/** Owns the browse state, mounts the keyboard handler, and switches between views.
 *
 * The split that matters: everything about *what is playing* comes from the backend
 * over the websocket, and everything about *what you are looking at* lives here. The
 * mockup kept both in one object; a real player has other front-ends - the buttons on
 * the mouse, a figure on the reader, Home Assistant - and this UI has to follow them.
 */

import { useCallback, useEffect, useMemo, useRef, useState } from "react";

import { api } from "./api/client";
import type { Album, HaConfig } from "./api/types";
import { AlbumModal } from "./components/AlbumModal";
import { AppHeader } from "./components/AppHeader";
import { BrowseView } from "./components/BrowseView";
import { Bubbles } from "./components/Bubbles";
import { HelpOverlay } from "./components/HelpOverlay";
import { ParentPanel } from "./components/ParentPanel";
import { PlayerBar } from "./components/PlayerBar";
import { PlayView } from "./components/PlayView";
import { RoomView } from "./components/RoomView";
import { useGridColumns } from "./hooks/useGridColumns";
import { useLibrary } from "./hooks/useLibrary";
import { usePlayerState } from "./hooks/usePlayerState";
import type { Action, UiState } from "./lib/keyboard";
import { handleKey, initialUiState } from "./lib/keyboard";
import { playPop } from "./lib/pop";
import type { Group, Results, SongHit } from "./lib/search";
import { groupOf, results as computeResults } from "./lib/search";

/** Volume when un-muting, matching the mockup. */
const UNMUTE_PERCENT = 60;

/** A podcast episode has no next/previous track to skip to - Next/Previous nudge the
 * position instead, the way scrubbing past an ad break usually works. */
const PODCAST_SKIP_SECONDS = 30;

export function App() {
  const [ui, setUi] = useState<UiState>(initialUiState);
  const library = useLibrary();
  const connection = usePlayerState(library.reload);
  const [gridRef, columns] = useGridColumns();
  const [parentMode, setParentMode] = useState(
    () => new URLSearchParams(location.search).get("parentMode") === "1",
  );
  // undefined: not yet resolved (hide the nav pill to avoid a flash). null: confirmed
  // absent - the room page is a separate opt-in feature, off by default.
  const [haConfig, setHaConfig] = useState<HaConfig | null | undefined>(undefined);

  useEffect(() => {
    void api.haConfig().then(setHaConfig);
  }, []);

  const state = connection.state;

  useEffect(() => {
    setUi((previous) => (previous.cols === columns ? previous : { ...previous, cols: columns }));
  }, [columns]);

  const results: Results = useMemo(
    () =>
      computeResults({
        albums: library.albums,
        search: ui.search,
        mode: ui.mode,
        group: ui.group,
        category: ui.category,
      }),
    [library.albums, ui.search, ui.mode, ui.group, ui.category],
  );

  const byId = useMemo(
    () => new Map(library.albums.map((album) => [album.id, album])),
    [library.albums],
  );
  const currentAlbum: Album | null = state?.album_id ? (byId.get(state.album_id) ?? null) : null;
  const openAlbum: Album | null = ui.openAlbumId ? (byId.get(ui.openAlbumId) ?? null) : null;

  const play = useCallback((albumId: string, trackIndex: number) => {
    playPop(300);
    setUi((previous) => ({ ...previous, view: "play", openAlbumId: null }));
    void api.play(albumId, trackIndex);
  }, []);

  const setVolume = useCallback(
    (percent: number) => {
      const clamped = Math.max(0, Math.min(100, percent));
      // Optimistic, so the bars move on the keypress rather than a frame later.
      connection.optimistic({ volume: clamped });
      void api.setVolume(clamped);
    },
    [connection],
  );

  const toggle = useCallback(() => {
    if (!state) return;
    if (state.album_id === null) {
      // Nothing loaded yet: space starts whatever is on screen, as in the mockup.
      const first = results.albums[0] ?? library.albums[0];
      if (first) play(first.id, 0);
      return;
    }
    connection.optimistic({ playing: !state.playing });
    void (state.playing ? api.pause() : api.resume());
  }, [connection, library.albums, play, results.albums, state]);

