import jsPDF from 'jspdf';
import autoTable from 'jspdf-autotable';
import { Party, Transaction } from '../types';

// --- CONFIGURATION ---
const BG_COLOR: [number, number, number] = [240, 234, 214]; // Beige
const BORDER_COLOR: [number, number, number] = [0, 0, 0];   // Black

// Helper: Currency Format
const FORMAT_CURRENCY = (amount: number) => {
    return new Intl.NumberFormat('en-IN', {
        minimumFractionDigits: 2,
        maximumFractionDigits: 2
    }).format(amount);
};

// Helper: Date Format
const FORMAT_DATE = (dateStr: string) => {
    if (!dateStr) return "";
    const dateObj = PARSE_DATE(dateStr) || new Date(dateStr);
    return `${dateObj.getDate().toString().padStart(2, '0')}/${(dateObj.getMonth() + 1).toString().padStart(2, '0')}/${dateObj.getFullYear().toString().slice(-2)}`;
};

const PARSE_DATE = (value?: string): Date | undefined => {
    if (!value) return undefined;

    const trimmed = String(value).trim();
    if (!trimmed) return undefined;

    const iso = trimmed.match(/^\d{4}-\d{2}-\d{2}(?:[T\s].*)?$/);
    if (iso) {
        const d = new Date(trimmed);
        return isNaN(d.getTime()) ? undefined : d;
    }

    const slash = trimmed.match(/^\d{1,2}\/\d{1,2}\/(\d{2}|\d{4})$/);
    if (slash) {
        const [aStr, bStr, yyStr] = trimmed.split('/');
        const a = Number(aStr);
        const b = Number(bStr);
        const yy = Number(yyStr);
        const year = yyStr.length === 2 ? 2000 + yy : yy;
        if (!a || !b || !year) return undefined;

        // Prefer en-IN DD/MM/YYYY, but support MM/DD/YYYY when clearly indicated.
        // - If first part > 12 -> it's DD/MM
        // - If second part > 12 -> it's MM/DD
        // - If both <= 12 -> default DD/MM
        const day = a > 12 ? a : b > 12 ? b : a;
        const month = a > 12 ? b : b > 12 ? a : b;

        const d = new Date(year, month - 1, day);
        return isNaN(d.getTime()) ? undefined : d;
    }

    const d = new Date(trimmed);
    return isNaN(d.getTime()) ? undefined : d;
};

const TO_ISO_DATE = (value?: string): string | undefined => {
    const d = PARSE_DATE(value);
    return d ? d.toISOString() : undefined;
};

const EXTRACT_DATE_FROM_TEXT = (text?: string): string | undefined => {
    if (!text) return undefined;

    const iso = text.match(/\b\d{4}-\d{2}-\d{2}\b/);
    if (iso?.[0]) return TO_ISO_DATE(iso[0]);

    const mdyOrDmy = text.match(/\b\d{1,2}\/\d{1,2}\/\d{4}\b/);
    if (!mdyOrDmy?.[0]) return undefined;

    return TO_ISO_DATE(mdyOrDmy[0]);
};

export const generateLedgerPDF = (party: Party, transactions: Transaction[]) => {
    const doc = new jsPDF();

    // --- 1. PAGE CONFIGURATION ---
    const PAGE_WIDTH = 210;
    const PAGE_HEIGHT = 297;
    const MARGIN = 14;
    const CONTENT_WIDTH = PAGE_WIDTH - (MARGIN * 2);

    // --- 2. SETUP & BACKGROUND ---
    doc.setFillColor(...BG_COLOR);
    doc.rect(0, 0, PAGE_WIDTH, PAGE_HEIGHT, 'F'); 

