freezmo/components/UploadScreen.tsx

"use client";

import { motion } from "framer-motion";
import { useAppReducedMotion as useReducedMotion } from "@/lib/motion-pref";
import { useRouter } from "next/navigation";
import { useCallback, useEffect, useMemo, useRef, useState, useSyncExternalStore } from "react";

import { AiDisclaimer } from "@/components/AiDisclaimer";
import { ApiError, generateDeck, type GenerateProgress } from "@/lib/client-api";
import {
  DOCUMENT_ACCEPT_ATTR,
  KIND_LABELS,
  describeDocumentError,
  documentKindOf,
  documentsToText,
  extractDocument,
  isDocumentFile,
  type DocumentKind,
  type ExtractedDocument,
} from "@/lib/documents";
import {
  ACCEPTED_TYPES,
  MAX_IMAGES,
  describeFileError,
  formatBytes,
  imageFilesFromDataTransfer,
  isImageFile,
  prepareImage,
  type PreparedImage,
} from "@/lib/image";
import { createFolder, folderStore } from "@/lib/folders";
import { haptic } from "@/lib/haptics";
import { useI18n } from "@/lib/i18n";
import { stepVariants } from "@/lib/motion";
import { UNORGANIZED_ID, type Difficulty } from "@/lib/schemas";
import { takePendingShare } from "@/lib/share-pending";
import { takeDeckSeed } from "@/lib/deck-seed";
import { upsertDeck } from "@/lib/storage";
import { showToast } from "@/lib/toast";
import { openSettings } from "@/lib/ui-events";
import { modelErrorCopy } from "@/lib/model-errors";
import { ModelErrorActions } from "@/components/ModelErrorActions";
import { useBackClose } from "@/lib/use-back-close";
import { useIsPhone } from "@/lib/use-phone";
import { useOnline } from "@/lib/use-online";
import { clearWizardDraft, loadWizardDraft, saveWizardDraft } from "@/lib/wizard-draft";
import { wizardBusy } from "@/lib/wizard-busy";
import { cn, uid } from "@/lib/utils";
import { CameraIcon, ChevronDownIcon, FolderIcon, IceCubeIcon, PlusIcon, SnowflakeIcon, SparklesIcon, SunIcon } from "@/components/icons";
import { SegmentedPill } from "@/components/SegmentedPill";
import { Button } from "@/components/ui";
import { LoadingState, type LoadingStage } from "@/components/LoadingState";
import { WizardActionBar } from "@/components/WizardActionBar";

type Phase = "idle" | "preparing" | "loading" | "error";

/** A document the user added, with its client-side extraction state. */
type DocItem = {
  id: string;
  name: string;
  kind: DocumentKind;
  status: "extracting" | "ready" | "error";
  progress?: string;
  extracted?: ExtractedDocument;
  error?: string;
};

const MAX_DOCUMENTS = 6;
/** Photos + rendered PDF pages + images embedded in documents. */
const MAX_IMAGES_TO_SEND = 12;
/** Cap for the merged text sent to the API. */
const MAX_TEXT_TO_SEND = 100_000;

function describeExtraction(
  document: ExtractedDocument,
  tr: (key: string, vars?: Record<string, string | number>) => string,
  pl: (n: number, base: string, vars?: Record<string, string | number>) => string,
): string {
  const parts = [
    pl(document.words, "upload.words", { n: document.words.toLocaleString() }),
    document.pages ? pl(document.pages, "upload.pages") : "",
    document.images.length ? pl(document.images.length, "upload.pageImages") : "",
    document.truncated ? tr("upload.truncated") : "",
  ];
  return parts.filter(Boolean).join(" · ");
}

const DIFFICULTIES: Array<{ value: Difficulty; labelKey: string; icon: React.ReactNode; blurbKey: string }> = [
  { value: "easy", labelKey: "upload.easy", icon: <SunIcon className="size-5" />, blurbKey: "upload.easyBlurb" },
  {
    value: "medium",
    labelKey: "upload.medium",
    icon: <SnowflakeIcon className="size-5" />,
    blurbKey: "upload.mediumBlurb",
  },
  { value: "hard", labelKey: "upload.hard", icon: <IceCubeIcon className="size-5" />, blurbKey: "upload.hardBlurb" },
];

const COUNT_OPTIONS = [8, 10, 12, 15];

const GENERATION_TIPS = ["upload.tip1", "upload.tip2", "upload.tip3", "upload.tip4"];

/** Same loading screen as the rest of the app (components/LoadingState). */
const UPLOAD_STAGES: LoadingStage[] = [
  { id: "vision", labelKey: "upload.vision1", messageKeys: ["upload.vision1", "upload.vision2", "upload.vision3"] },
  { id: "generation", labelKey: "upload.gen1", messageKeys: ["upload.gen1", "upload.gen2", "upload.gen3"] },
];

export function UploadScreen() {
  const router = useRouter();
  const { t, plural } = useI18n();
  const [images, setImages] = useState<PreparedImage[]>([]);
  const [documents, setDocuments] = useState<DocItem[]>([]);
  const [text, setText] = useState("");
  const [focus, setFocus] = useState("");
  const [difficulty, setDifficulty] = useState<Difficulty>("medium");
  const [folderId, setFolderId] = useState<string>(UNORGANIZED_ID);
  const [creatingFolder, setCreatingFolder] = useState(false);
  const [folderDraft, setFolderDraft] = useState("");
  const [count, setCount] = useState(10);
  const [phase, setPhase] = useState<Phase>("idle");
  const [error, setError] = useState<{ message: string; kind?: string } | null>(null);
  const [fileError, setFileError] = useState<string | null>(null);
  const [dragging, setDragging] = useState(false);
  const [progress, setProgress] = useState<GenerateProgress>({ stage: "vision", message: "" });
  /** Phones only: which step of the 3-step flow is showing. */
  const [step, setStep] = useState(1);
  /** 1 = moving forward (slides from the right), -1 = Back (from the left). */
  const [stepDir, setStepDir] = useState<1 | -1>(1);
  /** Phones only: the “paste text instead” field on step 1. */
  const [pasteOpen, setPasteOpen] = useState(false);
  const isPhone = useIsPhone();
  const reduceMotion = useReducedMotion();
  const online = useOnline();
  const [clipboardAvailable, setClipboardAvailable] = useState(false);

