import {
  createContext,
  forwardRef,
  ReactNode,
  useCallback,
  useContext,
  useEffect,
  useLayoutEffect,
  useRef,
  useState,
} from "react";
import {
  api,
  CardRef,
  COLORS,
  LEGALITY_FORMATS,
  LibraryFilter,
  legalStatusFor,
  maskToLetters,
  PreviewCard,
} from "./api";
import { useBackButton } from "./backButton";

// --- Icons ------------------------------------------------------------

const icon = (children: ReactNode) => (
  <svg
    viewBox="0 0 24 24"
    width="15"
    height="15"
    fill="none"
    stroke="currentColor"
    strokeWidth="2"
    strokeLinecap="round"
    strokeLinejoin="round"
  >
    {children}
  </svg>
);

const ICON_TRASH = icon(
  <>
    <polyline points="3 6 5 6 21 6" />
    <path d="M19 6l-1 14a2 2 0 0 1-2 2H8a2 2 0 0 1-2-2L5 6" />
    <path d="M10 11v6" />
    <path d="M14 11v6" />
    <path d="M9 6V4a1 1 0 0 1 1-1h4a1 1 0 0 1 1 1v2" />
  </>,
);
const ICON_COPY = icon(
  <>
    <rect x="9" y="9" width="13" height="13" rx="2" ry="2" />
    <path d="M5 15H4a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2h9a2 2 0 0 1 2 2v1" />
  </>,
);
const ICON_PENCIL = icon(<path d="M17 3a2.828 2.828 0 1 1 4 4L7.5 20.5 2 22l1.5-5.5L17 3z" />);
const ICON_CLOSE = icon(
  <>
    <line x1="18" y1="6" x2="6" y2="18" />
    <line x1="6" y1="6" x2="18" y2="18" />
  </>,
);
const ICON_HELP_CIRCLE = icon(
  <>
    <circle cx="12" cy="12" r="10" />
    <path d="M9.09 9a3 3 0 0 1 5.83 1c0 2-3 3-3 3" />
    <line x1="12" y1="17" x2="12.01" y2="17" />
  </>,
);
const ICON_ARROW_LEFT_CIRCLE = icon(
  <>
    <circle cx="12" cy="12" r="10" />
    <polyline points="12 8 8 12 12 16" />
    <line x1="16" y1="12" x2="8" y2="12" />
  </>,
);
const ICON_CARDS = icon(
  <>
    <rect x="4" y="2" width="12" height="17" rx="2" />
    <rect x="8" y="5" width="12" height="17" rx="2" />
  </>,
);
const ICON_DOWNLOAD = icon(
  <>
    <path d="M12 3v12" />
    <polyline points="7 11 12 16 17 11" />
    <path d="M4 18v1a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2v-1" />
  </>,
);
const ICON_UPLOAD = icon(
  <>
    <path d="M12 21V9" />
    <polyline points="7 13 12 8 17 13" />
    <path d="M4 18v1a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2v-1" />
  </>,
);

/**
 * A small round icon-only button, used consistently for lightweight actions
 * (rename, duplicate, delete, dismiss, close) throughout the app.
 * - `overlay`: dark translucent variant for sitting on top of card art.
 * - `danger`: tints red on hover, for destructive actions.
 */
export function IconButton({
  icon,
  label,
  onClick,
  overlay,
  danger,
  disabled,
}: {
  icon: ReactNode;
  label: string;
  onClick: (e: React.MouseEvent) => void;
  overlay?: boolean;
  danger?: boolean;
  disabled?: boolean;
}) {
  return (
    <button
      type="button"
      className={["icon-btn", overlay ? "icon-btn-overlay" : "", danger ? "icon-btn-danger" : ""]
        .filter(Boolean)
        .join(" ")}
      onClick={onClick}
      title={label}
      aria-label={label}
      disabled={disabled}
    >
      {icon}
    </button>
  );
}

export const Icons = {
  trash: ICON_TRASH,
  copy: ICON_COPY,
  pencil: ICON_PENCIL,
  close: ICON_CLOSE,
  helpCircle: ICON_HELP_CIRCLE,
  arrowLeftCircle: ICON_ARROW_LEFT_CIRCLE,
  cards: ICON_CARDS,
  download: ICON_DOWNLOAD,
  upload: ICON_UPLOAD,
};

// --- Dialogs ------------------------------------------------------------

/**
 * A centered modal dialog (backdrop + card) shared by [`ConfirmDialog`],
 * [`PromptDialog`], and other dialogs built outside this module (e.g. the
 * command palette). Dismisses on Escape, Android back, backdrop click, or the
 * title-bar close button — the explicit button matters most on mobile, where
 * there's no Escape key and a `wide` dialog can leave little to no backdrop
 * to tap.
 */
export function DialogFrame({
  title,
  children,
  onCancel,
  wide,
}: {
  title: string;
  children: ReactNode;
  onCancel: () => void;
  /** Wider variant for content that needs more room than a typical confirm/prompt box. */
  wide?: boolean;
}) {
  useEffect(() => {
    const onKey = (e: KeyboardEvent) => e.key === "Escape" && onCancel();
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, [onCancel]);
  useBackButton(onCancel);

  return (
    <div className="dialog-backdrop" onClick={onCancel}>
      <div className={`dialog ${wide ? "dialog-wide" : ""}`} onClick={(e) => e.stopPropagation()}>
        <div className="dialog-title-row">
          <h3 className="dialog-title">{title}</h3>
          <IconButton icon={Icons.close} label="Close" onClick={onCancel} />
        </div>
        {children}
      </div>
    </div>
  );
}

/** A confirm/cancel dialog for destructive or otherwise consequential actions. */
export function ConfirmDialog({
  title,
  message,
  confirmLabel = "Confirm",
  danger,
  onConfirm,
  onCancel,
}: {
  title: string;
  message: ReactNode;
  confirmLabel?: string;
  danger?: boolean;
  onConfirm: () => void;
  onCancel: () => void;
}) {
  return (
    <DialogFrame title={title} onCancel={onCancel}>
      <p className="dialog-message">{message}</p>
      <div className="dialog-actions">
        <button onClick={onCancel}>Cancel</button>
        <button className={danger ? "danger" : "primary"} onClick={onConfirm} autoFocus>
          {confirmLabel}
        </button>
      </div>
    </DialogFrame>
  );
}

/** A single-text-field dialog (rename, duplicate-as, etc.), Enter to confirm. */
export function PromptDialog({
  title,
  label,
  defaultValue,
  confirmLabel = "Save",
  error,
  onConfirm,
  onCancel,
}: {
  title: string;
  label: string;
  defaultValue: string;
  confirmLabel?: string;
  error?: string | null;
  onConfirm: (value: string) => void;
  onCancel: () => void;
}) {
  const [value, setValue] = useState(defaultValue);
  const inputRef = useRef<HTMLInputElement>(null);
  useEffect(() => inputRef.current?.select(), []);

  const confirm = () => {
    const v = value.trim();
    if (v) onConfirm(v);
  };

  return (
    <DialogFrame title={title} onCancel={onCancel}>
      <label className="dialog-field">
        <span className="muted">{label}</span>
        <input
          ref={inputRef}
          autoFocus
          value={value}
          onChange={(e) => setValue(e.target.value)}
          onKeyDown={(e) => e.key === "Enter" && confirm()}
        />
      </label>
      {error && <p className="dialog-error">{error}</p>}
      <div className="dialog-actions">
        <button onClick={onCancel}>Cancel</button>
        <button className="primary" onClick={confirm} disabled={!value.trim()}>
          {confirmLabel}
        </button>
      </div>
    </DialogFrame>
  );
}

