import pdfrw
import io
import base64

ANNOT_KEY = '/Annots'
ANNOT_FIELD_KEY = '/T'
ANNOT_RECT_KEY = '/Rect'
SUBTYPE_KEY = '/Subtype'
WIDGET_SUBTYPE_KEY = '/Widget'


def write_fillable_pdf(input_pdf_path, output_pdf_path, data_dict):
    """填写pdf模板并输出新的pdf"""
    template_pdf = pdfrw.PdfReader(input_pdf_path)
    pdf_pages = len(template_pdf.pages)
    template_pdf.Root.AcroForm.update(pdfrw.PdfDict(NeedAppearances=pdfrw.PdfObject('true')))
    for pagenum in range(pdf_pages):
        annotations = template_pdf.pages[pagenum][ANNOT_KEY]
        if annotations is None:
            continue
        for annotation in annotations:
            if annotation[SUBTYPE_KEY] == WIDGET_SUBTYPE_KEY:
                if annotation[ANNOT_FIELD_KEY]:
                    key = annotation[ANNOT_FIELD_KEY][1:-1]
                    if key in data_dict.keys():
                        annotation.update(
                            pdfrw.PdfDict(V='{}'.format(data_dict[key]))
                        )
    pdf_stream = io.BytesIO()
    pdfrw.PdfWriter().write(pdf_stream, template_pdf)
    base64.b64encode(pdf_stream.getvalue())

data_dict = {
   'name': '宋有哲',
   "conference": "世界教育者大会"
}

INVOICE_TEMPLATE_PATH = "src/assets/GuestPage.pdf"
INVOICE_OUTPUT_PATH = 'output/output.pdf'

if __name__ == '__main__':
    write_fillable_pdf(INVOICE_TEMPLATE_PATH, INVOICE_OUTPUT_PATH, data_dict)