        }

        if ($el.attr('data-skip-ai-process') !== undefined) {
            marker('skipped');
            return;
        }

        // Document wrappers must not be classified as signatures/quotes.
        if (!['html', 'body'].includes(tag)) {
            if (!keepSignatures && hasMarker($el, SIGNATURE_MARKERS)) {
                marker('signature');
                return;
            }

            let lastText = normalizeLine(buffer);
            if (!lastText) {
                for (let li = lines.length - 1; li >= 0; li--) {
                    if (lines[li].kind === 'text') {
                        lastText = lines[li].text;
                        break;
                    }
                }
            }
            const citePrecededByAttribution =
                tag === 'blockquote' &&
                ($el.attr('type') || '').toLowerCase() === 'cite' &&
                isStrongAttribution(lastText);

            const explicitQuote =
                !keepQuotes &&
                (
                    hasMarker($el, QUOTE_MARKERS) ||
                    citePrecededByAttribution
                );

            if (explicitQuote) {
                marker('quote');
                return;
            }

            if (
                !keepSignatures &&
                isSignatureCard(
                    $, node, requesterName,
                    hasPrecedingText || Boolean(normalizeLine(buffer))
                )
            ) {
                marker('signature');
                return;
            }
        }

        if (tag === 'hr') {
            marker('divider');
            return;
        }

        if (tag === 'br') {
            flush();
            return;
        }

        const block = BLOCK_TAGS.has(tag);
        if (block) flush();

        (node.children || []).forEach(walk);

        if (tag === 'td' || tag === 'th') {
            buffer += '\t';
        } else if (block) {
            flush();
        }
    }

    walk(root);
    flush();

    return lines;
}

/**
 * Recognize a contiguous reply-header cluster.
 *
 * Unlike collecting arbitrary headers from the next eight lines, this
 * stops at ordinary prose. "From:" in one paragraph and "Subject:" much
 * later cannot combine into a false reply boundary.
 */
function readReplyHeader(lines, start) {
    const fields = new Map();
    let end = start;

    while (end < lines.length && end - start < 8) {
        const entry = lines[end];
        if (entry.kind !== 'text') break;

        const match = entry.text.match(HEADER_LINE_RE);
        if (!match) break;

        const name = HEADER_NAMES[match[1].toLowerCase()];
        fields.set(name, match[2].trim());
        end++;
    }

    const sender = fields.get('from');
    if (!sender) return null;

    const hasDate = fields.has('date');
    const hasEmailSender = EMAIL_RE.test(sender);

    const confident =
        (
            fields.size >= 2 &&
            hasDate &&
            (hasEmailSender || fields.size >= 3)
        ) ||
        (
            fields.size >= 3 &&
            hasEmailSender &&
            fields.has('subject')
        );

    return confident ? { end } : null;
}

function nextRelevantIndex(lines, start) {
    let i = start;
    while (
        i < lines.length &&
        ['divider', 'skipped', 'signature'].includes(lines[i].kind)
    ) {
        i++;
    }
    return i;
}

/**
 * Remove explicit quote nodes and detect unmarked quoted tails.
 *
 * Explicit >-prefixed quotes can be interleaved with customer answers.
 * Do not truncate those answers merely because an attribution precedes
 * the first quoted line.
 */
function removeReplyNoise(entries) {
    const kept = [];

    for (let i = 0; i < entries.length; i++) {
        const entry = entries[i];
        if (entry.kind !== 'text') continue;

        const text = entry.text;

        if (/^>/.test(text)) continue;

        const header = readReplyHeader(entries, i);
        const attribution = isAttribution(text);
        const boundary = isExplicitTextBoundary(text);

        const underscoreHeader =
            UNDERSCORE_SEPARATOR_RE.test(text) &&
            readReplyHeader(entries, nextRelevantIndex(entries, i + 1));

        if (!header && !attribution && !boundary && !underscoreHeader) {
            kept.push(text);
            continue;
        }

        const after = header ? header.end : i + 1;
        const next = nextRelevantIndex(entries, after);
        const nextEntry = entries[next];

        const followedByExplicitQuote =
            nextEntry?.kind === 'quote' ||
            (
                nextEntry?.kind === 'text' &&
                /^>/.test(nextEntry.text)
            );

        if (followedByExplicitQuote) {
            // Remove only the attribution/header, not later answers.
            i = after - 1;
            continue;
        }

        if (header || boundary || underscoreHeader) {
            if (kept.length > 0) break;

            // A forward/quote at the beginning may be the ticket's entire
            // submitted content. Preserve its body rather than returning
            // an empty ticket; omit only the recognized header.
            i = after - 1;
            continue;
        }

        // Attribution-like prose without corroboration stays intact.
        kept.push(text);
    }

    return kept;
}

// Contact labels frequently occur in real signatures. They do not, by
// themselves, prove that a block is a structured intake submission.
const CONTACT_FIELD_LABEL_RE =
    /^(?:e-?mail|phone|telephone|mobile)\s*[:\t]/i;

// These fields strongly suggest submitted ticket/form data.
// Preserve them even when there is only one such label in the candidate.
const INTAKE_ONLY_FIELD_RE =
    /^(?:first\s*name|last\s*name|products?|timezone|time\s*zone)\s*[:\t]/i;

function hasStructuredForm(lines) {
    if (lines.some(line => INTAKE_ONLY_FIELD_RE.test(line))) {
        return true;
    }

    const fields = lines.filter(line => FORM_FIELD_RE.test(line));

    // Email + Phone can be signature details.
    // Organization + Email, Name + Phone, etc. remain protected.
    return (
        fields.length >= 2 &&
        fields.some(line => !CONTACT_FIELD_LABEL_RE.test(line))
    );
}

