# -*- coding: utf-8 -*-
#
# This file is part of Radicale Server - Calendar Server
# Copyright © 2008-2011 Guillaume Ayoub
# Copyright © 2008 Nicolas Kandel
# Copyright © 2008 Pascal Halter
#
# This library is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Radicale.  If not, see <http://www.gnu.org/licenses/>.

"""
XML and iCal requests manager.

Note that all these functions need to receive unicode objects for full
iCal requests (PUT) and string objects with charset correctly defined
in them for XML requests (all but PUT).

"""

try:
    from collections import OrderedDict
except ImportError:
    # Python 2.6
    OrderedDict = dict
import re
import xml.etree.ElementTree as ET

from radicale import client, config, ical


NAMESPACES = {
    "C": "urn:ietf:params:xml:ns:caldav",
    "D": "DAV:",
    "CS": "http://calendarserver.org/ns/",
    "ICAL": "http://apple.com/ns/ical/"}


NAMESPACES_REV = {}


for short, url in NAMESPACES.items():
    NAMESPACES_REV[url] = short
    if hasattr(ET, "register_namespace"):
        # Register namespaces cleanly with Python 2.7+ and 3.2+ ...
        ET.register_namespace("" if short == "D" else short, url)
    else:
        # ... and badly with Python 2.6 and 3.1
        ET._namespace_map[url] = short


CLARK_TAG_REGEX = re.compile(r"""
    {                        # {
    (?P<namespace>[^}]*)     # namespace URL
    }                        # }
    (?P<tag>.*)              # short tag name
    """, re.VERBOSE)


def _pretty_xml(element, level=0):
    """Indent an ElementTree ``element`` and its children."""
    i = "\n" + level * "  "
    if len(element):
        if not element.text or not element.text.strip():
            element.text = i + "  "
        if not element.tail or not element.tail.strip():
            element.tail = i
        for sub_element in element:
            _pretty_xml(sub_element, level + 1)
        # ``sub_element`` is always defined as len(element) > 0
        # pylint: disable=W0631
        if not sub_element.tail or not sub_element.tail.strip():
            sub_element.tail = i
        # pylint: enable=W0631
    else:
        if level and (not element.tail or not element.tail.strip()):
            element.tail = i
    if not level:
        return ET.tostring(element, config.get("encoding", "request"))


def _tag(short_name, local):
    """Get XML Clark notation {uri(``short_name``)}``local``."""
    return "{%s}%s" % (NAMESPACES[short_name], local)


def _tag_from_clark(name):
    """For a given name using the XML Clark notation returns a human-readable
    variant of the tag name for known namespaces. Otherwise returns the name
    as is.

    """
    match = CLARK_TAG_REGEX.match(name)
    if match and match.group('namespace') in NAMESPACES_REV:
        args = {
            'ns': NAMESPACES_REV[match.group('namespace')],
            'tag': match.group('tag')}
        tag_name = '%(ns)s:%(tag)s' % args
    else:
        tag_name = prop.tag
    return tag_name


def _response(code):
    """Return full W3C names from HTTP status codes."""
    return "HTTP/1.1 %i %s" % (code, client.responses[code])


def name_from_path(path, calendar):
    """Return Radicale item name from ``path``."""
    calendar_parts = calendar.local_path.strip("/").split("/")
    path_parts = path.strip("/").split("/")
    return path_parts[-1] if (len(path_parts) - len(calendar_parts)) else None


def props_from_request(root, actions=("set", "remove")):
    """Returns a list of properties as a dictionary."""

    result = OrderedDict()
    if not isinstance(root, ET.Element):
        root = ET.fromstring(root.encode("utf8"))

    for action in actions:
        action_element = root.find(_tag("D", action))
        if action_element is not None:
            break
    else:
        action_element = root

    prop_element = action_element.find(_tag("D", "prop"))
    if prop_element is not None:
        for prop in prop_element:
            result[_tag_from_clark(prop.tag)] = prop.text
    return result


def delete(path, calendar):
    """Read and answer DELETE requests.

    Read rfc4918-9.6 for info.

    """
    # Reading request
    calendar.remove(name_from_path(path, calendar))

    # Writing answer
    multistatus = ET.Element(_tag("D", "multistatus"))
    response = ET.Element(_tag("D", "response"))
    multistatus.append(response)

    href = ET.Element(_tag("D", "href"))
    href.text = path
    response.append(href)

    status = ET.Element(_tag("D", "status"))
    status.text = _response(200)
    response.append(status)

    return _pretty_xml(multistatus)


def propfind(path, xml_request, calendar, depth):
    """Read and answer PROPFIND requests.

    Read rfc4918-9.1 for info.

