#!/usr/local/bin/python

import os,sys

import re
import string

from fedd_util import *
from fedd_access_project import access_project

# Used to report errors parsing the configuration files, not in providing
# service
class parse_error(RuntimeError): pass

class config_file:
    """
    The implementation of access control based on mapping users to projects.

    Users can be mapped to existing projects or have projects created
    dynamically.  This implements both direct requests and proxies.
    """
    # Attributes that can be parsed from the configuration file
    bool_attrs = ("dynamic_projects", "project_priority", "create_debug")
    emulab_attrs = ("boss", "ops", "domain", "fileserver", "eventserver")
    id_attrs = ("testbed", "cert_file", "cert_pwd", "trusted_certs", "proxy",
	    "proxy_cert_file", "proxy_cert_pwd", "proxy_trusted_certs",
	    "dynamic_projects_url", "dynamic_projects_cert_file", 
	    "dynamic_projects_cert_pwd", "dynamic_projects_trusted_certs",
	    "create_experiment_cert_file", "create_experiment_cert_pwd",
	    "create_experiment_trusted_certs", "federation_script_dir",
	    "ssh_pubkey_file", "experiment_state_file")
    id_list_attrs = ("restricted",)


    def __init__(self, config=None):
	"""
	Initializer.  Parses a configuration if one is given.
	"""

	# Create instance attributes from the static lists
	for a in config_file.bool_attrs:
	    setattr(self, a, False)

	for a in config_file.emulab_attrs + config_file.id_attrs:
	    setattr(self, a, None)
	
	for a in config_file.id_list_attrs:
	    setattr(self, a, [])

	self.attrs = { }
	self.fedid_category = { }
	self.fedid_default = "user"
	self.access = { }

	if config:
	    self.read_config(config)

    def read_trust(self, trust):
	"""
	Read a trust file that splits fedids into testbeds, users or projects

	Format is:

	[type]
	fedid
	fedid
	default: type
	"""
	lineno = 0;
	cat = None
	cat_re = re.compile("\[(user|testbed|project)\]$", re.IGNORECASE)
	fedid_re = re.compile("[" + string.hexdigits + "]+$")
	default_re = re.compile("default:\s*(user|testbed|project)$", 
		re.IGNORECASE)

	f = open(trust, "r")
	for line in f:
	    lineno += 1
	    line = line.strip()
	    if len(line) == 0 or line.startswith("#"):
		continue
	    # Category line
	    m = cat_re.match(line)
	    if m != None:
		cat = m.group(1).lower()
		continue
	    # Fedid line
	    m = fedid_re.match(line)
	    if m != None:
		if cat != None:
		    self.fedid_category[fedid(hexstr=m.string)] = cat
		else:
		    raise parse_error(\
			    "Bad fedid in trust file (%s) line: %d" % \
			    (trust, lineno))
		continue
	    # default line
	    m = default_re.match(line)
	    if m != None:
		self.fedid_default = m.group(1).lower()
		continue
	    # Nothing matched - bad line, raise exception
	    f.close()
	    raise parse_error(\
		    "Unparsable line in trustfile %s line %d" % (trust, lineno))
	f.close()

    def read_config(self, config):
	"""
	Read a configuration file and set internal parameters.

	The format is more complex than one might hope.  The basic format is
	attribute value pairs separated by colons(:) on a signle line.  The
	attributes in bool_attrs, emulab_attrs and id_attrs can all be set
	directly using the name: value syntax.  E.g. 
	boss: hostname
	sets self.boss to hostname.  In addition, there are access lines of the
	form (tb, proj, user) -> (aproj, auser) that map the first tuple of
	names to the second for access purposes.  Names in the key (left side)
	can include "<NONE> or <ANY>" to act as wildcards or to require the
	fields to be empty.  Similarly aproj or auser can be <SAME> or
	<DYNAMIC> indicating that either the matching key is to be used or a
	dynamic user or project will be created.  These names can also be
	federated IDs (fedid's) if prefixed with fedid:.  Finally, the aproj
	can be followed with a colon-separated list of node types to which that
	project has access (or will have access if dynamic).
	Testbed attributes outside the forms above can be given using the
	format attribute: name value: value.  The name is a single word and the
	value continues to the end of the line.  Empty lines and lines startin
	with a # are ignored.