  /* System Back goes one wizard step back (phones), then leaves the page. */
  useBackClose(isPhone && step > 1, () => {
    setStepDir(-1);
    setStep((value) => Math.max(1, value - 1));
  });

  useEffect(() => {
    setClipboardAvailable(
      typeof navigator !== "undefined" && typeof navigator.clipboard?.readText === "function",
    );
  }, []);

  const folders = useSyncExternalStore(
    folderStore.subscribe,
    folderStore.getSnapshot,
    folderStore.getServerSnapshot,
  );
  const sortedFolders = useMemo(
    () => [...folders].sort((a, b) => a.name.localeCompare(b.name, undefined, { sensitivity: "base" })),
    [folders],
  );
  const targetFolder = folderId === UNORGANIZED_ID ? undefined : folderId;

  const fileInputRef = useRef<HTMLInputElement>(null);
  const cameraInputRef = useRef<HTMLInputElement>(null);
  const abortRef = useRef<AbortController | null>(null);
  /**
   * Mirrors of the current lists. React defers state updaters, so reading the
   * count from inside `setState` would silently skip work — always read these.
   */
  const imagesRef = useRef<PreparedImage[]>([]);
  const documentsRef = useRef<DocItem[]>([]);

  useEffect(() => {
    imagesRef.current = images;
  }, [images]);
  useEffect(() => {
    documentsRef.current = documents;
  }, [documents]);

  /* A loading run locks the mode switch (see WizardModeSwitch). */
  useEffect(() => {
    wizardBusy.set(phase === "loading");
  }, [phase]);
  useEffect(() => () => wizardBusy.set(false), []);

  /* Leaving the page mid-generation stops the request instead of letting it
     finish invisibly and save a deck the user never sees. The loading
     screen's Cancel button is the in-page way out. */
  useEffect(() => () => abortRef.current?.abort(), []);

  const addFiles = useCallback(async (files: File[]) => {
    if (files.length === 0) return;
    setFileError(null);
    setPhase("preparing");

    const problems: string[] = [];
    const imageFiles: File[] = [];
    const documentFiles: File[] = [];

    for (const file of files) {
      if (isImageFile(file)) {
        const problem = describeFileError(file);
        if (problem) problems.push(problem);
        else imageFiles.push(file);
      } else if (isDocumentFile(file)) {
        const problem = describeDocumentError(file);
        if (problem) problems.push(problem);
        else documentFiles.push(file);
      } else {
        problems.push(t("upload.unsupported", { name: file.name }));
      }
    }

    const documentRoom = Math.max(0, MAX_DOCUMENTS - documentsRef.current.length);
    const acceptedDocuments = documentFiles.slice(0, documentRoom);
    if (documentFiles.length > documentRoom) problems.push(t("upload.tooManyDocs", { n: MAX_DOCUMENTS }));

    // Documents are read asynchronously (pdf.js can take a while for scans).
    if (acceptedDocuments.length > 0) {
      for (const file of acceptedDocuments) {
        const kind = documentKindOf(file);
        if (!kind) continue;
        const item: DocItem = { id: uid("doc"), name: file.name, kind, status: "extracting" };
        documentsRef.current = [...documentsRef.current, item];
        setDocuments((current) => (current.some((entry) => entry.id === item.id) ? current : [...current, item]));

        const update = (patch: Partial<DocItem>) =>
          setDocuments((current) =>
            current.map((entry) => (entry.id === item.id ? { ...entry, ...patch } : entry)),
          );

        try {
          const extracted = await extractDocument(file, (progress) => update({ progress: progress.message }));
          update({ status: "ready", extracted, progress: undefined });
        } catch (error) {
          update({
            status: "error",
            error: error instanceof Error ? error.message : t("upload.couldNotReadDoc"),
          });
        }
      }
    }

    const photoRoom = Math.max(0, MAX_IMAGES - imagesRef.current.length);
    const acceptedImages = imageFiles.slice(0, photoRoom);
    if (imageFiles.length > photoRoom) problems.push(t("upload.tooManyPhotos", { n: MAX_IMAGES }));

    const prepared: PreparedImage[] = [];
    for (const file of acceptedImages) {
      try {
        prepared.push(await prepareImage(file));
      } catch {
        problems.push(t("upload.couldNotReadFile", { name: file.name }));
      }
    }
    if (prepared.length > 0) {
      imagesRef.current = [...imagesRef.current, ...prepared];
      setImages((current) => [...current, ...prepared]);
    }

    if (problems.length) setFileError(problems.slice(0, 3).join(" "));
    setPhase("idle");
  }, [t]);

  // Clipboard paste (Ctrl/⌘ + V) of screenshots or copied photos.
  useEffect(() => {
    const onPaste = (event: ClipboardEvent) => {
      if (phase === "loading") return;
      const target = event.target as HTMLElement | null;
      const isTextField = target && /^(INPUT|TEXTAREA)$/.test(target.tagName);
      const files = imageFilesFromDataTransfer(event.clipboardData);
      if (files.length > 0) {
        event.preventDefault();
        void addFiles(files);
        return;
      }
      if (!isTextField) {
        const pasted = event.clipboardData?.getData("text/plain")?.trim();
        if (pasted && pasted.length > 40) {
          event.preventDefault();
          setText((current) => (current ? `${current}\n${pasted}` : pasted));
        }
      }
    };
    window.addEventListener("paste", onPaste);
    return () => window.removeEventListener("paste", onPaste);
  }, [addFiles, phase]);

  const removeImage = (id: string) => {
    imagesRef.current = imagesRef.current.filter((image) => image.id !== id);
    setImages((current) => current.filter((image) => image.id !== id));
  };
  const removeDocument = (id: string) => {
    documentsRef.current = documentsRef.current.filter((entry) => entry.id !== id);
    setDocuments((current) => current.filter((entry) => entry.id !== id));
  };

  const readyDocuments = documents.filter((entry) => entry.status === "ready" && entry.extracted);
  const documentsBusy = documents.some((entry) => entry.status === "extracting");
  const documentImages = readyDocuments.flatMap((entry) => entry.extracted!.images);
  const documentText = documentsToText(readyDocuments.map((entry) => entry.extracted!));

  const totalBytes = images.reduce((sum, image) => sum + image.bytes, 0);
  const hasContent =
    images.length > 0 || documentImages.length > 0 || text.trim().length > 0 || documentText.trim().length > 0;
  const canGenerate = hasContent && !documentsBusy && phase !== "preparing";
  const imagesToSend = [...images.map((image) => image.dataUrl), ...documentImages.map((image) => image.dataUrl)].slice(
    0,
    MAX_IMAGES_TO_SEND,
  );
  const imagesSkipped =
    images.length + documentImages.length - imagesToSend.length;

