"use client";

import { useCallback, useEffect, useRef, useState } from "react";
import Link from "next/link";
import {
  ArrowRight,
  CheckCircle2,
  Clock3,
  FileText,
  Flame,
  LibraryBig,
  RefreshCw,
  Search,
  Trash2,
  UploadCloud,
  XCircle,
} from "lucide-react";
import { deleteDocument, listDocuments } from "@/lib/api/documents";
import type { ApiDocument, DocumentStatus, PreviousPaper } from "@/lib/api/types";
import { buildDemoSeedDocuments } from "@/lib/demo-seed-documents";
import { getLocalPreviousPapers } from "@/lib/frontend-local-store";
import { buildStudyIntentUrl } from "@/lib/study-intents";
import { cn } from "@/lib/utils";
import { getPublicDemoMode } from "@/lib/env";
import { hasLiveSession } from "@/lib/api/mode";
import { MaterialDeletePrompt } from "@/components/study-chat/MaterialDeletePrompt";

type SourcesSurface = "light" | "dark";
type HeadingLevel = "h1" | "h2";
type SourceFilter = "all" | "notes" | "chapter" | "question_paper";

const FILTERS: Array<{ value: SourceFilter; label: string }> = [
  { value: "all", label: "All" },
  { value: "notes", label: "Notes" },
  { value: "chapter", label: "Chapters" },
  { value: "question_paper", label: "Question papers" },
];

type SourcePalette = {
  root: string;
  heading: string;
  description: string;
  primaryButton: string;
  secondaryButton: string;
  toolbar: string;
  input: string;
  inputPlaceholder: string;
  icon: string;
  filterActive: string;
  filterInactive: string;
  count: string;
  subtleLink: string;
  card: string;
  cardTitle: string;
  cardMeta: string;
  divider: string;
  action: string;
  actionMuted: string;
  empty: string;
  emptyIcon: string;
  emptyTitle: string;
  emptyText: string;
  paperPanel: string;
  paperHeading: string;
  paperText: string;
  paperItem: string;
  infoPanel: string;
  infoText: string;
  skeleton: string;
  status: {
    ready: string;
    processing: string;
    failed: string;
    default: string;
  };
};

function getPalette(surface: SourcesSurface): SourcePalette {
  if (surface === "light") {
    return {
      root: "text-[#15161b]",
      heading: "text-[#15161b]",
      description: "text-[#737580]",
      primaryButton:
        "border border-[#17181b] bg-[#17181b] text-white hover:bg-[#303139] focus-visible:ring-[#17181b]/30",
      secondaryButton:
        "border border-[#dfe1e7] bg-white text-[#34363f] hover:border-[#c8cbd4] hover:bg-[#fafafa] focus-visible:ring-[#17181b]/20",
      toolbar: "border-[#dfe1e7] bg-white",
      input: "text-[#202128]",
      inputPlaceholder: "placeholder:text-[#989aa4]",
      icon: "text-[#747680]",
      filterActive: "border-[#b9bbc3] bg-[#17181b] text-white",
      filterInactive:
        "border-[#dfe1e7] bg-white text-[#666873] hover:border-[#bfc2cb] hover:text-[#25262c]",
      count: "text-[#737580]",
      subtleLink: "text-[#5b5d66] hover:text-[#17181b]",
      card: "border-[#e1e3e8] bg-white shadow-[0_8px_24px_rgba(20,22,29,0.035)] hover:border-[#c9ccd5] hover:shadow-[0_12px_30px_rgba(20,22,29,0.06)]",
      cardTitle: "text-[#202128] hover:text-[#17181b]",
      cardMeta: "text-[#858792]",
      divider: "border-[#ececf0]",
      action:
        "border-[#dfe1e7] bg-white text-[#34363f] hover:border-[#bfc2cb] hover:bg-[#fafafa] hover:text-[#17181b] focus-visible:ring-[#17181b]/20",
      actionMuted:
        "border-[#e7e8ed] text-[#62646e] hover:border-[#c9ccd5] hover:text-[#17181b] focus-visible:ring-[#17181b]/20",
      empty: "border-[#dedfe5] bg-[#fefefd]",
      emptyIcon: "border-[#e1e3e8] bg-[#f5f6f8] text-[#767883]",
      emptyTitle: "text-[#202128]",
      emptyText: "text-[#737580]",
      paperPanel: "border-[#e1e3e8] bg-white",
      paperHeading: "text-[#34363f]",
      paperText: "text-[#737580]",
      paperItem:
        "border-[#e5e6eb] bg-[#fafafa] text-[#4d4f58] hover:border-[#c9ccd5] hover:bg-white hover:text-[#17181b] focus-visible:ring-[#17181b]/20",
      infoPanel: "border-[#e1e3e8] bg-[#fafafa]",
      infoText: "text-[#737580]",
      skeleton: "border-[#e7e8ed] bg-white",
      status: {
        ready: "border-[#cfe4d7] bg-[#f3faf5] text-[#2f6b49]",
        processing: "border-[#ead9b8] bg-[#fffaf0] text-[#86621f]",
        failed: "border-[#ead1d1] bg-[#fff6f6] text-[#9b454d]",
        default: "border-[#e1e3e8] bg-[#f7f7f8] text-[#656772]",
      },
    };
  }

