import { calculateMatch, normalizePersonNameExtract } from './utils';

export type RuleExtractHints = {
    /** MSD fields typed in UI — used to find the same text inside the PDF (no "Name:" label needed). */
    msdPayload?: Record<string, unknown>;
    /** When `CSD_PO`, prefer buyer/beneficiary lines (Sold To, Bill To, …) over the first generic `Name:` (often supplier). */
    documentType?: string;
};

/**
 * Regex-based extraction logic for CPC-CSD documents.
 * Provides a lightweight alternative to Gemini for common patterns.
 * Field names align with MSD payloads from the CPC dashboard (e.g. authority_letter).
 */
function escapeRegExp(s: string): string {
    return s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

/** If MSD name appears verbatim (spacing flexible) in PDF text, return the matched span. */
function matchMsdNameInBody(body: string, expected: string): string | null {
    const e = String(expected || '').trim();
    if (e.length < 2) return null;
    const flex = escapeRegExp(e).replace(/\s+/g, '\\s+');
    const m = body.match(new RegExp(flex, 'i'));
    return m ? m[0].replace(/\s+/g, ' ').trim() : null;
}

/**
 * Same word as MSD on a line with other text (table cells, "Customer Arjun …") — strict substring match often fails.
 */
function findMsdNameTokenInOcr(body: string, expected: string): string | null {
    const h = String(expected || '').trim();
    if (h.length < 2 || !body.trim()) return null;
    const hl = h.toLowerCase();
    const noise = /^(qty|ref|date|page|gst|hsn|po|no|id|by|to|of|in|at|sl|sr|index|desc|amount|total)$/i;
    const lines = body.split(/\r?\n/).map((l) => l.trim()).filter((l) => l.length > 0);
    for (const line of lines) {
        if (line.length > 160) continue;
        if (line.toLowerCase() === hl) return line;
        const parts = line.split(/[\s,;:|/<>()[\]]+/).filter(Boolean);
        for (const raw of parts) {
            const p = raw.replace(/^[^A-Za-z\u0900-\u097F0-9]+|[^A-Za-z\u0900-\u097F0-9]+$/g, '');
            if (!p || p.length < 2 || noise.test(p)) continue;
            if (p.toLowerCase() === hl) return p;
        }
    }
    return null;
}

/** Pick a short line whose fuzzy score vs MSD is high (authority letters often put name on its own line). */
function pickNameLineByMsd(body: string, expected: string, minScore = 52): string | null {
    const exp = String(expected || '').trim();
    if (exp.length < 2 || !body.trim()) return null;
    let best: { line: string; score: number } | null = null;
    const lines = body.split(/\r?\n/).map((l) => l.trim()).filter((l) => l.length > 2 && l.length < 120);
    for (const line of lines) {
        if (/^(page|ref|no\.?|date|subject|to|from|dear|sir|madam|annex|schedule|authority|letter|royal|enfield|\d+\s*\/\s*\d+)/i.test(line)) {
            continue;
        }
        const s = calculateMatch(exp, line, 'authorized_person_name');
        if (s >= minScore && (!best || s > best.score)) {
            best = { line, score: s };
        }
    }
    return best?.line ?? null;
}

function normalizePan(s: string): string | null {
    const p = String(s || '')
        .toUpperCase()
        .replace(/\s/g, '');
    return /^[A-Z]{5}[0-9]{4}[A-Z]$/.test(p) ? p : null;
}

/** If MSD PAN appears in PDF text, return canonical PAN (OCR may split with spaces). */
function panFromMsdHint(body: string, msdPan: unknown): string | null {
    const p = normalizePan(String(msdPan ?? ''));
    if (!p || !body) return null;
    const compact = body.toUpperCase().replace(/[\s-]/g, '');
    return compact.includes(p) ? p : null;
}

/** If MSD amount digits appear in body, return normalized digit string for range match. */
function invoiceDigitsFromMsdHint(body: string, msdAmt: unknown): string | null {
    const d = String(msdAmt ?? '').replace(/[^\d.]/g, '');
    if (!d || d.length < 1) return null;
    const intPart = d.split('.')[0];
    if (intPart.length >= 2 && body.replace(/[^\d]/g, '').includes(intPart)) {
        return d;
    }
    return null;
}