/** Read-only informational dialog: a message plus an optional bulleted list
 * (e.g. unresolved card names after an import). Single "OK" dismiss button. */
export function InfoDialog({
  title,
  message,
  items,
  onClose,
}: {
  title: string;
  message?: ReactNode;
  items?: string[];
  onClose: () => void;
}) {
  return (
    <DialogFrame title={title} onCancel={onClose} wide={!!items?.length}>
      {message && <p className="dialog-message">{message}</p>}
      {items && items.length > 0 && (
        <ul className="dialog-list">
          {items.map((it, i) => (
            <li key={i}>{it}</li>
          ))}
        </ul>
      )}
      <div className="dialog-actions">
        <button className="primary" onClick={onClose} autoFocus>
          OK
        </button>
      </div>
    </DialogFrame>
  );
}

/** Floating snackbar offering to reverse the caller's last action. Auto-
 * dismisses on a timer managed by the caller (this component is purely
 * presentational) — pass `null`/omit rendering it once the window lapses. */
export function UndoBar({
  message,
  onUndo,
  onDismiss,
}: {
  message: string;
  onUndo: () => void;
  onDismiss: () => void;
}) {
  return (
    <div className="undo-bar">
      <span>{message}</span>
      <button className="primary" onClick={onUndo}>
        Undo
      </button>
      <button className="undo-bar-close" onClick={onDismiss} title="Dismiss">
        ×
      </button>
    </div>
  );
}

/** Modal shuffle-and-draw sample hand: shows the drawn cards and lets the
 * caller draw more or reshuffle, on top of a click/Escape-to-close backdrop. */
export function SampleHandModal({
  hand,
  libraryCount,
  onDrawOne,
  onNewHand,
  onClose,
}: {
  hand: CardRef[];
  libraryCount: number;
  onDrawOne: () => void;
  onNewHand: () => void;
  onClose: () => void;
}) {
  return (
    <DialogFrame title="Sample hand" onCancel={onClose} wide>
      <div className="row" style={{ gap: 10, marginBottom: 12 }}>
        <span className="muted" style={{ fontSize: 12 }}>
          {libraryCount} card{libraryCount === 1 ? "" : "s"} left in library
        </span>
        <span className="spacer" />
        <button onClick={onDrawOne} disabled={libraryCount === 0}>
          Draw a card
        </button>
        <button onClick={onNewHand}>New hand</button>
      </div>
      {hand.length > 0 ? (
        <div className="tile-grid">
          {hand.map((c, i) => (
            <CardTile key={`${c.oracle_id}-${i}`} card={c} />
          ))}
        </div>
      ) : (
        <p className="hint">Your deck has no cards to draw yet.</p>
      )}
      <div className="dialog-actions">
        <button className="primary" onClick={onClose} autoFocus>
          Close
        </button>
      </div>
    </DialogFrame>
  );
}

/**
 * Inline editor for a card's free-text storage location (e.g. "Box 1").
 * Saves on blur; used for owned cards that aren't in any deck.
 */
export function LocationField({
  oracleId,
  location,
  onSaved,
}: {
  oracleId: string;
  location: string;
  onSaved?: () => void;
}) {
  const [val, setVal] = useState(location);
  useEffect(() => setVal(location), [location]);

  const save = () => {
    if (val !== location) api.setLocation(oracleId, val).then(() => onSaved?.());
  };
  return (
    <input
      className="location-input"
      placeholder="Location…"
      value={val}
      onChange={(e) => setVal(e.target.value)}
      onBlur={save}
      onKeyDown={(e) => e.key === "Enter" && (e.target as HTMLInputElement).blur()}
    />
  );
}

/**
 * A small pill-shaped [− N +] quantity stepper, used consistently for owned-copy
 * counts on the Add Cards page and both Library views.
 *
 * - `overlay`: dark translucent variant for use atop card art (tile corners),
 *   instead of the default panel-toned variant used in rows/lists.
 * - `warn`: tints the pill amber (e.g. "assigned to more decks than owned").
 * - `pending`: dims the pill (e.g. mid grace-period before a 0-qty row is removed).
 */
export function QtyStepper({
  value,
  onDecrement,
  onIncrement,
  overlay,
  warn,
  pending,
}: {
  value: number;
  onDecrement: () => void;
  onIncrement: () => void;
  overlay?: boolean;
  warn?: boolean;
  pending?: boolean;
}) {
  return (
    <span
      className={[
        "qty-stepper",
        overlay ? "qty-stepper-overlay" : "",
        warn ? "warn" : "",
        pending ? "pending" : "",
      ]
        .filter(Boolean)
        .join(" ")}
    >
      <button
        type="button"
        className="qty-stepper-btn"
        onClick={onDecrement}
        disabled={value <= 0}
        title="Remove a copy"
      >
        −
      </button>
      <span className="qty-stepper-value">{value}</span>
      <button type="button" className="qty-stepper-btn" onClick={onIncrement} title="Add a copy">
        +
      </button>
    </span>
  );
}

/** Render a color-identity/colors bitmask as WUBRG pips (colorless = a "C" pip). */
export function ColorPips({ mask }: { mask: number }) {
  const letters = maskToLetters(mask);
  if (letters.length === 0) {
    return (
      <span className="pips">
        <span className="pip C">C</span>
      </span>
    );
  }
  return (
    <span className="pips">
      {letters.split("").map((c) => (
        <span key={c} className={`pip ${c}`}>
          {c}
        </span>
      ))}
    </span>
  );
}

/**
 * Small card-image thumbnail. Hovering it shows a cursor-tracking preview;
 * clicking it opens a larger, centered preview (with a flip button for
 * double-faced cards).
 */
export function CardThumb({ card }: { card: CardRef }) {
  const { handlers } = useHoverPreview();
  const { open } = useClickPreview();
  if (!card.image_uri) {
    return (
      <span className="thumb-empty" title="No image">
        🂠
      </span>
    );
  }
  return (
    <img
      className="card-thumb"
      src={card.image_uri}
      alt={card.name}
      loading="lazy"
      onClick={(e) => {
        e.stopPropagation();
        open(card);
      }}
      {...handlers(card)}
    />
  );
}

/**
 * A search input plus a results dropdown with keyboard navigation:
 * ↑/↓ move the highlight, Enter picks, mouse hover/click also work.
 * `value`/`onChange` are controlled by the caller (which runs the search).
 * Forwards a ref to the underlying `<input>` so callers can focus it
 * imperatively (e.g. redirecting a stray keystroke into the search box).
 */
export const CardSearchBox = forwardRef<
  HTMLInputElement,
  {
    placeholder: string;
    value: string;
    onChange: (v: string) => void;
    results: CardRef[];
    onPick: (card: CardRef) => void;
    autoFocus?: boolean;
    /** Larger, more prominent input (used for the primary Add Cards field). */
    big?: boolean;
  }
>(function CardSearchBox(
  { placeholder, value, onChange, results, onPick, autoFocus, big },
  forwardedRef,
) {
  const [sel, setSel] = useState(0);
  const inputRef = useRef<HTMLInputElement | null>(null);
  useEffect(() => setSel(0), [results]);

