#!/usr/bin/env python3

import requests
from bs4 import BeautifulSoup
import click

from enum import Enum

VERSION = '0.1.0'

sess = requests.Session()
base_headers = {
        # request (x)html form
        'Accept': 'text/html,application/xhtml+xml',
        'User-Agent': 'htformtool/{version}'.format(version=VERSION),
        }
# 
post_headers = {
        # request confirmation code
        'Accept': 'text/plain',
        }

def hide_ua(ctx, param, value):
    if not value or ctx.resilient_parsing:
        return
    base_headers['User-Agent'] = None

def split_on_ascii_whitespace(inp):
    start_position = 0
    end_position = 0
    tokens = []
    while start_position < len(inp) and inp[start_position] in '\x09\x0A\x0C\x0D\x20':
        start_position = start_position + 1
    while start_position < len(inp):
        end_position = start_position
        while end_position < len(inp) and inp[end_position] not in '\x09\x0A\x0C\x0D\x20':
            end_position = end_position + 1
        tokens.append(inp[start_position:end_position])
        start_position = end_position
        while start_position < len(inp) and inp[start_position] in '\x09\x0A\x0C\x0D\x20':
            start_position = start_position + 1
    return tokens

def ascii_lowercase(s):
    import string
    return s.translate(str.maketrans(string.ascii_uppercase, string.ascii_lowercase))

def get_encoding(label):
    # fuck
    if ascii_lowercase(label) not in ('unicode-1-1-utf-8', 'utf-8', 'utf8'):
        raise NotImplementedError
    import codecs
    return codecs.lookup('utf-8')

import re
newline_normalize = re.compile('\x0D(?!\x0A)|(?<!\x0D)\x0A')

def append_an_entry(l, name, value, no_line_break_normalization=False):
    # TODO might not be *strictly* correct
    name = newline_normalize.sub('\r\n', name)
    try:
        if not no_line_break_normalization:
            value = newline_normalize.sub('\r\n', value)
    except ValueError:
        pass
    l.append((name, value))

class FieldState(Enum):
    # normal <input> types
    HIDDEN = 'hidden'
    TEXT = 'text'
    SEARCH = 'search'
    TELEPHONE = 'tel'
    URL = 'url'
    EMAIL = 'email'
    PASSWORD = 'password'
    DATE = 'date'
    MONTH = 'month'
    WEEK = 'week'
    TIME = 'time'
    LOCAL_DATE_AND_TIME = 'datetime-local'
    NUMBER = 'number'
    RANGE = 'range'
    COLOR = 'color'
    CHECKBOX = 'checkbox'
    RADIO = 'radio'
    FILE = 'file'
    SUBMIT = 'submit'
    IMAGE = 'image'
    RESET = 'reset'
    BUTTON = 'button'

    # custom, htformtool-specific <input> types
    CREDENTIALS = 'credentials'

    # non-<input> types
    TEXTAREA = 'textarea'
    SELECT = 'select'

    # <button> types
    BSUBMIT = 'bsubmit'
    BRESET = 'breset'
    BBUTTON = 'bbutton'

    def is_button(self, submitter=None):
        if self in (FieldState.BSUBMIT, FieldState.IMAGE, FieldState.SUBMIT):
            return submitter is None or submitter == True
        if self in (FieldState.BRESET, FieldState.BBUTTON, FieldState.RESET, FieldState.BUTTON):
            return submitter is None or submitter == False
        return False

    def blocks_implicit_submission(self):
        return self in (FieldState.TEXT, FieldState.SEARCH, FieldState.URL, FieldState.TELEPHONE,
                FieldState.EMAIL, FieldState.PASSWORD, FieldState.DATE, FieldState.MONTH,
                FieldState.WEEK, FieldState.TIME, FieldState.LOCAL_DATE_AND_TIME, FieldState.NUMBER)

class ConstraintError(ValueError):
    pass

class FormData:
    """
    Represents the data to be submitted by the form.
    """

    def __init__(self, encoding, entry_list, action, enctype, method, target):
        self.encoding = encoding
        """The codec object that should be used to encode the form for sending"""
        self.entry_list = entry_list
        """The entry list"""
        self.action = action
        """The form's raw action (URL) (not parsed)"""
        self.enctype = enctype
        """The form's enctype"""
        self.method = method
        """The form's method (not sanitized)"""
        self.target = target
        """The form's target (not sanitized)"""

class Form:
    def __init__(self, form):
        self.form = form
        # these have the same length
        self.elements = []
        self.fields = []

    def submit(self, document_encoding, submitter=None):
        """
        Submits the form implicitly, or with the given submitter.

        Raises ValueError if the given submitter isn't a valid submitter.

