from __future__ import annotations

import csv
from io import BytesIO, StringIO

from reportlab.lib.pagesizes import A4
from reportlab.pdfgen import canvas


def export_expenses_csv(expenses):
    output = StringIO()
    writer = csv.writer(output)
    writer.writerow(['Date', 'Title', 'Vendor', 'Category', 'Amount', 'Currency', 'Payment method', 'Tags'])
    for expense in expenses:
        writer.writerow([
            expense.purchase_date.isoformat(),
            expense.title,
            expense.vendor,
            expense.category.name_en if expense.category else '',
            str(expense.amount),
            expense.currency,
            expense.payment_method,
            expense.tags,
        ])
    return output.getvalue()


def export_expenses_pdf(expenses, title: str = 'Expenses'):
    buffer = BytesIO()
    pdf = canvas.Canvas(buffer, pagesize=A4)
    width, height = A4
    y = height - 40
    pdf.setFont('Helvetica-Bold', 14)
    pdf.drawString(40, y, title)
    y -= 30
    pdf.setFont('Helvetica', 10)
    for expense in expenses:
        line = f'{expense.purchase_date.isoformat()} | {expense.title} | {expense.amount} {expense.currency}'
        pdf.drawString(40, y, line[:100])
        y -= 16
        if y < 60:
            pdf.showPage()
            y = height - 40
            pdf.setFont('Helvetica', 10)
    pdf.save()
    buffer.seek(0)
    return buffer.read()