  return {
    root: "text-white",
    heading: "text-white",
    description: "text-white/52",
    primaryButton:
      "border border-white/[0.08] bg-white text-black hover:bg-white/90 focus-visible:ring-white/35",
    secondaryButton:
      "border border-white/[0.1] bg-white/[0.02] text-white/70 hover:border-white/20 hover:bg-white/[0.05] hover:text-white focus-visible:ring-white/25",
    toolbar: "border-white/[0.08] bg-white/[0.02]",
    input: "text-white",
    inputPlaceholder: "placeholder:text-white/30",
    icon: "text-white/40",
    filterActive: "border-white/20 bg-white/[0.07] text-white",
    filterInactive:
      "border-white/[0.08] bg-transparent text-white/50 hover:border-white/15 hover:text-white/80",
    count: "text-white/50",
    subtleLink: "text-white/50 hover:text-white",
    card: "border-white/[0.08] bg-[#0b0b0c] hover:border-white/[0.15]",
    cardTitle: "text-white hover:text-white",
    cardMeta: "text-white/50",
    divider: "border-white/[0.08]",
    action:
      "border-white/[0.1] bg-white/[0.02] text-white/70 hover:border-white/20 hover:bg-white/[0.05] hover:text-white focus-visible:ring-white/25",
    actionMuted:
      "border-white/[0.08] text-white/55 hover:border-white/15 hover:text-white focus-visible:ring-white/25",
    empty: "border-white/[0.12] bg-black/30",
    emptyIcon: "border-white/[0.1] bg-white/[0.035] text-white/40",
    emptyTitle: "text-white",
    emptyText: "text-white/52",
    paperPanel: "border-white/[0.08] bg-white/[0.02]",
    paperHeading: "text-white/70",
    paperText: "text-white/60",
    paperItem:
      "border-white/[0.06] text-white/70 hover:border-white/20 hover:text-white focus-visible:ring-white/25",
    infoPanel: "border-white/[0.08] bg-white/[0.02]",
    infoText: "text-white/50",
    skeleton: "border-white/[0.06] bg-white/[0.02]",
    status: {
      ready: "border-emerald-300/20 bg-emerald-300/[0.08] text-emerald-200/80",
      processing: "border-amber-300/20 bg-amber-300/[0.08] text-amber-200/80",
      failed: "border-rose-300/20 bg-rose-300/[0.08] text-rose-200/80",
      default: "border-white/[0.08] bg-white/[0.05] text-white/50",
    },
  };
}

function shouldShowDemoSources(): boolean {
  const mode = getPublicDemoMode();
  if (mode === "demo") return true;
  if (mode === "live") return false;
  return !hasLiveSession();
}

