import {
  createContext,
  ReactNode,
  useCallback,
  useContext,
  useEffect,
  useRef,
  useState,
} from "react";
import { api, CardRef, COLORS, maskToLetters } from "./api";

/**
 * 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).
 */
export function CardSearchBox({
  placeholder,
  value,
  onChange,
  results,
  onPick,
  autoFocus,
  big,
}: {
  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;
}) {
  const [sel, setSel] = useState(0);
  const inputRef = useRef<HTMLInputElement>(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={inputRef}
        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>
      )}
    </>
  );
}

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

interface HoverApi {
  enter: (card: CardRef, e: React.MouseEvent) => void;
  move: (e: React.MouseEvent) => void;
  leave: () => void;
}
interface ClickApi {
  open: (card: CardRef) => 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: CardRef; 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: CardRef) => {
    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]);

  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: CardRef) => 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 }) {
  // Prefer the right of the cursor; flip left if it would overflow.
  let left = x + GAP;
  if (left + PREVIEW_W + PAD > window.innerWidth) left = x - PREVIEW_W - GAP;
  const top = Math.max(PAD, Math.min(y - PREVIEW_H / 2, window.innerHeight - PREVIEW_H - PAD));
  return (
    <img
      className="hover-card"
      src={card.image_uri}
      alt={card.name}
      style={{ left, top, width: PREVIEW_W }}
    />
  );
}

function ClickPreviewModal({
  state,
  onClose,
  onFlip,
}: {
  state: { card: CardRef; showBack: boolean };
  onClose: () => void;
  onFlip: () => void;
}) {
  const { card, showBack } = state;
  const src = showBack && card.back_image_uri ? card.back_image_uri : card.image_uri;
  return (
    <div className="preview-modal-backdrop" onClick={onClose}>
      <div className="preview-modal" onClick={(e) => e.stopPropagation()}>
        <img className="preview-modal-img" src={src} alt={card.name} />
        <button className="preview-modal-close" onClick={onClose} title="Close (Esc)">
          ✕
        </button>
        {card.back_image_uri && (
          <button className="preview-modal-flip" onClick={onFlip} title="Show the other side">
            ⟲ Flip
          </button>
        )}
      </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";
}

function firstSubtype(typeLine: string): string {
  const parts = typeLine.split("—");
  if (parts.length < 2) return "No subtype";
  return parts[1].trim().split(/\s+/)[0] || "No 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"
        ? firstSubtype(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") {
    const rank = (l: string) => {
      const i = TYPE_PRIORITY.indexOf(l);
      return i === -1 ? TYPE_PRIORITY.length : i;
    };
    groups.sort((a, b) => rank(a.label) - rank(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>
  );
}

// --- 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. */
export function useViewMode(key: string): [ViewMode, (m: ViewMode) => void] {
  const [mode, setMode] = useState<ViewMode>(
    () => (localStorage.getItem(key) as ViewMode) || "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,
  footer,
}: {
  card: CardRef;
  corner?: ReactNode;
  footer?: ReactNode;
}) {
  const { open } = useClickPreview();
  return (
    <div className="tile">
      <div className="tile-img-wrap">
        {card.image_uri ? (
          <img
            className="tile-img"
            src={card.image_uri}
            alt={card.name}
            loading="lazy"
            onClick={() => open(card)}
          />
        ) : (
          <div className="tile-noimg">{card.name}</div>
        )}
        {corner && <div className="tile-corner">{corner}</div>}
      </div>
      {footer && <div className="tile-footer">{footer}</div>}
    </div>
  );
}

/** Clickable WUBRG toggles that edit a bitmask value. */
export function ColorToggles({
  value,
  onChange,
}: {
  value: number;
  onChange: (mask: number) => void;
}) {
  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>
      ))}
    </span>
  );
}