  // Keep focus in the box after a pick so cards can be added in a rapid streak.
  function pick(card: CardRef) {
    onPick(card);
    inputRef.current?.focus();
  }

  function onKeyDown(e: React.KeyboardEvent) {
    if (e.key === "ArrowDown") {
      e.preventDefault();
      setSel((s) => Math.min(s + 1, results.length - 1));
    } else if (e.key === "ArrowUp") {
      e.preventDefault();
      setSel((s) => Math.max(s - 1, 0));
    } else if (e.key === "Enter" && results[sel]) {
      e.preventDefault();
      pick(results[sel]);
    }
  }

  return (
    <>
      <input
        ref={(el) => {
          inputRef.current = el;
          if (typeof forwardedRef === "function") forwardedRef(el);
          else if (forwardedRef) (forwardedRef as React.MutableRefObject<HTMLInputElement | null>).current = el;
        }}
        autoFocus={autoFocus}
        style={{
          width: "100%",
          marginBottom: 8,
          ...(big ? { fontSize: 16, padding: "10px 12px" } : {}),
        }}
        placeholder={placeholder}
        value={value}
        onChange={(e) => onChange(e.target.value)}
        onKeyDown={onKeyDown}
      />
      {results.length > 0 && (
        <ul className="result-list" style={{ marginBottom: 14 }}>
          {results.map((c, i) => (
            <li
              key={c.oracle_id}
              style={i === sel ? { background: "var(--accent-subtle)" } : undefined}
              onMouseEnter={() => setSel(i)}
              onClick={() => pick(c)}
            >
              <ColorPips mask={c.color_identity} />
              <span className="card-name">{c.name}</span>
              <span className="card-type">{c.type_line}</span>
            </li>
          ))}
        </ul>
      )}
    </>
  );
});

/**
 * A chip-based multi-value text filter with autocomplete: selected values
 * render as removable chips, and typing filters `suggestions` into a
 * dropdown (↑/↓ to move, Enter to pick — or Enter with no match adds the
 * typed text verbatim, so it's not limited to only-suggested values).
 * Backspace on an empty input quick-removes the last chip.
 */
export function TagInput({
  values,
  onChange,
  suggestions,
  placeholder,
}: {
  values: string[];
  onChange: (values: string[]) => void;
  suggestions: string[];
  placeholder?: string;
}) {
  const [text, setText] = useState("");
  const [sel, setSel] = useState(0);

  const query = text.trim().toLowerCase();
  const filtered = query
    ? suggestions
        .filter((s) => !values.some((v) => v.toLowerCase() === s.toLowerCase()))
        .filter((s) => s.toLowerCase().includes(query))
        .slice(0, 8)
    : [];

  useEffect(() => setSel(0), [text]);

  function addValue(v: string) {
    const trimmed = v.trim();
    if (!trimmed) return;
    if (!values.some((x) => x.toLowerCase() === trimmed.toLowerCase())) {
      onChange([...values, trimmed]);
    }
    setText("");
  }

  function removeValue(v: string) {
    onChange(values.filter((x) => x !== v));
  }

  function onKeyDown(e: React.KeyboardEvent) {
    if (e.key === "ArrowDown" && filtered.length > 0) {
      e.preventDefault();
      setSel((s) => Math.min(s + 1, filtered.length - 1));
    } else if (e.key === "ArrowUp" && filtered.length > 0) {
      e.preventDefault();
      setSel((s) => Math.max(s - 1, 0));
    } else if (e.key === "Enter") {
      e.preventDefault();
      if (filtered[sel]) addValue(filtered[sel]);
      else if (text.trim()) addValue(text);
    } else if (e.key === "Backspace" && text === "" && values.length > 0) {
      onChange(values.slice(0, -1));
    } else if (e.key === "Escape") {
      setText("");
    }
  }

  return (
    <div className="tag-input">
      <div className="tag-chips">
        {values.map((v) => (
          <span key={v} className="tag-chip">
            {v}
            <button
              type="button"
              className="tag-chip-remove"
              onClick={() => removeValue(v)}
              title={`Remove ${v}`}
            >
              ×
            </button>
          </span>
        ))}
        <input
          className="tag-chip-input"
          value={text}
          onChange={(e) => setText(e.target.value)}
          onKeyDown={onKeyDown}
          placeholder={values.length === 0 ? placeholder : ""}
        />
      </div>
      {filtered.length > 0 && (
        <ul className="result-list tag-suggestions">
          {filtered.map((s, i) => (
            <li
              key={s}
              style={i === sel ? { background: "var(--accent-subtle)" } : undefined}
              onMouseEnter={() => setSel(i)}
              onClick={() => addValue(s)}
            >
              {s}
            </li>
          ))}
        </ul>
      )}
    </div>
  );
}

// --- Hover + click preview -------------------------------------------------

interface HoverApi {
  enter: (card: CardRef, e: React.MouseEvent) => void;
  move: (e: React.MouseEvent) => void;
  leave: () => void;
}
interface ClickApi {
  open: (card: PreviewCard) => void;
}
const HoverCtx = createContext<HoverApi | null>(null);
const ClickCtx = createContext<ClickApi | null>(null);

/**
 * Provides card-image previews app-wide: a small floating preview that
 * tracks the cursor while hovering (see [`useHoverPreview`]), and a larger
 * centered modal on click (see [`useClickPreview`]) — with a flip button for
 * double-faced cards. Wrap the app once.
 */
export function HoverPreviewProvider({ children }: { children: ReactNode }) {
  const [hover, setHover] = useState<{ card: CardRef; x: number; y: number } | null>(null);
  const [clicked, setClicked] = useState<{ card: PreviewCard; showBack: boolean } | null>(null);

  const enter = useCallback((card: CardRef, e: React.MouseEvent) => {
    if (card.image_uri) setHover({ card, x: e.clientX, y: e.clientY });
  }, []);
  const move = useCallback((e: React.MouseEvent) => {
    setHover((s) => (s ? { ...s, x: e.clientX, y: e.clientY } : s));
  }, []);
  const leave = useCallback(() => setHover(null), []);

  const open = useCallback((card: PreviewCard) => {
    if (!card.image_uri) return;
    setHover(null);
    setClicked({ card, showBack: false });
  }, []);
  const close = useCallback(() => setClicked(null), []);
  const flip = useCallback(() => setClicked((c) => (c ? { ...c, showBack: !c.showBack } : c)), []);

  useEffect(() => {
    if (!clicked) return;
    const onKey = (e: KeyboardEvent) => e.key === "Escape" && close();
    window.addEventListener("keydown", onKey);
    return () => window.removeEventListener("keydown", onKey);
  }, [clicked, close]);
  useBackButton(close, !!clicked);

  return (
    <HoverCtx.Provider value={{ enter, move, leave }}>
      <ClickCtx.Provider value={{ open }}>
        {children}
        {!clicked && hover && <FloatingCard card={hover.card} x={hover.x} y={hover.y} />}
        {clicked && <ClickPreviewModal state={clicked} onClose={close} onFlip={flip} />}
      </ClickCtx.Provider>
    </HoverCtx.Provider>
  );
}

/** Returns a `handlers(card)` factory to spread onto a row/cell for hover preview. */
export function useHoverPreview() {
  const api = useContext(HoverCtx);
  return {
    handlers: (card: CardRef) =>
      api
        ? {
            onMouseEnter: (e: React.MouseEvent) => api.enter(card, e),
            onMouseMove: (e: React.MouseEvent) => api.move(e),
            onMouseLeave: () => api.leave(),
          }
        : {},
  };
}