  /* Restore a draft after an OS kill / reload; clear it on success. */
  useEffect(() => {
    const draft = loadWizardDraft("deck");
    if (!draft) return;
    if (draft.text) setText(draft.text);
    if (draft.focus) setFocus(draft.focus);
    if (draft.difficulty === "easy" || draft.difficulty === "medium" || draft.difficulty === "hard") {
      setDifficulty(draft.difficulty);
    }
    if (draft.count) setCount(draft.count);
    if (draft.folderId) setFolderId(draft.folderId);
    if (draft.images?.length) setImages(draft.images);
  }, []);

  /* Content shared in from another app (share target) lands here. */
  useEffect(() => {
    const pending = takePendingShare();
    if (!pending) return;
    if (pending.text) setText((current) => (current ? `${current}\n${pending.text}` : pending.text));
    if (pending.files.length > 0) void addFiles(pending.files);
  }, [addFiles]);

  /* Homework → "Turn into a study deck": content + options pre-filled. */
  useEffect(() => {
    const seed = takeDeckSeed();
    if (!seed) return;
    setText(seed.text);
    if (seed.difficulty) setDifficulty(seed.difficulty);
    if (seed.count) setCount(seed.count);
    if (seed.step && seed.step > 1) setStep(seed.step);
  }, []);

  /* Persist the draft while the user works (debounced, best-effort). */
  useEffect(() => {
    if (phase === "loading") return;
    const timer = window.setTimeout(() => {
      saveWizardDraft("deck", { text, focus, difficulty, count, folderId, images });
    }, 400);
    return () => window.clearTimeout(timer);
  }, [text, focus, difficulty, count, folderId, images, phase]);

  const generate = async () => {
    if (!canGenerate) return;
    setError(null);
    setPhase("loading");
    setProgress({
      stage: imagesToSend.length ? "vision" : "generation",
      message: imagesToSend.length ? t("upload.vision1") : t("upload.gen1"),
    });

    const controller = new AbortController();
    abortRef.current = controller;

    const mergedText = [text.trim(), documentText.trim()].filter(Boolean).join("\n\n").slice(0, MAX_TEXT_TO_SEND);

    try {
      const { deck } = await generateDeck(
        {
          images: imagesToSend.length ? imagesToSend : undefined,
          text: mergedText || undefined,
          focus: focus.trim() || undefined,
          difficulty,
          count,
        },
        { onProgress: setProgress, signal: controller.signal },
      );

      const now = Date.now();
      const stored = {
        ...deck,
        id: uid("deck"),
        folderId: targetFolder,
        createdAt: now,
        updatedAt: now,
        attempts: 0,
      };
      upsertDeck(stored);
      clearWizardDraft("deck");
      router.push(`/deck/${stored.id}`);
    } catch (generateError) {
      setError({
        message:
          generateError instanceof ApiError
            ? generateError.message
            : t("upload.genericError"),
        kind: generateError instanceof ApiError ? generateError.kind : undefined,
      });
      setPhase("error");
    } finally {
      abortRef.current = null;
    }
  };

  /* Shared controls: the desktop card and the phone step 2 render the same
     folder / difficulty / count pickers, so their markup lives in one place. */
  const folderPicker = (
    <div className="space-y-2">
      <span className="text-[11px] font-semibold uppercase tracking-wide text-[var(--text-subtle)]">
        {t("upload.freezeInto")}
      </span>
      <div className="flex flex-wrap items-center gap-2">
        {[{ id: UNORGANIZED_ID, name: t("common.unorganized") }, ...sortedFolders].map((folder) => {
          const active = folderId === folder.id;
          return (
            <button
              key={folder.id}
              type="button"
              aria-pressed={active}
              onClick={() => {
                haptic("toggle");
                setFolderId(folder.id);
              }}
              className={cn(
                "inline-flex items-center gap-1.5 rounded-full border px-3.5 py-1.5 text-[13px] font-medium transition",
                active
                  ? "border-accent-500 bg-accent-50 text-accent-800 dark:bg-accent-500/20 dark:text-accent-100"
                  : "border-[var(--hairline)] text-frost-600 hover:text-frost-900 dark:text-frost-300 dark:hover:text-white",
              )}
            >
              <FolderIcon className="size-4" />
              {folder.name}
            </button>
          );
        })}
        {creatingFolder ? (
          <span className="inline-flex items-center gap-1">
            <input
              autoFocus
              value={folderDraft}
              onChange={(event) => setFolderDraft(event.target.value)}
              onKeyDown={(event) => {
                event.stopPropagation();
                if (event.key === "Escape") {
                  setCreatingFolder(false);
                  setFolderDraft("");
                }
                if (event.key === "Enter") {
                  const created = createFolder(folderDraft);
                  if ("folder" in created) {
                    setFolderId(created.folder.id);
                    setFolderDraft("");
                    setCreatingFolder(false);
                  } else {
                    setFileError(created.error);
                  }
                }
              }}
              aria-label={t("common.newFolderName")}
              placeholder={t("upload.folderPlaceholder")}
              maxLength={60}
              enterKeyHint="done"
              autoCapitalize="words"
              autoComplete="off"
              spellCheck={false}
              className="w-32 rounded-xl border border-[var(--hairline)] bg-[var(--surface-strong)] px-3 py-1.5 text-sm outline-none"
            />
            <Button
              size="sm"
              onClick={() => {
                const created = createFolder(folderDraft);
                if ("folder" in created) {
                  setFolderId(created.folder.id);
                  setFolderDraft("");
                  setCreatingFolder(false);
                } else {
                  setFileError(created.error);
                }
              }}
            >
              {t("common.add")}
            </Button>
          </span>
        ) : (
          <button
            type="button"
            onClick={() => setCreatingFolder(true)}
            className="inline-flex items-center gap-1.5 rounded-xl border border-dashed border-[var(--hairline)] px-3 py-1.5 text-sm font-semibold text-frost-600 transition-colors hover:text-accent-700 dark:text-frost-400 dark:hover:text-accent-200"
          >
            <PlusIcon className="size-4" /> {t("common.newFolder")}
          </button>
        )}
      </div>
    </div>
  );

