'use client';

import { useCallback, useEffect, useRef, useState } from 'react';
import { Loader2, CheckCircle2, AlertTriangle, Undo2 } from 'lucide-react';
import BottomSheet from '@/components/BottomSheet';
import {
  RUN_EVENT,
  collectMatched,
  matchInvoice,
  saveReviewNote,
  undoMatched,
  type InvoiceMatchResult,
  type MatchedLine,
  type ReviewLine,
} from '@/lib/invoiceCheck';

interface InvoiceMatchHostProps {
  /** Lines just marked collected: drop them from the driver's list. */
  onCollected: (ids: string[]) => void;
  /** Lines put back: reload the driver's list. */
  onRestored: () => void;
  /** The sheet closed: the page asks about anything still to collect. */
  onClosed?: () => void;
}

// Beta helper, mounted once on the driver page. Renders nothing until a PO's
// "Check invoice" runs. It marks only exact matches collected (same product,
// invoice quantity = ordered quantity); everything uncertain is listed for the
// driver and left alone. Every auto-collected line can be undone.
export default function InvoiceMatchHost({ onCollected, onRestored, onClosed }: InvoiceMatchHostProps) {
  const [open, setOpen] = useState(false);
  const [busy, setBusy] = useState(false);
  const [poNumber, setPoNumber] = useState('');
  const [result, setResult] = useState<InvoiceMatchResult | null>(null);
  const [collected, setCollected] = useState<MatchedLine[]>([]);
  const [failedIds, setFailedIds] = useState<string[]>([]);
  const [error, setError] = useState('');
  const [noteFor, setNoteFor] = useState<string | null>(null);
  const [noteText, setNoteText] = useState('');
  const [noteBusy, setNoteBusy] = useState(false);
  const [noteError, setNoteError] = useState('');
  const [savedNotes, setSavedNotes] = useState<string[]>([]);
  const running = useRef(false);

  const run = useCallback(
    async (po: string) => {
      if (running.current) return;
      running.current = true;
      setPoNumber(po);
      setOpen(true);
      setBusy(true);
      setError('');
      setResult(null);
      setCollected([]);
      setFailedIds([]);
      setNoteFor(null);
      setSavedNotes([]);
      try {
        const r = await matchInvoice(po);
        setResult(r);
        const done: MatchedLine[] = [];
        const failed: string[] = [];
        for (const line of r.matched) {
          try {
            await collectMatched(line);
            done.push(line);
          } catch (e) {
            console.warn('[invoice-match] collect failed for', line.id, e);
            failed.push(line.id);
          }
        }
        setCollected(done);
        setFailedIds(failed);
        if (done.length > 0) onCollected(done.map((l) => l.id));
      } catch (e) {
        setError(e instanceof Error ? e.message : 'Check failed');
      } finally {
        setBusy(false);
        running.current = false;
      }
    },
    [onCollected],
  );

  useEffect(() => {
    const handler = (e: Event) => {
      const po = (e as CustomEvent<{ poNumber?: string }>).detail?.poNumber;
      if (po) void run(po);
    };
    window.addEventListener(RUN_EVENT, handler);
    return () => window.removeEventListener(RUN_EVENT, handler);
  }, [run]);

  const undo = async (lines: MatchedLine[]) => {
    const kept: MatchedLine[] = [];
    for (const line of lines) {
      try {
        await undoMatched(line);
      } catch (e) {
        console.warn('[invoice-match] undo failed for', line.id, e);
        kept.push(line);
      }
    }
    setCollected((prev) => prev.filter((l) => kept.some((k) => k.id === l.id) || !lines.some((x) => x.id === l.id)));
    onRestored();
  };

  const saveNote = async (line: ReviewLine) => {
    if (!noteText.trim()) {
      setNoteError('Write the reason first.');
      return;
    }
    setNoteBusy(true);
    setNoteError('');
    try {
      await saveReviewNote(line, noteText);
      setSavedNotes((prev) => [...prev, line.id]);
      setNoteFor(null);
      setNoteText('');
    } catch (e) {
      console.warn('[invoice-match] note failed for', line.id, e);
      setNoteError('Could not save the note. Try again.');
    } finally {
      setNoteBusy(false);
    }
  };

  if (!open) return null;

  const close = () => {
    setOpen(false);
    onClosed?.();
  };