/** Returns `open(card)` to trigger the larger click-to-preview modal. */
export function useClickPreview() {
  const api = useContext(ClickCtx);
  return { open: (card: PreviewCard) => api?.open(card) };
}

const PREVIEW_W = 320;
const PREVIEW_H = 446; // ~ card aspect for the normal image
const GAP = 24;
const PAD = 12;

function FloatingCard({ card, x, y }: { card: CardRef; x: number; y: number }) {
  // Battles/Planes/Phenomena store their image portrait-shaped with the
  // content itself rotated, so the box footprint swaps (landscape) and the
  // image inside gets rotated 90° back into place — see `CardRef.horizontal`.
  const boxW = card.horizontal ? PREVIEW_H : PREVIEW_W;
  const boxH = card.horizontal ? PREVIEW_W : PREVIEW_H;
  // Prefer the right of the cursor; flip left if it would overflow.
  let left = x + GAP;
  if (left + boxW + PAD > window.innerWidth) left = x - boxW - GAP;
  const top = Math.max(PAD, Math.min(y - boxH / 2, window.innerHeight - boxH - PAD));
  return (
    <div className="hover-card" style={{ left, top, width: boxW, height: boxH }}>
      <img
        className="hover-card-img"
        src={card.image_uri}
        alt={card.name}
        style={
          card.horizontal
            ? {
                position: "absolute",
                top: "50%",
                left: "50%",
                width: PREVIEW_W,
                height: PREVIEW_H,
                transform: "translate(-50%, -50%) rotate(90deg)",
              }
            : undefined
        }
      />
    </div>
  );
}

// Landscape (post-rotation) aspect ratio of a Scryfall "normal" card image —
// the raw file is portrait (488x680); rotated 90° it reads as 680x488.
const ROTATED_ASPECT = 680 / 488;

/** The largest landscape box (matching `.preview-modal-img`'s own
 * `max-width: min(720px, 90vw)` / `max-height: 90vh` bounds) for a rotated
 * horizontal-card preview. Recomputed on resize so it stays live like the
 * CSS-only sizing used for normal (portrait) cards.
 *
 * `dfc` (when wide enough for side-by-side faces) shrinks the budget to
 * roughly match a DFC back face's own `min(430px, 43vw)` box (see the `.preview-modal-dfc .preview-modal-img`
 * rule) and leaves headroom below for the info tile — pass it whenever the
 * horizontal front face has a sibling back face, so a transformed Battle
 * doesn't render at full single-card size next to a much smaller back face
 * and push the info tile off-screen.
 *
 * `fitH` (compact mode, see `ClickPreviewModal`) overrides both with the
 * exact art height budget left over after the pane toolbar. */
function useRotatedPreviewBox(dfc: boolean, fitH: number | null) {
  const compute = () => {
    // Faces only sit side by side at the `.preview-modal-dfc` ≥860px
    // breakpoint; below it they flip one at a time, so use the full budget.
    const sideBySide = dfc && fitH === null && window.innerWidth >= 860;
    const boundW = sideBySide ? Math.min(430, window.innerWidth * 0.43) : Math.min(720, window.innerWidth * 0.9);
    const boundH = fitH ?? (sideBySide ? window.innerHeight * 0.55 : window.innerHeight * 0.9);
    const w = Math.min(boundW, boundH * ROTATED_ASPECT);
    return { w, h: w / ROTATED_ASPECT };
  };
  const [box, setBox] = useState(compute);
  useEffect(() => {
    setBox(compute());
    const onResize = () => setBox(compute());
    window.addEventListener("resize", onResize);
    return () => window.removeEventListener("resize", onResize);
  }, [dfc, fitH]);
  return box;
}

/** Legality status pills for every tracked format, e.g. inside the
 * click-preview modal's info tile. Not-legal formats are shown too (dimmed)
 * so the list reads as a complete checklist rather than a partial one. */
function LegalityPills({ legalities }: { legalities: number }) {
  return (
    <div className="preview-info-legal-grid">
      {LEGALITY_FORMATS.map((f) => {
        const status = legalStatusFor(legalities, f.label);
        return (
          <span key={f.key} className={`legal-pill legal-${status}`}>
            {f.label}
          </span>
        );
      })}
    </div>
  );
}

/** Details panel shown alongside the card art in the click-to-preview modal:
 * type/mana/color, price, ownership context (when the caller had a
 * `LibraryCard`/`DeckEntry` to hand — see `PreviewCard`), and per-format
 * legality. */
const CardInfoTile = forwardRef<HTMLDivElement, { card: PreviewCard }>(function CardInfoTile({ card }, ref) {
  return (
    <div className="preview-info" ref={ref}>
      <div className="preview-info-name">{card.name}</div>
      <div className="preview-info-type">{card.type_line}</div>
      <div className="preview-info-row">
        <span className="preview-info-mv">Mana value {card.mana_value}</span>
        <ColorPips mask={card.colors} />
      </div>
      {card.price_usd > 0 && (
        <div className="preview-info-price">${card.price_usd.toFixed(2)}</div>
      )}
      {card.quantity_owned !== undefined && (
        <div className="preview-info-section">
          <span className="preview-info-label">Owned</span>
          <span>
            {card.quantity_owned} cop{card.quantity_owned === 1 ? "y" : "ies"}
          </span>
        </div>
      )}
      {card.decks && card.decks.length > 0 && (
        <div className="preview-info-section">
          <span className="preview-info-label">In decks</span>
          <div className="preview-info-deck-chips">
            {card.decks.map((d) => (
              <span key={d} className="badge">
                {d}
              </span>
            ))}
          </div>
        </div>
      )}
      <div className="preview-info-section">
        <span className="preview-info-label">Legalities</span>
        <LegalityPills legalities={card.legalities} />
      </div>
    </div>
  );
});

type PreviewPane = "card" | "info";

// Compact-mode toolbar height and the modal's flex gap — keep in sync with
// `.preview-modal-bar` / `.preview-modal` in styles.css.
const PREVIEW_BAR_H = 36;
const PREVIEW_GAP = 16;

/** Segmented control for the compact (one-pane-at-a-time) click preview:
 * front face / back face (double-faced cards only) / info tile. */
function PreviewPaneToggle({
  hasBack,
  showBack,
  pane,
  onSelect,
}: {
  hasBack: boolean;
  showBack: boolean;
  pane: PreviewPane;
  onSelect: (pane: PreviewPane, back: boolean) => void;
}) {
  const btn = (label: string, active: boolean, onClick: () => void) => (
    <button className={active ? "active" : ""} onClick={onClick}>
      {label}
    </button>
  );
  return (
    <span className="view-toggle">
      {btn(hasBack ? "Front" : "Card", pane === "card" && !showBack, () => onSelect("card", false))}
      {hasBack && btn("Back", pane === "card" && showBack, () => onSelect("card", true))}
      {btn("Info", pane === "info", () => onSelect("info", showBack))}
    </span>
  );
}

function ClickPreviewModal({
  state,
  onClose,
  onFlip,
}: {
  state: { card: PreviewCard; showBack: boolean };
  onClose: () => void;
  onFlip: () => void;
}) {
  const { card, showBack } = state;
  const hasBack = !!card.back_image_uri;
  const backdropRef = useRef<HTMLDivElement>(null);
  const modalRef = useRef<HTMLDivElement>(null);
  const infoRef = useRef<HTMLDivElement>(null);
  // Compact mode: when the full layout (art + info tile) would be taller than
  // the viewport — i.e. on phones, where the tile wraps below the art — show
  // one pane at a time above a Front/Back/Info toggle instead of making the
  // user scroll. Decided by measuring the full layout itself: every resize
  // drops back to it, and the layout effect below re-measures and switches
  // before paint, so there's no flash and no feedback loop (compact mode is
  // never what gets measured). The art's size doesn't depend on the image
  // having loaded (see `.preview-modal-img`), so measuring on mount is exact.
  // `fit` holds the measurements compact mode sizes itself from; null = full.
  const [fit, setFit] = useState<{ avail: number; infoH: number } | null>(null);
  const [pane, setPane] = useState<PreviewPane>("card");
  const [measureKey, setMeasureKey] = useState(0);
  const artBudget = fit && fit.avail - PREVIEW_BAR_H - PREVIEW_GAP;
  const rotatedBox = useRotatedPreviewBox(hasBack, artBudget);
  useEffect(() => {
    const onResize = () => {
      setFit(null);
      setMeasureKey((k) => k + 1);
    };
    window.addEventListener("resize", onResize);
    return () => window.removeEventListener("resize", onResize);
  }, []);
  useLayoutEffect(() => {
    const backdrop = backdropRef.current;
    const modal = modalRef.current;
    if (fit || !backdrop || !modal) return;
    const cs = getComputedStyle(backdrop);
    const avail = backdrop.clientHeight - parseFloat(cs.paddingTop) - parseFloat(cs.paddingBottom);
    if (modal.getBoundingClientRect().height > avail) {
      setFit({ avail, infoH: infoRef.current?.getBoundingClientRect().height ?? 0 });
    }
  }, [fit, measureKey, card, showBack]);