  const difficultyPicker = (
    <div role="radiogroup" aria-label={t("upload.difficultyAria")} className="grid grid-cols-3 gap-2">
      {DIFFICULTIES.map((option) => {
        const selected = difficulty === option.value;
        return (
          <button
            key={option.value}
            type="button"
            role="radio"
            aria-checked={selected}
            onClick={() => {
              haptic("toggle");
              setDifficulty(option.value);
            }}
            className={cn(
              "relative flex flex-col items-center gap-1 overflow-hidden rounded-2xl border px-2 py-3 text-center backdrop-blur-xl transition-colors",
              selected && isPhone
                ? "border-transparent"
                : selected
                  ? "border-accent-400 bg-accent-50/80 shadow-lift dark:bg-accent-500/20"
                  : "border-white/60 bg-white/45 backdrop-blur-xl hover:bg-white/70 dark:border-white/12 dark:bg-white/[0.05]",
            )}
          >
            {selected && isPhone ? (
              <SegmentedPill
                layoutId="difficulty-pill"
                plain
                className="rounded-2xl border border-accent-400 bg-accent-50/80 shadow-lift dark:bg-accent-500/20"
              />
            ) : null}
            <span aria-hidden className="relative z-10 text-frost-600 dark:text-frost-200">
              {option.icon}
            </span>
            <span className="relative z-10 text-sm font-bold text-[var(--text)]">{t(option.labelKey)}</span>
            <span className="relative z-10 hidden text-[11px] text-frost-600 sm:block dark:text-frost-400">{t(option.blurbKey)}</span>
          </button>
        );
      })}
    </div>
  );

  const countPicker = (
    <div className="flex flex-wrap items-center gap-2">
      <span className="text-[11px] font-semibold uppercase tracking-wide text-[var(--text-subtle)]">
        {t("upload.activities")}
      </span>
      {COUNT_OPTIONS.map((option) => (
        <button
          key={option}
          type="button"
          aria-pressed={count === option}
          onClick={() => {
            haptic("toggle");
            setCount(option);
          }}
          className={cn(
            "relative min-w-12 overflow-hidden rounded-xl border-2 px-3 py-1.5 text-sm font-bold transition",
            count === option && isPhone
              ? "border-transparent"
              : count === option
                ? "grad-ice border-transparent text-[#06111f]"
                : "border-[var(--hairline)] text-[var(--text-muted)] hover:bg-[var(--hover)]",
          )}
        >
          {count === option && isPhone ? <SegmentedPill layoutId="count-pill" className="rounded-xl" /> : null}
          <span className={cn("relative z-10", count === option && isPhone && "text-[#06111f]")}>{option}</span>
        </button>
      ))}
    </div>
  );

  const errorCard = error ? (
    <div
      role="alert"
      className="animate-rise rounded-3xl border-2 border-rose-300 bg-rose-50/95 p-4 text-sm text-rose-900 dark:border-rose-400/40 dark:bg-rose-400/10 dark:text-rose-100"
    >
      <p className="font-bold">
        {modelErrorCopy(error.kind)?.title ??
          (error.kind === "needs_key"
            ? t("upload.errNeedsKey")
            : error.kind === "rate_limited"
              ? t("upload.errRate")
              : error.kind === "auth"
                ? t("upload.errAuth")
                : t("upload.errFailed"))}
      </p>
      <p className="mt-1">{modelErrorCopy(error.kind)?.body ?? error.message}</p>
      <div className="mt-3 flex flex-wrap gap-2">
        {error.kind === "needs_key" || error.kind === "auth" ? (
          <Button size="sm" onClick={() => openSettings("key")}>
            {t("upload.openSettings")}
          </Button>
        ) : null}
        <ModelErrorActions kind={error.kind} />
        <Button
          size="sm"
          variant={error.kind === "needs_key" || error.kind === "auth" ? "secondary" : "primary"}
          onClick={() => void generate()}
        >
          {t("common.retry")}
        </Button>
      </div>
    </div>
  ) : null;

  const phoneHelper = !online
    ? t("offline.generate")
    : documentsBusy
      ? t("upload.readingDocs")
      : hasContent
        ? t("upload.ready")
        : t("upload.addToStart");

  if (phase === "loading") {
    return (
      <LoadingState
        stages={UPLOAD_STAGES}
        activeStage={progress.stage}
        message={progress.message}
        tipKeys={GENERATION_TIPS}
        onCancel={() => abortRef.current?.abort()}
      />
    );
  }

  /* Phones: the 3-step flow. Same state as the desktop card, different shape. */
  if (isPhone) {
    const stepLabel =
      step === 1 ? t("upload.phone.notes") : step === 2 ? t("upload.phone.options") : t("upload.phone.summary");
    const stepDesc =
      step === 1
        ? t("upload.phone.notesDesc", { images: MAX_IMAGES, documents: MAX_DOCUMENTS })
        : step === 2
          ? t("upload.phone.optionsDesc")
          : t("upload.phone.summaryDesc");
    const filesSummary =
      images.length > 0 || documents.length > 0
        ? [
            images.length > 0 ? plural(images.length, "upload.photoCount") : "",
            documents.length > 0 ? plural(documents.length, "upload.docSummary") : "",
          ]
            .filter(Boolean)
            .join(" · ")
        : t("upload.summaryText");
    const difficultyLabel =
      difficulty === "easy" ? t("upload.easy") : difficulty === "hard" ? t("upload.hard") : t("upload.medium");
    const folderLabel =
      folderId === UNORGANIZED_ID
        ? t("common.unorganized")
        : (sortedFolders.find((folder) => folder.id === folderId)?.name ?? t("common.unorganized"));
    const editStep = (target: 1 | 2 | 3) => {
      setStepDir(target < step ? -1 : 1);
      setStep(target);
    };
    const fileInput = (
      <input
        ref={fileInputRef}
        type="file"
        aria-hidden="true"
        tabIndex={-1}
        accept={`${ACCEPTED_TYPES.join(",")},${DOCUMENT_ACCEPT_ATTR}`}
        multiple
        className="sr-only"
        onChange={(event) => {
          void addFiles(Array.from(event.target.files ?? []));
          event.target.value = "";
        }}
      />
    );
    const cameraInput = (
      <input
        ref={cameraInputRef}
        type="file"
        aria-hidden="true"
        tabIndex={-1}
        accept="image/*"
        capture="environment"
        className="sr-only"
        onChange={(event) => {
          void addFiles(Array.from(event.target.files ?? []));
          event.target.value = "";
        }}
      />
    );

    return (
      <div className="relative">
        {errorCard}

        {/* progress: thin bar + “1 / 3” */}
        <div className="mt-1 flex items-center gap-3">
          <div
            role="progressbar"
            aria-label={stepLabel}
            aria-valuemin={1}
            aria-valuemax={3}
            aria-valuenow={step}
            className="h-1 flex-1 overflow-hidden rounded-full bg-[var(--track)]"
          >
            <div
              className="grad-ice h-full rounded-full transition-[width] duration-300 motion-reduce:transition-none"
              style={{ width: `${(step / 3) * 100}%` }}
            />
          </div>
          <span className="shrink-0 text-[11px] font-semibold tabular-nums text-[var(--text-subtle)]">
            {t("common.stepOf", { n: step, total: 3 })}
          </span>
        </div>