  /** The one place a keyboard action, a click or a tap all end up. */
  const run = useCallback(
    (actions: Action[]) => {
      for (const action of actions) {
        switch (action.type) {
          case "ui":
            setUi((previous) => ({ ...previous, ...action.patch }));
            break;
          case "play":
            play(action.albumId, action.trackIndex);
            break;
          case "toggle":
            toggle();
            break;
          case "next":
            playPop(260);
            if (currentAlbum && groupOf(currentAlbum) === "podcasts") {
              const target = Math.min(
                state?.duration ?? 0,
                (state?.position ?? 0) + PODCAST_SKIP_SECONDS,
              );
              connection.optimistic({ position: target });
              void api.seek(target);
            } else {
              connection.optimistic({ position: 0 });
              void api.next();
            }
            break;
          case "previous":
            playPop(260);
            if (currentAlbum && groupOf(currentAlbum) === "podcasts") {
              const target = Math.max(0, (state?.position ?? 0) - PODCAST_SKIP_SECONDS);
              connection.optimistic({ position: target });
              void api.seek(target);
            } else {
              connection.optimistic({ position: 0 });
              void api.previous();
            }
            break;
          case "volume":
            setVolume((state?.volume ?? 0) + action.delta);
            break;
          case "seek": {
            if (state?.duration) {
              const target = Math.max(
                0,
                Math.min(state.duration, (state?.position ?? 0) + action.delta),
              );
              connection.optimistic({ position: target });
              void api.seek(target);
            }
            break;
          }
          case "pop":
            playPop(action.freq);
            break;
        }
      }
    },
    [connection, currentAlbum, play, setVolume, state, toggle],
  );

  // Held in a ref so the listener is installed once rather than on every state change.
  const latest = useRef({ ui, results, run });
  latest.current = { ui, results, run };

  useEffect(() => {
    const onKeyDown = (event: KeyboardEvent) => {
      const target = event.target as HTMLElement | null;
      // Parent mode has real text fields; typing a title into one must not start a song.
      if (target && /^(INPUT|TEXTAREA|SELECT)$/.test(target.tagName)) return;

      const current = latest.current;
      const actions = handleKey(event, current.ui, current.results);
      if (!actions.length) return;
      event.preventDefault();
      current.run(actions);
    };
    window.addEventListener("keydown", onKeyDown);
    return () => window.removeEventListener("keydown", onKeyDown);
  }, []);

  const onEnterGroup = (group: Group, category: string | null) => {
    playPop(category ? 440 : 380);
    setUi((previous) => ({ ...previous, group, category, search: "", selIndex: 0 }));
  };

  const onBackToRoot = () => {
    playPop(380);
    setUi((previous) => ({ ...previous, group: null, category: null, selIndex: 0 }));
  };

  const onCategory = (key: string | null) => {
    if (key) playPop(440);
    setUi((previous) => ({ ...previous, category: key, selIndex: 0 }));
  };

  const onOpenAlbum = (album: Album, navIndex: number) => {
    // A podcast episode is a single track behaving like an audiobook of one chapter -
    // there's nothing a metadata popup would add, so it just starts playing.
    if (groupOf(album) === "podcasts") {
      setUi((previous) => ({ ...previous, selIndex: navIndex }));
      play(album.id, 0);
      return;
    }
    playPop(420);
    setUi((previous) => ({ ...previous, openAlbumId: album.id, selIndex: navIndex }));
  };

  const onOpenCurrentAlbum = () => {
    if (!currentAlbum) return;
    playPop(420);
    setUi((previous) => ({ ...previous, openAlbumId: currentAlbum.id }));
  };

  const onPlaySong = (hit: SongHit) => play(hit.album.id, hit.index);
  const onSeek = (target: number) => {
    connection.optimistic({ position: target });
    void api.seek(target);
  };
  const onMute = () => setVolume(state && state.volume > 0 ? 0 : UNMUTE_PERCENT);

  return (
    <div className="stage">
      <Bubbles />

      {ui.view === "browse" && state && (
        <div
          style={{
            position: "relative",
            zIndex: 1,
            height: "100%",
            display: "flex",
            flexDirection: "column",
          }}
        >
          <AppHeader
            status={<ConnectionDot online={connection.online} state={state} />}
            link={
              haConfig
                ? {
                    label: "💡 Mein Zimmer",
                    onClick: () => setUi((previous) => ({ ...previous, view: "room" })),
                  }
                : undefined
            }
          />
          <BrowseView
            results={results}
            group={ui.group}
            albums={library.albums}
            mode={ui.mode}
            search={ui.search}
            category={ui.category}
            selIndex={ui.selIndex}
            currentAlbumId={state.album_id}
            gridRef={gridRef}
            onEnterGroup={onEnterGroup}
            onBackToRoot={onBackToRoot}
            onCategory={onCategory}
            onOpenAlbum={onOpenAlbum}
            onPlaySong={onPlaySong}
          />
        </div>
      )}

