# https://github.com/FineUploader/server-examples/blob/master/python/django-fine-uploader

from django.conf import settings
from django import forms
from django.forms import ClearableFileInput

import os, os.path
import tempfile
import shutil

__all__ = (
    'handle_upload', 'save_upload', 'FineUploadForm', 'FineUploadFileInput'
)


def combine_chunks(total_parts, total_size, source_folder, dest):
    if not os.path.exists(os.path.dirname(dest)):
        os.makedirs(os.path.dirname(dest))

    with open(dest, 'wb+') as destination:
        for i in range(total_parts):
            part = os.path.join(source_folder, str(i))
            with open(part, 'rb') as source:
                destination.write(source.read())


def save_upload(f, path):
    if not os.path.exists(os.path.dirname(path)):
        os.makedirs(os.path.dirname(path))
    with open(path, 'wb+') as destination:
        if hasattr(f, 'multiple_chunks') and f.multiple_chunks():
            for chunk in f.chunks():
                destination.write(chunk)
        else:
            destination.write(f.read())


# pass callback function to post_upload
def handle_upload(f, fileattrs, upload_dir, post_upload=None):
    chunks_dir = os.path.join(tempfile.gettempdir(), 'chunk_upload_tmp')
    if not os.path.exists(os.path.dirname(chunks_dir)):
        os.makedirs(os.path.dirname(chunks_dir))
    chunked = False
    dest_folder = upload_dir
    dest = os.path.join(dest_folder, fileattrs['qqfilename'])

    # Chunked
    if fileattrs.get('qqtotalparts') and int(fileattrs['qqtotalparts']) > 1:
        chunked = True
        dest_folder = os.path.join(chunks_dir, fileattrs['qquuid'])
        dest = os.path.join(dest_folder, fileattrs['qqfilename'], str(fileattrs['qqpartindex']))
    save_upload(f, dest)

    # If the last chunk has been sent, combine the parts.
    if chunked and (fileattrs['qqtotalparts'] - 1 == fileattrs['qqpartindex']):
        combine_chunks(fileattrs['qqtotalparts'],
            fileattrs['qqtotalfilesize'],
            source_folder=os.path.dirname(dest),
            dest=os.path.join(upload_dir, fileattrs['qqfilename']))
        shutil.rmtree(os.path.dirname(os.path.dirname(dest)))
    
    if post_upload and (not chunked or fileattrs['qqtotalparts'] - 1 == fileattrs['qqpartindex']):
        post_upload()


class FineUploadForm(forms.Form):
    qqfile = forms.FileField()
    qquuid = forms.CharField()
    qqfilename = forms.CharField()
    qqpartindex = forms.IntegerField(required=False)
    qqchunksize = forms.IntegerField(required=False)
    qqpartbyteoffset = forms.IntegerField(required=False)
    qqtotalfilesize = forms.IntegerField(required=False)
    qqtotalparts = forms.IntegerField(required=False)


class FineUploadFileInput(ClearableFileInput):
    template_name = 'widgets/fine_uploader.html'
    def fine_uploader_id(self, name):
        return name + '_' + 'fine_uploader'

    def get_context(self, name, value, attrs):
        context = super().get_context(name, value, attrs)
        context['widget'].update({
            'fine_uploader_id': self.fine_uploader_id(name),
        })
        return context