#!/usr/bin/env python

"""
Copyright (c) 2006-2012 sqlmap developers (http://sqlmap.org/)
See the file 'doc/COPYING' for copying permission
"""

import re

from lib.core.common import extractRegexResult, getFilteredPageContent, listToStrValue, removeDynamicContent, \
    wasLastRequestDBMSError, wasLastRequestHTTPError
from lib.core.data import conf, kb, logger
from lib.core.exception import sqlmapNoneDataException
from lib.core.settings import DEFAULT_PAGE_ENCODING, DIFF_TOLERANCE, HTML_TITLE_REGEX, MIN_RATIO, MAX_RATIO, \
    REFLECTED_VALUE_MARKER, LOWER_RATIO_BOUND, UPPER_RATIO_BOUND

from lib.core.threads import getCurrentThreadData

def comparison(page, headers, code=None, getRatioValue=False, pageLength=None):
    return _adjust(_comparison(page, headers, code, getRatioValue, pageLength), getRatioValue)

def _adjust(condition, getRatioValue):
    if not any((conf.string, conf.notString, conf.regexp, conf.code)):
        # Negative logic approach is used in raw page comparison scheme as that what is "different" than original
        # PAYLOAD.WHERE.NEGATIVE response is considered as True; in switch based approach negative logic is not
        # applied as that what is by user considered as True is that what is returned by the comparison mechanism
        # itself
        retVal = not condition if kb.negativeLogic and condition is not None and not getRatioValue else condition
    else:
        retVal = condition if not getRatioValue else (MAX_RATIO if condition else MIN_RATIO)

    return retVal

def _comparison(page, headers, code, getRatioValue, pageLength):
    threadData = getCurrentThreadData()

    if kb.testMode:
        threadData.lastComparisonPage = page

    if page is None and pageLength is None:
        return None

    seqMatcher = threadData.seqMatcher
    seqMatcher.set_seq1(kb.pageTemplate)

    if any((conf.string, conf.notString, conf.regexp)):
        rawResponse = "%s%s" % (listToStrValue(headers.headers if headers else ""), page)

        # String to match in page when the query is True and/or valid
        if conf.string:
            return conf.string in rawResponse

        # String to match in page when the query is False and/or invalid
        if conf.notString:
            return conf.notString not in rawResponse

        # Regular expression to match in page when the query is True and/or valid
        if conf.regexp:
            return re.search(conf.regexp, rawResponse, re.I | re.M) is not None

    # HTTP code to match when the query is valid
    if isinstance(code, int) and conf.code:
        return conf.code == code

    if page:
        # In case of an DBMS error page return None
        if kb.errorIsNone and (wasLastRequestDBMSError() or wasLastRequestHTTPError()):
            return None

        # Dynamic content lines to be excluded before comparison
        if not kb.nullConnection:
            page = removeDynamicContent(page)
            seqMatcher.set_seq1(removeDynamicContent(kb.pageTemplate))

        if not pageLength:
            pageLength = len(page)

    if kb.nullConnection and pageLength:
        if not seqMatcher.a:
            errMsg = "problem occured while retrieving original page content "
            errMsg += "which prevents sqlmap from continuation. Please rerun, "
            errMsg += "and if the problem persists turn off any optimization switches"
            raise sqlmapNoneDataException, errMsg

        ratio = 1. * pageLength / len(seqMatcher.a)

        if ratio > 1.:
            ratio = 1. / ratio
    else:
        # Preventing "Unicode equal comparison failed to convert both arguments to Unicode"
        # (e.g. if one page is PDF and the other is HTML)
        if isinstance(seqMatcher.a, str) and isinstance(page, unicode):
            page = page.encode(kb.pageEncoding or DEFAULT_PAGE_ENCODING, 'ignore')
        elif isinstance(seqMatcher.a, unicode) and isinstance(page, str):
            seqMatcher.a = seqMatcher.a.encode(kb.pageEncoding or DEFAULT_PAGE_ENCODING, 'ignore')

        seq1, seq2 = None, None

        if conf.titles:
            seq1 = extractRegexResult(HTML_TITLE_REGEX, seqMatcher.a)
            seq2 = extractRegexResult(HTML_TITLE_REGEX, page)
        else:
            seq1 = getFilteredPageContent(seqMatcher.a, True) if conf.textOnly else seqMatcher.a
            seq2 = getFilteredPageContent(page, True) if conf.textOnly else page

        if seq1 is None or seq2 is None:
            return None

        seq1 = seq1.replace(REFLECTED_VALUE_MARKER, "")
        seq2 = seq2.replace(REFLECTED_VALUE_MARKER, "")

        count = 0
        while count < min(len(seq1), len(seq2)):
            if seq1[count] == seq2[count]:
                count += 1
            else:
                break
        if count:
            seq1 = seq1[count:]
            seq2 = seq2[count:]

        seqMatcher.set_seq1(seq1)
        seqMatcher.set_seq2(seq2)

        ratio = round(seqMatcher.quick_ratio(), 3)

    # If the url is stable and we did not set yet the match ratio and the
    # current injected value changes the url page content
    if kb.matchRatio is None:
        if ratio >= LOWER_RATIO_BOUND and ratio <= UPPER_RATIO_BOUND:
            kb.matchRatio = ratio
            logger.debug("setting match ratio for current parameter to %.3f" % kb.matchRatio)

    # If it has been requested to return the ratio and not a comparison
    # response
    if getRatioValue:
        return ratio

    elif ratio > UPPER_RATIO_BOUND:
        return True

    elif kb.matchRatio is None:
        return None

    else:
        return (ratio - kb.matchRatio) > DIFF_TOLERANCE