async function fetchSources() {
  let docs = await listDocuments();
  if (docs.length === 0 && shouldShowDemoSources()) {
    docs = buildDemoSeedDocuments();
  }
  return { docs, papers: getLocalPreviousPapers() };
}

function statusText(status: DocumentStatus) {
  if (status === "ready") return "Ready to study";
  if (status === "processing" || status === "uploaded") return "Reading material";
  if (status === "failed") return "Could not read";
  return "Saved source";
}

function formatDate(iso: string) {
  const date = new Date(iso);
  if (Number.isNaN(date.getTime())) return "Date unavailable";
  return new Intl.DateTimeFormat("en", { dateStyle: "medium" }).format(date);
}

function getDocumentMeta(document: ApiDocument) {
  if (document.chunk_count > 0) {
    return `${document.chunk_count} ${document.chunk_count === 1 ? "section" : "sections"}`;
  }
  const fileName = document.file_name.toLowerCase();
  if (document.file_type.includes("pdf") || fileName.endsWith(".pdf")) return "PDF";
  if (document.file_type.includes("text") || fileName.endsWith(".txt")) return "TXT";
  return "Study material";
}

function matchesFilter(document: ApiDocument, filter: SourceFilter) {
  if (filter === "all") return true;
  const materialType = (document.material_type ?? "").toLowerCase();
  if (filter === "notes") return materialType.includes("note");
  return materialType.includes(filter);
}

function FilterButton({
  active,
  label,
  onClick,
  palette,
}: {
  active: boolean;
  label: string;
  onClick: () => void;
  palette: SourcePalette;
}) {
  return (
    <button
      type="button"
      aria-pressed={active}
      onClick={onClick}
      className={cn(
        "inline-flex min-h-10 shrink-0 items-center justify-center rounded-xl border px-3.5 text-xs font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2",
        active ? palette.filterActive : palette.filterInactive,
      )}
    >
      {label}
    </button>
  );
}

function StatusBadge({
  status,
  palette,
}: {
  status: DocumentStatus;
  palette: SourcePalette;
}) {
  const tone =
    status === "ready"
      ? palette.status.ready
      : status === "processing" || status === "uploaded"
        ? palette.status.processing
        : status === "failed"
          ? palette.status.failed
          : palette.status.default;

  return (
    <span
      className={cn(
        "inline-flex shrink-0 items-center gap-1.5 rounded-full border px-2.5 py-1 text-[10px] font-semibold",
        tone,
      )}
    >
      {status === "ready" ? (
        <CheckCircle2 aria-hidden="true" className="size-3" />
      ) : status === "processing" || status === "uploaded" ? (
        <Clock3 aria-hidden="true" className="size-3" />
      ) : status === "failed" ? (
        <XCircle aria-hidden="true" className="size-3" />
      ) : (
        <FileText aria-hidden="true" className="size-3" />
      )}
      {statusText(status)}
    </span>
  );
}

export function SourcesView({
  surface = "dark",
  headingLevel = "h2",
}: {
  surface?: SourcesSurface;
  headingLevel?: HeadingLevel;
}) {
  const palette = getPalette(surface);
  const [documents, setDocuments] = useState<ApiDocument[]>([]);
  const [papers, setPapers] = useState<PreviousPaper[]>([]);
  const [error, setError] = useState<string | null>(null);
  const [isLoading, setIsLoading] = useState(true);
  const [query, setQuery] = useState("");
  const [filter, setFilter] = useState<SourceFilter>("all");
  const [confirmDeleteId, setConfirmDeleteId] = useState<string | null>(null);
  const [deletingId, setDeletingId] = useState<string | null>(null);
  const [deleteError, setDeleteError] = useState<{
    id: string;
    message: string;
  } | null>(null);
  const requestRef = useRef(0);
  const canDeleteSources = !shouldShowDemoSources() && hasLiveSession();