        {/* the step name is the headline; the page title lives in the chrome */}
        <h1 className="mt-4 text-[26px] font-semibold leading-tight tracking-[-0.02em] text-[var(--text)]">
          {stepLabel}
        </h1>
        <p className="mt-1 text-[14px] text-frost-600 dark:text-frost-300">{stepDesc}</p>

        <motion.div
          key={step}
          initial="initial"
          animate="animate"
          variants={stepVariants(stepDir, !!reduceMotion)}
          className="mt-5"
        >
          {step === 1 ? (
            <div className="space-y-3">
              <button
                type="button"
                onClick={() => fileInputRef.current?.click()}
                className="press flex min-h-32 w-full flex-col items-center justify-center gap-2 rounded-3xl border-2 border-dashed border-[var(--glass-border)] bg-[var(--surface-strong)] px-4 py-6 text-center transition hover:border-accent-400"
              >
                <span
                  aria-hidden
                  className="grid size-12 place-items-center rounded-2xl bg-[var(--surface-sunken)] text-accent-600 dark:text-accent-200"
                >
                  <PlusIcon className="size-6" />
                </span>
                <span className="text-[15px] font-semibold text-[var(--text)]">{t("upload.addPhotosFiles")}</span>
              </button>

              <div className="grid grid-cols-2 gap-2">
                <Button variant="secondary" size="lg" className="touch-target" onClick={() => cameraInputRef.current?.click()}>
                  <CameraIcon className="size-4" /> {t("upload.camera")}
                </Button>
                <Button
                  variant="secondary"
                  size="lg"
                  className="touch-target"
                  aria-expanded={pasteOpen || text.trim().length > 0}
                  onClick={() => setPasteOpen((value) => !value)}
                >
                  {t("upload.pasteInstead")}
                </Button>
              </div>
              {clipboardAvailable ? (
                <Button
                  variant="ghost"
                  size="lg"
                  className="touch-target w-full"
                  onClick={() => {
                    void (async () => {
                      try {
                        const clip = await navigator.clipboard.readText();
                        if (clip) {
                          setText((current) => (current ? `${current}\n${clip}` : clip));
                          setPasteOpen(true);
                        }
                        haptic("tap");
                      } catch {
                        setFileError(t("upload.clipboardDenied"));
                      }
                    })();
                  }}
                >
                  {t("upload.pasteClipboard")}
                </Button>
              ) : null}
              {pasteOpen || text.trim().length > 0 ? (
                <textarea
                  value={text}
                  onChange={(event) => setText(event.target.value)}
                  onKeyDown={(event) => {
                    if (event.key === "Enter" && !event.shiftKey) {
                      event.preventDefault();
                      if (hasContent && !documentsBusy) {
                        setStepDir(1);
                        setStep(2);
                      }
                    }
                  }}
                  rows={5}
                  placeholder={t("upload.pastedPlaceholder")}
                  aria-label={t("upload.pastedNotes")}
                  inputMode="text"
                  enterKeyHint="done"
                  autoComplete="off"
                  autoCapitalize="sentences"
                  spellCheck
                  className="w-full resize-y rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
                />
              ) : null}

              {images.length > 0 || documents.length > 0 ? (
                <ul className="flex flex-wrap items-center gap-2">
                  {images.map((image) => (
                    <li key={image.id} className="relative">
                      {/* eslint-disable-next-line @next/next/no-img-element */}
                      <img
                        src={image.dataUrl}
                        alt=""
                        className="size-14 rounded-xl border border-[var(--hairline)] object-cover"
                      />
                      <button
                        type="button"
                        onClick={() => {
                          const removed = images.find((entry) => entry.id === image.id);
                          removeImage(image.id);
                          if (removed) {
                            showToast({
                              message: t("toast.fileRemoved"),
                              actionLabel: t("toast.undo"),
                              onAction: () =>
                                setImages((current) =>
                                  current.some((entry) => entry.id === removed.id) ? current : [...current, removed],
                                ),
                            });
                          }
                        }}
                        aria-label={t("upload.remove", { name: image.name })}
                        className="absolute -right-1.5 -top-1.5 grid size-6 place-items-center rounded-full bg-frost-950/80 text-[11px] font-bold text-white"
                      >
                        ✕
                      </button>
                    </li>
                  ))}
                  {documents.map((entry) => (
                    <li
                      key={entry.id}
                      className="inline-flex max-w-full items-center gap-1.5 rounded-full border border-[var(--hairline)] bg-[var(--surface-strong)] py-1 pl-2 pr-1"
                    >
                      <span className="rounded-md bg-[var(--surface-sunken)] px-1.5 py-0.5 text-[10px] font-bold uppercase text-[var(--text-muted)]">
                        {KIND_LABELS[entry.kind]}
                      </span>
                      <span className="max-w-32 truncate text-[12.5px] font-medium text-[var(--text)]" title={entry.name}>
                        {entry.name}
                      </span>
                      {entry.status === "extracting" ? (
                        <span className="text-[11px] text-[var(--text-subtle)]" title={entry.progress ?? t("upload.reading")}>
                          …
                        </span>
                      ) : null}
                      {entry.status === "error" ? (
                        <span className="text-[11px] font-bold text-rose-600 dark:text-rose-300" title={entry.error}>
                          !
                        </span>
                      ) : null}
                      <button
                        type="button"
                        onClick={() => {
                          const snapshot = documents.find((doc) => doc.id === entry.id);
                          removeDocument(entry.id);
                          if (snapshot) {
                            showToast({
                              message: t("toast.fileRemoved"),
                              actionLabel: t("toast.undo"),
                              onAction: () =>
                                setDocuments((current) =>
                                  current.some((doc) => doc.id === snapshot.id) ? current : [...current, snapshot],
                                ),
                            });
                          }
                        }}
                        aria-label={t("upload.remove", { name: entry.name })}
                        className="grid size-6 place-items-center rounded-full text-[11px] font-bold text-[var(--text-subtle)] transition hover:bg-[var(--hover)] hover:text-[var(--text)]"
                      >
                        ✕
                      </button>
                    </li>
                  ))}
                </ul>
              ) : (
                <p className="rounded-2xl border border-dashed border-[var(--hairline)] px-4 py-3 text-center text-[12.5px] text-[var(--text-subtle)]">
                  {t("upload.nothingAdded")}
                </p>
              )}