    // --- 3. DATA PREPARATION ---
    const ledgerEvents: Array<
        | { kind: 'bill'; date: string; tx: Transaction }
        | { kind: 'payment'; date: string; tx: Transaction; payment: any }
    > = [];

    for (const tx of transactions) {
        const billDateIso = TO_ISO_DATE(tx.bill_date) || tx.bill_date;
        ledgerEvents.push({ kind: 'bill', date: billDateIso, tx });

        const payments = tx.payments || [];
        const validPayments = payments.filter((p: any) => String(p.mode).toLowerCase() !== 'due');

        for (const p of validPayments) {
            const paymentDateRaw =
                (p as any).payment_date ||
                (p as any).created_at ||
                (p as any).date ||
                EXTRACT_DATE_FROM_TEXT((p as any).reference) ||
                tx.bill_date;

            const paymentDateIso = TO_ISO_DATE(paymentDateRaw) || TO_ISO_DATE(tx.bill_date) || tx.bill_date;

            const billTime = (PARSE_DATE(billDateIso) || new Date(billDateIso)).getTime();
            const payTime = (PARSE_DATE(paymentDateIso) || new Date(paymentDateIso)).getTime();
            const safePaymentDate = payTime < billTime ? billDateIso : paymentDateIso;

            ledgerEvents.push({ kind: 'payment', date: safePaymentDate, tx, payment: p });
        }

        const recordedPaid = validPayments.reduce((sum: number, p: any) => sum + (Number(p.amount) || 0), 0);
        const extraPaid = (Number(tx.paid_amount) || 0) - recordedPaid;

        if (extraPaid > 0) {
            const paymentDateRaw =
                (tx as any).updated_at ||
                (tx as any).created_at ||
                tx.bill_date;

            const paymentDateIso = TO_ISO_DATE(paymentDateRaw) || billDateIso;
            const billTime = (PARSE_DATE(billDateIso) || new Date(billDateIso)).getTime();
            const payTime = (PARSE_DATE(paymentDateIso) || new Date(paymentDateIso)).getTime();
            const safePaymentDate = payTime < billTime ? billDateIso : paymentDateIso;

            ledgerEvents.push({
                kind: 'payment',
                date: safePaymentDate,
                tx,
                payment: { mode: 'payment', amount: extraPaid, reference: undefined, __synthetic: true },
            });
        }
    }

    ledgerEvents.sort((a, b) => {
        const ta = new Date(a.date).getTime();
        const tb = new Date(b.date).getTime();
        if (ta !== tb) return ta - tb;
        if (a.kind !== b.kind) return a.kind === 'bill' ? -1 : 1;
        const na = a.tx.bill_number || '';
        const nb = b.tx.bill_number || '';
        return na.localeCompare(nb);
    });

    let runningBalance = 0;

    const tableRows = ledgerEvents.map(ev => {
        const tx = ev.tx;

        const typeStr = String(tx.bill_type).toUpperCase();
        const numStr = tx.bill_number ? tx.bill_number.toUpperCase() : "";

        const isJawaakFromNumber = numStr.startsWith('JAWAAK');
        const isAwaakFromNumber = numStr.startsWith('AWAAK');
        const isAwaak = isAwaakFromNumber ? true : isJawaakFromNumber ? false : typeStr === 'AWAAK';

        if (ev.kind === 'bill') {
            let itemDetails = "";
            if (tx.items && tx.items.length > 0) {
                tx.items.forEach(item => {
                    let wStr = "";
                    if (Array.isArray(item.poti_weights)) wStr = item.poti_weights.join(",");
                    else if (item.poti_weights) wStr = String(item.poti_weights);

                    const prefix = itemDetails ? "\n" : "";
                    itemDetails += `${prefix}${item.mirchi_name}`;
                    if (wStr) itemDetails += ` (${wStr})`;
                });
            }

            let billParticulars = `No: ${tx.bill_number}`;
            if (tx.is_return) billParticulars += " (RETURN)";
            if (itemDetails) billParticulars += `\n${itemDetails}`;

            let totalPoti = 0;
            tx.items?.forEach(i => totalPoti += Number(i.poti_count) || 0);

            let billDebit = 0;
            let billCredit = 0;

            if (isAwaak) {
                if (tx.is_return) billDebit = tx.total_amount;
                else billCredit = tx.total_amount;
            } else {
                if (tx.is_return) billCredit = tx.total_amount;
                else billDebit = tx.total_amount;
            }

            runningBalance = runningBalance + billDebit - billCredit;

            return {
                date: FORMAT_DATE(ev.date),
                particulars: billParticulars,
                poti: totalPoti > 0 ? totalPoti.toString() : "-",
                credit: billCredit > 0 ? FORMAT_CURRENCY(billCredit) : "-",
                debit: billDebit > 0 ? FORMAT_CURRENCY(billDebit) : "-",
                balance: `${FORMAT_CURRENCY(Math.abs(runningBalance))} ${runningBalance >= 0 ? 'Dr' : 'Cr'}`,
                isMainRow: true
            };
        }

