#!/usr/bin/python
# -*- coding: utf-8 -*-

'''A simple to deploy WSGI webdav implementation.

Copyright 2010-2012 Petteri Aimonen <jpa@wd.mail.kapsi.fi>

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

   1. Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.

   2. Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.
'''

__program_name__ = 'EasyDAV'
__version__ = "0.5-dev"

import cgi
import kid
import kid.parser
import logging
import os
import os.path
import shutil
import sys
import tempfile
import zipfile

import davutils
from davutils import DAVError
from requestinfo import RequestInfo
from wsgi_input_wrapper import WSGIInputWrapper
import webdavconfig as config

def initialize_logging():
    '''Initialize python logging module based on configuration file.
    Mark completion by setting logging.log_init_done to True.
    '''
    formatter = logging.Formatter(
    '%(asctime)s %(process)d %(levelname)s %(message)s')
    
    logging.getLogger().setLevel(config.log_level)
    
    if config.log_file:
        mypath = os.path.dirname(os.path.abspath(__file__))
        logfile = os.path.join(mypath, config.log_file)
        filehandler = logging.FileHandler(filename = logfile)
        filehandler.setFormatter(formatter)
        logging.getLogger().addHandler(filehandler)
    
    if sys.stderr.isatty():
        streamhandler = logging.StreamHandler(sys.stderr)
        streamhandler.setFormatter(formatter)
        logging.getLogger().addHandler(streamhandler)
    
    logging.log_init_done = True

# Just initialize logs as soon as this module is imported.
if not hasattr(logging, 'log_init_done'):
    initialize_logging()

multistatus = kid.load_template('multistatus.kid')
dirindex = kid.load_template('dirindex.kid')
activelock = kid.load_template('activelock.kid')

def handle_options(reqinfo, start_response):
    '''Handle an OPTIONS request.'''
    reqinfo.assert_nobody()
    if reqinfo.lockmanager:
        start_response('200 OK', [('DAV', '1,2')])
    else:
        start_response('200 OK', [('DAV', '1')])
    return ""

def get_resourcetype(path):
    '''Return the contents for <DAV:resourcetype> property.'''
    if os.path.isdir(path):
        element = kid.parser.Element('{DAV:}collection')
        return kid.parser.ElementStream([
            (kid.parser.START, element),
            (kid.parser.END, element)
        ])
    else:
        return ''

def get_supportedlock(path):
    '''Return the contents for <DAV:supportedlock> property.'''
    if os.path.isdir(path):
        return kid.parser.XML('''
            <D:lockentry xmlns:D="DAV">
                <D:lockscope><D:exclusive /></D:lockscope>
                <D:locktype><D:write /></D:locktype>
            </D:lockentry>
            <D:lockentry xmlns:D="DAV">
                <D:lockscope><D:shared /></D:lockscope>
                <D:locktype><D:write /></D:locktype>
            </D:lockentry>
        ''')
    else:
        return ''

# All supported properties.
# Key is the element name inside DAV:prop element.
# Value is tuple of functions: (get, set)
# Get takes a file name and returns string.
# Set takes a file name and a string value.
# Set may be None to specify protected property.
property_handlers = {
    '{DAV:}creationdate': (
        lambda path: davutils.get_isoformat(os.path.getctime(path)),
        None
    ),
    '{DAV:}getcontentlength': (
        lambda path: str(os.path.getsize(path)),
        None
    ),
    '{DAV:}getetag': (
        davutils.create_etag,
        None
    ),
    '{DAV:}getlastmodified': (
        lambda path: davutils.get_rfcformat(os.path.getmtime(path)),
        davutils.set_mtime
    ),
    '{DAV:}getcontenttype': (
        davutils.get_mimetype,
        None
    ),
    '{DAV:}resourcetype': (
        get_resourcetype,
        None
    )
}

if config.lock_db is not None:
    property_handlers['{DAV:}supportedlock'] = (get_supportedlock, None)

def read_properties(real_path, requested):
    '''Return a propstats dictionary for the file specified by real_path.
    The argument 'requested' is either a list of property names,
    or the special value 'propname'.
    In the second case this function returns all defined properties but no
    values.
    '''
    propstats = {}
    