/** Supplier / letterhead lines — not the CSD customer individual name. */
const RE_COMPANY_NAME_HINT =
    /\b(LIMITED|LTD\.?|L\.?\s*L\.?\s*P\.?|PVT\.?\s*LTD|PRIVATE\s+LIMITED|PVT|PTE|INC\.?|CORP|CORPORATION|INDIA\s+LTD|MOTORS?|AUTOMOBILES?|DEALERS?|ENTERPRISES?|SALES\s*(?:&|AND)?\s*SERVICE|WORKS|AGENCIES)\b/i;

function looksLikeCompanyLine(s: string): boolean {
    const x = String(s || '').trim();
    if (!x) return false;
    if (RE_COMPANY_NAME_HINT.test(x)) return true;
    if (/^[A-Z0-9.&\s\-]{14,}$/.test(x) && !/\s{2,}/.test(x)) return true;
    return false;
}

function trimBuyerCapture(raw: string): string {
    let s = String(raw || '').replace(/\r/g, '').trim();
    s = s.replace(/^[:\-–—\s]+/, '');
    const cut = s.split(/\b(?:GSTIN|PAN|Phone|Tel|Email|E-?mail|Mob|Mobile|Address|Qty|Quantity|Part)\b/i)[0];
    s = (cut ?? s).trim();
    return s.replace(/\s+/g, ' ').trim();
}

function isCsdPoHints(hints?: RuleExtractHints): boolean {
    const dt = String(hints?.documentType || '').toUpperCase();
    return dt.includes('CSD_PO') || dt.includes('PURCHASE_ORDER');
}

/** Many CSD PO line-items print: 16-digit card/UIN then customer name then plot no / address (Description column). */
const RE_VEHICLE_TOKENS =
    /^(ROYAL|ENFIELD|METEOR|CLASSIC|BULLET|HIMALAYAN|INTERCEPTOR|CONTINENTAL|STELLAR|THUNDER|BS-?VI|BSVI|SUPER|VARIANT|MODEL|CC|HP|ABS|QTY|HSN)$/i;

function isPlausibleHumanNameFromPoDescription(s: string): boolean {
    const x = String(s || '')
        .replace(/\s+/g, ' ')
        .trim();
    if (x.length < 3 || x.length > 72) return false;
    const parts = x.split(/\s+/).filter(Boolean);
    if (parts.length < 1 || parts.length > 6) return false;
    if (looksLikeCompanyLine(x)) return false;
    for (const p of parts) {
        if (RE_VEHICLE_TOKENS.test(p)) return false;
    }
    return parts.some((p) => /^[A-Za-z\u0900-\u097F]{2,}$/.test(p));
}

/**
 * Pattern: `5312423002619089 KALAIYARASAN K 71` — 16 digits (optional spaces in groups of 4),
 * then name tokens, then often a short plot/house number or newline/address.
 */
function extractCsdPoNameInDescriptionColumn(body: string): string | null {
    const norm = body.replace(/\r\n/g, '\n').replace(/\u00a0/g, ' ');
    const digitRes: RegExp[] = [/\b\d{4}\s+\d{4}\s+\d{4}\s+\d{4}\b/g, /\b\d{16}\b/g];
    const seenAt = new Set<number>();

    for (const re of digitRes) {
        re.lastIndex = 0;
        let dm: RegExpExecArray | null;
        while ((dm = re.exec(norm)) !== null) {
            const compact = dm[0].replace(/\s/g, '');
            if (compact.length !== 16 || !/^\d{16}$/.test(compact)) continue;
            if (seenAt.has(dm.index)) continue;
            seenAt.add(dm.index);

            const tail = norm.slice(dm.index + dm[0].length).replace(/^\s+/, '');
            let nm = tail.match(
                /^([A-Za-z\u0900-\u097F]+(?:\s+[A-Za-z\u0900-\u097F]+){0,5})(?=\s+\d{1,4}\b|\s*\n|\s*$)/i
            );
            if (!nm?.[1]) {
                const loose = tail.match(/^([A-Za-z\u0900-\u097F]{2,25})\b/i);
                if (loose?.[1] && isPlausibleHumanNameFromPoDescription(loose[1])) nm = loose;
            }
            if (!nm?.[1]) continue;
            const candidate = nm[1].replace(/\s+/g, ' ').trim();
            if (isPlausibleHumanNameFromPoDescription(candidate)) {
                return candidate;
            }
        }
    }
    return null;
}

/**
 * CSD / defence-style POs usually put the customer under Sold To / Bill To / card holder,
 * not under the first "Name:" (often dealer contact).
 */
function extractCsdPoBuyerFromLabels(body: string): string | null {
    const norm = body.replace(/\r\n/g, '\n');
    const patterns: RegExp[] = [
        /(?:^|\n)\s*Sold\s*To\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i,
        /(?:^|\n)\s*Bill\s*To\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i,
        /(?:^|\n)\s*Ship\s*To\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i,
        /(?:^|\n)\s*Consignee\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i,
        /(?:^|\n)\s*(?:Buyer|Purchaser)\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i,
        /(?:^|\n)\s*Customer\s*(?:Name|Details)?\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i,
        /(?:^|\n)\s*CSD\s*Card(?:\s*Holder)?\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i,
        /(?:^|\n)\s*Card\s*Holder(?:\s*Name)?\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i,
        /(?:^|\n)\s*Beneficiary\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i,
        /(?:^|\n)\s*Name\s*of\s*(?:the\s*)?(?:Purchaser|Buyer|Customer)\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i,
        /(?:^|\n)\s*(?:Ordered|Order)\s*(?:By|Placed\s*By)\s*[:\-]?\s*\n*\s*([^\n\r]{2,120})/i
    ];
    for (const re of patterns) {
        const m = norm.match(re);
        if (!m?.[1]) continue;
        const line = trimBuyerCapture(m[1]);
        if (line.length < 2 || line.length > 100) continue;
        if (/^(page|date|amount|total|ref|subject)\b/i.test(line)) continue;
        return line;
    }
    return null;
}