// Hard-wrapped disclaimer text (a signature block or pasted legal footer
// wrapped at a fixed column, using literal newlines instead of <br>) can
// split a trigger phrase across two physical lines, e.g.:
//   "...if you have received this e-mail in"
//   "error please notify the sender..."
// Joining a line with the one right after it lets the phrase regexes match
// across that wrap point. REQUEST_LINE_RE is still tested against the
// unjoined line only, so a genuine new paragraph still breaks the boundary.
function withNextLine(lines, i) {
    return i + 1 < lines.length ? `${lines[i]} ${lines[i + 1]}` : lines[i];
}

function findTrailingDisclaimerBoundary(lines, end) {
    for (let i = Math.max(1, end - 20); i < end; i++) {
        const anchor = lines[i];
        const anchorJoined = withNextLine(lines, i);

        if (!DISCLAIMER_RE.test(anchor) && !DISCLAIMER_RE.test(anchorJoined)) continue;

        const rest = lines.slice(i + 1, end);

        // Conservative: an unrelated paragraph after the notice makes
        // its extent ambiguous, so do not delete the whole tail.
        if (rest.every((line, j) => {
            const joined = withNextLine(rest, j);
            return (
                DISCLAIMER_RE.test(line) ||
                DISCLAIMER_RE.test(joined) ||
                (
                    !REQUEST_LINE_RE.test(line) &&
                    (
                        LEGAL_CONTINUATION_RE.test(line) ||
                        LEGAL_CONTINUATION_RE.test(joined) ||
                        isContactLine(line) ||
                        /^©|^copyright\b/i.test(line)
                    )
                )
            );
        })) {
            return i;
        }
    }

    return -1;
}

function findSignatureBoundary(lines, end, requesterName) {
    const floor = Math.max(1, end - SIGNATURE_LOOKBACK);

    for (let i = floor; i < end; i++) {
        const line = lines[i];

        const isBoundary =
            SIGNOFF_RE.test(line) ||
            SIGNATURE_SEPARATOR_RE.test(line) ||
            MOBILE_SIGNATURE_RE.test(line);

        if (!isBoundary) continue;

        const tail = lines.slice(i + 1, end);

        if (isSignatureTail(tail, requesterName)) {
            return i;
        }
    }

    return -1;
}

function findUnmarkedSignatureBoundary(lines, end, requesterName) {
    const floor = Math.max(1, end - SIGNATURE_LOOKBACK);
    const window = lines.slice(floor, end);

    // Protect structured submitted data before considering any cut point.
    if (hasStructuredForm(window)) return -1;

    for (let i = floor; i < end - 1; i++) {
        const name = lines[i];
        if (!looksLikeName(name, requesterName)) continue;

        const tail = lines.slice(i + 1, end);
        if (!tail.length) continue;

        if (!isSignatureTail(tail, requesterName)) continue;

        const knownName = Boolean(
            requesterName &&
            normalizeName(name) === normalizeName(requesterName)
        );

        const hasContact = tail.some(isContactLine);
        const hasTitle = tail.some(isTitleLine);
        const hasCompany = tail.some(isCompanyLine);

        if (
            (knownName && (hasContact || hasTitle)) ||
            (hasContact && (hasTitle || hasCompany))
        ) {
            let cut = i;
            while (cut > 1 && SIGNATURE_STATUS_LINE_RE.test(lines[cut - 1])) {
                cut--;
            }
            return cut;
        }
    }

    return -1;
}

function stripTrailingEmailNoise(lines, requesterName) {
    if (!lines.length) return '';

    let end = lines.length;

    const disclaimer = findTrailingDisclaimerBoundary(lines, end);
    if (disclaimer >= 0) end = disclaimer;

    let signature = findSignatureBoundary(lines, end, requesterName);

    if (signature < 0) {
        signature = findUnmarkedSignatureBoundary(lines, end, requesterName);
    }

    if (signature >= 0) end = signature;

    return lines.slice(0, end).join('\n');
}

/**
 * @param {string} html
 * @param {string} [requesterName]
 * @returns {string}
 */
function htmlEmailToText(html, requesterName) {
    if (html == null || html === '') return '';

    // Fail explicitly on unexpected API payloads instead of converting an
    // object to "[object Object]" or silently producing an empty message.
    if (typeof html !== 'string') {
        throw new TypeError('htmlEmailToText: html must be a string');
    }

    const name = typeof requesterName === 'string' ? requesterName : undefined;
    const $ = cheerio.load(html);
    const root = $('body').get(0) || $.root().get(0);

    const entries = renderEmailLines($, root, name);
    const lines = removeReplyNoise(entries);
    const cleaned = stripTrailingEmailNoise(lines, name);

    if (cleaned) return cleaned;

    // Never let the heuristics turn a non-empty message into an empty one.
    // Re-render with quote/signature containers kept. Hidden,
    // display:none, and data-skip-ai-process content stays excluded,
    // because those checks run above the options gates.
    const fallbackEntries = renderEmailLines($, root, name, {
        keepQuotes: true,
        keepSignatures: true,
    });

    const fallbackLines = removeReplyNoise(fallbackEntries);
    const fallbackText = stripTrailingEmailNoise(fallbackLines, name);

    if (fallbackText) return fallbackText;

    // Last resort: return everything textual rather than an empty ticket.
    return fallbackEntries
        .filter(entry => entry.kind === 'text')
        .map(entry => entry.text)
        .filter(Boolean)
        .join('\n');
}

module.exports = { htmlEmailToText };