    if requested == 'propname':
        propstats['200 OK'] = []
        for propname in property_handlers.keys():
            propstats['200 OK'].append((propname, ''))
        return propstats
    
    for prop in requested:
        if not property_handlers.has_key(prop):
            davutils.add_to_dict_list(propstats, '404 Not Found: Property', (prop, ''))
            continue
        
        try:
            value = property_handlers[prop][0](real_path)
            davutils.add_to_dict_list(propstats, '200 OK', (prop, value))
        except Exception, e:
            logging.error('Property handler ' + repr(prop) + ' failed',
                exc_info = True)
            davutils.add_to_dict_list(propstats, '500 ' + str(e), (prop, ''))
    
    return propstats

def handle_propfind(reqinfo, start_response):
    '''Handle propfind request by listing files and their associated
    properties.
    '''
    depth = reqinfo.get_depth('infinity')
    request_props = reqinfo.parse_propfind_body(property_handlers.keys())
    real_path = reqinfo.get_request_path('r')
    
    result_files = []
    for path in davutils.search_directory(real_path, depth):
        try:
            reqinfo.assert_read(path)
        except DAVError, e:
            if e.httpstatus.startswith('403'):
                continue # Skip forbidden paths from listing
            raise
        
        real_url = reqinfo.get_url(path)
        propstats = read_properties(path, request_props)
        result_files.append((real_url, propstats))

    start_response('207 Multistatus',
        [('Content-Type', 'text/xml; charset=utf-8')])
    t = multistatus.Template(result_files = result_files)
    return [t.serialize(output = 'xml')]
     
def proppatch_verify_instruction(real_path, instruction):
    '''Verify that the property can be set on the file, or throw a DAVError.
    Used to verify instructions before they are executed.
    '''
    command, propname, propelement = instruction
    
    if command == 'set':
        if propelement.getchildren():
            raise DAVError('409 Conflict: XML property values are not supported')
        
        if not property_handlers.has_key(propname):
            raise DAVError('403 Forbidden: No such property')
        
        if property_handlers[propname][1] is None:
            raise DAVError('403 Forbidden',
                '<DAV:cannot-modify-protected-property/>')
    
    elif command == 'remove':
        # No properties to remove so far.
        raise DAVError('403 Forbidden: Properties cannot be removed')

def handle_proppatch(reqinfo, start_response):
    '''Modify properties on a single file.'''
    instructions = reqinfo.parse_proppatch()
    real_path = reqinfo.get_request_path('w')
    real_url = reqinfo.get_url(real_path)
    
    propstats = {}
    
    # Servers MUST process PROPPATCH instructions in
    # document order. Instructions MUST either all be
    # executed or none executed. (RFC4918)
    for instruction in instructions:
        try:
            proppatch_verify_instruction(real_path, instruction)
            davutils.add_to_dict_list(propstats, '200 OK', (instruction[1], ''))
        except DAVError, e:
            davutils.add_to_dict_list(propstats, e, (instruction[1], ''))
    
    if propstats.keys() != ['200 OK']:
        if propstats.has_key('200 OK'):
            propstats['424 Failed Dependency'] = propstats['200 OK']
            del propstats['200 OK']
    else:
        for command, propname, propelement in instructions:
            property_handlers[propname][1](real_path, propelement.text)
    
    start_response('207 Multistatus',
        [('Content-Type', 'text/xml; charset=utf-8')])
    t = multistatus.Template(result_files = [(real_url, propstats)])
    return [t.serialize(output = 'xml')]

def handle_put(reqinfo, start_response):
    '''Write to a single file, possibly replacing an existing one.'''
    real_path = reqinfo.get_request_path('w')
    
    if os.path.isdir(real_path):
        raise DAVError('405 Method Not Allowed: Overwriting directory')
    
    if os.path.exists(real_path):
        etag = davutils.create_etag(real_path)
    else:
        etag = None
    