        const p = ev.payment;
        const amount = Number(p.amount) || 0;
        let payDebit = 0;
        let payCredit = 0;

        if (isAwaak) {
            if (tx.is_return) payCredit = amount;
            else payDebit = amount;
        } else {
            if (tx.is_return) payDebit = amount;
            else payCredit = amount;
        }

        runningBalance = runningBalance + payDebit - payCredit;

        const modeStr = String(p.mode || '').charAt(0).toUpperCase() + String(p.mode || '').slice(1);
        let payDesc = (p as any).__synthetic ? `   [Payment]` : `   [${modeStr}]`;
        if (p.reference) payDesc += ` ${p.reference}`;

        return {
            date: FORMAT_DATE(ev.date),
            particulars: payDesc,
            poti: "-",
            credit: payCredit > 0 ? FORMAT_CURRENCY(payCredit) : "-",
            debit: payDebit > 0 ? FORMAT_CURRENCY(payDebit) : "-",
            balance: `${FORMAT_CURRENCY(Math.abs(runningBalance))} ${runningBalance >= 0 ? 'Dr' : 'Cr'}`,
            isMainRow: false
        };
    });

    // --- 4. GENERATE TABLE ---
    autoTable(doc, {
        startY: 35,
        tableWidth: CONTENT_WIDTH,
        margin: { left: MARGIN, right: MARGIN },
        
        head: [[
            'Date', 
            'Particulars', 
            'Poti', 
            'Credit\n(Jama)', 
            'Debit\n(Nave)', 
            'Balance'
        ]],
        
        body: tableRows.map(r => [r.date, r.particulars, r.poti, r.credit, r.debit, r.balance]),
        
        theme: 'grid', 
        
        styles: {
            fillColor: false,
            textColor: 0,
            lineColor: 0, 
            lineWidth: 0.1,
            font: 'helvetica',
            fontSize: 9,
            valign: 'top',
            cellPadding: 3,
            overflow: 'linebreak'
        },
        
        headStyles: {
            fillColor: false, 
            textColor: 0,
            fontStyle: 'bold',
            halign: 'center',
            valign: 'middle',
            lineWidth: 0.1, 
        },
        
        columnStyles: {
            0: { cellWidth: 20, halign: 'center' }, // Date
            1: { cellWidth: 72, halign: 'left' },   // Particulars
            2: { cellWidth: 12, halign: 'center' }, // Poti
            3: { cellWidth: 26, halign: 'right' },  // Credit
            4: { cellWidth: 26, halign: 'right' },  // Debit
            5: { cellWidth: 26, halign: 'right', fontStyle: 'bold' } // Balance
        },

        didParseCell: (data) => {
            const rowIdx = data.row.index;
            const rowData = tableRows[rowIdx];
            if (data.section === 'body' && data.column.index === 1 && rowData?.isMainRow) {
                data.cell.styles.fontStyle = 'bold';
            }
        },

        didDrawPage: (data) => {
            // Border
            doc.setDrawColor(...BORDER_COLOR);
            doc.setLineWidth(0.4);
            doc.rect(MARGIN, MARGIN, CONTENT_WIDTH, PAGE_HEIGHT - (MARGIN * 2));

            // Header
            if (data.pageNumber === 1) {
                const startX = MARGIN + 4;
                const startY = 25;

                doc.setFontSize(14); 
                doc.setFont("helvetica", "bold"); 
                doc.text("Name of A/c :", startX, startY);

                const labelWidth = doc.getTextWidth("Name of A/c :  ");
                doc.text(party.name, startX + labelWidth, startY);

                if (party.city || party.phone) {
                    doc.setFontSize(9);
                    doc.setFont("helvetica", "normal");
                    const subText = [party.city, party.phone].filter(Boolean).join(" - ");
                    doc.text(subText, startX, startY + 6);
                }
            }
        }
    });

    const cleanName = party.name.replace(/[^a-zA-Z0-9]/g, '_');
    doc.save(`${cleanName}_Ledger.pdf`);
};