  // In compact mode the modal gets a fixed box — as wide and tall as the
  // largest pane (capped to the screen), toolbar pinned to its bottom — so
  // switching panes never moves the toolbar. Mirrors the CSS sizing of the
  // art (`.preview-modal-img`) and info tile (`.preview-info`).
  let compactStyle: React.CSSProperties | undefined;
  if (fit && artBudget !== null) {
    const vw = window.innerWidth;
    const portraitW = Math.min(488, vw * 0.9, (artBudget * 488) / 680);
    const faces = [
      card.horizontal ? rotatedBox : { w: portraitW, h: (portraitW * 680) / 488 },
      ...(hasBack ? [{ w: portraitW, h: (portraitW * 680) / 488 }] : []),
    ];
    const paneW = Math.max(Math.min(320, vw * 0.9), ...faces.map((f) => f.w));
    const paneH = Math.min(artBudget, Math.max(fit.infoH, ...faces.map((f) => f.h)));
    compactStyle = {
      width: paneW,
      height: paneH + PREVIEW_GAP + PREVIEW_BAR_H,
      ["--preview-img-h" as string]: `${artBudget}px`,
    };
  }
  const compact = !!fit;

  const selectPane = (next: PreviewPane, back: boolean) => {
    setPane(next);
    if (back !== showBack) onFlip();
  };

  // Both faces are always in the DOM when the card has one; a wide-viewport
  // media query shows them side by side (no flip needed), while a narrow one
  // shows only the "active" face and the flip button toggles between them.
  return (
    <div className="preview-modal-backdrop" ref={backdropRef} onClick={onClose}>
      <div
        ref={modalRef}
        style={compactStyle}
        className={[
          "preview-modal",
          hasBack ? "preview-modal-dfc" : "",
          compact ? "preview-modal-compact" : "",
          compact && pane === "info" ? "preview-modal-show-info" : "",
        ]
          .filter(Boolean)
          .join(" ")}
        onClick={(e) => e.stopPropagation()}
      >
        <div className="preview-modal-faces">
          {/* Only the front face can be horizontal (Battles) — a transformed
              Battle's back face is always a normal, correctly-oriented
              creature card, per `CardRef.horizontal`'s doc comment. */}
          {card.horizontal ? (
            <div
              className={`preview-modal-img preview-modal-img-rotated ${showBack ? "" : "active"}`}
              style={{ width: rotatedBox.w, height: rotatedBox.h }}
            >
              <img
                className="preview-modal-rotate-img"
                src={card.image_uri}
                alt={card.name}
                style={{ width: rotatedBox.h, height: rotatedBox.w }}
              />
            </div>
          ) : (
            <img
              className={`preview-modal-img ${showBack ? "" : "active"}`}
              src={card.image_uri}
              alt={card.name}
            />
          )}
          {hasBack && (
            <img
              className={`preview-modal-img ${showBack ? "active" : ""}`}
              src={card.back_image_uri}
              alt={`${card.name} (back)`}
            />
          )}
          <span className="preview-modal-close">
            <IconButton icon={Icons.close} label="Close (Esc)" onClick={onClose} overlay />
          </span>
          {hasBack && (
            <button className="preview-modal-flip" onClick={onFlip} title="Show the other side">
              ⟲ Flip
            </button>
          )}
        </div>
        <CardInfoTile ref={infoRef} card={card} />
        {compact && (
          <div className="preview-modal-bar">
            <PreviewPaneToggle hasBack={hasBack} showBack={showBack} pane={pane} onSelect={selectPane} />
            <IconButton icon={Icons.close} label="Close (Esc)" onClick={onClose} overlay />
          </div>
        )}
      </div>
    </div>
  );
}

// --- Grouping -------------------------------------------------------------

export type GroupMode = "none" | "type" | "subtype" | "cmc" | "colors";

export const GROUP_OPTIONS: { value: GroupMode; label: string }[] = [
  { value: "none", label: "No grouping" },
  { value: "type", label: "Card type" },
  { value: "subtype", label: "Subtype" },
  { value: "cmc", label: "Mana value" },
  { value: "colors", label: "Color identity" },
];

// Priority for choosing a card's primary type from its (multi-type) type line.
const TYPE_PRIORITY = [
  "Creature",
  "Planeswalker",
  "Battle",
  "Land",
  "Artifact",
  "Enchantment",
  "Instant",
  "Sorcery",
];

function primaryType(typeLine: string): string {
  const left = typeLine.split("—")[0];
  for (const t of TYPE_PRIORITY) if (left.includes(t)) return t;
  const words = left.trim().split(/\s+/);
  return words[words.length - 1] || "Other";
}

/** Where a primary type falls in [`TYPE_PRIORITY`] — used both to order
 * type groups and to sort cards by type. */
function typeRank(primary: string): number {
  const i = TYPE_PRIORITY.indexOf(primary);
  return i === -1 ? TYPE_PRIORITY.length : i;
}

/** e.g. "Creature — Chimera" — prefixed with the primary type so cards group
 * by (type, subtype) rather than colliding on a subtype shared across types. */
function subtypeLabel(typeLine: string): string {
  const parts = typeLine.split("—");
  const subtype = parts.length < 2 ? "No subtype" : parts[1].trim().split(/\s+/)[0] || "No subtype";
  return `${primaryType(typeLine)} — ${subtype}`;
}

function colorLabel(mask: number): string {
  const letters = maskToLetters(mask);
  return letters === "" ? "Colorless" : letters;
}

/** Group cards by the chosen attribute, returning ordered groups. */
export function groupCards<T extends CardRef>(
  cards: T[],
  mode: GroupMode,
): { label: string; cards: T[] }[] {
  if (mode === "none") return [{ label: "", cards }];

  const keyOf = (c: T) =>
    mode === "type"
      ? primaryType(c.type_line)
      : mode === "subtype"
        ? subtypeLabel(c.type_line)
        : mode === "cmc"
          ? `Mana value ${c.mana_value}`
          : colorLabel(c.color_identity);

  const map = new Map<string, T[]>();
  for (const c of cards) {
    const k = keyOf(c);
    const arr = map.get(k);
    if (arr) arr.push(c);
    else map.set(k, [c]);
  }

  const groups = [...map.entries()].map(([label, cs]) => ({ label, cards: cs }));
  if (mode === "type") {
    groups.sort((a, b) => typeRank(a.label) - typeRank(b.label) || a.label.localeCompare(b.label));
  } else if (mode === "cmc") {
    groups.sort((a, b) => a.cards[0].mana_value - b.cards[0].mana_value);
  } else {
    groups.sort((a, b) => a.label.localeCompare(b.label));
  }
  return groups;
}