    if not reqinfo.check_ifmatch(etag):
        raise DAVError('412 Precondition Failed')
    
    new_file = not os.path.exists(real_path)
    if not new_file:
        # Unlink the old file to reset mode bits.
        # This has the additional benefit that old GET operations can
        # continue even if the file is replaced.
        os.unlink(real_path)

    outfile = open(real_path, 'wb')
    block_generator = davutils.read_blocks(reqinfo.wsgi_input)
    davutils.write_blocks(outfile, block_generator)
    
    if new_file:
        start_response('201 Created', [])
    else:
        start_response('204 No Content', [])
    
    return ""

def handle_get(reqinfo, start_response):
    '''Download a single file or show directory index.'''
    reqinfo.assert_nobody()
    real_path = reqinfo.get_request_path('r')
    
    if os.path.isdir(real_path):
        return handle_dirindex(reqinfo, start_response)
    
    etag = davutils.create_etag(real_path)
    if not reqinfo.check_ifmatch(etag):
        raise DAVError('412 Precondition Failed')
    
    start_response('200 OK',
        [('Content-Type', davutils.get_mimetype(real_path)),
         ('Etag', etag),
         ('Content-Length', str(os.path.getsize(real_path))),
         ('Last-Modified', davutils.get_rfcformat(os.path.getmtime(real_path)))])
    
    if reqinfo.environ['REQUEST_METHOD'] == 'HEAD':
        return ''
    
    infile = open(real_path, 'rb')
    return davutils.read_blocks(infile)

def handle_mkcol(reqinfo, start_response):
    '''Create a new directory.'''
    reqinfo.assert_nobody()
    real_path = reqinfo.get_request_path('w')
    
    if os.path.exists(real_path):
        raise DAVError('405 Method Not Allowed: Collection already exists')

    os.mkdir(real_path)
    
    start_response('201 Created', [])
    return ""

def purge_locks(lockmanager, real_path):
    '''Remove all locks when a resource is moved or removed.'''
    rel_path = davutils.get_relpath(real_path, config.root_dir)
    
    for lock in lockmanager.get_locks(rel_path, True):
        if not davutils.path_inside_directory(lock.path, rel_path):
            continue
        lockmanager.release_lock(lock.path, lock.urn)

def handle_delete(reqinfo, start_response):
    '''Delete a file or a directory.'''
    reqinfo.assert_nobody()
    real_path = reqinfo.get_request_path('wd')
    
    # Locks on parent directory prohibit deletion of members.
    reqinfo.assert_locks(os.path.dirname(real_path))
    
    if not os.path.exists(real_path):
        raise DAVError('404 Not Found')
    
    if os.path.isdir(real_path):
        shutil.rmtree(real_path)
    else:
        os.unlink(real_path)
    
    purge_locks(reqinfo.lockmanager, real_path)
    
    start_response('204 No Content', [])
    return ""

def handle_copy_move(reqinfo, start_response):
    '''Copy or move a file or a directory.'''
    reqinfo.assert_nobody()
    depth = reqinfo.get_depth()
    real_source = reqinfo.get_request_path('r')
    real_dest = reqinfo.get_destination_path('w')
    
    new_resource = not os.path.exists(real_dest)
    if not new_resource:
        if not reqinfo.get_overwrite():
            raise DAVError('412 Precondition Failed: Would overwrite')
        elif os.path.isdir(real_dest):
            shutil.rmtree(real_dest)
        else:
            os.unlink(real_dest)
    
    if reqinfo.environ['REQUEST_METHOD'] == 'COPY':
        if os.path.isdir(real_source):
            if depth == 0:
                os.mkdir(real_dest)
                shutil.copystat(real_source, real_dest)
            else:
                shutil.copytree(real_source, real_dest, symlinks = True)
        else:
            shutil.copy2(real_source, real_dest)
    else:
        real_source = reqinfo.get_request_path('wd')
        shutil.move(real_source, real_dest)
        purge_locks(reqinfo.lockmanager, real_source)
    
    if new_resource:
        start_response('201 Created', [])
    else:
        start_response('204 No Content', [])
    return ""    