  return (
    <BottomSheet title="Invoice check" subtitle={`PO ${poNumber} · beta`} onClose={close}>
      {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}. Nothing was changed — carry on as normal.
        </p>
      )}
      {result && !busy && (
        <>
          {collected.length > 0 && (
            <section className="mb-3">
              <p className="text-[13px] font-bold text-[#125a3e] mb-1">
                Marked collected ({collected.length})
              </p>
              <ul className="divide-y divide-[rgba(38,37,30,0.08)]">
                {collected.map((l) => (
                  <li key={l.id} className="py-2.5 flex items-start gap-3">
                    <CheckCircle2 size={20} className="text-[#125a3e] flex-shrink-0 mt-0.5" aria-hidden="true" />
                    <p className="flex-1 min-w-0 text-[14px] text-[#26251e] leading-snug break-words">
                      {l.description} <span className="text-[rgba(38,37,30,0.55)]">× {l.quantity}</span>
                      {l.po_number !== poNumber && (
                        <span className="block text-[12px] text-[rgba(38,37,30,0.55)]">PO {l.po_number}</span>
                      )}
                    </p>
                    <button
                      type="button"
                      onClick={() => void undo([l])}
                      className="h-9 px-3 rounded-lg text-[12px] font-semibold text-[#6c5a99] bg-[#efeaf7] flex items-center gap-1 touch-manipulation"
                    >
                      <Undo2 size={13} aria-hidden="true" /> Undo
                    </button>
                  </li>
                ))}
              </ul>
            </section>
          )}
          {failedIds.length > 0 && (
            <p className="text-[13px] text-[#8a5a02] mb-3">
              {failedIds.length} matching item{failedIds.length === 1 ? '' : 's'} couldn’t be marked collected — collect {failedIds.length === 1 ? 'it' : 'them'} as normal.
            </p>
          )}
          {result.review.length > 0 && (
            <section className="mb-3">
              <p className="text-[13px] font-bold text-[#8a5a02] mb-1">Check these yourself ({result.review.length})</p>
              <ul className="divide-y divide-[rgba(38,37,30,0.08)]">
                {result.review.map((l) => (
                  <li key={l.id} className="py-2.5 flex gap-3">
                    <AlertTriangle size={20} className="text-[#8a5a02] flex-shrink-0 mt-0.5" aria-hidden="true" />
                    <div className="min-w-0">
                      <p className="text-[14px] text-[#26251e] leading-snug break-words">{l.description}</p>
                      <p className="text-[12px] text-[rgba(38,37,30,0.7)] break-words">{l.reason}</p>
                      {savedNotes.includes(l.id) ? (
                        <p className="text-[12px] font-semibold text-[#125a3e] mt-1">Note saved</p>
                      ) : noteFor === l.id ? (
                        <div className="mt-2">
                          <label htmlFor={`note-${l.id}`} className="block text-[12px] font-semibold text-[#26251e] mb-1">
                            Ask the supplier why it differs, then write their answer. We can’t be invoiced for what we haven’t received.
                          </label>
                          <textarea
                            id={`note-${l.id}`}
                            value={noteText}
                            onChange={(e) => setNoteText(e.target.value)}
                            rows={3}
                            className="w-full rounded-lg border border-[rgba(38,37,30,0.2)] bg-white p-2 text-[14px] text-[#26251e]"
                            placeholder="Reason from the supplier…"
                          />
                          {noteError && <p className="text-[12px] text-[#cf2d56] mt-1">{noteError}</p>}
                          <div className="flex gap-2 mt-2">
                            <button
                              type="button"
                              disabled={noteBusy}
                              onClick={() => void saveNote(l)}
                              className="h-10 px-4 rounded-lg text-[13px] font-semibold bg-[#26251e] text-white disabled:opacity-60 touch-manipulation"
                            >
                              {noteBusy ? 'Saving…' : 'Save note'}
                            </button>
                            <button
                              type="button"
                              disabled={noteBusy}
                              onClick={() => { setNoteFor(null); setNoteText(''); setNoteError(''); }}
                              className="h-10 px-4 rounded-lg text-[13px] font-semibold bg-[#efeaf7] text-[#6c5a99] touch-manipulation"
                            >
                              Cancel
                            </button>
                          </div>
                        </div>
                      ) : (
                        <button
                          type="button"
                          onClick={() => { setNoteFor(l.id); setNoteText(''); setNoteError(''); }}
                          className="mt-1.5 h-9 px-3 rounded-lg text-[12px] font-semibold bg-[#efeaf7] text-[#6c5a99] touch-manipulation"
                        >
                          Add a note
                        </button>
                      )}
                    </div>
                  </li>
                ))}
              </ul>
            </section>
          )}
          {result.matched.length === 0 && result.review.length === 0 && (
            <p className="text-[15px] text-[#26251e] py-3">
              {result.error
                ? `Couldn’t read the invoice: ${result.error}`
                : 'None of your assigned items for this supplier were found on the invoice.'}
            </p>
          )}
          {result.error && (result.matched.length > 0 || result.review.length > 0) && (
            <p className="text-[12px] text-[#8a5a02] mb-2">Note: {result.error}</p>
          )}
        </>
      )}
      {!busy && (
        <button
          type="button"
          onClick={close}
          className="mt-1 h-12 w-full rounded-xl text-[15px] font-semibold bg-[#26251e] text-white touch-manipulation"
        >
          Done
        </button>
      )}
    </BottomSheet>
  );
}