        Raises ConstraintError if this field's no-validate state is false and one or more of the form's fields is invalid. (note: ConstraintError is a subtype of ValueError)

        Returns a FormData object, or None if implicit submission is not allowed.
        """
        if submitter is not None:
            if not submitter in self.fields:
                raise ValueError
            if not submitter.is_button(submitter=True):
                raise ValueError
            if not submitter.no_validate():
                for field in self.fields:
                    field.check_value()
        elif not self.form.get('novalidate'):
            blocks_implicit_submission = 0
            for field in self.fields:
                field.check_value()
                if submitter is None:
                    if field.is_button(submitter=True):
                        blocks_implicit_submission = 0
                        submitter = field
                    elif field._blocks_implicit_submission():
                        blocks_implicit_submission += 1
            if blocks_implicit_submission > 1:
                return None

        encoding = document_encoding
        if self.form.get('accept-charset') is not None:
            candidate_enc_labels = split_on_ascii_whitespace(self.form['accept-charset'])
            candidate_enc = []
            for token in candidate_enc_labels:
                enc = get_encoding(token)
                if enc is not None:
                    candidate_enc.append(enc)
            if not candidate_enc:
                encoding = get_encoding('utf-8')
            else:
                encoding = candidate_enc[0]

        controls = self.fields
        entry_list = []
        for field in controls:
            if field.is_button() and field is not submitter:
                continue
            if field.is_checkable() and not field.is_checked():
                continue
            if field.is_image_button():
                name = field.field['name'] + '.' if field.field.get('name') else ''
                namex = name + 'x'
                namey = name + 'y'
                append_an_entry(entry_list, namex, 0)
                append_an_entry(entry_list, namey, 0)
                continue
            name = field.field['name']
            if field.is_select():
                for option in field.get_options():
                    raise NotImplementedError
            elif field.is_checkable():
                append_an_entry(entry_list, name, field.get_value())
            elif field.is_file():
                raise NotImplementedError
            elif field.is_hidden() and name == '_charset_':
                raise NotImplementedError
            elif field.is_textarea():
                raise NotImplementedError
            else:
                append_an_entry(name, field.get_value())
            if field.has_valid_dirname():
                dirname = field.field['dirname']
                raise NotImplementedError

        action = None
        if submitter is not None and submitter.field.get('formaction') is not None:
            action = submitter.field['formaction']
        if action is None and self.form.get('action'):
            action = self.form['action']
        if action is None:
            action = ''

        enctype = None
        if submitter is not None and submitter.field.get('formenctype') is not None:
            enctype = submitter.field['formenctype']
        if enctype is None and self.form.get('enctype'):
            enctype = self.form['enctype']
        enctype = ascii_lowercase(enctype)
        if enctype not in ('application/x-www-form-urlencoded', 'multipart/form-data', 'text/plain'):
            enctype = 'application/x-www-form-urlencoded'

        method = None
        if submitter is not None and submitter.field.get('formmethod') is not None:
            method = submitter.field['formmethod']
        if method is None and self.form.get('method'):
            method = self.form['method']
        method = ascii_lowercase(method)
        if method not in ('get', 'post', 'dialog'):
            method = 'get'

        # WARNING: NOT SANITIZED
        target = None
        if submitter is not None and submitter.field.get('formtarget') is not None:
            target = submitter.field['formtarget']
        else:
            if self.form.get('target') is not None:
                target = self.form['target']
            elif self.form.find_parent('[document]').base is not None and self.form.find_parent('[document]').base.get('target') is not None:
                target = self.form.find_parent('[document]').base['target'] 
            else:
                target = ''

        return FormData(encoding, entry_list, action, enctype, method, target)

class FormField:
    def __init__(self, form, field):
        self.field = field
        self.form = form
        form.fields.append(self)

        if field.name == 'input':
            ftype = ascii_lowercase(field.get('type', 'text'))
            if ftype not in ('textarea', 'selection', 'bbutton', 'bsubmit', 'breset'):
                try:
                    state = FieldState(ftype)
                except ValueError:
                    state = FieldState.TEXT
            else:
                state = FieldState.TEXT
        elif field.name == 'button':
            ftype = ascii_lowercase(field.get('type', 'submit'))
            if ftype == 'reset':
                state = FieldState.BRESET
            elif ftype == 'button':
                state = FieldState.BBUTTON
            else:
                state = FieldState.BSUBMIT
        elif field.name == 'textarea':
            state = FieldState.TEXTAREA
        elif field.name == 'select':
            state = FieldName.SELECT
        self.state = state

        self.reset()

    def reset(self):
        if self.is_checkable():
            self._checked = self.field.get('checked') is not None
        if self.is_select():
            self.options = []
            raise NotImplementedError
        if self._is_text_based():
            self.text = self.field.get('value') or ''

    def _is_text_based(self):
        raise NotImplementedError

    def is_button(self, submitter=None):
        self.state.is_button(submitter=submitter)

    def blocks_implicit_submission(self):
        self.state.blocks_implicit_submission()

    def is_textarea(self):
        return self.state == FieldState.TEXTAREA

    def is_image_button(self):
        return self.state == FieldState.IMAGE

    def is_radio(self, name=None):
        return self.state == FieldState.RADIO and (name is None or self.field.get('name') == name)

    def is_file(self):
        return self.state == FieldState.FILE

    def is_checkable(self):
        return self.state in (FieldState.CHECKBOX, FieldState.RADIO)

    def is_checked(self):
        if not self.is_checkable():
            raise ValueError
        return self._checked

