import { useCallback, useEffect, useRef, useState } from 'react';
import { useFocusTrap } from '../../lib/use-focus-trap';
import { VOCAB } from '../../lib/collection-vocabulary.js';
import { Button } from '../ui';
import ReviewCardItem from './ReviewCardItem';

function confidencePercent(confidence) {
  if (confidence == null || Number.isNaN(confidence)) return null;
  return confidence <= 1 ? Math.round(confidence * 100) : Math.round(confidence);
}

function CheckoutFooter({
  selectedCount,
  isProcessing,
  commitError,
  onCommitOwned,
  onOpenListPicker,
}) {
  const selectHintId = 'checkout-select-hint';

  return (
    <div
      className="px-4 sm:px-6 py-4 glass-panel-strong"
      style={{
        borderTop: '1px solid var(--border)',
        paddingBottom: 'max(1rem, env(safe-area-inset-bottom))',
      }}
    >
      {commitError && (
        <div
          className="mb-3 px-3 py-2 rounded-lg text-sm"
          style={{
            backgroundColor: 'color-mix(in srgb, var(--color-error) 12%, transparent)',
            border: '1px solid color-mix(in srgb, var(--color-error) 35%, transparent)',
            color: 'var(--color-error)',
          }}
          role="alert"
        >
          {commitError}
        </div>
      )}
      {selectedCount === 0 && (
        <p
          id={selectHintId}
          className="mb-2 text-sm"
          style={{ color: 'var(--text-secondary)' }}
        >
          Select at least one card
        </p>
      )}
      <Button
        variant="primary"
        size="lg"
        className="w-full"
        onClick={onCommitOwned}
        disabled={selectedCount === 0}
        loading={isProcessing}
        aria-describedby={selectedCount === 0 ? selectHintId : undefined}
      >
        {selectedCount > 0
          ? `${VOCAB.ADD_TO_MY_COLLECTION} (${selectedCount})`
          : VOCAB.ADD_TO_MY_COLLECTION}
      </Button>
      <Button
        variant="ghost"
        size="lg"
        className="w-full mt-2"
        onClick={onOpenListPicker}
        disabled={selectedCount === 0 || isProcessing}
      >
        {VOCAB.ADD_TO_LIST}
      </Button>
    </div>
  );
}

export function ScannerCheckoutContent({
  queue,
  onOpenListPicker,
  onEmpty,
  headerId = 'checkout-sheet-title',
}) {
  const [commitError, setCommitError] = useState(null);
  const initialSelectionDoneRef = useRef(false);

  const cartCards = queue.scannedCards.filter((card) => !card.processed);
  const selectedCount = cartCards.filter((card) => queue.selectedCards.has(card.id)).length;
  const lowConfidenceCount = cartCards.filter((card) => {
    const pct = confidencePercent(card.confidence);
    return pct != null && pct < 70;
  }).length;

  useEffect(() => {
    if (initialSelectionDoneRef.current) return;
    cartCards.forEach((card) => {
      if (!queue.selectedCards.has(card.id)) {
        queue.toggleCardSelection(card.id);
      }
    });
    initialSelectionDoneRef.current = true;
  }, [cartCards, queue]);

  useEffect(() => {
    if (cartCards.length === 0) {
      onEmpty?.();
    }
  }, [cartCards.length, onEmpty]);

  const handleCommitOwned = async () => {
    setCommitError(null);
    const beforeIds = cartCards
      .filter((card) => queue.selectedCards.has(card.id))
      .map((card) => card.id);

    if (beforeIds.length === 0) return;

    const successfulIds = await queue.commitSelectedToOwned();
    if (!successfulIds?.length) {
      setCommitError('Could not add cards. Try again.');
    }
  };

  return (
    <>
      <div className="px-4 sm:px-6 pb-2">
        <h2
          id={headerId}
          className="text-lg font-semibold"
          style={{ color: 'var(--text-primary)' }}
        >
          {cartCards.length} {cartCards.length === 1 ? 'card' : 'cards'} scanned
        </h2>
        {lowConfidenceCount > 0 && (
          <p className="text-sm mt-1" style={{ color: 'var(--accent-ember)' }}>
            {lowConfidenceCount} {lowConfidenceCount === 1 ? 'needs' : 'need'} review
          </p>
        )}
      </div>