/** Dropdown for choosing a [`GroupMode`]. */
export function GroupBySelect({
  value,
  onChange,
}: {
  value: GroupMode;
  onChange: (m: GroupMode) => void;
}) {
  return (
    <label className="group-by">
      <span className="muted">Group by</span>
      <select value={value} onChange={(e) => onChange(e.target.value as GroupMode)}>
        {GROUP_OPTIONS.map((o) => (
          <option key={o.value} value={o.value}>
            {o.label}
          </option>
        ))}
      </select>
    </label>
  );
}

// --- Sorting ----------------------------------------------------------

export type SortMode = "name" | "mv" | "color" | "type" | "qty" | "price";

export const SORT_OPTIONS: { value: SortMode; label: string }[] = [
  { value: "name", label: "Name" },
  { value: "mv", label: "Mana value" },
  { value: "color", label: "Color identity" },
  { value: "type", label: "Card type" },
  { value: "qty", label: "Quantity owned" },
  { value: "price", label: "Price" },
];

export type SortDir = "asc" | "desc";

/** Sort cards by the chosen attribute; ties always break by name so the
 * order stays stable and predictable regardless of `mode`. Grouping (see
 * [`groupCards`]) determines section order independently — sort this array
 * first, then group it, and each group keeps this order internally. */
export function sortCards<T extends CardRef & { quantity_owned: number }>(
  cards: T[],
  mode: SortMode,
  dir: SortDir,
): T[] {
  const sorted = [...cards].sort((a, b) => {
    const cmp =
      mode === "name"
        ? a.name.localeCompare(b.name)
        : mode === "mv"
          ? a.mana_value - b.mana_value || a.name.localeCompare(b.name)
          : mode === "color"
            ? colorLabel(a.color_identity).localeCompare(colorLabel(b.color_identity)) ||
              a.name.localeCompare(b.name)
            : mode === "type"
              ? typeRank(primaryType(a.type_line)) - typeRank(primaryType(b.type_line)) ||
                a.name.localeCompare(b.name)
              : mode === "qty"
                ? a.quantity_owned - b.quantity_owned || a.name.localeCompare(b.name)
                : a.price_usd - b.price_usd || a.name.localeCompare(b.name);
    return dir === "asc" ? cmp : -cmp;
  });
  return sorted;
}

/** Dropdown + ascending/descending toggle for choosing a [`SortMode`]. */
export function SortBySelect({
  value,
  dir,
  onChangeValue,
  onToggleDir,
}: {
  value: SortMode;
  dir: SortDir;
  onChangeValue: (m: SortMode) => void;
  onToggleDir: () => void;
}) {
  return (
    <span className="row" style={{ gap: 4 }}>
      <label className="group-by">
        <span className="muted">Sort by</span>
        <select value={value} onChange={(e) => onChangeValue(e.target.value as SortMode)}>
          {SORT_OPTIONS.map((o) => (
            <option key={o.value} value={o.value}>
              {o.label}
            </option>
          ))}
        </select>
      </label>
      <button
        type="button"
        className="sort-dir-btn"
        onClick={onToggleDir}
        title={dir === "asc" ? "Ascending — click for descending" : "Descending — click for ascending"}
      >
        {dir === "asc" ? "↑" : "↓"}
      </button>
    </span>
  );
}

// --- Stats widgets (sidebar "Your library" panel, per-deck analysis) ------

/** A single numeric stat in a small panel tile, e.g. "42 / unique". */
export function StatTile({ value, label }: { value: string | number; label: string }) {
  return (
    <div className="stat-tile">
      <span className="stat-tile-value">{value}</span>
      <span className="stat-tile-label">{label}</span>
    </div>
  );
}

/** A segmented WUBRG(+colorless) bar sized proportionally to `colorCounts`. */
export function ColorDistributionBar({
  colorCounts,
  colorlessCount,
}: {
  colorCounts: [number, number, number, number, number]; // W, U, B, R, G
  colorlessCount: number;
}) {
  const segs: [string, number][] = [
    ["W", colorCounts[0]],
    ["U", colorCounts[1]],
    ["B", colorCounts[2]],
    ["R", colorCounts[3]],
    ["G", colorCounts[4]],
    ["C", colorlessCount],
  ];
  if (segs.every(([, count]) => count === 0)) return null;
  return (
    <div className="color-bar">
      {segs.map(([code, count]) =>
        count > 0 ? (
          <span
            key={code}
            className={`color-bar-seg ${code}`}
            style={{ flexGrow: count }}
            title={`${code === "C" ? "Colorless" : code}: ${count.toLocaleString()}`}
          />
        ) : null,
      )}
    </div>
  );
}

/** A mana-value histogram (bar height proportional to the largest bucket),
 * each bar segmented by color like {@link ColorDistributionBar}. */
export function ManaCurve({
  buckets,
}: {
  buckets: {
    label: string;
    count: number;
    colorCounts: [number, number, number, number, number]; // W, U, B, R, G
    colorlessCount: number;
  }[];
}) {
  const max = Math.max(1, ...buckets.map((b) => b.count));
  return (
    <div className="mana-curve">
      {buckets.map((b) => {
        const segs: [string, number][] = [
          ["W", b.colorCounts[0]],
          ["U", b.colorCounts[1]],
          ["B", b.colorCounts[2]],
          ["R", b.colorCounts[3]],
          ["G", b.colorCounts[4]],
          ["C", b.colorlessCount],
        ];
        return (
          <div key={b.label} className="mana-curve-col">
            <span className="mana-curve-count">{b.count || ""}</span>
            <div className="mana-curve-bar" style={{ height: `${(b.count / max) * 100}%` }}>
              {segs.map(([code, count]) =>
                count > 0 ? (
                  <span
                    key={code}
                    className={`mana-curve-seg ${code}`}
                    style={{ flexGrow: count }}
                    title={`${code === "C" ? "Colorless" : code}: ${count.toLocaleString()}`}
                  />
                ) : null,
              )}
            </div>
            <span className="mana-curve-label">{b.label}</span>
          </div>
        );
      })}
    </div>
  );
}

// --- Persistence ----------------------------------------------------------

/** useState that mirrors its value to localStorage (JSON), so it survives
 * remounts and app restarts. */
export function usePersistedState<T>(key: string, initial: T): [T, (v: T) => void] {
  const [val, setVal] = useState<T>(() => {
    const raw = localStorage.getItem(key);
    if (raw === null) return initial;
    try {
      return JSON.parse(raw) as T;
    } catch {
      return initial;
    }
  });
  const set = useCallback(
    (v: T) => {
      localStorage.setItem(key, JSON.stringify(v));
      setVal(v);
    },
    [key],
  );
  return [val, set];
}

// --- View mode (list vs. image tiles) ------------------------------------

export type ViewMode = "list" | "tiles";

/** View-mode state persisted to localStorage so it survives tab switches.
 *
 * With nothing persisted yet, the default itself is width-aware: List's wide
 * multi-column table forces horizontal scrolling on a phone, so narrow
 * screens start on Tiles (a reflowing grid, no horizontal scroll) instead.
 * This only picks the *default* — once a mode is explicitly chosen it's
 * remembered and used everywhere, same as before. */
export function useViewMode(key: string): [ViewMode, (m: ViewMode) => void] {
  const [mode, setMode] = useState<ViewMode>(() => {
    const saved = localStorage.getItem(key) as ViewMode | null;
    if (saved) return saved;
    return typeof window !== "undefined" && window.innerWidth <= 720 ? "tiles" : "list";
  });
  const set = useCallback(
    (m: ViewMode) => {
      localStorage.setItem(key, m);
      setMode(m);
    },
    [key],
  );
  return [mode, set];
}