    def is_select(self):
        return self.field.name == 'select'

    def has_valid_dirname(self):
        raise NotImplementedError
        #return (self.is_textarea() or (self.field.name == 'input' and self.field.get('type') not in NOT_TEXT)) and bool(self.field.get('dirname'))

    def get_options(self, selected=None, disabled=False):
        if not self.is_select():
            raise ValueError
        raise NotImplementedError

    def set_checked(self, checkedness=True):
        if not self.is_checkable():
            raise ValueError
        if self.is_radio():
            if not checkedness:
                raise ValueError # you can't really un-check a radio
            for field in self.form.fields:
                if field.is_radio(name=self.field['name']) and field.is_checked():
                    field._checked = False
        self._checked = checkedness

    def set_value(self, value):
        raise NotImplementedError

    def get_value(self):
        if self.is_checkable():
            return self.field.get('value', default='on')
        raise NotImplementedError

    def check_value(self):
        """
        Checks if the value in this field satisfies the constraints.

        Raises ConstraintError if it doesn't.
        """
        raise NotImplementedError

    def no_validate(self):
        """
        Returns this element's no-validate state.

        Raises ValueError if this element is not a submitter button.
        """
        if not self.is_button(submitter=True):
            raise ValueError
        if self.field.get('formnovalidate') is not None:
            return True
        if self.form.form.get('novalidate') is not None:
            return True
        return False

    def submit(self, document_encoding):
        """
        Submits the form with this field as submitter.

        Raises ValueError if this field isn't a valid submitter.

        Raises ConstraintError if this field's no-validate state is false and one or more of the form's fields is invalid. (note: ConstraintError is a subtype of ValueError)

        Returns the form data in the correct serialization format, as specified by the form element.
        """
        self.form.submit(document_encoding=document_encoding, submitter=self)

def extract_forms(document):
    forms = [Form(form) for form in document.find_all('form')]
    forms_with_id = {form.form['id']: form for form in forms if form.form.get('id') is not None}
    forms_by_object = {form.form: form for form in forms}
    for element in document.find_all(['button', 'input', 'select', 'textarea']):
        element_form = element.get('form')
        if element_form is not None:
            element_form = forms_with_id.get(element_form)
        if element_form is None:
            element_form = element.find_parent('form')
            if element_form is not None:
                element_form = forms_by_object[element_form]
            #element_form = element.parent
            #while element_form is not None:
            #    if element_form.name == 'form':
            #        element_form = forms_by_object[element_form]
            #        break
        if element_form is not None:
            element_form.elements.append(element)
    # we don't need these anymore
    del forms_with_id
    del forms_by_object
    
    # disabled controls
    def should_keep(field):
        def is_disabled(field):
            if field.get('disabled') is not None:
                return True
            for parent in field.find_parents('fieldset'):
                if parent.get('disabled') is not None:
                    if parent.legend is not None and parent.legend in field.parents:
                        return False
                    else:
                        return True
            return False

        if is_disabled(field):
            return False
        if (not (field.name == 'input' and field.get('type') == 'image')) and not field.get('name'):
            return False
        # weird edge-case
        if field.get('name') == 'isindex':
            return False
        return True

    # clean up
    for form in forms:
        # TODO clean this up
        newelements = [FormField(form, field) for field in form.elements if should_keep(field)]
        form.elements = [ff.field for ff in newelements]

    return forms

@click.command()
@click.option('--encoding', default='', help='Overrides the character encoding of the document.', metavar='ENCODING')
@click.option('--fallback-encoding', default='utf-8', help='Sets the encoding used if the encoding can\'t be determined by another means. Ignored if --encoding is used.', show_default=True, metavar='ENCODING')
@click.option('--hide-ua', is_flag=True, help='Prevent sending the User-Agent string.', expose_value=False, is_eager=True, callback=hide_ua)
@click.version_option(version=VERSION, prog_name="htformtool")
@click.argument('url')
def htformtool(encoding, fallback_encoding, url):
    sess.headers.update(base_headers)
    sess.headers.update({'Accept-Charset': encoding or fallback_encoding})
    r = sess.get(url)
    try:
        if not click.confirm("Using {}, continue?".format(r.url), default=True):
            return
    except click.Abort:
        click.echo("") # just a newline
        return
    try:
        if r.headers['Content-Type'].startswith('text/html'):
            isXML = False
        elif r.headers['Content-Type'].startswith('application/xhtml+xml'):
            isXML = True
        else:
            # not an acceptable content type, ignore it.
            click.echo("No HTML found.")
            return
    except IndexError:
        # no content-type, just assume HTML. it's probably good enough for our needs.
        isXML = None
    if encoding:
        r.encoding = encoding
    if r.encoding is None:
        # FIXME
        r.encoding = fallback_encoding
    soup = BeautifulSoup(r.content, "xml" if isXML else "html5lib")
    forms = extract_forms(soup)
    if not forms:
        click.echo("No forms found.")
    else:
        click.echo("There are {} forms:".format(len(forms)))
        # TODO
        click.echo(forms)


if __name__ == '__main__':
    htformtool()