#!/usr/bin/env python3
# make_text_invisible.py
# Usage: python make_text_invisible.py text.pdf out.pdf
# Produces a single-page PDF identical visually but with text made invisible (selectable/searchable).
# Requires: pip install pymupdf

import sys
import fitz  # pymupdf
import os

if len(sys.argv) != 4:
    print("Usage: python make_text_invisible.py text.pdf sig.png out.pdf", file=sys.stderr)
    sys.exit(2)

in_path, sig_path, out_path = sys.argv[1], sys.argv[2], sys.argv[3]

doc = fitz.open(in_path)
if doc.page_count < 1:
    print("Input has no pages", file=sys.stderr)
    sys.exit(1)

# operate only on first page (single-page input assumed)
page = doc.load_page(0)
w, h = page.rect.width, page.rect.height

# create new doc and a blank page with same size
out = fitz.open()
newp = out.new_page(width=w, height=h)

# # copy original page's visible content as an image to preserve exact appearance
# pix = page.get_pixmap(matrix=fitz.Matrix(1, 1), alpha=False)
# img_bytes = pix.tobytes("png")
# newp.insert_image(fitz.Rect(0, 0, w, h), stream=img_bytes)

newp.insert_image(newp.rect, filename=sig_path, keep_proportion=False)

# extract text spans (positions, fonts, sizes)
td = page.get_text("dict")

for block in td.get("blocks", []):
    for line in block.get("lines", []):
        for span in line.get("spans", []):

            txt = span.get("text", "")
            if not txt:
                continue

            origin = span.get("origin")
            if origin:
                x, y = origin[0], origin[1]
            else:
                bbox = span.get("bbox", [0,0,0,0])
                x, y = bbox[0], bbox[3]

            # Use PDF invisible text rendering: render_mode=3 (neither fill nor stroke) is invisible but selectable.
            try:
                size = span.get("size", 12)
                newp.insert_text((x, y), txt, fontsize=size, color=(0, 0, 0, 0), render_mode=3)
            except Exception:
                print(f"Failed to insert text: '{txt}'")

out.save(out_path, garbage=4, deflate=True)
out.close()
doc.close()