import * as fs from 'fs';
import * as path from 'path';
import { PDFDocument, rgb, StandardFonts, PageSizes } from 'pdf-lib';

const FONT_SEARCH_PATHS = [
  'C:/Windows/Fonts/NotoSansSC-VF.ttf',
  'C:/Windows/Fonts/NotoSansJP-VF.ttf',
  path.join(__dirname, '..', '..', '..', 'assets', 'fonts', 'NotoSansSC-VF.ttf'),
  '/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc',
];

let cachedFontBytes: Buffer | null = null;

function findFont(): Buffer {
  if (cachedFontBytes) return cachedFontBytes;
  for (const p of FONT_SEARCH_PATHS) {
    try {
      if (fs.existsSync(p)) {
        cachedFontBytes = fs.readFileSync(p);
        return cachedFontBytes;
      }
    } catch { }
  }
  return Buffer.alloc(0);
}

interface PdfReportOptions {
  title: string;
  subtitle?: string;
  sections: PdfSection[];
}

interface PdfSection {
  title: string;
  lines: string[];
}

export async function generateAssessmentPdf(options: PdfReportOptions): Promise<Buffer> {
  const doc = await PDFDocument.create();

  let font: any;
  const fontBytes = findFont();
  if (fontBytes.length > 0) {
    try {
      font = await doc.embedFont(fontBytes, { subset: true });
    } catch {
      font = undefined;
    }
  }
  if (!font) {
    font = await doc.embedFont(StandardFonts.Helvetica);
  }

  const pageWidth = PageSizes.A4[0];
  const pageHeight = PageSizes.A4[1];
  const margin = 50;
  const fontSize = 10;
  const titleSize = 20;
  const sectionSize = 13;
  const lineHeight = fontSize * 1.6;

  let page = doc.addPage([pageWidth, pageHeight]);
  let y = pageHeight - margin;

  function newPage() {
    page = doc.addPage([pageWidth, pageHeight]);
    y = pageHeight - margin;
  }

  function drawText(text: string, size: number, color: any, offsetY: number) {
    if (y < margin + offsetY) newPage();
    page.drawText(text, { x: margin, y, size, font, color });
    y -= offsetY;
  }

  drawText(options.title, titleSize, rgb(0, 0, 0), titleSize * 1.8);

  if (options.subtitle) {
    drawText(options.subtitle, 9, rgb(0.4, 0.4, 0.4), 16);
  }

  for (const section of options.sections) {
    y -= 8;
    drawText(section.title, sectionSize, rgb(0.1, 0.1, 0.1), sectionSize * 1.8);

    for (const line of section.lines) {
      if (!line) continue;
      for (const chunk of line.split('\n')) {
        drawText(chunk || ' ', fontSize, rgb(0.2, 0.2, 0.2), lineHeight);
      }
    }
  }

  drawText('--- End of Report ---', 8, rgb(0.6, 0.6, 0.6), 20);

  return Buffer.from(await doc.save());
}