from twisted.internet import defer
from util import PappyException
import http
import shlex


"""
context.py

Functions and classes involved with managing the current context and filters
"""

scope = []
base_filters = []
active_filters = []
active_requests = []

class FilterParseError(PappyException):
    pass

class Filter(object):

    def __init__(self, filter_string):
        self.filter_func = self.from_filter_string(filter_string)
        self.filter_string = filter_string

    def __call__(self, *args, **kwargs):
        return self.filter_func(*args, **kwargs)

    @staticmethod
    def from_filter_string(filter_string):
        args = shlex.split(filter_string)
        field = args[0]
        relation = args[1]
        new_filter = None

        negate = False
        if relation[0] == 'n' and len(relation) > 1:
            negate = True
            relation = relation[1:]

        # Raises exception if invalid
        comparer = get_relation(relation)

        if field in ("all",):
            new_filter = gen_filter_by_all(comparer, args[2], negate)
        elif field in ("host", "domain", "hs", "dm"):
            new_filter = gen_filter_by_host(comparer, args[2], negate)
        elif field in ("path", "pt"):
            new_filter = gen_filter_by_path(comparer, args[2], negate)
        elif field in ("body", "bd", "data", "dt"):
            new_filter = gen_filter_by_body(comparer, args[2], negate)
        elif field in ("verb", "vb"):
            new_filter = gen_filter_by_verb(comparer, args[2], negate)
        elif field in ("param", "pm"):
            if len(args) > 4:
                comparer2 = get_relation(args[3])
                new_filter = gen_filter_by_params(comparer, args[2],
                                                  comparer2, args[4], negate)
            else:
                new_filter = gen_filter_by_params(comparer, args[2],
                                                  negate=negate)
        elif field in ("header", "hd"):
            if len(args) > 4:
                comparer2 = get_relation(args[3])
                new_filter = gen_filter_by_headers(comparer, args[2],
                                                   comparer2, args[4], negate)
            else:
                new_filter = gen_filter_by_headers(comparer, args[2],
                                                   negate=negate)
        elif field in ("rawheaders", "rh"):
            new_filter = gen_filter_by_raw_headers(comparer, args[2], negate)
        elif field in ("sentcookie", "sck"):
            if len(args) > 4:
                comparer2 = get_relation(args[3])
                new_filter = gen_filter_by_submitted_cookies(comparer, args[2],
                                                             comparer2, args[4], negate)
            else:
                new_filter = gen_filter_by_submitted_cookies(comparer, args[2],
                                                             negate=negate)
        elif field in ("setcookie", "stck"):
            if len(args) > 4:
                comparer2 = get_relation(args[3])
                new_filter = gen_filter_by_set_cookies(comparer, args[2],
                                                       comparer2, args[4], negate)
            else:
                new_filter = gen_filter_by_set_cookies(comparer, args[2],
                                                       negate=negate)
        elif field in ("statuscode", "sc", "responsecode"):
            new_filter = gen_filter_by_response_code(comparer, args[2], negate)
        elif field in ("responsetime", "rt"):
            pass
        else:
            raise FilterParseError("%s is not a valid field" % field)

        if new_filter is not None:
            return new_filter
        else:
            raise FilterParseError("Error creating filter")


def filter_reqs(requests, filters):
    to_delete = []
    # Could definitely be more efficient, but it stays like this until
    # it impacts performance
    for filt in filters:
        for req in requests:
            if not filt(req):
                to_delete.append(req)
        new_requests = [r for r in requests if r not in to_delete]
        requests = new_requests
        to_delete = []
    return requests

def cmp_is(a, b):
    return str(a) == str(b)

def cmp_contains(a, b):
    return (b.lower() in a.lower())

def cmp_exists(a, b=None):
    return (a is not None)

def cmp_len_eq(a, b):
    return (len(a) == int(b))

def cmp_len_gt(a, b):
    return (len(a) > int(b))

def cmp_len_lt(a, b):
    return (len(a) < int(b))

def cmp_eq(a, b):
    return (int(a) == int(b))

def cmp_gt(a, b):
    return (int(a) > int(b))

def cmp_lt(a, b):
    return (int(a) < int(b))


