import { useState, useMemo } from 'react';
import { useNomenclatureData } from '../../contexts/NomenclatureDataContext';
import NomenclatureManagementOverlay from './NomenclatureManagementOverlay';
import './NomenclatureDropdown.css';

export default function NomenclatureDropdown({
    nomenclatureCode,
    value,
    onChange,
    label,
    disabled = false,
}) {
    const { definitions, getActiveEntries, isLoading } = useNomenclatureData();
    const [showOverlay, setShowOverlay] = useState(false);

    const nomenclature = definitions[nomenclatureCode];
    const activeEntries = useMemo(
        () => getActiveEntries(nomenclatureCode),
        [getActiveEntries, nomenclatureCode]
    );

    if (!nomenclature) {
        if (isLoading) {
            return (
                <div className="nui-dropdown">
                    {label && <label className="nui-dropdown-label">{label}</label>}
                    <select disabled className="nui-dropdown-select">
                        <option>Loading...</option>
                    </select>
                </div>
            );
        }
        return null;
    }

    const displayLabel = label || nomenclature.name;

    // SELECTOR type: choices come from selector_options, value is the option string.
    // No manage button - options are configured in the admin screen, not while weighing.
    if (nomenclature.kind === 'selector') {
        const options = nomenclature.selector_options || [];
        const isUnknown = value && !options.some(o => o.value === value);

        return (
            <div className="nui-dropdown">
                <label className="nui-dropdown-label">{displayLabel}</label>
                <select
                    className="nui-dropdown-select"
                    value={value || ''}
                    onChange={(e) => onChange(e.target.value || undefined)}
                    disabled={disabled}
                >
                    <option value="">-- Select --</option>
                    {options.map(opt => (
                        <option key={opt.value} value={opt.value}>{opt.label}</option>
                    ))}
                    {isUnknown && (
                        <option value={value}>{value} (unknown)</option>
                    )}
                </select>
            </div>
        );
    }

    // LOOKUP type: select dropdown + manage button
    if (nomenclature.kind === 'lookup') {
        const handleSelectChange = (e) => {
            const val = e.target.value;
            onChange(val ? parseInt(val, 10) : undefined);
        };

        const handleOverlaySelect = (entryId) => {
            onChange(entryId);
            setShowOverlay(false);
        };

        return (
            <div className="nui-dropdown">
                <label className="nui-dropdown-label">{displayLabel}</label>
                <div className="nui-dropdown-row">
                    <select
                        className="nui-dropdown-select"
                        value={value || ''}
                        onChange={handleSelectChange}
                        disabled={disabled}
                    >
                        <option value="">-- Select --</option>
                        {activeEntries.map(entry => (
                            <option key={entry.id} value={entry.id}>
                                {entry.display_value}
                            </option>
                        ))}
                    </select>
                    <button
                        className="nui-dropdown-manage-btn"
                        onClick={() => setShowOverlay(true)}
                        disabled={disabled}
                        type="button"
                        title={`Manage ${displayLabel}`}
                    >
                        &#8230;
                    </button>
                </div>

                <NomenclatureManagementOverlay
                    nomenclatureCode={nomenclatureCode}
                    isOpen={showOverlay}
                    onClose={() => setShowOverlay(false)}
                    mode="select"
                    initialSelection={value || null}
                    onSelect={handleOverlaySelect}
                />
            </div>
        );
    }

    // FIELD type: render appropriate input
    const fieldDef = nomenclature.fields?.[0];
    if (!fieldDef) return null;

    if (fieldDef.field_type === 'bool') {
        return (
            <div className="nui-dropdown">
                <label className="nui-dropdown-label nui-dropdown-label--checkbox">
                    <input
                        type="checkbox"
                        checked={value || false}
                        onChange={(e) => onChange(e.target.checked)}
                        disabled={disabled}
                        className="nui-dropdown-checkbox"
                    />
                    {displayLabel}
                </label>
            </div>
        );
    }

    if (fieldDef.field_type === 'number') {
        return (
            <div className="nui-dropdown">
                <label className="nui-dropdown-label">{displayLabel}</label>
                <input
                    type="number"
                    className="nui-dropdown-input"
                    value={value ?? ''}
                    onChange={(e) => onChange(e.target.value === '' ? undefined : Number(e.target.value))}
                    disabled={disabled}
                />
            </div>
        );
    }

    if (fieldDef.field_type === 'choice' && fieldDef.choices) {
        return (
            <div className="nui-dropdown">
                <label className="nui-dropdown-label">{displayLabel}</label>
                <select
                    className="nui-dropdown-select"
                    value={value || ''}
                    onChange={(e) => onChange(e.target.value || undefined)}
                    disabled={disabled}
                >
                    <option value="">-- Select --</option>
                    {fieldDef.choices.map(c => (
                        <option key={c} value={c}>{c}</option>
                    ))}
                </select>
            </div>
        );
    }

    // Default: text input
    return (
        <div className="nui-dropdown">
            <label className="nui-dropdown-label">{displayLabel}</label>
            <input
                type="text"
                className="nui-dropdown-input"
                value={value || ''}
                onChange={(e) => onChange(e.target.value || undefined)}
                disabled={disabled}
            />
        </div>
    );
}