              {documents
                .filter((entry) => entry.status === "error")
                .map((entry) => (
                  <p key={entry.id} className="text-[12px] font-medium text-rose-600 dark:text-rose-300">
                    {entry.name}: {entry.error}
                  </p>
                ))}

              {phase === "preparing" ? (
                <p className="text-[12.5px] font-medium text-[var(--text-muted)]">{t("upload.compressing")}</p>
              ) : null}
              {fileError ? (
                <p role="alert" className="text-xs font-semibold text-rose-600 dark:text-rose-300">
                  {fileError}
                </p>
              ) : null}

              {fileInput}
              {cameraInput}
            </div>
          ) : null}

          {step === 2 ? (
            <div className="space-y-5">
              <div className="space-y-2">
                {folderPicker}
                <p className="text-[12px] text-[var(--text-subtle)]">{t("upload.phone.folderHelp")}</p>
              </div>
              <div className="space-y-2">
                <p className="text-[11px] font-semibold uppercase tracking-wide text-[var(--text-subtle)]">
                  {t("upload.difficultyAria")}
                </p>
                {difficultyPicker}
                <p className="text-[12px] text-[var(--text-subtle)]">{t("upload.phone.difficultyHelp")}</p>
              </div>
              <div className="space-y-2">
                {countPicker}
                <p className="text-[12px] text-[var(--text-subtle)]">{t("upload.phone.activitiesHelp")}</p>
              </div>
              <details className="group rounded-2xl border border-[var(--hairline)] bg-[var(--surface-sunken)] p-3">
                <summary className="flex cursor-pointer list-none items-center gap-2 text-[13px] font-semibold text-[var(--text)] [&::-webkit-details-marker]:hidden">
                  <ChevronDownIcon className="size-4 shrink-0 transition-transform group-open:rotate-180" />
                  {t("upload.focusExtra")}
                </summary>
                <div className="space-y-3 pt-3">
                  <div className="space-y-1.5">
                    <label
                      htmlFor="notes-text-phone"
                      className="text-[11px] font-semibold uppercase tracking-wide text-[var(--text-subtle)]"
                    >
                      {t("upload.pastedNotes")}
                    </label>
                    <textarea
                      id="notes-text-phone"
                      value={text}
                      onChange={(event) => setText(event.target.value)}
                      rows={4}
                      placeholder={t("upload.pastedPlaceholder")}
                      className="w-full resize-y rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
                    />
                  </div>
                  <div className="space-y-1.5">
                    <label
                      htmlFor="focus-phone"
                      className="text-[11px] font-semibold uppercase tracking-wide text-[var(--text-subtle)]"
                    >
                      {t("upload.topicHint")}
                    </label>
                    <input
                      id="focus-phone"
                      value={focus}
                      onChange={(event) => setFocus(event.target.value)}
                      placeholder={t("upload.topicPlaceholder")}
                      inputMode="text"
                      enterKeyHint="done"
                      autoComplete="off"
                      autoCapitalize="sentences"
                      spellCheck={false}
                      className="w-full rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
                    />
                  </div>
                </div>
              </details>
            </div>
          ) : null}

          {step === 3 ? (
            <div className="space-y-4">
              {images.length > 0 || documents.length > 0 ? (
                <ul className="flex flex-wrap items-center gap-2">
                  {images.map((image) => (
                    <li key={image.id}>
                      {/* eslint-disable-next-line @next/next/no-img-element */}
                      <img
                        src={image.dataUrl}
                        alt=""
                        className="size-12 rounded-xl border border-[var(--hairline)] object-cover"
                      />
                    </li>
                  ))}
                  {documents.map((entry) => (
                    <li
                      key={entry.id}
                      className="inline-flex max-w-full items-center gap-1.5 rounded-full border border-[var(--hairline)] bg-[var(--surface-strong)] px-2.5 py-1.5"
                    >
                      <span className="rounded-md bg-[var(--surface-sunken)] px-1.5 py-0.5 text-[10px] font-bold uppercase text-[var(--text-muted)]">
                        {KIND_LABELS[entry.kind]}
                      </span>
                      <span className="max-w-32 truncate text-[12.5px] font-medium text-[var(--text)]" title={entry.name}>
                        {entry.name}
                      </span>
                    </li>
                  ))}
                </ul>
              ) : null}

              <dl className="overflow-hidden rounded-2xl border border-[var(--hairline)] bg-[var(--surface-sunken)] px-3">
                {[
                  { label: t("upload.summary.files"), value: filesSummary, target: 1 as const },
                  { label: t("upload.difficultyAria"), value: difficultyLabel, target: 2 as const },
                  { label: t("upload.activities"), value: plural(count, "deck.activities"), target: 2 as const },
                  { label: t("upload.summary.folder"), value: folderLabel, target: 2 as const },
                ].map((row, index) => (
                  <div
                    key={row.label}
                    className={cn(
                      "flex items-center justify-between gap-3 py-2.5",
                      index > 0 && "border-t border-[var(--hairline-soft)]",
                    )}
                  >
                    <dt className="shrink-0 text-[12px] text-[var(--text-subtle)]">{row.label}</dt>
                    <dd className="flex min-w-0 items-center gap-2">
                      <span className="truncate text-[13px] font-medium text-[var(--text)]">{row.value}</span>
                      <button
                        type="button"
                        onClick={() => editStep(row.target)}
                        className="shrink-0 text-[12px] font-semibold text-accent-700 dark:text-accent-200"
                      >
                        {t("common.edit")}
                      </button>
                    </dd>
                  </div>
                ))}
              </dl>

              <p className="text-[12.5px] text-[var(--text-subtle)]">{phoneHelper}</p>
              <AiDisclaimer />
            </div>
          ) : null}
        </motion.div>

