import { useState, useEffect } from "react";
import { Modal, Button, Form, Table, Alert } from "react-bootstrap";
import { generateQr, OrderGroup, OrderGroupMember, QrRecipient } from "../../../../types";

type Props = {
    isOpen: boolean;
    onClose: () => void;
    group: OrderGroup;
    payerLogin: string;
    bankAccount: string;
    bankAccountHolder: string;
    groupId?: string;
};

type DinerEntry = {
    login: string;
    member: OrderGroupMember;
    included: boolean;
};

export default function PayForGroupModal({ isOpen, onClose, group, payerLogin, bankAccount, bankAccountHolder, groupId }: Readonly<Props>) {
    const [diners, setDiners] = useState<DinerEntry[]>([]);
    const [error, setError] = useState<string | null>(null);
    const [loading, setLoading] = useState(false);
    const [success, setSuccess] = useState(false);

    useEffect(() => {
        if (!isOpen) return;
        const entries: DinerEntry[] = (Object.entries(group.members) as [string, OrderGroupMember][]).map(([login, member]) => ({
            login,
            member,
            included: login !== payerLogin,
        }));
        setDiners(entries);
        setError(null);
        setSuccess(false);
    }, [isOpen, group, payerLogin]);

    const memberCount = diners.length;
    const fees = group.fees ?? 0;
    const shipping = group.shipping ?? 0;
    const tip = group.tip ?? 0;
    const totalFees = fees + shipping + tip;
    const feeShare = memberCount > 0 ? Math.round(totalFees / memberCount * 100) / 100 : 0;

    const getMemberTotal = (entry: DinerEntry): number => {
        const base = entry.member.amount ?? 0;
        const surcharge = entry.member.surchargeAmount ?? 0;
        const discountType = group.discountType;
        const discountValue = group.discountValue ?? 0;
        const discount = discountValue > 0
            ? (discountType === 'percent'
                ? Math.round((base + surcharge) * discountValue / 100 * 100) / 100
                : Math.round(discountValue / memberCount * 100) / 100)
            : 0;
        return Math.round((base + surcharge + feeShare - discount) * 100) / 100;
    };

    const includedNonPayers = diners.filter(d => d.included && d.login !== payerLogin);

    const handleInclude = (login: string, checked: boolean) => {
        setDiners(prev => prev.map(d => d.login === login ? { ...d, included: checked } : d));
    };

    const handleGenerate = async () => {
        setError(null);
        const recipients: QrRecipient[] = [];

        for (const d of diners) {
            if (!d.included || d.login === payerLogin) continue;
            const total = getMemberTotal(d);
            if (total <= 0) {
                setError(`Celková částka pro ${d.login} musí být kladná`);
                return;
            }
            const amountStr = total.toString();
            if (amountStr.includes('.') && amountStr.split('.')[1].length > 2) {
                setError(`Částka pro ${d.login} má více než 2 desetinná místa`);
                return;
            }
            recipients.push({
                login: d.login,
                purpose: `Objednávka ${group.name}`.substring(0, 60),
                amount: total,
            });
        }

        if (recipients.length === 0) {
            setError("Nebyl vybrán žádný příjemce");
            return;
        }

        setLoading(true);
        try {
            const response = await generateQr({
                body: { recipients, bankAccount, bankAccountHolder, ...(groupId ? { groupId } : {}) },
            });
            if (response.error) {
                setError((response.error as any).error || 'Nastala chyba při generování QR kódů');
            } else {
                setSuccess(true);
                setTimeout(() => onClose(), 2000);
            }
        } catch (e: any) {
            setError(e.message || 'Nastala chyba při generování QR kódů');
        } finally {
            setLoading(false);
        }
    };

    const hasFees = totalFees > 0;

    return (
        <Modal show={isOpen} onHide={onClose} size="lg">
            <Modal.Header closeButton>
                <Modal.Title><h2>Generovat QR — {group.name}</h2></Modal.Title>
            </Modal.Header>
            <Modal.Body>
                {success ? (
                    <Alert variant="success">
                        QR kódy byly úspěšně vygenerovány! Uživatelé je uvidí v sekci „Nevyřízené platby".
                    </Alert>
                ) : (
                    <>
                        <p>Zaplatili jste za skupinu. Vyberte, komu vygenerovat QR kód k úhradě.</p>