def gen_filter_by_attr(comparer, val, attr, negate=False):
    """
    Filters by an attribute whose name is shared by the request and response
    objects
    """
    def f(req):
        req_match = comparer(getattr(req, attr), val)
        if req.response:
            rsp_match = comparer(getattr(req.response, attr), val)
        else:
            rsp_match = False

        result = req_match or rsp_match
        if negate:
            return not result
        else:
            return result

    return f

def gen_filter_by_all(comparer, val, negate=False):
    def f(req):
        req_match = comparer(req.full_request, val)
        if req.response:
            rsp_match = comparer(req.response.full_response, val)
        else:
            rsp_match = False

        result = req_match or rsp_match
        if negate:
            return not result
        else:
            return result

    return f

def gen_filter_by_host(comparer, val, negate=False):
    def f(req):
        result = comparer(req.host, val)
        if negate:
            return not result
        else:
            return result

    return f

def gen_filter_by_body(comparer, val, negate=False):
    return gen_filter_by_attr(comparer, val, 'raw_data', negate=negate)

def gen_filter_by_raw_headers(comparer, val, negate=False):
    return gen_filter_by_attr(comparer, val, 'raw_headers', negate=negate)

def gen_filter_by_response_code(comparer, val, negate=False):
    def f(req):
        if req.response:
            result = comparer(req.response.response_code, val)
        else:
            result = False
        if negate:
            return not result
        else:
            return result

    return f
        
def gen_filter_by_path(comparer, val, negate=False):
    def f(req):
        result = comparer(req.path, val)
        if negate:
            return not result
        else:
            return result

    return f

def gen_filter_by_responsetime(comparer, val, negate=False):
    def f(req):
        result = comparer(req.rsptime, val)
        if negate:
            return not result
        else:
            return result

    return f

def gen_filter_by_verb(comparer, val, negate=False):
    def f(req):
        result = comparer(req.verb, val)
        if negate:
            return not result
        else:
            return result

    return f

def check_repeatable_dict(d, comparer1, val1, comparer2=None, val2=None, negate=False):
    result = False
    for k, v in d.all_pairs():
        if comparer2:
            key_matches = comparer1(k, val1)
            val_matches = comparer2(v, val2)
            if key_matches and val_matches:
                result = True
                break
        else:
            # We check if the first value matches either
            key_matches = comparer1(k, val1)
            val_matches = comparer1(v, val1)
            if key_matches or val_matches:
                result = True
                break
    if negate:
        return not result
    else:
        return result

def gen_filter_by_repeatable_dict_attr(attr, keycomparer, keyval, valcomparer=None,
                                       valval=None, negate=False, check_req=True,
                                       check_rsp=True):
    def f(req):
        matched = False
        d = getattr(req, attr)
        if check_req and check_repeatable_dict(d, keycomparer, keyval, valcomparer, valval):
            matched = True
        if check_rsp and req.response:
            d = getattr(req.response, attr)
            if check_repeatable_dict(d, keycomparer, keyval, valcomparer, valval):
                matched = True
        if negate:
            return not matched
        else:
            return matched

    return f

def gen_filter_by_headers(keycomparer, keyval, valcomparer=None, valval=None,
                          negate=False):
    return gen_filter_by_repeatable_dict_attr('headers', keycomparer, keyval,
                                              valcomparer, valval, negate=negate)

def gen_filter_by_submitted_cookies(keycomparer, keyval, valcomparer=None,
                                    valval=None, negate=False):
    return gen_filter_by_repeatable_dict_attr('cookies', keycomparer, keyval,
                                              valcomparer, valval, negate=negate,
                                              check_rsp=False)

def gen_filter_by_set_cookies(keycomparer, keyval, valcomparer=None,
                              valval=None, negate=False):
    def f(req):
        if not req.response:
            return False

        for k, c in req.response.cookies.all_pairs():
            if keycomparer(c.key, keyval):
                if not valcomparer:
                    return True
                else:
                    if valcomparer(c.val, valval):
                        return True
                
