import os, magic, copy

from django import forms
from .models import Expense, Revenue


class CleanInvoiceForm(forms.ModelForm):
    """
    We have to define this form explicitly because we want our ImageField to accept PDF files as well as images,
    and we cannot change the clean_* methods with an autogenerated form from inside views.py
    """
    invoice = forms.FileField()

    def clean_invoice(self):
        # get the uploaded file from cleaned_data
        uploaded_file = self.cleaned_data['invoice']
        # is this a valid image?
        try:
            # create an ImageField instance
            im = forms.ImageField()
            # now check if the file is a valid image
            im.to_python(uploaded_file)
        except forms.ValidationError:
            # file is not a valid image, so check if it's a pdf
            # do a deep copy so we dont mess with the file object we might be passing on
            testfile = copy.deepcopy(uploaded_file)
            # read the uploaded file into memory (the webserver limits uploads to a reasonable max size so this should be safe)
            mimetype = magic.from_buffer(testfile.open().read(), mime=True)
            if mimetype != "application/pdf":
                raise forms.ValidationError("Only images and PDF files allowed")

        # this is either a valid image, or has mimetype application/pdf, all good
        return uploaded_file


class ExpenseCreateForm(CleanInvoiceForm):
    class Meta:
        model = Expense
        fields = ['description', 'amount', 'invoice_date', 'invoice', 'paid_by_bornhack', 'responsible_team']


class ExpenseUpdateForm(forms.ModelForm):
    class Meta:
        model = Expense
        fields = ['description', 'amount', 'invoice_date', 'paid_by_bornhack', 'responsible_team']


class RevenueCreateForm(CleanInvoiceForm):
    class Meta:
        model = Revenue
        fields = ['description', 'amount', 'invoice_date', 'invoice', 'responsible_team']


class RevenueUpdateForm(forms.ModelForm):
    class Meta:
        model = Revenue
        fields = ['description', 'amount', 'invoice_date', 'responsible_team']