        {/* The action bar is portalled to <body> — never inside the animated
            content wrapper, where a transform would break position: fixed. */}
        <WizardActionBar>
          {step === 1 ? (
            <Button
              variant="secondary"
              size="lg"
              className="touch-target flex-1"
              onClick={() => router.push("/")}
            >
              {t("common.cancel")}
            </Button>
          ) : (
            <Button
              variant="secondary"
              size="lg"
              className="touch-target flex-1"
              onClick={() => {
                setStepDir(-1);
                setStep((value) => Math.max(1, value - 1));
              }}
            >
              {t("common.back")}
            </Button>
          )}
          {step < 3 ? (
            <Button
              size="lg"
              className="touch-target flex-[1.5]"
              onClick={() => {
                setStepDir(1);
                setStep((value) => Math.min(3, value + 1));
              }}
              disabled={!hasContent || documentsBusy}
            >
              {t("common.next")}
            </Button>
          ) : (
            <Button size="lg" className="touch-target flex-[1.5]" onClick={() => void generate()} disabled={!canGenerate || !online}>
              <SparklesIcon className="size-5" /> {t("upload.freezeDeck")}
            </Button>
          )}
        </WizardActionBar>
      </div>
    );
  }

  return (
    <div className="relative">
      <div className="relative space-y-5">
        <section className="space-y-2">
          <h1 className="flex flex-wrap items-center gap-x-3 gap-y-1 text-[28px] font-semibold leading-tight tracking-[-0.02em] text-[var(--text)] text-balance sm:text-[32px]">
            <SnowflakeIcon className="size-8 shrink-0 text-frost-500 dark:text-frost-200" />
            <span>{t("upload.title")}</span>
          </h1>
          <p className="max-w-xl text-[15px] text-frost-600 dark:text-frost-300">
            {t("upload.intro")}
          </p>
        </section>

        {/* Dedicated flow: this page is the Study Deck uploader. Homework has
            its own screen (/homework), reached from the mode switch above, the
            centre tab or the library's homework tab. */}


        {errorCard}

        {/* ---------------------------------------------------------- */}
        <section
          aria-label={t("upload.addPhotosAria")}
          onDragOver={(event) => {
            event.preventDefault();
            setDragging(true);
          }}
          onDragLeave={() => setDragging(false)}
          onDrop={(event) => {
            event.preventDefault();
            setDragging(false);
            void addFiles(imageFilesFromDataTransfer(event.dataTransfer));
          }}
          className={cn(
            "card relative overflow-hidden p-4 transition-all sm:p-5",
            dragging && "border-frost-400 bg-frost-50 ring-4 ring-frost-200 dark:bg-frost-500/10 dark:ring-frost-500/30",
          )}
        >
          <div className="flex flex-wrap items-center justify-between gap-3">
            <div>
              <h2 className="text-[15px] font-semibold tracking-[-0.01em] text-[var(--text)]">{t("upload.step1")}</h2>
              <p className="text-[12.5px] text-[var(--text-subtle)]">
                {t("upload.step1Help", { images: MAX_IMAGES, documents: MAX_DOCUMENTS })}
              </p>
            </div>
            <div className="flex flex-wrap gap-2">
              <Button variant="secondary" size="sm" onClick={() => fileInputRef.current?.click()}>
                <FolderIcon className="size-4" /> {t("upload.chooseFiles")}
              </Button>
              <Button variant="secondary" size="sm" onClick={() => cameraInputRef.current?.click()}>
                <CameraIcon className="size-4" /> {t("upload.camera")}
              </Button>
            </div>
          </div>

          <input
            ref={fileInputRef}
            type="file"
        aria-hidden="true"
        tabIndex={-1}
            accept={`${ACCEPTED_TYPES.join(",")},${DOCUMENT_ACCEPT_ATTR}`}
            multiple
            className="sr-only"
            onChange={(event) => {
              void addFiles(Array.from(event.target.files ?? []));
              event.target.value = "";
            }}
          />
          <input
            ref={cameraInputRef}
            type="file"
        aria-hidden="true"
        tabIndex={-1}
            accept="image/*"
            capture="environment"
            className="sr-only"
            onChange={(event) => {
              void addFiles(Array.from(event.target.files ?? []));
              event.target.value = "";
            }}
          />

          {images.length === 0 ? (
            <button
              type="button"
              onClick={() => fileInputRef.current?.click()}
              className="mt-4 flex w-full flex-col items-center gap-2 rounded-2xl border-2 border-dashed border-white/70 bg-white/40 px-4 py-10 text-center backdrop-blur-xl transition hover:border-accent-300 hover:bg-white/65 dark:border-white/15 dark:bg-white/[0.05] dark:hover:bg-white/[0.09]"
            >
              <span aria-hidden className="animate-float text-frost-500 dark:text-frost-200">
                <SnowflakeIcon className="size-12" />
              </span>
              <span className="text-[14px] font-medium text-[var(--text)]">
                {t("upload.dropHere")}
              </span>
              <span className="text-[12.5px] text-[var(--text-subtle)]">
                {t("upload.formats")}
              </span>
            </button>
          ) : (
            <ul className="mt-4 grid grid-cols-3 gap-2 sm:grid-cols-4">
              {images.map((image) => (
                <li key={image.id} className="group relative overflow-hidden rounded-2xl border border-frost-200 dark:border-white/15">
                  {/* eslint-disable-next-line @next/next/no-img-element */}
                  <img
                    src={image.dataUrl}
                    alt={image.name}
                    className="aspect-square w-full object-cover"
                  />
                  <button
                    type="button"
                    onClick={() => removeImage(image.id)}
                    aria-label={t("upload.remove", { name: image.name })}
                    className="absolute right-1 top-1 grid size-7 place-items-center rounded-full bg-frost-950/70 text-xs font-bold text-white transition hover:bg-rose-600"
                  >
                    ✕
                  </button>
                  <span className="absolute inset-x-0 bottom-0 bg-frost-950/60 px-2 py-1 text-[10px] font-semibold text-white">
                    {formatBytes(image.bytes)}
                  </span>
                </li>
              ))}
              {images.length < MAX_IMAGES ? (
                <li>
                  <button
                    type="button"
                    onClick={() => fileInputRef.current?.click()}
                    className="grid aspect-square w-full place-items-center rounded-2xl border-2 border-dashed border-white/70 text-2xl text-accent-500 backdrop-blur-xl transition hover:border-accent-300 hover:bg-white/60 dark:border-white/15 dark:text-accent-200"
                    aria-label={t("upload.addMorePhotos")}
                  >
                    +
                  </button>
                </li>
              ) : null}
            </ul>
          )}