  const loadSources = useCallback(async () => {
    const requestId = ++requestRef.current;
    setIsLoading(true);
    setError(null);
    try {
      const { docs, papers: nextPapers } = await fetchSources();
      if (requestId !== requestRef.current) return;
      setDocuments(docs);
      setPapers(nextPapers);
    } catch {
      if (requestId !== requestRef.current) return;
      if (shouldShowDemoSources()) {
        setDocuments(buildDemoSeedDocuments());
        setPapers(getLocalPreviousPapers());
      } else {
        setError("Could not load your sources. Check your connection and retry.");
      }
    } finally {
      if (requestId === requestRef.current) setIsLoading(false);
    }
  }, []);

  useEffect(() => {
    const timeoutId = window.setTimeout(() => void loadSources(), 0);
    return () => {
      window.clearTimeout(timeoutId);
      requestRef.current += 1;
    };
  }, [loadSources]);

  const normalizedQuery = query.trim().toLowerCase();
  const filteredDocs = documents
    .filter((document) => {
      const searchableText = [
        document.title,
        document.file_name,
        document.subject,
        document.chapter,
      ]
        .filter(Boolean)
        .join(" ")
        .toLowerCase();
      return (
        (!normalizedQuery || searchableText.includes(normalizedQuery)) &&
        matchesFilter(document, filter)
      );
    })
    .sort((a, b) => b.created_at.localeCompare(a.created_at));

  async function removeSource(documentId: string) {
    setDeletingId(documentId);
    setDeleteError(null);
    try {
      await deleteDocument(documentId);
      setDocuments((current) =>
        current.filter((document) => document.id !== documentId),
      );
      setConfirmDeleteId(null);
    } catch {
      setDeleteError({
        id: documentId,
        message:
          "Could not delete this source. It is still available. Check your connection and retry.",
      });
      setConfirmDeleteId(documentId);
    } finally {
      setDeletingId(null);
    }
  }

  const Heading = headingLevel === "h1" ? "h1" : "h2";
  const filterLabel = FILTERS.find((item) => item.value === filter)?.label;
  const hasDocuments = documents.length > 0;

  return (
    <div className={cn("w-full", palette.root)} aria-busy={isLoading}>
      <header className="mb-7 flex flex-col gap-4 sm:mb-8 sm:flex-row sm:items-end sm:justify-between">
        <div className="min-w-0">
          <Heading
            id="sources-title"
            className={cn("text-2xl font-semibold tracking-[-0.025em] sm:text-3xl", palette.heading)}
          >
            Sources
          </Heading>
          <p className={cn("mt-2 max-w-2xl text-sm leading-6", palette.description)}>
            Uploaded PDFs and TXT files available to your study workspace. Study actions unlock after a source is ready.
          </p>
        </div>
        <Link
          href="/upload"
          className={cn(
            "inline-flex min-h-11 shrink-0 items-center justify-center gap-2 rounded-xl px-5 text-sm font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2",
            palette.primaryButton,
          )}
        >
          <UploadCloud aria-hidden="true" className="size-4" />
          Add material
        </Link>
      </header>

      <div className="mb-6 flex flex-col gap-3 sm:flex-row sm:items-center">
        <div
          role="search"
          aria-label="Search sources"
          className={cn(
            "flex min-w-0 flex-1 items-center gap-2 rounded-xl border px-3.5 transition focus-within:ring-4",
            palette.toolbar,
            surface === "light"
              ? "focus-within:border-[#17181b] focus-within:ring-[#17181b]/10"
              : "focus-within:border-white/20 focus-within:ring-white/10",
          )}
        >
          <Search aria-hidden="true" className={cn("size-4 shrink-0", palette.icon)} />
          <label htmlFor="sources-search" className="sr-only">
            Search sources
          </label>
          <input
            id="sources-search"
            value={query}
            onChange={(event) => setQuery(event.target.value)}
            placeholder="Search by title, file, subject, or chapter"
            className={cn(
              "h-11 min-w-0 flex-1 bg-transparent text-sm outline-none",
              palette.input,
              palette.inputPlaceholder,
            )}
          />
          {query ? (
            <button
              type="button"
              onClick={() => setQuery("")}
              aria-label="Clear source search"
              className={cn(
                "inline-flex min-h-9 shrink-0 items-center rounded-lg px-2 text-xs font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2",
                palette.actionMuted,
              )}
            >
              Clear
            </button>
          ) : null}
        </div>
        <div
          aria-label="Filter sources by material type"
          className="flex max-w-full gap-2 overflow-x-auto pb-1 sm:pb-0"
        >
          {FILTERS.map((item) => (
            <FilterButton
              key={item.value}
              active={filter === item.value}
              label={item.label}
              onClick={() => setFilter(item.value)}
              palette={palette}
            />
          ))}
        </div>
      </div>