/** Segmented control switching between the list and image-tile layouts. */
export function ViewToggle({
  mode,
  onChange,
}: {
  mode: ViewMode;
  onChange: (m: ViewMode) => void;
}) {
  return (
    <span className="view-toggle">
      <button
        className={mode === "list" ? "active" : ""}
        onClick={() => onChange("list")}
        title="List view"
      >
        ☰ List
      </button>
      <button
        className={mode === "tiles" ? "active" : ""}
        onClick={() => onChange("tiles")}
        title="Image tiles"
      >
        ▦ Tiles
      </button>
    </span>
  );
}

/**
 * A single card rendered as a full image tile, with optional corner + footer.
 * Clicking the image opens a larger click-to-preview modal.
 */
export function CardTile({
  card,
  corner,
  cornerLeft,
  cornerBottomLeft,
  footer,
  selected,
  rotated,
}: {
  card: CardRef;
  corner?: ReactNode;
  /** Rendered top-left, e.g. a selection checkbox (see `selected`). */
  cornerLeft?: ReactNode;
  /** Rendered bottom-left, e.g. a secondary per-card action button. */
  cornerBottomLeft?: ReactNode;
  footer?: ReactNode;
  /** Highlights the tile and keeps `cornerLeft` visible without hovering. */
  selected?: boolean;
  /** Caller wants Horizontal view — only actually rotates when `card.horizontal`
   *  is also true, so mixed results (e.g. a set with both Sieges and normal
   *  cards) don't spin the ones that are already right-side up. */
  rotated?: boolean;
}) {
  const { open } = useClickPreview();
  const showRotated = !!rotated && card.horizontal;
  return (
    <div className={`tile ${selected ? "tile-selected" : ""} ${showRotated ? "tile-rotated" : ""}`}>
      <div className={showRotated ? "tile-img-wrap-rotated" : "tile-img-wrap"}>
        {card.image_uri ? (
          showRotated ? (
            <img
              className="tile-img-rotated"
              src={card.image_uri}
              alt={card.name}
              loading="lazy"
              onClick={() => open(card)}
            />
          ) : (
            <img
              className="tile-img"
              src={card.image_uri}
              alt={card.name}
              loading="lazy"
              onClick={() => open(card)}
            />
          )
        ) : (
          <div className="tile-noimg">{card.name}</div>
        )}
        {cornerLeft && <div className="tile-corner-left">{cornerLeft}</div>}
        {corner && <div className="tile-corner">{corner}</div>}
        {cornerBottomLeft && <div className="tile-corner-bottom-left">{cornerBottomLeft}</div>}
        {card.price_usd > 0 && (
          <div className="tile-corner-bottom-right">
            <span className="tile-badge">${card.price_usd.toFixed(2)}</span>
          </div>
        )}
      </div>
      {footer && <div className="tile-footer">{footer}</div>}
    </div>
  );
}

/** Clickable WUBRG toggles that edit a bitmask value. */
export function ColorToggles({
  value,
  onChange,
  colorless,
  onColorlessChange,
  colorlessTitle,
}: {
  value: number;
  onChange: (mask: number) => void;
  /** Renders a "C" pip alongside the colours when provided.
   *
   *  Colourlessness can't live in the bitmask: 0 there already means "don't
   *  filter by colour", so there'd be no way to say "no colours at all" — which
   *  is exactly what you need to find a colourless commander's card pool. */
  colorless?: boolean;
  onColorlessChange?: (v: boolean) => void;
  colorlessTitle?: string;
}) {
  return (
    <span className="color-toggles">
      {COLORS.map((c) => (
        <span
          key={c.code}
          title={c.label}
          className={`pip ${c.code} ${value & c.bit ? "on" : ""}`}
          onClick={() => onChange(value ^ c.bit)}
        >
          {c.code}
        </span>
      ))}
      {onColorlessChange && (
        <span
          title={colorlessTitle ?? "Colorless"}
          className={`pip C ${colorless ? "on" : ""}`}
          onClick={() => onColorlessChange(!colorless)}
        >
          C
        </span>
      )}
    </span>
  );
}

// --- Shared card criteria -------------------------------------------------

/** Ringed planet — a card from another world/property (Universes Beyond). */
const ICON_CROSSOVER = icon(
  <>
    <circle cx="12" cy="11" r="6" />
    <ellipse cx="12" cy="11" rx="11" ry="4" transform="rotate(-20 12 11)" />
  </>,
);
/** Monitor — exists only on Arena/MTGO. */
const ICON_SCREEN = icon(
  <>
    <rect x="3" y="4" width="18" height="12" rx="2" />
    <path d="M9 20h6" />
    <path d="M12 16v4" />
  </>,
);
/** Smiley — the joke sets. */
const ICON_SMILEY = icon(
  <>
    <circle cx="12" cy="12" r="9" />
    <path d="M8.5 14.5a4.5 4.5 0 0 0 7 0" />
    <line x1="9" y1="9.5" x2="9.01" y2="9.5" />
    <line x1="15" y1="9.5" x2="15.01" y2="9.5" />
  </>,
);
/** Crown — can head a Commander deck. */
const ICON_CROWN = icon(
  <>
    <path d="M3 8l3.5 3L12 5l5.5 6L21 8l-1.5 10h-15z" />
    <line x1="5" y1="21" x2="19" y2="21" />
  </>,
);
/** An empty rules box — a vanilla creature, all body and no text. */
const ICON_BLANK_BOX = icon(
  <>
    <rect x="3" y="4" width="18" height="16" rx="2" />
    <line x1="3" y1="9" x2="21" y2="9" />
  </>,
);
/** An open package — cards you don't have a copy of yet. */
const ICON_PACKAGE = icon(
  <>
    <path d="M21 8l-9-5-9 5 9 5 9-5z" />
    <path d="M3 8v8l9 5 9-5V8" />
    <path d="M12 13v8" />
  </>,
);

/**
 * Card-origin and numeric criteria shared by the Library and Card Search
 * filter panels. Kept here rather than duplicated in both views, since they
 * must stay in step: a filter that behaves differently between browsing what
 * you own and searching everything would be a bug, not a feature.
 *
 * Numeric fields are strings so the inputs can be empty (meaning "no bound")
 * rather than coercing a blank to 0.
 */
export type CardCriteria = {
  excludeUb: boolean;
  excludeDigital: boolean;
  excludeFunny: boolean;
  priceMin: string;
  priceMax: string;
  legalIn: string;
  canBeCommander: boolean;
  vanillaOnly: boolean;
  notOwned: boolean;
  powerMin: string;
  powerMax: string;
  toughMin: string;
  toughMax: string;
};

export const EMPTY_CRITERIA: CardCriteria = {
  excludeUb: false,
  excludeDigital: false,
  excludeFunny: false,
  priceMin: "",
  priceMax: "",
  legalIn: "",
  canBeCommander: false,
  vanillaOnly: false,
  notOwned: false,
  powerMin: "",
  powerMax: "",
  toughMin: "",
  toughMax: "",
};

export function useCardCriteria(key: string): [CardCriteria, (patch: Partial<CardCriteria>) => void] {
  const [value, setValue] = usePersistedState<CardCriteria>(key, EMPTY_CRITERIA);
  // Merged over the defaults so a stored object written before a field existed
  // doesn't leave it undefined.
  const merged = { ...EMPTY_CRITERIA, ...value };
  const patch = useCallback(
    (p: Partial<CardCriteria>) => setValue({ ...EMPTY_CRITERIA, ...value, ...p }),
    [setValue, value],
  );
  return [merged, patch];
}

const num = (s: string): number | null => (s.trim() === "" ? null : Number(s));

