import datetime
import io
from pathlib import Path

from django.core.files import File
from pypdf import PdfReader, PdfWriter
from pypdf.constants import FieldDictionaryAttributes as FA  # noqa: N814

from .models import Bill, Wiref


def generate_pdf(wiref):
    if wiref is None or wiref.status != Wiref.Status.OPENED:
        return False

    bills = Bill.objects.filter(wiref=wiref).order_by("date")

    # Get data for pdf
    data = {}
    data_invoice = {}  # Own dict for fixing text to multiline
    for count, elem in enumerate(bills):
        data.update(
            {
                f"DatumRow{count + 1}": str(elem.date.strftime("%d.%m.%Y")),
                f"VerwendungszweckRow{count + 1}": elem.purpose,
                # Replace decimal separator from '.' to ','
                f"BetragRow{count + 1}": str(elem.amount).replace(".", ","),
            },
        )
        data_invoice.update(
            {
                f"RechnungsaustellerinRow{count + 1}": elem.invoice,
            },
        )

    # Get budget year
    today = datetime.datetime.now(tz=datetime.UTC).date()
    if today.month < 7:
        budget_year = f"{today.year - 1}-{today.year}"
    else:
        budget_year = f"{today.year}-{today.year + 1}"

    # Get total of all bills of wiref form
    total = 0
    for elem in bills:
        total += elem.amount

    data.update(
        {
            "Rechnungsnummer": str(wiref.wiref_id),
            "Budgetjahr": budget_year,
            # Replace decimal separator from '.' to ','
            "Summe": str(total).replace(".", ","),
        },
    )

    # Write data in pdf
    pdf_path = Path(Path(__file__).parent) / "static/wiref/Vorlage.pdf"
    reader = PdfReader(pdf_path)
    writer = PdfWriter()
    writer.append(reader)

    writer.update_page_form_field_values(
        writer.pages[0],
        data,
    )

    # Add invoices and fix text to multiline
    writer.update_page_form_field_values(
        writer.pages[0],
        data_invoice,
        flags=FA.FfBits.Multiline,
    )

    with io.BytesIO() as bytes_stream:
        writer.write(bytes_stream)

        # Save pdf in wiref
        wiref_name = f"Abrechnungsformular-{wiref.wiref_id}.pdf"
        wiref.file_field.save(wiref_name, File(bytes_stream, wiref_name))

    return True