                        {error && (
                            <Alert variant="danger" onClose={() => setError(null)} dismissible>
                                {error}
                            </Alert>
                        )}

                        {hasFees && (
                            <div className="d-flex gap-3 mb-2 text-muted" style={{ fontSize: '0.9em' }}>
                                {fees > 0 && <span>Poplatky: <strong>{fees} Kč</strong></span>}
                                {shipping > 0 && <span>Doprava: <strong>{shipping} Kč</strong></span>}
                                {tip > 0 && <span>Spropitné: <strong>{tip} Kč</strong></span>}
                                <span>→ {feeShare} Kč/os.</span>
                            </div>
                        )}
                        {group.discountValue != null && group.discountValue > 0 && (
                            <div className="mb-2 text-success" style={{ fontSize: '0.9em' }}>
                                Sleva: {group.discountType === 'percent' ? `${group.discountValue}%` : `${group.discountValue} Kč`}
                            </div>
                        )}

                        <Table striped bordered hover responsive size="sm">
                            <thead>
                                <tr>
                                    <th style={{ width: 40 }}></th>
                                    <th>Člen</th>
                                    <th style={{ width: 90 }} className="text-end">Základ</th>
                                    <th style={{ width: 90 }} className="text-end">Příplatek</th>
                                    {hasFees && <th style={{ width: 90 }} className="text-end">Poplatek</th>}
                                    <th style={{ width: 90 }} className="text-end fw-bold">Celkem</th>
                                </tr>
                            </thead>
                            <tbody>
                                {diners.map(d => {
                                    const isPayer = d.login === payerLogin;
                                    const total = getMemberTotal(d);
                                    const surcharge = d.member.surchargeAmount ?? 0;
                                    return (
                                        <tr key={d.login} className={!d.included && !isPayer ? 'text-muted' : ''}>
                                            <td className="text-center">
                                                {isPayer ? (
                                                    <small className="text-muted">plátce</small>
                                                ) : (
                                                    <Form.Check
                                                        type="checkbox"
                                                        checked={d.included}
                                                        onChange={e => handleInclude(d.login, e.target.checked)}
                                                    />
                                                )}
                                            </td>
                                            <td>
                                                <strong>{d.login}</strong>
                                                {d.member.surchargeText && (
                                                    <small className="text-muted ms-1">({d.member.surchargeText})</small>
                                                )}
                                            </td>
                                            <td className="text-end">
                                                {(d.member.amount ?? 0) > 0 ? `${d.member.amount} Kč` : <span className="text-muted">—</span>}
                                            </td>
                                            <td className="text-end">
                                                {surcharge > 0 ? `${surcharge} Kč` : <span className="text-muted">—</span>}
                                            </td>
                                            {hasFees && (
                                                <td className="text-end">
                                                    {feeShare > 0 ? `${feeShare} Kč` : '—'}
                                                </td>
                                            )}
                                            <td className="text-end fw-bold">
                                                {total > 0 ? `${total} Kč` : <span className="text-muted">—</span>}
                                            </td>
                                        </tr>
                                    );
                                })}
                            </tbody>
                        </Table>
                    </>
                )}
            </Modal.Body>
            <Modal.Footer>
                {!success && (
                    <>
                        <span className="me-auto text-muted">Příjemci: {includedNonPayers.length}</span>
                        <Button variant="secondary" onClick={onClose} disabled={loading}>Storno</Button>
                        <Button
                            variant="primary"
                            onClick={handleGenerate}
                            disabled={loading || includedNonPayers.length === 0}
                        >
                            {loading ? 'Generuji...' : 'Vygenerovat QR'}
                        </Button>
                    </>
                )}
                {success && (
                    <Button variant="secondary" onClick={onClose}>Zavřít</Button>
                )}
            </Modal.Footer>
        </Modal>
    );
}