/** Fold criteria into the filter sent to the backend. */
export function applyCardCriteria(c: CardCriteria): Partial<LibraryFilter> {
  return {
    exclude_universes_beyond: c.excludeUb,
    exclude_digital_only: c.excludeDigital,
    exclude_funny: c.excludeFunny,
    price_min: num(c.priceMin),
    price_max: num(c.priceMax),
    legal_in: c.legalIn || null,
    can_be_commander: c.canBeCommander,
    vanilla_only: c.vanillaOnly,
    not_owned: c.notOwned,
    power_min: num(c.powerMin),
    power_max: num(c.powerMax),
    toughness_min: num(c.toughMin),
    toughness_max: num(c.toughMax),
  };
}

/**
 * Whether these criteria amount to a search in their own right.
 *
 * The three "exclude" toggles deliberately don't count: they refine a result
 * set rather than select one, so ticking "hide Un-sets" on its own shouldn't
 * make Card Search pull every card in the database. Choosing a format, a
 * power range, or "not owned" is a real query, and does.
 */
export function criteriaActive(c: CardCriteria): boolean {
  return (
    c.canBeCommander ||
    c.vanillaOnly ||
    c.notOwned ||
    c.legalIn !== "" ||
    [c.priceMin, c.priceMax, c.powerMin, c.powerMax, c.toughMin, c.toughMax].some(
      (v) => v.trim() !== "",
    )
  );
}

function RangePair({
  label,
  min,
  max,
  onMin,
  onMax,
  step,
  prefix,
}: {
  label: string;
  min: string;
  max: string;
  onMin: (v: string) => void;
  onMax: (v: string) => void;
  step?: string;
  prefix?: string;
}) {
  return (
    <div className="field">
      <label>{label}</label>
      <div className="row">
        {prefix && <span className="muted">{prefix}</span>}
        <input
          type="number"
          step={step}
          style={{ width: 70 }}
          placeholder="min"
          value={min}
          onChange={(e) => onMin(e.target.value)}
        />
        <span className="muted">–</span>
        {prefix && <span className="muted">{prefix}</span>}
        <input
          type="number"
          step={step}
          style={{ width: 70 }}
          placeholder="max"
          value={max}
          onChange={(e) => onMax(e.target.value)}
        />
      </div>
    </div>
  );
}

export function CardCriteriaFields({
  value: c,
  onChange,
  hideNotOwned,
}: {
  value: CardCriteria;
  onChange: (patch: Partial<CardCriteria>) => void;
  /** Omit the "Not owned" toggle — for the Library tab, which already shows
   *  nothing but owned cards, so the filter would just be a no-op there. */
  hideNotOwned?: boolean;
}) {
  return (
    <>
      <div className="field">
        <label>Legal in</label>
        <select value={c.legalIn} onChange={(e) => onChange({ legalIn: e.target.value })}>
          <option value="">Any format</option>
          {LEGALITY_FORMATS.map((f) => (
            <option key={f.key} value={f.key}>
              {f.label}
            </option>
          ))}
        </select>
      </div>

      <RangePair
        label="Price (USD)"
        prefix="$"
        step="0.01"
        min={c.priceMin}
        max={c.priceMax}
        onMin={(v) => onChange({ priceMin: v })}
        onMax={(v) => onChange({ priceMax: v })}
      />
      <RangePair
        label="Power"
        min={c.powerMin}
        max={c.powerMax}
        onMin={(v) => onChange({ powerMin: v })}
        onMax={(v) => onChange({ powerMax: v })}
      />
      <RangePair
        label="Toughness"
        min={c.toughMin}
        max={c.toughMax}
        onMin={(v) => onChange({ toughMin: v })}
        onMax={(v) => onChange({ toughMax: v })}
      />

      <div className="field">
        <label>Quick filters</label>
        <div className="icon-toggles">
          {/* Exclusions read as "no X" — tinted with the danger colour when
              active, so removing things looks different from selecting them. */}
          <IconToggle
            icon={ICON_CROSSOVER}
            label="Hide Universes Beyond"
            hint="Cards that only exist as another property — Lord of the Rings, Warhammer 40,000, Marvel. Normal cards reprinted in those sets stay."
            exclude
            on={c.excludeUb}
            onToggle={() => onChange({ excludeUb: !c.excludeUb })}
          />
          <IconToggle
            icon={ICON_SCREEN}
            label="Hide digital-only"
            hint="Arena and MTGO cards such as Alchemy rebalances, which don't exist on paper."
            exclude
            on={c.excludeDigital}
            onToggle={() => onChange({ excludeDigital: !c.excludeDigital })}
          />
          <IconToggle
            icon={ICON_SMILEY}
            label="Hide Un-set cards"
            hint="Unglued, Unhinged, Unstable and Unfinity joke cards."
            exclude
            on={c.excludeFunny}
            onToggle={() => onChange({ excludeFunny: !c.excludeFunny })}
          />
          <span className="icon-toggles-sep" />
          <IconToggle
            icon={ICON_CROWN}
            label="Only cards that can be a commander"
            hint="Legendary creatures, plus cards whose rules text says they can be your commander."
            on={c.canBeCommander}
            onToggle={() => onChange({ canBeCommander: !c.canBeCommander })}
          />
          <IconToggle
            icon={ICON_BLANK_BOX}
            label="Only vanilla creatures"
            hint="Creatures with an empty rules box. Includes Adventure and Prepared cards whose creature half has no abilities."
            on={c.vanillaOnly}
            onToggle={() => onChange({ vanillaOnly: !c.vanillaOnly })}
          />
          {!hideNotOwned && (
            <IconToggle
              icon={ICON_PACKAGE}
              label="Not owned"
              hint="Only cards you don't have a single copy of yet."
              on={c.notOwned}
              onToggle={() => onChange({ notOwned: !c.notOwned })}
            />
          )}
        </div>
      </div>
    </>
  );
}

/**
 * A single icon filter toggle, styled like [`ColorToggles`]' pips: dim when
 * off, lit with a ring when on. `exclude` marks a filter that *removes* cards
 * rather than selecting them, which is worth distinguishing visually since
 * both live in the same row.
 */
function IconToggle({
  icon,
  label,
  hint,
  on,
  exclude,
  onToggle,
}: {
  icon: ReactNode;
  label: string;
  hint: string;
  on: boolean;
  exclude?: boolean;
  onToggle: () => void;
}) {
  return (
    <button
      type="button"
      className={`icon-toggle ${exclude ? "exclude" : ""} ${on ? "on" : ""}`}
      // Title carries the full explanation the old inline hint text did — the
      // whole point of this row is to stop that prose eating the panel.
      title={`${label}\n\n${hint}`}
      aria-label={label}
      aria-pressed={on}
      onClick={onToggle}
    >
      {icon}
      {/* A slash over the glyph when an exclusion is active, so "hidden" is
          legible without reading the tooltip. */}
      {exclude && on && <span className="icon-toggle-slash" />}
    </button>
  );
}

/** Compact relative time, e.g. "2h ago" — for "updated"/"synced" stamps. */
export function formatRelativeTime(epochSeconds: number): string {
  const diffSec = Math.round((Date.now() - epochSeconds * 1000) / 1000);
  if (diffSec < 30) return "just now";
  const mins = Math.round(diffSec / 60);
  if (mins < 60) return `${mins}m ago`;
  const hours = Math.round(mins / 60);
  if (hours < 24) return `${hours}h ago`;
  const days = Math.round(hours / 24);
  if (days < 30) return `${days}d ago`;
  const months = Math.round(days / 30);
  if (months < 12) return `${months}mo ago`;
  return `${Math.round(months / 12)}y ago`;
}