#!/home/user/.pypdf/bin/python3

import sys
import pypdf
from pypdf.generic import create_string_object,Destination,FloatObject,NameObject,RectangleObject,DictionaryObject,TreeObject,ArrayObject
from typing import cast

fn = sys.argv[1]
scale = float(sys.argv[2])
moveleft = float(sys.argv[3])
movedown = float(sys.argv[4])

# ----- transformation

M = [scale,0,0,scale,-moveleft,-movedown]

def transformpoint(x,y):
  x,y = x.as_numeric(),y.as_numeric()
  x,y = M[0]*x+M[2]*y+M[4],M[1]*x+M[3]*y+M[5]
  x,y = FloatObject(x),FloatObject(y)
  return x,y

def transformrectangle(r):
  xLL,yLL,xUR,yUR = r
  xLL,yLL = transformpoint(xLL,yLL)
  xUR,yUR = transformpoint(xUR,yUR)
  return xLL,yLL,xUR,yUR

# ----- initial copy

output = pypdf.PdfWriter(clone_from=fn)

# ----- transform page contents

for page in output.pages:
  page.add_transformation(M)
  page.compress_content_streams()

# ----- transform destinations

def dest_transform(key,value):
  if value[1] != '/XYZ': return
  x,y = value[2:4]
  x,y = transformpoint(x,y)
  value[2:4] = x,y

def dest_walk(tree):
  tree = cast(TreeObject,tree)
  if '/Kids' in tree:
    for kid in tree['/Kids']:
      dest_walk(kid.get_object())
  elif '/Names' in tree:
    names = tree['/Names']
    i = 0
    while i+2 <= len(names):
      key = cast(str,names[i].get_object())
      i += 1
      if not isinstance(key,str): continue
      value = names[i].get_object()
      if isinstance(value,DictionaryObject) and '/D' in value:
        value = value['/D']
      dest_transform(key,value)
  else:
    for key,value in tree.items():
      value = value.get_object()
      if isinstance(value,DictionaryObject):
        value = value['/D']
      dest_transform(key,value)

catalog = output._root_object
if '/Dests' in catalog:
  dest_walk(catalog['/Dests'])
elif '/Names' in catalog:
  names = cast(ArrayObject,catalog['/Names'])
  if '/Dests' in names:
    dest_walk(names['/Dests'])

# ----- transform links

scaledannots = set()

for page in output.pages:
  if '/Annots' in page:
    for a in page['/Annots']:
      if a.idnum in scaledannots: continue
      scaledannots.add(a.idnum)
      r = a.get_object()['/Rect']
      a.get_object().update({NameObject('/Rect'):RectangleObject(transformrectangle(r))})

# ----- ship it

output.write(sys.stdout.buffer)