      {ui.view === "play" && state && (
        <PlayView
          state={state}
          album={currentAlbum}
          onToggle={toggle}
          onNext={() => run([{ type: "next" }])}
          onPrevious={() => run([{ type: "previous" }])}
          onSeek={onSeek}
          onVolume={setVolume}
          onMute={onMute}
          onBrowse={() => setUi((previous) => ({ ...previous, view: "browse" }))}
          onOpenAlbum={onOpenCurrentAlbum}
        />
      )}

      {ui.view === "room" && haConfig && (
        <RoomView
          config={haConfig}
          onBrowse={() => setUi((previous) => ({ ...previous, view: "browse" }))}
        />
      )}

      {openAlbum && state && (
        <AlbumModal
          album={openAlbum}
          currentAlbumId={state.album_id}
          currentTrackIndex={state.track_index}
          onClose={() => setUi((previous) => ({ ...previous, openAlbumId: null }))}
          onPlay={(trackIndex) => play(openAlbum.id, trackIndex)}
        />
      )}

      <button
        onClick={() => setUi((previous) => ({ ...previous, showHelp: !previous.showHelp }))}
        title="Zaubertasten (F1)"
        style={{
          position: "absolute",
          top: 18,
          right: 24,
          zIndex: 3,
          width: 44,
          height: 44,
          background: "oklch(97% 0.01 210 / .95)",
          border: "none",
          borderRadius: 999,
          boxShadow: "0 6px 18px oklch(15% 0.05 210 / .4)",
          fontSize: 20,
          fontWeight: 900,
          color: "var(--ink)",
          cursor: "pointer",
        }}
      >
        ?
      </button>

      {ui.showHelp && (
        <HelpOverlay onClose={() => setUi((previous) => ({ ...previous, showHelp: false }))} />
      )}

      {ui.view === "browse" && state && (
        <PlayerBar
          state={state}
          album={currentAlbum}
          onToggle={toggle}
          onNext={() => run([{ type: "next" }])}
          onPrevious={() => run([{ type: "previous" }])}
          onSeek={onSeek}
          onVolume={setVolume}
          onMute={onMute}
          onOpenPlayView={() => setUi((previous) => ({ ...previous, view: "play" }))}
        />
      )}

      {parentMode && <ParentPanel onClose={() => setParentMode(false)} />}

      {(!state || library.loading) && <Splash error={library.error} />}
    </div>
  );
}

function ConnectionDot({ online, state }: { online: boolean; state: { active_figure: string | null } }) {
  const label = !online ? "Keine Verbindung" : state.active_figure ? `🧸 ${state.active_figure}` : null;
  if (!label) return null;
  return (
    <div
      style={{
        fontSize: 14,
        fontWeight: 800,
        color: online ? "var(--paper)" : "oklch(75% 0.16 30)",
        background: "oklch(97% 0.01 210 / .16)",
        padding: "6px 14px",
        borderRadius: 999,
      }}
    >
      {label}
    </div>
  );
}

function Splash({ error }: { error: string | null }) {
  return (
    <div
      className="overlay"
      style={{ zIndex: 10, background: "oklch(20% 0.045 210 / .92)", flexDirection: "column", gap: 18 }}
    >
      <img
        src="/dolphin-mascot.png"
        alt=""
        style={{ width: 140, height: 140, objectFit: "contain", animation: "dolphinBob 1.6s ease-in-out infinite" }}
      />
      <div style={{ fontSize: 22, fontWeight: 800, color: "var(--paper)" }}>
        {error ? "Der Delphin ist nicht erreichbar …" : "Einen Moment …"}
      </div>
    </div>
  );
}