      <p className="sr-only" role="status" aria-live="polite">
        {isLoading
          ? "Loading sources."
          : error
            ? error
            : normalizedQuery || filter !== "all"
              ? `${filteredDocs.length} ${filteredDocs.length === 1 ? "source" : "sources"} shown.`
              : `${documents.length} ${documents.length === 1 ? "source" : "sources"} available.`}
      </p>

      {error ? (
        <div
          role="alert"
          className={cn(
            "mb-5 flex flex-col gap-3 rounded-2xl border px-4 py-4 text-sm sm:flex-row sm:items-center sm:justify-between",
            surface === "light"
              ? "border-[#ead1d1] bg-[#fff6f6] text-[#7f3d45]"
              : "border-rose-300/18 bg-rose-300/[0.06] text-rose-50/82",
          )}
        >
          <p>{hasDocuments ? "Could not refresh your sources. Showing the last available list." : error}</p>
          <button
            type="button"
            onClick={() => void loadSources()}
            className={cn(
              "inline-flex min-h-10 shrink-0 items-center justify-center gap-2 rounded-xl border px-4 text-xs font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2",
              palette.secondaryButton,
            )}
          >
            <RefreshCw aria-hidden="true" className="size-3.5" />
            Retry
          </button>
        </div>
      ) : null}

      <div className="grid gap-6 lg:grid-cols-12">
        <section className="min-w-0 lg:col-span-8" aria-labelledby="sources-list-title">
          <div className="mb-4 flex items-center justify-between gap-3">
            <h3 id="sources-list-title" className={cn("text-xs font-semibold uppercase tracking-[0.12em]", palette.count)}>
              Study materials · {filteredDocs.length}
            </h3>
            <Link
              href="/documents"
              className={cn("inline-flex min-h-9 items-center gap-1 text-xs font-semibold focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2", palette.subtleLink)}
            >
              Full library
              <ArrowRight aria-hidden="true" className="size-3.5" />
            </Link>
          </div>

          {isLoading && !hasDocuments ? (
            <div role="status" aria-label="Loading sources" className="grid gap-4 sm:grid-cols-2">
              <span className="sr-only">Loading your study material</span>
              {Array.from({ length: 4 }).map((_, index) => (
                <div
                  key={index}
                  aria-hidden="true"
                  className={cn("h-44 animate-pulse rounded-2xl border", palette.skeleton)}
                />
              ))}
            </div>
          ) : null}

          {!isLoading && filteredDocs.length === 0 && (!error || hasDocuments) ? (
            <div className={cn("flex min-h-64 flex-col items-center justify-center rounded-2xl border border-dashed px-6 py-12 text-center", palette.empty)}>
              <span className={cn("mb-4 grid size-12 place-items-center rounded-2xl border", palette.emptyIcon)}>
                <LibraryBig aria-hidden="true" className="size-6" />
              </span>
              <h3 className={cn("text-base font-semibold", palette.emptyTitle)}>
                {normalizedQuery ? `No sources match “${query.trim()}”` : filter !== "all" ? `No ${filterLabel?.toLowerCase()} available` : "No uploaded sources yet"}
              </h3>
              <p className={cn("mx-auto mt-2 max-w-md text-sm leading-6", palette.emptyText)}>
                {normalizedQuery || filter !== "all"
                  ? "Try a different search or clear the material filter."
                  : "Upload a selectable-text PDF or TXT file. Images and scanned PDFs are not supported yet."}
              </p>
              {normalizedQuery || filter !== "all" ? (
                <button
                  type="button"
                  onClick={() => {
                    setQuery("");
                    setFilter("all");
                  }}
                  className={cn(
                    "mt-5 inline-flex min-h-10 items-center justify-center rounded-xl px-4 text-xs font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2",
                    palette.secondaryButton,
                  )}
                >
                  Clear filters
                </button>
              ) : (
                <Link
                  href="/upload"
                  className={cn(
                    "mt-5 inline-flex min-h-11 items-center justify-center gap-2 rounded-xl px-5 text-sm font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2",
                    palette.primaryButton,
                  )}
                >
                  <UploadCloud aria-hidden="true" className="size-4" />
                  Upload first material
                </Link>
              )}
            </div>
          ) : null}