export class CpcRuleExtractService {
    /**
     * If Vertex returned a supplier-style string but OCR shows a clear buyer line, prefer the buyer line.
     */
    static refineCsdPoCustomerName(ocrText: string, customerName: unknown): string | null {
        const cur = String(customerName ?? '').trim();
        const text = String(ocrText || '');
        const fromDesc = extractCsdPoNameInDescriptionColumn(text);
        const fromLabels = extractCsdPoBuyerFromLabels(text);
        const buyer = fromDesc || fromLabels;
        if (!buyer) return cur.length >= 2 ? cur : null;
        if (!cur) return buyer;
        if (looksLikeCompanyLine(cur) && !looksLikeCompanyLine(buyer)) return buyer;
        return cur;
    }

    static extractWithRules(ocrText: string, hints?: RuleExtractHints) {
        const t = String(ocrText || "");
        const msd = hints?.msdPayload || {};
        const isCsdPo = isCsdPoHints(hints);

        // Matches 12 digit Aadhaar (with optional spaces)
        const aadhaarMatch = t.match(/\b\d{4}\s?\d{4}\s?\d{4}\b/);

        // Matches currency patterns
        const invoiceMatch = t.match(/(?:₹|Rs\.?|INR)\s?[\d,]+(?:\.\d{1,2})?/i);

        // Matches common order/auth patterns
        const orderMatch = t.match(/\b(?:PO|ORDER|AUTH|AUTHORIZATION)\s*[:\-]?\s*([A-Z0-9\-\/]{4,})/i);

        // Matches "Name: [Value]" / "Authorised Person" / applicant-style labels
        const nameMatch = t.match(/\bName\s*[:\-]\s*([A-Za-z][A-Za-z0-9\s.'-]{2,79})/i);
        const authPersonMatch = t.match(
            /\b(?:authorized|authorised)\s+person\s*[:\-]\s*([A-Za-z][A-Za-z0-9\s.'-]{2,79})/i
        );
        const applicantMatch = t.match(
            /\b(?:applicant|holder|customer|borrower|dealer)\s*[:\-]\s*([A-Za-z][A-Za-z0-9\s.'-]{2,79})/i
        );
        let displayNameRaw = isCsdPo
            ? extractCsdPoNameInDescriptionColumn(t) || extractCsdPoBuyerFromLabels(t) || ''
            : '';
        if (!displayNameRaw) {
            displayNameRaw = (authPersonMatch?.[1] || nameMatch?.[1] || applicantMatch?.[1] || '').trim();
        }

        // MSD-guided: name often appears in body exactly as user typed (no label) — same idea as manual compare in CPC-CSD UI flow
        if (!displayNameRaw) {
            const fromAuth = msd.customer_name ?? msd.authorized_person_name ?? msd.name;
            const hint = String(fromAuth ?? '').trim();
            if (hint) {
                const minFuzzy = hint.length <= 10 ? 40 : 52;
                displayNameRaw =
                    matchMsdNameInBody(t, hint) ||
                    findMsdNameTokenInOcr(t, hint) ||
                    pickNameLineByMsd(t, hint, minFuzzy) ||
                    '';
            }
        }

