// Minimaler, abhängigkeitsfreier PDF-Generator.
// Rendert die E-Mail (Kopf + Klartext-Body) als einfaches Text-PDF.
// Bewusst schlicht (v1): kein HTML-Rendering, keine Bilder — dafür keine
// externen Libraries. Reicht für eine lesbare Aktenkopie der Mail.

const Pdf = {
  /**
   * Erzeugt ein PDF-File aus den Mail-Metadaten.
   * @param {object} meta  Ergebnis von Mail.getMeta()
   * @returns {File}
   */
  fromMail(meta) {
    const header = [
      `Von:      ${meta.senderName ? meta.senderName + " <" + meta.senderEmail + ">" : meta.senderEmail}`,
      `An:       ${meta.to}`,
      meta.cc ? `CC:       ${meta.cc}` : null,
      `Datum:    ${this._fmtDate(meta.date)}`,
      `Betreff:  ${meta.subject}`,
      "",
      "----------------------------------------------------------------------",
      "",
    ].filter((l) => l !== null);

    const lines = header.concat(this._wrap(meta.bodyText || "", 95));
    const bytes = this._build(lines);
    const name = `${(meta.subject || "email").replace(/[\\/:*?"<>|]+/g, "_").slice(0, 80) || "email"}.pdf`;
    return new File([bytes], name, { type: "application/pdf" });
  },

  // --- PDF-Aufbau -----------------------------------------------------------

  _build(allLines) {
    const PAGE_W = 595, PAGE_H = 842;        // A4 in pt
    const MARGIN = 50, FONT = 10, LEADING = 14;
    const linesPerPage = Math.floor((PAGE_H - 2 * MARGIN) / LEADING);

    // Seiten aufteilen
    const pages = [];
    for (let i = 0; i < allLines.length; i += linesPerPage) {
      pages.push(allLines.slice(i, i + linesPerPage));
    }
    if (pages.length === 0) pages.push([""]);

    const objects = []; // {id, body}  body als latin1-String
    const addObj = (body) => { objects.push(body); return objects.length; };

    // Platzhalter-IDs vorab festlegen
    // 1 Catalog, 2 Pages, 3 Font, dann je Seite: PageObj + ContentObj
    const catalogId = 1, pagesId = 2, fontId = 3;
    objects.length = 0;
    objects.push("", "", ""); // reserviere 1..3

    const pageIds = [];
    const contentIds = [];
    pages.forEach((pageLines) => {
      const stream = this._contentStream(pageLines, MARGIN, PAGE_H - MARGIN, FONT, LEADING);
      const contentId = addObj(
        `<< /Length ${stream.length} >>\nstream\n${stream}\nendstream`
      );
      const pageId = addObj(
        `<< /Type /Page /Parent ${pagesId} 0 R ` +
        `/MediaBox [0 0 ${PAGE_W} ${PAGE_H}] ` +
        `/Resources << /Font << /F1 ${fontId} 0 R >> >> ` +
        `/Contents ${contentId} 0 R >>`
      );
      pageIds.push(pageId);
      contentIds.push(contentId);
    });

    objects[catalogId - 1] = `<< /Type /Catalog /Pages ${pagesId} 0 R >>`;
    objects[pagesId - 1] =
      `<< /Type /Pages /Count ${pageIds.length} ` +
      `/Kids [${pageIds.map((id) => `${id} 0 R`).join(" ")}] >>`;
    objects[fontId - 1] =
      `<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica /Encoding /WinAnsiEncoding >>`;

    // Serialisieren mit xref
    let pdf = "%PDF-1.4\n";
    const offsets = [];
    objects.forEach((body, idx) => {
      offsets[idx] = pdf.length;
      pdf += `${idx + 1} 0 obj\n${body}\nendobj\n`;
    });

    const xrefOffset = pdf.length;
    pdf += `xref\n0 ${objects.length + 1}\n`;
    pdf += "0000000000 65535 f \n";
    offsets.forEach((off) => {
      pdf += `${String(off).padStart(10, "0")} 00000 n \n`;
    });
    pdf +=
      `trailer\n<< /Size ${objects.length + 1} /Root ${catalogId} 0 R >>\n` +
      `startxref\n${xrefOffset}\n%%EOF`;

    return this._latin1Bytes(pdf);
  },

  _contentStream(lines, x, yTop, font, leading) {
    let s = `BT\n/F1 ${font} Tf\n${leading} TL\n${x} ${yTop} Td\n`;
    lines.forEach((line, i) => {
      if (i > 0) s += "T*\n";
      s += `(${this._escape(line)}) Tj\n`;
    });
    s += "ET";
    return s;
  },

  _wrap(text, width) {
    const out = [];
    (text || "").split(/\r?\n/).forEach((para) => {
      if (para.length <= width) { out.push(para); return; }
      let line = "";
      para.split(/\s+/).forEach((word) => {
        if ((line + " " + word).trim().length > width) {
          if (line) out.push(line);
          // sehr lange Wörter hart umbrechen
          while (word.length > width) { out.push(word.slice(0, width)); word = word.slice(width); }
          line = word;
        } else {
          line = line ? `${line} ${word}` : word;
        }
      });
      if (line) out.push(line);
    });
    return out;
  },

  _escape(s) {
    return this._toLatin1(s).replace(/[\\()]/g, "\\$&");
  },

  _toLatin1(s) {
    // Zeichen außerhalb Latin-1 durch '?' ersetzen.
    return (s || "").replace(/[^\x00-\xFF]/g, "?");
  },

  _latin1Bytes(str) {
    const bytes = new Uint8Array(str.length);
    for (let i = 0; i < str.length; i++) bytes[i] = str.charCodeAt(i) & 0xff;
    return bytes;
  },

  _fmtDate(d) {
    try {
      return new Intl.DateTimeFormat("de-DE", {
        dateStyle: "medium", timeStyle: "short",
      }).format(d);
    } catch (_) {
      return String(d);
    }
  },
};

if (typeof module !== "undefined") module.exports = { Pdf };