          {!isLoading && filteredDocs.length > 0 ? (
            <div className="grid gap-4 sm:grid-cols-2">
              {filteredDocs.map((document) => {
                const sourceTitle = document.title?.trim() || document.file_name || "Untitled source";
                const isReady = document.status === "ready";
                return (
                  <article
                    key={document.id}
                    className={cn("flex min-w-0 flex-col rounded-2xl border p-4 transition", palette.card)}
                    aria-labelledby={`source-title-${document.id}`}
                  >
                    <div className="flex items-start justify-between gap-3">
                      <span className={cn("grid size-10 shrink-0 place-items-center rounded-xl border", palette.emptyIcon)}>
                        <FileText aria-hidden="true" className="size-5" />
                      </span>
                      <StatusBadge status={document.status} palette={palette} />
                    </div>
                    <div className="mt-4 min-w-0 flex-1">
                      <h4 id={`source-title-${document.id}`} className="min-w-0">
                        <Link
                          href={`/documents/${document.id}`}
                          title={sourceTitle}
                          className={cn("block truncate text-sm font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2", palette.cardTitle)}
                        >
                          {sourceTitle}
                        </Link>
                      </h4>
                      <p className={cn("mt-1 truncate text-xs", palette.cardMeta)}>
                        {[document.subject, document.chapter].filter(Boolean).join(" · ") || "General study material"}
                      </p>
                    </div>
                    <div className={cn("mt-4 flex items-center justify-between gap-3 border-t pt-3 text-[11px]", palette.divider, palette.cardMeta)}>
                      <span>{getDocumentMeta(document)}</span>
                      <time dateTime={document.created_at}>{formatDate(document.created_at)}</time>
                    </div>
                    <div className={cn("mt-3 flex flex-wrap gap-2 border-t pt-3", palette.divider)}>
                      {isReady ? (
                        <>
                          <Link
                            href={buildStudyIntentUrl({
                              intent: "explain_source",
                              sourceId: document.id,
                              prompt: `Explain ${sourceTitle} in simple exam language`,
                            })}
                            aria-label={`Ask DocDoe about ${sourceTitle}`}
                            className={cn("inline-flex min-h-10 items-center gap-1.5 rounded-xl px-3 text-xs font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2", palette.action)}
                          >
                            Ask DocDoe
                            <ArrowRight aria-hidden="true" className="size-3.5" />
                          </Link>
                          <Link
                            href={buildStudyIntentUrl({
                              intent: "generate_quiz",
                              sourceId: document.id,
                              prompt: `Quiz me from ${sourceTitle}`,
                            })}
                            aria-label={`Quiz me from ${sourceTitle}`}
                            className={cn("inline-flex min-h-10 items-center rounded-xl px-3 text-xs font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2", palette.actionMuted)}
                          >
                            Quiz
                          </Link>
                          <Link
                            href={buildStudyIntentUrl({
                              intent: "create_video_plan",
                              sourceId: document.id,
                              prompt: `Create a study video plan from ${sourceTitle}`,
                            })}
                            aria-label={`Plan a video from ${sourceTitle}`}
                            className={cn("inline-flex min-h-10 items-center rounded-xl px-3 text-xs font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2", palette.actionMuted)}
                          >
                            Video plan
                          </Link>
                        </>
                      ) : (
                        <Link
                          href={`/documents/${document.id}`}
                          className={cn("inline-flex min-h-10 items-center gap-1.5 rounded-xl px-3 text-xs font-semibold transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2", palette.action)}
                        >
                          {document.status === "failed" ? "Review source" : "View progress"}
                          <ArrowRight aria-hidden="true" className="size-3.5" />
                        </Link>
                      )}
                      {canDeleteSources && confirmDeleteId !== document.id ? (
                        <button
                          type="button"
                          onClick={() => {
                            setDeleteError(null);
                            setConfirmDeleteId(document.id);
                          }}
                          className={cn("ml-auto inline-flex min-h-10 items-center gap-1.5 rounded-xl px-3 text-xs font-semibold text-[#a13f49] transition hover:bg-[#fff2f3] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[#b43d4b]/30 focus-visible:ring-offset-2", surface === "light" ? "" : "text-red-300/70 hover:bg-red-400/10 hover:text-red-200")}
                          aria-label={`Delete ${sourceTitle}`}
                        >
                          <Trash2 aria-hidden="true" className="size-3.5" />
                          Delete
                        </button>
                      ) : null}
                    </div>
                    {confirmDeleteId === document.id ? (
                      <div className="mt-3">
                        <MaterialDeletePrompt
                          title={sourceTitle}
                          deleting={deletingId === document.id}
                          error={deleteError?.id === document.id ? deleteError.message : null}
                          onConfirm={() => void removeSource(document.id)}
                          onCancel={() => {
                            if (deletingId) return;
                            setConfirmDeleteId(null);
                            setDeleteError(null);
                          }}
                        />
                      </div>
                    ) : null}
                  </article>
                );
              })}
            </div>
          ) : null}
        </section>