        return False

    return f

def gen_filter_by_get_params(keycomparer, keyval, valcomparer=None, valval=None,
                         negate=False):
    def f(req):
        matched = False
        for k, v in req.get_params.all_pairs():
            if keycomparer(k, keyval):
                if not valcomparer:
                    matched = True
                else:
                    if valcomparer(v, valval):
                        matched = True
        if negate:
            return not matched
        else:
            return matched

    return f

def gen_filter_by_post_params(keycomparer, keyval, valcomparer=None, valval=None,
                         negate=False):
    def f(req):
        matched = False
        for k, v in req.post_params.all_pairs():
            if keycomparer(k, keyval):
                if not valcomparer:
                    matched = True
                else:
                    if valcomparer(v, valval):
                        matched = True
        if negate:
            return not matched
        else:
            return matched


    return f

def gen_filter_by_params(keycomparer, keyval, valcomparer=None, valval=None,
                         negate=False):
    def f(req):
        matched = False
        # purposely don't pass negate here, otherwise we get double negatives
        f1 = gen_filter_by_post_params(keycomparer, keyval, valcomparer, valval)
        f2 = gen_filter_by_get_params(keycomparer, keyval, valcomparer, valval)
        if f1(req):
            matched = True
        if f2(req):
            matched = True

        if negate:
            return not matched
        else:
            return matched

    return f

def get_relation(s):
    # Gets the relation function associated with the string
    # Returns none if not found
    if s in ("is",):
        return cmp_is
    elif s in ("contains", "ct"):
        return cmp_contains
    elif s in ("containsr", "ctr"):
        # TODO
        return None
    elif s in ("exists", "ex"):
        return cmp_exists
    elif s in ("Leq", "L="):
        return cmp_len_eq
    elif s in ("Lgt", "L>"):
        return cmp_len_gt
    elif s in ("Llt", "L<"):
        return cmp_len_lt
    elif s in ("eq", "="):
        return cmp_eq
    elif s in ("gt", ">"):
        return cmp_gt
    elif s in ("lt", "<"):
        return cmp_lt

    raise FilterParseError("Invalid relation: %s" % s)

@defer.inlineCallbacks
def init():
    yield reload_from_storage()

@defer.inlineCallbacks
def reload_from_storage():
    global active_requests
    active_requests = yield http.Request.load_from_filters(active_filters)

def add_filter(filt):
    global active_requests
    global active_filters
    active_filters.append(filt)
    active_requests = filter_reqs(active_requests, active_filters)

def add_request(req):
    global active_requests
    if passes_filters(req, active_filters):
        active_requests.append(req)
        
def filter_recheck():
    global active_requests
    global active_filters
    new_reqs = []
    for req in active_requests:
        if passes_filters(req, active_filters):
            new_reqs.append(req)
    active_requests = new_reqs
    
def passes_filters(request, filters):
    for filt in filters:
        if not filt(request):
            return False
    return True

def sort(key=None):
    global active_requests
    if key:
        active_requests = sorted(active_requests, key=key)
    else:
        active_requests = sorted(active_requests, key=lambda r: r.reqid)
    
def in_scope(request):
    global scope
    return passes_filters(request, scope)
    
def set_scope(filters):
    global scope
    scope = filters
    
def save_scope():
    global active_filters
    global scope
    scope = active_filters[:]

@defer.inlineCallbacks
def reset_to_scope():
    global active_filters
    global scope
    active_filters = scope[:]
    yield reload_from_storage()
    
def print_scope():
    global scope
    for f in scope:
        print f.filter_string

@defer.inlineCallbacks
def store_scope(dbpool):
    # Delete the old scope
    yield dbpool.runQuery(
        """
        DELETE FROM scope
        """
    );

    # Insert the new scope
    i = 0
    for f in scope:
        yield dbpool.runQuery(
            """
            INSERT INTO scope (filter_order, filter_string) VALUES (?, ?);
            """,
            (i, f.filter_string)
        );
        i += 1
        
@defer.inlineCallbacks
def load_scope(dbpool):
    global scope
    rows = yield dbpool.runQuery(
            """
            SELECT filter_order, filter_string FROM scope;
            """,
        )
    rows = sorted(rows, key=lambda r: int(r[0]))
    new_scope = []
    for row in rows:
        new_filter = Filter(row[1])
        new_scope.append(new_filter)
    scope = new_scope