# Generate CSV files for models

import csv
from django.db.models.loading import get_model, get_apps, get_models
from django.db.models import BooleanField
from django.contrib.admin.views.decorators import staff_member_required
from django.http import Http404, HttpResponse
from django.shortcuts import render_to_response
from django.template.defaultfilters import yesno

__all__ = ( 'spreadsheet', )

def _field_extractor_function(field):
    """Return a function that extracts a given field from an instance of a model."""
    if field.choices:
        return (lambda o: getattr(o, 'get_%s_display' % field.name)())
    elif isinstance(field, BooleanField):
        return (lambda o: yesno(getattr(o, field.name), "Yes,No"))
    else:
        return (lambda o: str(getattr(o, field.name)))

@staff_member_required
def spreadsheet(request, app_label, model_name):
    """Return a CSV file for this table."""

    # Get the fields of the table
    model = get_model(app_label, model_name)
    if not model:
        raise Http404
    fields = model._meta.fields
    field_funcs = [ _field_extractor_function(f) for f in fields ]

    # set the HttpResponse
    response = HttpResponse(mimetype='text/csv')
    response['Content-Disposition'] = 'attachment; filename=%s-%s.csv' % (app_label, model_name)
    writer = csv.writer(response, quoting=csv.QUOTE_ALL)

    # Write the header of the CSV file
    writer.writerow([ f.verbose_name for f in fields ])

    # Write all rows of the CSV file
    for o in model.objects.all():
        writer.writerow([ func(o) for func in field_funcs ])

    # All done
    return response

# The URL for the spreadsheet
#
# urlpatterns += patterns('foo.utils.spreadsheets',
#     (r"^spreadsheets/(?P<app_label>\w+)/(?P<model_name>\w+)/$", "spreadsheet"), # Return a CSV file for this model
# )