wsgiapp.py

# wsgiapp.py - tiny web service wrapper. URL dispatch; req/resp objects; logging; static
# files, genshi templates, json and repr data; plays nice with mod_wsgi. 99 lines of code.
# http://grep.ro/blog/2009/06/python_web_service

from os import path
app_root_fspath = path.dirname(__file__)

# mod_wsgi: we need the virtualenv site-packages, and our current folder, on sys.path
import site
site.addsitedir(path.join(app_root_fspath,
    '../python-2.5/lib/python2.5/site-packages'))
site.addsitedir(app_root_fspath)

import devel_monitor # auto-reloader (code at http://bit.ly/mod_wsgi_code_changes)
devel_monitor.start(interval=1.0)

from cStringIO import StringIO
import logging
try:
    import json
except ImportError:
    import simplejson as json
from werkzeug import Request, Response, SharedDataMiddleware
from werkzeug.routing import Map, Rule
from werkzeug.exceptions import NotFound, BadRequest
from genshi.template import TemplateLoader

import css_diff # the "busines logic"

genshi_templates = TemplateLoader(app_root_fspath, auto_reload=True)

def JsonResponse(data):
    return Response(json.dumps(data), mimetype='application/json')

def ReprResponse(data):
    return Response(repr(data), mimetype='text/plain')

def GenshiResponse(template_fname, **args):
    template = genshi_templates.load(template_fname)
    html = template.generate(**args).render()
    return Response(html, mimetype='text/html')

def read_file(fname):
    f = open(path.join(app_root_fspath, fname))
    data = f.read()
    f.close()
    return data

def staticfile_view(request, thefile):
    if thefile == 'index':
        return Response(read_file('index.html'), mimetype='text/html')
    elif thefile == 'zopext':
        return Response(read_file('Naaya.cssfixer.py'), mimetype='text/plain')
    else:
        raise ValueError("Don't know how to serve file \"%s\"" % thefile)

def css_diff_view(request):
    # process request, set up logging
    if request.method != 'POST':
        raise BadRequest("please use POST")
    default_css = request.form.get('default_css')
    current_css = request.form.get('current_css')
    output_format = request.args.get('format')
    if default_css is None:
        raise BadRequest("missing POST parameter default_css")
    if current_css is None:
        raise BadRequest("missing POST parameter current_css")

    log_data = StringIO()
    log_handler = logging.StreamHandler(log_data)
    css_diff.log.addHandler(log_handler)

    # run the actual method
    result = css_diff.study_css(default_css, current_css)

    # tear down logger, compose response
    css_diff.log.removeHandler(log_handler)

    if output_format == 'log':
        return Response(log_data.getvalue(), mimetype='text/plain')
    elif output_format == 'html':
        return GenshiResponse('css_diff_out.html',
            log_data=log_data.getvalue(), **result)
    elif output_format == 'json':
        return JsonResponse(result)
    else:
        return ReprResponse(result)

url_map = Map([
    Rule('/', endpoint=staticfile_view, defaults={'thefile': 'index'}),
    Rule('/Naaya.cssfixer.py', endpoint=staticfile_view, defaults={'thefile': 'zopext'}),
    Rule('/css_diff', endpoint=css_diff_view),
])

@Request.application
def application(request):
    return url_map.bind_to_environ(request.environ).dispatch(
        lambda view, params: view(request, **params), catch_http_exceptions=True)