      <div
        className="flex-1 overflow-y-auto px-4 sm:px-6 py-3"
        style={{ minHeight: 0 }}
      >
        {cartCards.map((card) => (
          <ReviewCardItem
            key={card.id}
            card={card}
            selected={queue.selectedCards.has(card.id)}
            onToggleSelect={() => queue.toggleCardSelection(card.id)}
            showCheckbox
            confidence={card.confidence}
            onIncrement={() => queue.incrementCardQuantity(card.id)}
            onDecrement={() => queue.decrementCardQuantity(card.id)}
            onUpdateMetadata={(patch) => queue.updateCardMetadata(card.id, patch)}
            onRemove={() => queue.removeScannedCard(card.id)}
            isAdding={queue.addingCardIds?.has(card.id)}
          />
        ))}
      </div>

      <CheckoutFooter
        selectedCount={selectedCount}
        isProcessing={queue.isProcessing}
        commitError={commitError}
        onCommitOwned={handleCommitOwned}
        onOpenListPicker={onOpenListPicker}
      />
    </>
  );
}

export default function ScannerCheckoutSheet({
  queue,
  onClose,
  onOpenListPicker,
  trapActive = true,
}) {
  const sheetRef = useFocusTrap(trapActive);
  const backdropRef = useRef(null);

  useEffect(() => {
    const backdrop = backdropRef.current;
    const sheet = sheetRef.current;
    if (!backdrop || !sheet) return undefined;

    requestAnimationFrame(() => {
      backdrop.dataset.visible = 'true';
      sheet.dataset.visible = 'true';
    });

    if (!trapActive) return undefined;

    const handler = (e) => {
      if (e.key === 'Escape') onClose();
    };
    document.addEventListener('keydown', handler);
    return () => document.removeEventListener('keydown', handler);
  }, [onClose, sheetRef, trapActive]);

  const handleBackdropClick = useCallback(
    (e) => {
      if (e.target === e.currentTarget) onClose();
    },
    [onClose]
  );

  return (
    <div
      ref={backdropRef}
      className="fixed inset-0 z-40 checkout-backdrop"
      onClick={handleBackdropClick}
      role="dialog"
      aria-modal="true"
      aria-labelledby="checkout-sheet-title"
    >
      <div
        ref={sheetRef}
        className="fixed bottom-0 left-0 right-0 glass-panel-strong rounded-t-2xl overflow-hidden checkout-sheet flex flex-col"
      >
        <div className="relative flex items-center justify-center pt-3 pb-2 px-4">
          <div
            className="w-10 h-1 rounded-full"
            style={{ backgroundColor: 'var(--text-secondary)', opacity: 0.4 }}
            aria-hidden="true"
          />
          <button
            type="button"
            onClick={onClose}
            className="absolute right-3 top-2 flex items-center justify-center rounded-lg"
            style={{
              minWidth: 44,
              minHeight: 44,
              color: 'var(--text-secondary)',
            }}
            aria-label="Close cart"
          >
            <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" aria-hidden="true">
              <path d="M18 6L6 18M6 6l12 12" />
            </svg>
          </button>
        </div>

        <ScannerCheckoutContent
          queue={queue}
          onOpenListPicker={onOpenListPicker}
          onEmpty={onClose}
        />
      </div>

      <style jsx>{`
        .checkout-backdrop {
          background: transparent;
          backdrop-filter: none;
          -webkit-backdrop-filter: none;
          transition: background 300ms ease-out, backdrop-filter 300ms ease-out,
            -webkit-backdrop-filter 300ms ease-out;
        }
        .checkout-backdrop[data-visible='true'] {
          background: var(--modal-scrim);
          backdrop-filter: blur(var(--glass-blur-high));
          -webkit-backdrop-filter: blur(var(--glass-blur-high));
        }
        .checkout-sheet {
          max-height: 85vh;
          transform: translateY(100%);
          transition: transform 300ms ease-out;
        }
        .checkout-sheet[data-visible='true'] {
          transform: translateY(0);
        }
      `}</style>
    </div>
  );
}