# hgweb/wsgicgi.py - CGI->WSGI translator

#

# Copyright 2006 Eric Hopper <hopper@omnifarious.org>

#

# This software may be used and distributed according to the terms

# of the GNU General Public License, incorporated herein by reference.

#

# This was originally copied from the public domain code at

# http://www.python.org/dev/peps/pep-0333/#the-server-gateway-side

import os, sys

def launch(application):

    environ = dict(os.environ.items())

    environ['wsgi.input']        = sys.stdin

    environ['wsgi.errors']       = sys.stderr

    environ['wsgi.version']      = (1,0)

    environ['wsgi.multithread']  = False

    environ['wsgi.multiprocess'] = True

    environ['wsgi.run_once']    = True

    if environ.get('HTTPS','off') in ('on','1'):

        environ['wsgi.url_scheme'] = 'https'

    else:

        environ['wsgi.url_scheme'] = 'http'

    headers_set = []

    headers_sent = []

    out = sys.stdout

    def write(data):

        if not headers_set:

             raise AssertionError("write() before start_response()")

        elif not headers_sent:

             # Before the first output, send the stored headers

             status, response_headers = headers_sent[:] = headers_set

             out.write('Status: %s\r\n' % status)

             for header in response_headers:

                 out.write('%s: %s\r\n' % header)

             out.write('\r\n')

        out.write(data)

        out.flush()

    def start_response(status,response_headers,exc_info=None):

        if exc_info:

            try:

                if headers_sent:

                    # Re-raise original exception if headers sent

                    raise exc_info[0], exc_info[1], exc_info[2]

            finally:

                exc_info = None     # avoid dangling circular ref

        elif headers_set:

            raise AssertionError("Headers already set!")

        headers_set[:] = [status,response_headers]

        return write

    result = application(environ, start_response)

    try:

        for data in result:

            if data:    # don't send headers until body appears

                write(data)

        if not headers_sent:

            write('')   # send headers now if body was empty

    finally:

        if hasattr(result,'close'):

            result.close()