          {documents.length > 0 ? (
            <ul className="mt-3 space-y-2">
              {documents.map((entry) => (
                <li
                  key={entry.id}
                  className="flex items-start gap-3 rounded-2xl border border-white/60 bg-white/50 p-3 backdrop-blur-xl dark:border-white/12 dark:bg-white/[0.06]"
                >
                  <span className="grid size-10 shrink-0 place-items-center rounded-xl bg-frost-100 text-[10px] font-extrabold uppercase tracking-wide text-frost-700 dark:bg-white/10 dark:text-frost-100">
                    {KIND_LABELS[entry.kind]}
                  </span>
                  <div className="min-w-0 flex-1">
                    <p className="truncate text-sm font-semibold text-[var(--text)]" title={entry.name}>
                      {entry.name}
                    </p>
                    {entry.status === "extracting" ? (
                      <p className="text-xs font-medium text-frost-700 dark:text-frost-200">
                        {entry.progress ?? t("upload.reading")}
                      </p>
                    ) : null}
                    {entry.status === "error" ? (
                      <p className="text-xs font-medium text-rose-600 dark:text-rose-300">{entry.error}</p>
                    ) : null}
                    {entry.status === "ready" && entry.extracted ? (
                      <>
                        <p className="text-[12.5px] text-[var(--text-subtle)]">
                          {describeExtraction(entry.extracted, t, plural)}
                        </p>
                        {entry.extracted.words === 0 && entry.extracted.images.length === 0 ? (
                          <p className="text-xs font-medium text-amber-700 dark:text-amber-300">
                            {t("upload.noReadable")}
                          </p>
                        ) : null}
                        {entry.extracted.warnings.map((warning) => (
                          <p key={warning} className="text-[12.5px] text-[var(--text-subtle)]">
                            ⓘ {warning}
                          </p>
                        ))}
                      </>
                    ) : null}
                  </div>
                  <button
                    type="button"
                    onClick={() => removeDocument(entry.id)}
                    aria-label={t("upload.remove", { name: entry.name })}
                    className="grid size-7 shrink-0 place-items-center rounded-full bg-frost-950/10 text-xs font-bold text-frost-900 transition hover:bg-rose-500 hover:text-white dark:bg-white/10 dark:text-frost-50"
                  >
                    ✕
                  </button>
                </li>
              ))}
            </ul>
          ) : null}

          {images.length > 0 || documents.length > 0 ? (
            <p className="mt-2 text-[12.5px] text-[var(--text-subtle)]">
              {images.length > 0
                ? plural(images.length, "upload.photoSummary", { size: formatBytes(totalBytes) })
                : ""}
              {images.length > 0 && documents.length > 0 ? " · " : ""}
              {documents.length > 0
                ? `${plural(documents.length, "upload.docSummary")}${
                    documentImages.length
                      ? ` (${plural(documentImages.length, "upload.docImages")})`
                      : ""
                  }`
                : ""}
              {imagesSkipped > 0
                ? ` · ${plural(imagesSkipped, "upload.skipImages", { max: MAX_IMAGES_TO_SEND })}`
                : ""}
            </p>
          ) : null}

          {phase === "preparing" ? (
            <p className="mt-2 text-[12.5px] font-medium text-[var(--text-muted)]">{t("upload.compressing")}</p>
          ) : null}
          {fileError ? (
            <p role="alert" className="mt-2 text-xs font-semibold text-rose-600 dark:text-rose-300">
              {fileError}
            </p>
          ) : null}
        </section>

        {/* ---------------------------------------------------------- */}
        <section className="card space-y-4 p-4 sm:p-5">
          <div>
            <h2 className="text-[15px] font-semibold tracking-[-0.01em] text-[var(--text)]">{t("upload.step2")}</h2>
            <p className="text-[12.5px] text-[var(--text-subtle)]">
              {t("upload.step2Help")}
            </p>
          </div>

          <div className="space-y-1.5">
            <label htmlFor="notes-text" className="text-[11px] font-semibold uppercase tracking-wide text-[var(--text-subtle)]">
              {t("upload.pastedNotes")}
            </label>
            <textarea
              id="notes-text"
              value={text}
              onChange={(event) => setText(event.target.value)}
              rows={4}
              placeholder={t("upload.pastedPlaceholder")}
              className="w-full resize-y rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
            />
          </div>

          <div className="space-y-1.5">
            <label htmlFor="focus" className="text-[11px] font-semibold uppercase tracking-wide text-[var(--text-subtle)]">
              {t("upload.topicHint")}
            </label>
            <input
              id="focus"
              value={focus}
              onChange={(event) => setFocus(event.target.value)}
              placeholder={t("upload.topicPlaceholder")}
              className="w-full rounded-2xl border border-white/60 bg-white/55 px-4 py-3 text-sm text-frost-950 outline-none backdrop-blur-xl transition placeholder:text-frost-400 focus:border-accent-400 dark:border-white/12 dark:bg-white/[0.07] dark:text-frost-50"
            />
          </div>
        </section>

        {/* ---------------------------------------------------------- */}
        <section className="card space-y-4 p-4 sm:p-5">
          <h2 className="text-[15px] font-semibold tracking-[-0.01em] text-[var(--text)]">{t("upload.step3")}</h2>
          {folderPicker}
          {difficultyPicker}
          {countPicker}
        </section>

        {/* Same CTA block as the homework flow: full-width button with the
            helper line centred underneath, in the page flow — no sticky bar. */}
        <div className="space-y-2">
          <Button
            size="lg"
            className="touch-target w-full"
            onClick={() => void generate()}
            disabled={!canGenerate}
          >
            <SparklesIcon className="size-5" /> {t("upload.freezeDeck")}
          </Button>
          <p className="text-center text-[12px] text-[var(--text-subtle)]">
            {documentsBusy
              ? t("upload.readingDocs")
              : hasContent
                ? t("upload.ready")
                : t("upload.addToStart")}
          </p>
          <AiDisclaimer />
        </div>
      </div>
    </div>
  );
}

/* ------------------------------------------------------------------ */
/* Loading state                                                       */
/* ------------------------------------------------------------------ */