# hgweb/common.py - Utility functions needed by hgweb_mod and hgwebdir_mod

#

# Copyright 21 May 2005 - (c) 2005 Jake Edge <jake@edge2.net>

# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>

#

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

# GNU General Public License version 2 or any later version.

import errno, mimetypes, os

HTTP_OK = 200

HTTP_NOT_MODIFIED = 304

HTTP_BAD_REQUEST = 400

HTTP_UNAUTHORIZED = 401

HTTP_FORBIDDEN = 403

HTTP_NOT_FOUND = 404

HTTP_METHOD_NOT_ALLOWED = 405

HTTP_SERVER_ERROR = 500

# Hooks for hgweb permission checks; extensions can add hooks here. Each hook

# is invoked like this: hook(hgweb, request, operation), where operation is

# either read, pull or push. Hooks should either raise an ErrorResponse

# exception, or just return.

# It is possible to do both authentication and authorization through this.

permhooks = []

def checkauthz(hgweb, req, op):

    '''Check permission for operation based on request data (including

    authentication info). Return if op allowed, else raise an ErrorResponse

    exception.'''

    user = req.env.get('REMOTE_USER')

    deny_read = hgweb.configlist('web', 'deny_read')

    if deny_read and (not user or deny_read == ['*'] or user in deny_read):

        raise ErrorResponse(HTTP_UNAUTHORIZED, 'read not authorized')

    allow_read = hgweb.configlist('web', 'allow_read')

    result = (not allow_read) or (allow_read == ['*'])

    if not (result or user in allow_read):

        raise ErrorResponse(HTTP_UNAUTHORIZED, 'read not authorized')

    if op == 'pull' and not hgweb.allowpull:

        raise ErrorResponse(HTTP_UNAUTHORIZED, 'pull not authorized')

    elif op == 'pull' or op is None: # op is None for interface requests

        return

    # enforce that you can only push using POST requests

    if req.env['REQUEST_METHOD'] != 'POST':

        msg = 'push requires POST request'

        raise ErrorResponse(HTTP_METHOD_NOT_ALLOWED, msg)

    # require ssl by default for pushing, auth info cannot be sniffed

    # and replayed

    scheme = req.env.get('wsgi.url_scheme')

    if hgweb.configbool('web', 'push_ssl', True) and scheme != 'https':

        raise ErrorResponse(HTTP_OK, 'ssl required')

    deny = hgweb.configlist('web', 'deny_push')

    if deny and (not user or deny == ['*'] or user in deny):

        raise ErrorResponse(HTTP_UNAUTHORIZED, 'push not authorized')

    allow = hgweb.configlist('web', 'allow_push')

    result = allow and (allow == ['*'] or user in allow)

    if not result:

        raise ErrorResponse(HTTP_UNAUTHORIZED, 'push not authorized')

# Add the default permhook, which provides simple authorization.

permhooks.append(checkauthz)

class ErrorResponse(Exception):

    def __init__(self, code, message=None, headers=[]):

        Exception.__init__(self)

        self.code = code

        self.headers = headers

        if message is not None:

            self.message = message

        else:

            self.message = _statusmessage(code)

def _statusmessage(code):

    from BaseHTTPServer import BaseHTTPRequestHandler

    responses = BaseHTTPRequestHandler.responses

    return responses.get(code, ('Error', 'Unknown error'))[0]

def statusmessage(code, message=None):

    return '%d %s' % (code, message or _statusmessage(code))

def get_mtime(spath):

    cl_path = os.path.join(spath, "00changelog.i")

    if os.path.exists(cl_path):

        return os.stat(cl_path).st_mtime

    else:

        return os.stat(spath).st_mtime

def staticfile(directory, fname, req):

    """return a file inside directory with guessed Content-Type header

    fname always uses '/' as directory separator and isn't allowed to

    contain unusual path components.

    Content-Type is guessed using the mimetypes module.

    Return an empty string if fname is illegal or file not found.

    """

    parts = fname.split('/')

    for part in parts:

        if (part in ('', os.curdir, os.pardir) or

            os.sep in part or os.altsep is not None and os.altsep in part):

            return ""

    fpath = os.path.join(*parts)

    if isinstance(directory, str):

        directory = [directory]

    for d in directory:

        path = os.path.join(d, fpath)

        if os.path.exists(path):

            break

    try:

        os.stat(path)

        ct = mimetypes.guess_type(path)[0] or "text/plain"

        req.respond(HTTP_OK, ct, length = os.path.getsize(path))

        return open(path, 'rb').read()

    except TypeError:

        raise ErrorResponse(HTTP_SERVER_ERROR, 'illegal filename')

    except OSError, err:

        if err.errno == errno.ENOENT:

            raise ErrorResponse(HTTP_NOT_FOUND)

        else:

            raise ErrorResponse(HTTP_SERVER_ERROR, err.strerror)

def paritygen(stripecount, offset=0):

    """count parity of horizontal stripes for easier reading"""

    if stripecount and offset:

        # account for offset, e.g. due to building the list in reverse

        count = (stripecount + offset) % stripecount

        parity = (stripecount + offset) / stripecount & 1

    else:

        count = 0

        parity = 0

    while True:

        yield parity

        count += 1

        if stripecount and count >= stripecount:

            parity = 1 - parity

            count = 0

def get_contact(config):

    """Return repo contact information or empty string.

    web.contact is the primary source, but if that is not set, try

    ui.username or $EMAIL as a fallback to display something useful.

    """

    return (config("web", "contact") or

            config("ui", "username") or

            os.environ.get("EMAIL") or "")

def caching(web, req):

    tag = str(web.mtime)

    if req.env.get('HTTP_IF_NONE_MATCH') == tag:

        raise ErrorResponse(HTTP_NOT_MODIFIED)

    req.headers.append(('ETag', tag))