// Book-detail annotations banner (objective 7): every note and highlight
// on the book, friendly location labels (never a raw cfi:epubcfi(…) string
// in UI or export headers), per-row reader jumps via ?loc=, and the
// WEB-ONLY export (single .md or one-file-per-item zip). Item formatting
// is identical in both modes:
//   location note: "# <friendly label>" header + note source as body
//   highlight:     "# <highlight text>" header + note source as body
//   (no note → header only)
// Rows expand to the rich markup through the same markdown pipeline the
// reader uses (renderNoteHtml — sanitized at render time).
import { renderNoteHtml, stripNote } from "./markdown";

interface AnnotationRow {
  /** stable key for x-for */
  key: string;
  /** note | highlight */
  kind: "note" | "highlight";
  /** human location label (Section N / Page N / NN% / source words) */
  label: string;
  /** compact preview line: stripped markdown (note) or capped selection */
  preview: string;
  /** expanded view, split so the highlight→note boundary is explicit:
   *  the escaped selection text, then the note's markdown-rendered HTML
   *  (empty when the row has no note body). */
  richSelection: string;
  richNote: string;
  /** the ?loc= handoff value for the jump */
  loc: string;
  /** row accent color (swatch) */
  color: string;
  /** highlight rows: whether a note rides on the highlight (Edit-note vs
   *  Add-note label). Note rows always true. */
  hasNote: boolean;
  expanded: boolean;
}

interface AnnotationSource {
  row: AnnotationRow;
  /** full markdown body under the export header ("" when none) */
  source: string;
  /** highlight selection text (the export header for highlight rows) */
  highlightText: string;
}

/** Friendly human location label; mirrors the app's positionHint(). */
function friendlyAnnotationLabel(position: string | null | undefined, fallbackText: string): string {
  const raw = (position ?? "").trim();
  if (raw) {
    // PDF/comic anchors: "page:N"
    if (raw.startsWith("page:")) {
      const n = parseInt(raw.slice(5), 10);
      if (Number.isFinite(n) && n > 0) return `Page ${n}`;
    }
    // Reflowable location notes: "cfi:epubcfi(...)"
    const cfi = raw.startsWith("cfi:") ? raw.slice(4).trim() : raw;
    const m = /epubcfi\(\s*\/6\/(\d+)/.exec(cfi);
    if (m) {
      // The spine step counts 1-based element pairs; /6/N!/ → section N/2.
      const spine = Math.floor(parseInt(m[1], 10) / 2) - 1;
      if (spine >= 0) return `Section ${spine + 1}`;
    }
  }
  // Spec fallback: the text's first few words (never a raw locator).
  const words = stripNote(fallbackText || "").replace(/\s+/g, " ").trim();
  if (words) {
    const cut = words.length > 42 ? words.slice(0, words.lastIndexOf(" ", 42)) || words.slice(0, 42) : words;
    return cut;
  }
  return "Location";
}

/** PDF highlights store their page inside the epubcfi_start column as a
 *  JSON descriptor {"v":1,"page":N,"rects":[…]} — parse it off. */
function pdfEnvelopePage(cfi: string): number | null {
  if (cfi.startsWith("{")) {
    try {
      const a = JSON.parse(cfi);
      if (a && typeof a.page === "number") return a.page;
    } catch {
      /* not ours */
    }
  }
  return null;
}

function buildAnnotationRows(
  notes: any[],
  highlights: any[],
): { rows: AnnotationRow[]; sources: AnnotationSource[] } {
  const rows: AnnotationRow[] = [];
  const sources: AnnotationSource[] = [];

  for (const n of notes) {
    const content = n.content ?? "";
    const label = friendlyAnnotationLabel(n.position, content);
    const loc = n.position ?? "";
    const row: AnnotationRow = {
      key: `note-${n.id}`,
      kind: "note",
      label,
      preview: stripNote(content) || "(empty note)",
      richSelection: "",
      richNote: renderNoteHtml(content),
      loc,
      color: "var(--accent)",
      hasNote: true,
      expanded: false,
    };
    rows.push(row);
    sources.push({
      row,
      source: content,
      highlightText: "",
    });
  }

  for (const h of highlights) {
    const selection = (h.selection_text ?? "").trim();
    const note = (h.note_text ?? "").trim();
    const color = h.color || "#ffff00";
    const envelopePage = pdfEnvelopePage(h.epubcfi_start ?? "");
    const cfi = (h.epubcfi_start ?? "").trim();
    const pct = typeof h.percentage_start === "number" ? h.percentage_start : null;

    let label = "Location";
    let loc = "";
    if (envelopePage != null) {
      label = `Page ${envelopePage + 1}`;
      // ?loc= speaks 1-based pages
      loc = `page:${envelopePage + 1}`;
    } else if (cfi || pct != null) {
      label = friendlyAnnotationLabel(cfi || null, selection);
    }
    if (envelopePage == null && cfi.startsWith("epubcfi(")) {
      loc = `cfi:${cfi}`;
    }
    if (!loc && pct != null) {
      label = `${Math.round(pct * 100)}%`;
    }

    const capped = selection.length > 80 ? selection.slice(0, 80) + "…" : selection;
    // Expanded body, split at the highlight→note boundary: the escaped
    // selection, then the note's rendered markdown under a labeled divider
    // (rendered by the banner template).
    const richSelection = escapeHtmlForRich(selection);
    const richNote = note ? renderNoteHtml(note) : "";

    const row: AnnotationRow = {
      key: `hl-${h.id}`,
      kind: "highlight",
      label,
      preview: capped || "(empty highlight)",
      richSelection,
      richNote,
      loc,
      color,
      hasNote: !!note,
      expanded: false,
    };
    rows.push(row);
    sources.push({ row, source: note, highlightText: selection });
  }

  return { rows, sources };
}

function escapeHtmlForRich(text: string): string {
  return text
    .replace(/&/g, "&amp;")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;");
}

/** The export item text — identical in single and multi modes. */
function annotationItemMarkdown(source: AnnotationSource): string {
  if (source.row.kind === "highlight") {
    const body = source.source ? "\n\n" + source.source.trim() : "";
    return `# ${source.highlightText || "(highlight)"}${body}\n`;
  }
  const body = source.source.trim();
  return `# ${source.row.label}\n${body ? "\n" + body : ""}\n`;
}

function triggerDownload(blob: Blob, filename: string): void {
  const url = URL.createObjectURL(blob);
  const a = document.createElement("a");
  a.href = url;
  a.download = filename;
  document.body.appendChild(a);
  a.click();
  a.remove();
  setTimeout(() => URL.revokeObjectURL(url), 5000);
}

function bannerBookTitle(): string {
  const h1 = document.querySelector("h1")?.textContent?.trim();
  const clean = (h1 || "").replace(/[\\/:*?"<>|]/g, "").slice(0, 80);
  return clean || "book";
}

export {
  buildAnnotationRows,
  annotationItemMarkdown,
  triggerDownload,
  bannerBookTitle,
  type AnnotationRow,
  type AnnotationSource,
};