        // Title / ALL CAPS line fallback — include short single names (e.g. "Arjun") skipped by older rules
        if (!displayNameRaw) {
            const lines = t.split(/\r?\n/).map((l) => l.trim()).filter(Boolean);
            const noiseLine = /^(qty|ref|date|page|gst|hsn|po|no|id|total|amount|index|desc|sl)$/i;
            for (const line of lines) {
                if (line.length < 3 || line.length > 80) continue;
                if (noiseLine.test(line)) continue;
                if (/^(ref|date|subject|to|from|dear|page|annex|authority|letter|royal|enfield|cpc|csd)\b/i.test(line)) {
                    continue;
                }
                if (isCsdPo && looksLikeCompanyLine(line)) {
                    continue;
                }
                const words = line.split(/\s+/).filter(Boolean);
                const singleName =
                    words.length === 1 &&
                    /^[A-Za-z\u0900-\u097F]{2,25}$/.test(words[0]) &&
                    !RE_VEHICLE_TOKENS.test(words[0]) &&
                    !looksLikeCompanyLine(words[0]);
                const multiAllCaps =
                    /^[A-Z][A-Z0-9\s.'-]{4,70}$/.test(line) && words.length >= 2;
                if (singleName || multiAllCaps) {
                    displayNameRaw = line;
                    break;
                }
                const titleCaseName =
                    words.length >= 1 &&
                    words.length <= 4 &&
                    words.every((w) => /^[A-Za-z\u0900-\u097F]{2,}$/.test(w)) &&
                    !words.some((w) => RE_VEHICLE_TOKENS.test(w)) &&
                    line[0] === line[0].toUpperCase() &&
                    /[a-z\u0900-\u097F]/.test(line) &&
                    !looksLikeCompanyLine(line);
                if (titleCaseName && line.length <= 48) {
                    displayNameRaw = line;
                    break;
                }
            }
        }

        let displayName = displayNameRaw.length >= 2 ? displayNameRaw.replace(/\s+/g, ' ').trim() : null;
        if (isCsdPo && displayName) {
            displayName = CpcRuleExtractService.refineCsdPoCustomerName(t, displayName) ?? displayName;
        }
        if (displayName) {
            const n = normalizePersonNameExtract(displayName);
            if (n) displayName = n;
        }

        // PAN (Indian format) + MSD hint (PDF may lack strict word boundaries)
        let panFromRegex = t.match(/\b([A-Z]{5}[0-9]{4}[A-Z])\b/i);
        let panVal = panFromRegex ? String(panFromRegex[1]).toUpperCase() : null;
        if (!panVal && msd.pan_number != null) {
            panVal = panFromMsdHint(t, msd.pan_number);
        }

        // Numeric amount for range matching against MSD invoice_value
        const amountDigits = invoiceMatch
            ? String(invoiceMatch[0]).replace(/[^\d.]/g, '').replace(/^\.+|\.+$/g, '')
            : null;
        let invoiceValueNormalized =
            amountDigits && amountDigits.length ? amountDigits : null;
        if (!invoiceValueNormalized) {
            invoiceValueNormalized =
                invoiceDigitsFromMsdHint(t, msd.po_amount) ||
                invoiceDigitsFromMsdHint(t, msd.letter_amount) ||
                invoiceDigitsFromMsdHint(t, msd.invoice_value);
        }

        const stampPresent = /(stamp|seal|authorized signatory|signature)/i.test(t);
        const govtStampPresent = /(govt\.?\s*stamp|government\s*seal|govt\.?\s*signatory|official\s*stamp|authorized\s*signatory)/i.test(t) || stampPresent;
        const stampYesNo = govtStampPresent ? 'yes' : 'no';
        const poOrOrder = orderMatch ? orderMatch[1].trim() : null;
        const aadhaarDigits = aadhaarMatch ? aadhaarMatch[0].replace(/\s/g, '').trim() : null;

        return {
            extracted_fields: {
                authorized_person_name: displayName,
                customer_name: displayName,
                pan_number: panVal,
                order_or_authorisation_number: poOrOrder,
                po_number: poOrOrder,
                order_or_auth_number: poOrOrder,
                invoice_value: invoiceValueNormalized,
                po_amount: invoiceValueNormalized,
                letter_amount: invoiceValueNormalized,
                aadhaar_number: aadhaarDigits,
                aadhar_number: aadhaarDigits,
                stamp_or_signatory_present: stampPresent,
                stamp_sign_present: stampPresent,
                govt_signatory_and_stamp_present: stampYesNo,
                signature_and_stamp: stampYesNo
            },
            field_confidence: {
                authorized_person_name: displayName ? 0.65 : 0.2,
                customer_name: displayName ? 0.65 : 0.2,
                pan_number: panVal ? 0.85 : 0.2,
                order_or_authorisation_number: orderMatch ? 0.7 : 0.2,
                po_number: orderMatch ? 0.7 : 0.2,
                order_or_auth_number: orderMatch ? 0.7 : 0.2,
                invoice_value: invoiceValueNormalized ? 0.7 : 0.2,
                po_amount: invoiceValueNormalized ? 0.7 : 0.2,
                letter_amount: invoiceValueNormalized ? 0.7 : 0.2,
                aadhaar_number: aadhaarMatch ? 0.85 : 0.2,
                aadhar_number: aadhaarMatch ? 0.85 : 0.2,
                stamp_or_signatory_present: stampPresent ? 0.55 : 0.3,
                stamp_sign_present: stampPresent ? 0.55 : 0.3,
                govt_signatory_and_stamp_present: govtStampPresent ? 0.55 : 0.3,
                signature_and_stamp: govtStampPresent ? 0.55 : 0.3
            }
        };
    }
}