'use client';

import { useEffect, useState } from 'react';
import { ScanSearch, Loader2, CheckCircle2, AlertTriangle, XCircle, HelpCircle } from 'lucide-react';
import BottomSheet from '@/components/BottomSheet';
import { cn } from '@/lib/utils';
import {
  checkInvoice,
  invoiceCheckBase,
  readSeen,
  rememberSeen,
  type InvoiceCheckResult,
  type Verdict,
} from '@/lib/invoiceCheck';

interface InvoiceCheckProps {
  poNumber: string;
  /** Invoice pages already uploaded for this PO; the helper needs at least one. */
  pages: number;
  size?: 'sm' | 'lg';
}

const STYLE: Record<Verdict, { icon: typeof CheckCircle2; row: string; label: string }> = {
  green: { icon: CheckCircle2, row: 'text-[#125a3e]', label: 'Matches' },
  amber: { icon: AlertTriangle, row: 'text-[#8a5a02]', label: 'Check' },
  red: { icon: XCircle, row: 'text-[#cf2d56]', label: 'Mismatch' },
  unchecked: { icon: HelpCircle, row: 'text-[rgba(38,37,30,0.55)]', label: 'Not checked' },
};

// Beta helper. Renders nothing unless the driver switched it on in
// Settings → Beta, so the normal PO buttons are untouched. It only reads:
// tapping "Check invoice" asks WFDASH to compare the photo with the lines
// collected on this PO and shows the answer. It never blocks anything.
export default function InvoiceCheck({ poNumber, pages, size = 'sm' }: InvoiceCheckProps) {
  const [enabled, setEnabled] = useState(false);
  const [open, setOpen] = useState(false);
  const [busy, setBusy] = useState(false);
  const [result, setResult] = useState<InvoiceCheckResult | null>(null);
  const [error, setError] = useState('');
  const [seen, setSeen] = useState<'ok' | 'override' | undefined>();

  useEffect(() => {
    setEnabled(Boolean(invoiceCheckBase()));
    setSeen(readSeen()[poNumber]);
  }, [poNumber]);

  if (!enabled || !poNumber || pages === 0) return null;

  const run = async () => {
    if (busy) return;
    setOpen(true);
    setBusy(true);
    setError('');
    setResult(null);
    try {
      setResult(await checkInvoice(poNumber));
    } catch (e) {
      setError(e instanceof Error ? e.message : 'Check failed');
    } finally {
      setBusy(false);
    }
  };

  const finish = () => {
    if (result) {
      const how = result.all_green ? 'ok' : 'override';
      rememberSeen(poNumber, how);
      setSeen(how);
    }
    setOpen(false);
  };

  const lg = size === 'lg';
  const btn = lg
    ? 'h-12 w-full rounded-xl text-[15px] font-semibold flex items-center justify-center gap-2 touch-manipulation'
    : 'h-9 px-3 rounded-lg text-[13px] font-semibold flex items-center gap-1.5 touch-manipulation';

  return (
    <>
      <button
        type="button"
        onClick={run}
        aria-label={`Check the invoice for PO ${poNumber} (beta)`}
        className={cn(btn, 'bg-[#efeaf7] text-[#6c5a99] active:bg-[#ded5ef]')}
      >
        <ScanSearch size={lg ? 18 : 14} aria-hidden="true" />
        <span>{lg ? `Check invoice (beta)${seen ? ' · seen' : ''}` : 'Check'}</span>
      </button>

      {open && (
        <BottomSheet title="Invoice check" subtitle={`PO ${poNumber} · beta`} onClose={() => setOpen(false)}>
          {busy && (
            <p className="flex items-center gap-2 text-[15px] text-[#26251e] py-4">
              <Loader2 size={18} className="animate-spin" aria-hidden="true" />
              Reading the invoice… this can take up to a minute.
            </p>
          )}
          {error && (
            <p className="text-[15px] text-[#cf2d56] py-3">
              Couldn’t check: {error}. You can carry on as normal.
            </p>
          )}
          {result && (
            <>
              {result.lines.length === 0 ? (
                <p className="text-[15px] text-[#26251e] py-3">No collected lines on this PO to check yet.</p>
              ) : (
                <ul className="divide-y divide-[rgba(38,37,30,0.08)]">
                  {result.lines.map((l) => {
                    const st = STYLE[l.verdict];
                    const Icon = st.icon;
                    return (
                      <li key={l.id} className="py-3 flex gap-3">
                        <Icon size={20} className={cn('flex-shrink-0 mt-0.5', st.row)} aria-hidden="true" />
                        <div className="min-w-0">
                          <p className="text-[14px] text-[#26251e] leading-snug break-words">
                            {l.description || 'Item'} <span className="text-[rgba(38,37,30,0.55)]">× {l.qty_collected}</span>
                          </p>
                          <p className={cn('text-[12px] font-semibold', st.row)}>{st.label}</p>
                          {l.reason && <p className="text-[12px] text-[rgba(38,37,30,0.7)] break-words">{l.reason}</p>}
                        </div>
                      </li>
                    );
                  })}
                </ul>
              )}
              {result.error && (
                <p className="text-[12px] text-[#8a5a02] mt-2">Note: {result.error}</p>
              )}
              <button
                type="button"
                onClick={finish}
                className={cn(
                  'mt-3 h-12 w-full rounded-xl text-[15px] font-semibold touch-manipulation',
                  result.all_green ? 'bg-[#18714f] text-white' : 'bg-[#26251e] text-white'
                )}
              >
                {result.all_green ? 'All good — continue' : 'I’ve checked — continue anyway'}
              </button>
            </>
          )}
          {!busy && (
            <button
              type="button"
              onClick={() => setOpen(false)}
              className="mt-2 h-11 w-full rounded-xl text-[14px] font-semibold text-[#6c5a99] touch-manipulation"
            >
              {result ? 'Close' : 'Close — carry on as normal'}
            </button>
          )}
        </BottomSheet>
      )}
    </>
  );
}