from tkinter import *
from tkinter import filedialog
import PyPDF2
from reportlab.pdfgen import canvas
import codecs

def pdf_to_word():
    pdf_file = filedialog.askopenfilename(title = "Chọn tệp PDF", filetypes = (("PDF files", "*.pdf"), ("all files", "*.*")))
    try:
        pdf_reader = PyPDF2.PdfFileReader(open(pdf_file, 'rb'))
    except Exception as e:
        print("Lỗi khi mở tệp PDF: ", e)
        return
    word_file = filedialog.asksaveasfilename(title = "Lưu tệp Word", defaultextension=".txt", filetypes = (("Text files", "*.txt"), ("all files", "*.*")))
    with open(word_file, 'w', encoding='utf-8') as text_file:
        for page in range(pdf_reader.numPages):
            text = pdf_reader.getPage(page).extractText()
            text_file.write(text)

def word_to_pdf():
    word_file = filedialog.askopenfilename(title = "Chọn tệp Word", filetypes = (("Text files", "*.txt"), ("all files", "*.*")))
    pdf_file = filedialog.asksaveasfilename(title = "Lưu tệp PDF", defaultextension=".pdf", filetypes = (("PDF files", "*.pdf"), ("all files", "*.*")))

    c = canvas.Canvas(pdf_file)
    with open(word_file, 'r', encoding='utf-8') as text_file:
        text = text_file.read()
        c.drawString(72, 720, text)
    c.save()

root = Tk()
root.title("Chuyển đổi PDF - Word")

pdf_to_word_button = Button(root, text = "PDF to Word", command = pdf_to_word)
pdf_to_word_button.pack()

word_to_pdf_button = Button(root, text = "Word to PDF", command = word_to_pdf)
word_to_pdf_button.pack()

root.mainloop()

tại sao khi mình chuyển đổi thì lại ra một file trắng không có chữ ạ