def handle_lock(reqinfo, start_response):
    '''Create a lock or refresh an existing one.'''
    timeout = reqinfo.get_timeout()
    depth = reqinfo.get_depth()
    real_path = reqinfo.get_request_path('wl')
    rel_path = davutils.get_relpath(real_path, config.root_dir)
    
    if not reqinfo.lockmanager:
        raise DAVError('501 Not Implemented: Lock support disabled')

    if not reqinfo.length:
        # Handle lock refresh
        lock = reqinfo.lockmanager.refresh_lock(rel_path,
            reqinfo.provided_tokens[0][1], timeout)
    else:
        # Create new lock
        shared, owner = reqinfo.parse_lock_body()
        lock = reqinfo.lockmanager.create_lock(rel_path,
            shared, owner, depth, timeout)
    
    if not os.path.exists(real_path):
        status = "201 Created"
        open(real_path, 'w').write('')
    else:
        status = "200 OK"
    
    start_response(status,
        [('Content-Type', 'text/xml; charset=utf-8'),
         ('Lock-Token', lock.urn)])
    t = activelock.Template(lock = lock, reqinfo = reqinfo,
        part_only = False)
    return [t.serialize(output = 'xml')]

def handle_unlock(reqinfo, start_response):
    '''Remove an existing lock.'''
    real_path = reqinfo.get_request_path('r')
    rel_path = davutils.get_relpath(real_path, config.root_dir)
    urn = reqinfo.environ.get('HTTP_LOCK_TOKEN', '').strip(' <>')

    if not reqinfo.lockmanager:
        raise DAVError('501 Not implemented: Lock support disabled')    

    reqinfo.lockmanager.release_lock(rel_path, urn)
    start_response('204 No Content', [])
    return ""

def handle_dirindex(reqinfo, start_response, message = None):
    '''Handle a GET request for a directory.
    Result is unimportant for DAV clients and only ment for WWW browsers.
    '''
    
    if 'r' not in config.html_interface:
        start_response('200 OK', [('Content-Type', 'text/html; charset=utf-8')])
        return ['<html><body><p>Mount this directory using WebDAV.</p>' +
                '<p>HTML interface is currently disabled.</p>' +
                '<p>' + __program_name__ + ' ' + __version__ + '</p>']
    
    real_path = reqinfo.get_request_path('r')
    real_url = reqinfo.get_url(real_path)
    
    # No parent directory link in repository root
    has_parent = (reqinfo.root_url.rstrip('/') != real_url.rstrip('/'))
    
    # Check whether to allow file upload.
    try:
        reqinfo.assert_write(real_path)
        can_write = 'w' in config.html_interface
    except DAVError:
        can_write = False
    
    files = os.listdir(real_path)
    for filename in files:
        try:
            reqinfo.assert_read(os.path.join(real_path, filename))
        except DAVError, e:
            if e.httpstatus.startswith('403'):
                files.remove(filename) # Remove forbidden files from listing
    
    files.sort(key = lambda f: not os.path.isdir(os.path.join(real_path, f)))
    
    start_response('200 OK', [('Content-Type', 'text/html; charset=utf-8')])
    t = dirindex.Template(
        real_url = real_url, real_path = real_path, reqinfo = reqinfo,
        files = files, has_parent = has_parent, message = message,
        can_write = can_write
    )
    return [t.serialize(output = 'xhtml')]

def handle_post(reqinfo, start_response):
    '''Handle a POST request.
    Used for file uploads and deletes in the HTML GUI.
    '''
    if 'w' not in config.html_interface:
        raise DAVError('403 HTML interface is configured as read-only')
    
    fields = cgi.FieldStorage(fp = reqinfo.wsgi_input, environ = reqinfo.environ)
    real_path = reqinfo.get_request_path('r')
    message = ""
    
    if fields.getfirst('file'):
        f = fields['file']
        dest_path = os.path.join(real_path, f.filename)
        reqinfo.assert_write(dest_path)
        
        if os.path.isdir(dest_path):
            raise DAVError('405 Method Not Allowed: Overwriting directory')
    
        if os.path.exists(dest_path):
            os.unlink(dest_path)
        
        outfile = open(dest_path, 'wb')
        davutils.write_blocks(outfile, davutils.read_blocks(f.file))
        
        message = "Successfully uploaded " + f.filename + "."
    
