#!/usr/bin/env python3
import sys, os, subprocess, re, shutil, json, tempfile, struct
from pypdf import PdfReader, PdfWriter

INKSCAPE_TIMEOUT = 30

def fallback_page(reader, i, path):
    w = PdfWriter()
    w.add_page(reader.pages[i])
    with open(path, 'wb') as fh:
        w.write(fh)

tmpdir = sys.argv[1]
bg_pdf = sys.argv[2]
output = sys.argv[3]

content_file = next(
    (os.path.join(tmpdir, f) for f in os.listdir(tmpdir) if f.endswith('.content')), None
)
if not content_file:
    sys.exit(1)

with open(content_file) as f:
    data = json.load(f)

doc_uuid = os.path.basename(content_file)[:-8]
rm_dir   = os.path.join(tmpdir, doc_uuid)
page_ids = [p['id'] for p in data.get('cPages', {}).get('pages', [])]

page_rm = {}
for i, pid in enumerate(page_ids):
    rm = os.path.join(rm_dir, pid + '.rm')
    if os.path.exists(rm):
        page_rm[i] = rm

if not page_rm:
    sys.exit(1)

reader  = PdfReader(bg_pdf)
n_pages = len(reader.pages)
work    = tempfile.mkdtemp()
parts   = []

for i in range(n_pages):
    part_out = os.path.join(work, 'p' + str(i) + '.pdf')

    if i not in page_rm:
        fallback_page(reader, i, part_out)
        parts.append(part_out)
        continue

    try:
        # PDF-Seitengröße in Punkten
        pdf_w_pt = float(reader.pages[i].mediabox.width)
        pdf_h_pt = float(reader.pages[i].mediabox.height)
        dpi = 150
        png_w = int(round(pdf_w_pt * dpi / 72))
        png_h = int(round(pdf_h_pt * dpi / 72))

        # Bg-Seite als PNG rendern
        bg_base = os.path.join(work, 'bg' + str(i))
        subprocess.run(
            ['pdftoppm', '-r', str(dpi), '-png', '-f', str(i+1), '-l', str(i+1),
             '-singlefile', bg_pdf, bg_base],
            capture_output=True, timeout=20
        )
        bg_png = bg_base + '.png'
        if not os.path.exists(bg_png):
            raise FileNotFoundError('PNG fehlt')

        # .rm -> SVG
        svg_out = os.path.join(work, 'a' + str(i) + '.svg')
        r = subprocess.run(['rmc', '-t', 'svg', '-o', svg_out, page_rm[i]],
                           capture_output=True, timeout=20)
        if r.returncode != 0 or not os.path.exists(svg_out):
            raise RuntimeError('rmc fehlgeschlagen')

        svg = open(svg_out).read()

        # Weissen Hintergrund entfernen
        svg = re.sub(
            r'<rect\b[^>]*/?>',
            lambda m: '' if re.search(r'fill\s*[=:]\s*["\']?\s*(?:white|#fff(?:fff)?)', m.group(0), re.I) else m.group(0),
            svg
        )

        # ViewBox X-Offset auslesen
        vb = re.search(r'viewBox=["\']([^"\']+)["\']', svg)
        vb_vals = [float(x) for x in vb.group(1).split()] if vb else [0, 0, pdf_w_pt, pdf_h_pt]
        vb_x = vb_vals[0]
        vb_y = vb_vals[1]

        # Inneren SVG-Inhalt extrahieren
        inner_m = re.search(r'<svg[^>]*>(.*)</svg>', svg, re.DOTALL)
        inner = inner_m.group(1) if inner_m else ''

        # Annotation-Koordinaten sind in PDF-Punkten
        # Skalierung: PDF-Punkte -> PNG-Pixel
        pts_to_px = png_w / pdf_w_pt
        # reMarkable Seitenrand proportional zur PDF-Breite (empirisch: 75.5pt bei A4)
        rm_margin_left = 75.5 * pdf_w_pt / 595.275
        # reMarkable Seitenrand proportional zur PDF-Breite (empirisch: 75.5pt bei A4)
        rm_margin_left = 75.5 * pdf_w_pt / 595.275

        # Composite SVG
        comp_svg = os.path.join(work, 'c' + str(i) + '.svg')
        with open(comp_svg, 'w') as fh:
            fh.write('<?xml version="1.0" encoding="UTF-8"?>\n')
            fh.write('<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"')
            fh.write(' width="' + str(pdf_w_pt) + 'pt"')
            fh.write(' height="' + str(pdf_h_pt) + 'pt"')
            fh.write(' viewBox="0 0 ' + str(png_w) + ' ' + str(png_h) + '">\n')
            fh.write('  <image xlink:href="file://' + bg_png + '" href="file://' + bg_png + '"')
            fh.write(' width="' + str(png_w) + '" height="' + str(png_h) + '"/>\n')
            fh.write('  <g transform="scale(' + str(pts_to_px) + ',' + str(pts_to_px) + ')')
            fh.write(' translate(' + str(-vb_x + rm_margin_left) + ',' + str(-vb_y) + ')">\n')
            fh.write('    ' + inner + '\n')
            fh.write('  </g>\n')
            fh.write('</svg>')

        # Composite -> PDF
        r = subprocess.run(
            ['inkscape', comp_svg, '--export-type=pdf', '--export-filename=' + part_out],
            capture_output=True, timeout=INKSCAPE_TIMEOUT
        )
        if r.returncode != 0 or not os.path.exists(part_out) or os.path.getsize(part_out) < 100:
            raise RuntimeError('inkscape fehlgeschlagen')

        parts.append(part_out)
        print('  Seite ' + str(i+1) + ' mit Annotation', flush=True)

    except Exception as e:
        print('  Seite ' + str(i+1) + ' Fallback: ' + str(e), flush=True)
        fallback_page(reader, i, part_out)
        parts.append(part_out)

if len(parts) == 1:
    shutil.copy(parts[0], output)
elif parts:
    subprocess.run(['pdfunite'] + parts + [output], check=True)

shutil.rmtree(work)