	Parsing errors result in a parse_error exception being raised.
	"""
	lineno=0
	name_expr = "["+string.ascii_letters + string.digits + "\.\-_]+"
	fedid_expr = "fedid:[" + string.hexdigits + "]+"
	key_name = "(<ANY>|<NONE>|"+fedid_expr + "|"+ name_expr + ")"
	access_proj = "(<DYNAMIC>(?::" + name_expr +")*|"+ \
		"<SAME>" + "(?::" + name_expr + ")*|" + \
		fedid_expr + "(?::" + name_expr + ")*|" + \
		name_expr + "(?::" + name_expr + ")*)"
	access_name = "(<DYNAMIC>|<SAME>|" + fedid_expr + "|"+ name_expr + ")"

	bool_re = re.compile('(' + '|'.join(config_file.bool_attrs) + 
		'):\s+(true|false)', re.IGNORECASE)
	string_re = re.compile( "(" + \
		'|'.join(config_file.emulab_attrs + config_file.id_attrs) + \
		'):\s*(.*)', re.IGNORECASE)
	list_re = re.compile("(" + '|'.join(config_file.id_list_attrs) + \
		"):\s*(.*)", re.IGNORECASE)
	attr_re = re.compile('attribute:\s*([\._\-a-z0-9]+)\s+value:\s*(.*)',
		re.IGNORECASE)
	access_re = re.compile('\('+key_name+'\s*,\s*'+key_name+'\s*,\s*'+
		key_name+'\s*\)\s*->\s*\('+access_proj + '\s*,\s*' + 
		access_name + '\s*\)', re.IGNORECASE)
	trustfile_re = re.compile("trustfile:\s*(.*)", re.IGNORECASE)

	def parse_name(n):
	    if n.startswith('fedid:'): return fedid(n[len('fedid:'):])
	    else: return n

	f = open(config, "r");
	for line in f:
	    lineno += 1
	    line = line.strip();
	    if len(line) == 0 or line.startswith('#'):
		continue

	    # Boolean attribute line
	    m = bool_re.match(line);
	    if m != None:
		attr, val = m.group(1,2)
		setattr(self, attr.lower(), bool(val.lower() == "true"))
		continue

	    # String attribute line
	    m = string_re.match(line)
	    if m != None:
		attr, val = m.group(1,2)
		setattr(self, attr.lower(), val)
		continue

	    # List attributes
	    m = list_re.match(line)
	    if m != None:
		attr, val = m.group(1,2)
		l = getattr(self, attr.lower())
		l.append(val)
		continue


	    # Extended (attribute: x value: y) attribute line
	    m = attr_re.match(line)
	    if m != None:
		attr, val = m.group(1,2)
		self.attrs[attr] = val
		continue

	    # Access line (t, p, u) -> (ap, au) line
	    m = access_re.match(line)
	    if m != None:
		access_key = tuple([ parse_name(x) for x in m.group(1,2,3)])
		aps = m.group(4).split(":");
		if aps[0] == 'fedid:':
		    del aps[0]
		    aps[0] = fedid(hexstr=aps[0])

		au = m.group(5)
		if au.startswith("fedid:"):
		    au = fedid(hexstr=aus[len("fedid:"):])

		access_val = (access_project(aps[0], aps[1:]), au)

		self.access[access_key] = access_val
		continue

	    # Trustfile inclusion
	    m = trustfile_re.match(line)
	    if m != None:
		self.read_trust(m.group(1))
		continue

	    # Nothing matched to here: unknown line - raise exception
	    f.close()
	    raise parse_error("Unknown statement at line %d of %s" % \
		    (lineno, config))
	f.close()

if __name__ == '__main__':
    if sys.argv[1]:
	config = config_file(sys.argv[1])
	for a in [ a for a in dir(config) if a[0] != '_'  \
		and not callable(getattr(config,a))]:
	    print "%s: %s" % (a, getattr(config, a))