        <aside className="space-y-5 lg:col-span-4" aria-label="Source guidance">
          <section className={cn("rounded-2xl border p-5", palette.paperPanel)} aria-labelledby="pyq-intelligence-title">
            <div className={cn("flex items-center gap-2 text-xs font-semibold uppercase tracking-[0.12em]", palette.paperHeading)}>
              <Flame aria-hidden="true" className="size-3.5" />
              <h3 id="pyq-intelligence-title">Question-paper evidence</h3>
            </div>
            <p className={cn("mt-2 text-sm leading-6", palette.paperText)}>
              Question papers you add here can support pattern analysis. DocDoe does not infer PYQ signals without paper evidence.
            </p>
            <div className="mt-4 space-y-2 text-sm">
              {papers.length > 0 ? (
                papers.slice(0, 5).map((paper) => (
                  <Link
                    key={paper.id}
                    href={buildStudyIntentUrl({ intent: "analyze_pyq", sourceId: paper.id })}
                    className={cn("block rounded-xl border p-3 transition focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2", palette.paperItem)}
                  >
                    {paper.title?.trim() || "Question paper"}
                  </Link>
                ))
              ) : (
                <p className={cn("text-xs leading-5", palette.paperText)}>
                  No question papers are available yet.
                </p>
              )}
            </div>
            <Link
              href="/previous-papers"
              className={cn("mt-4 inline-flex min-h-9 items-center gap-1 text-xs font-semibold focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2", palette.subtleLink)}
            >
              Open paper analyzer
              <ArrowRight aria-hidden="true" className="size-3.5" />
            </Link>
          </section>

          <section className={cn("rounded-2xl border p-5 text-xs leading-5", palette.infoPanel, palette.infoText)} aria-labelledby="source-actions-title">
            <h3 id="source-actions-title" className={cn("font-semibold", palette.heading)}>
              What happens when a source is ready?
            </h3>
            <p className="mt-2">
              Open the document to inspect its reading status. Once ready, Ask DocDoe, Quiz, and Video plan hand off to the current Study Chat with this source selected.
            </p>
          </section>
        </aside>
      </div>
    </div>
  );
}