    if fields.getfirst('btn_remove'):
        filenames = fields.getlist('select')
        
        for f in filenames:
            rm_path = os.path.join(real_path, f)
            reqinfo.assert_write(rm_path)
            
            if os.path.isdir(rm_path):
                shutil.rmtree(rm_path)
            else:
                os.unlink(rm_path)
        
        message = "Successfully removed " + str(len(filenames)) + " files."
    
    if fields.getfirst('btn_download'):
        filenames = fields.getlist('select')
        datafile = tempfile.TemporaryFile()
        zipobj = zipfile.ZipFile(datafile, 'w', zipfile.ZIP_DEFLATED, True)
        
        def check_read(path):
            '''Callback function for zipping to verify that each file in
            the zip has access rights.'''
            try:
                reqinfo.assert_read(path)
                return True
            except DAVError:
                return False
        
        for f in filenames:
            file_path = os.path.join(real_path, f)
            reqinfo.assert_read(file_path)
            davutils.add_to_zip_recursively(zipobj, file_path,
                config.root_dir, check_read)
        
        zipobj.close()
        
        start_response('200 OK', [
            ('Content-Type', 'application/zip'),
            ('Content-Length', str(datafile.tell()))
        ])
        
        datafile.seek(0)
        return davutils.read_blocks(datafile)
    
    return handle_dirindex(reqinfo, start_response, message)

request_handlers = {
    'OPTIONS': handle_options,
    'PROPFIND': handle_propfind,
    'PROPPATCH': handle_proppatch,
    'GET': handle_get,
    'HEAD': handle_get,
    'PUT': handle_put,
    'MKCOL': handle_mkcol,
    'DELETE': handle_delete,
    'COPY': handle_copy_move,
    'MOVE': handle_copy_move,
    'LOCK': handle_lock,
    'UNLOCK': handle_unlock,
    'POST': handle_post,
}

def main(environ, start_response):
    '''Main WSGI program to handle requests. Calls handlers from
    request_handlers.
    '''
    try:
        logging.info(environ.get('REMOTE_ADDR')
            + ' ' + environ.get('REQUEST_METHOD')
            + ' ' + environ.get('PATH_INFO'))
        
        request_method = environ.get('REQUEST_METHOD', '').upper()
        
        if environ.get('HTTP_EXPECT') and __name__ == '__main__':
            # Expect should work with fcgi etc., but not with the simple_server
            # that is used for testing.
            start_response('400 Bad Request: Expect not supported', [])
            return ""
        
        environ['wsgi.input'] = WSGIInputWrapper(environ)
        
        try:
            reqinfo = RequestInfo(environ)
            if request_handlers.has_key(request_method):
                return request_handlers[request_method](reqinfo, start_response)
            else:
                raise DAVError('501 Not Implemented')
        except DAVError, e:
            environ['wsgi.input'].read() # Discard request body
            if not e.body:
                logging.warn(e.httpstatus)
                start_response(e.httpstatus, [('Content-Type', 'text/plain')])
                return [e.httpstatus]
            else:
                logging.warn(e.httpstatus + ' ' + e.body)
                start_response(e.httpstatus, [('Content-Type', 'text/xml')])
                return [e.body]
    except:
        import traceback
        
        exc = traceback.format_exc()
        logging.error('Request handler crashed', exc_info = 1)
        
        if isinstance(environ['wsgi.input'], WSGIInputWrapper):
            environ['wsgi.input'].read()
        
        try:
            start_response('500 Internal Server Error',
                [('Content-Type', 'text/plain')])
        except AssertionError:
            # Ignore duplicate start_response
            pass
        
        return [exc]

if __name__ == '__main__':
    from wsgiref.simple_server import make_server
    server = make_server('localhost', 8080, main)
    server.serve_forever()