    """
    # Reading request
    root = ET.fromstring(xml_request.encode("utf8"))

    prop_element = root.find(_tag("D", "prop"))
    props = [prop.tag for prop in prop_element]

    # Writing answer
    multistatus = ET.Element(_tag("D", "multistatus"))

    if calendar:
        if depth == "0":
            items = [calendar]
        else:
            # Depth is 1, infinity or not specified
            # We limit ourselves to depth == 1
            items = [calendar] + calendar.components
    else:
        items = []

    for item in items:
        is_calendar = isinstance(item, ical.Calendar)

        response = ET.Element(_tag("D", "response"))
        multistatus.append(response)

        href = ET.Element(_tag("D", "href"))
        href.text = path if is_calendar else path + item.name
        response.append(href)

        propstat = ET.Element(_tag("D", "propstat"))
        response.append(propstat)

        prop = ET.Element(_tag("D", "prop"))
        propstat.append(prop)

        for tag in props:
            element = ET.Element(tag)
            if tag == _tag("D", "resourcetype") and is_calendar:
                tag = ET.Element(_tag("C", "calendar"))
                element.append(tag)
                tag = ET.Element(_tag("D", "collection"))
                element.append(tag)
            elif tag == _tag("D", "owner"):
                if calendar.owner:
                    element.text = calendar.owner
            elif tag == _tag("D", "getcontenttype"):
                element.text = "text/calendar"
            elif tag == _tag("CS", "getctag") and is_calendar:
                element.text = item.etag
            elif tag == _tag("D", "getetag"):
                element.text = item.etag
            elif tag == _tag("D", "displayname") and is_calendar:
                element.text = calendar.name
            elif tag == _tag("D", "principal-URL"):
                # TODO: use a real principal URL, read rfc3744-4.2 for info
                tag = ET.Element(_tag("D", "href"))
                tag.text = path
                element.append(tag)
            elif tag in (
                _tag("D", "principal-collection-set"),
                _tag("C", "calendar-user-address-set"),
                _tag("C", "calendar-home-set")):
                tag = ET.Element(_tag("D", "href"))
                tag.text = path
                element.append(tag)
            elif tag == _tag("C", "supported-calendar-component-set"):
                # This is not a Todo
                # pylint: disable=W0511
                for component in ("VTODO", "VEVENT", "VJOURNAL"):
                    comp = ET.Element(_tag("C", "comp"))
                    comp.set("name", component)
                    element.append(comp)
                # pylint: enable=W0511
            elif tag == _tag("D", "current-user-privilege-set"):
                privilege = ET.Element(_tag("D", "privilege"))
                privilege.append(ET.Element(_tag("D", "all")))
                element.append(privilege)
            elif tag == _tag("D", "supported-report-set"):
                for report_name in (
                    "principal-property-search", "sync-collection"
                    "expand-property", "principal-search-property-set"):
                    supported = ET.Element(_tag("D", "supported-report"))
                    report_tag = ET.Element(_tag("D", "report"))
                    report_tag.text = report_name
                    supported.append(report_tag)
                    element.append(supported)
            prop.append(element)

        status = ET.Element(_tag("D", "status"))
        status.text = _response(200)
        propstat.append(status)

    return _pretty_xml(multistatus)


def _add_propstat_to(element, tag, status_number):
    """Adds a propstat structure to the given element for the
    following `tag` with the given `status_number`."""
    propstat = ET.Element(_tag("D", "propstat"))
    element.append(propstat)

    prop = ET.Element(_tag("D", "prop"))
    propstat.append(prop)

    if '{' in tag:
        clark_tag = tag
    else:
        clark_tag = _tag(*tag.split(':', 1))
    prop_tag = ET.Element(clark_tag)
    prop.append(prop_tag)

    status = ET.Element(_tag("D", "status"))
    status.text = _response(status_number)
    propstat.append(status)


def proppatch(path, xml_request, calendar):
    """Read and answer PROPPATCH requests.

    Read rfc4918-9.2 for info.

    """
    # Reading request
    root = ET.fromstring(xml_request.encode("utf8"))
    props_to_set = props_from_request(root, actions=('set',))
    props_to_remove = props_from_request(root, actions=('remove',))

    # Writing answer
    multistatus = ET.Element(_tag("D", "multistatus"))

    response = ET.Element(_tag("D", "response"))
    multistatus.append(response)

    href = ET.Element(_tag("D", "href"))
    href.text = path
    response.append(href)

    with calendar.props as calendar_props:
        for short_name, value in props_to_set.items():
            calendar_props[short_name] = value
            _add_propstat_to(response, short_name, 200)
        for short_name in props_to_remove:
            try:
                del calendar_props[short_name]
            except KeyError:
                _add_propstat_to(response, short_name, 412)
            else:
                _add_propstat_to(response, short_name, 200)

    return _pretty_xml(multistatus)


def put(path, ical_request, calendar):
    """Read PUT requests."""
    name = name_from_path(path, calendar)
    if name in (item.name for item in calendar.items):
        # PUT is modifying an existing item
        calendar.replace(name, ical_request)
    else:
        # PUT is adding a new item
        calendar.append(name, ical_request)


def report(path, xml_request, calendar):
    """Read and answer REPORT requests.

    Read rfc3253-3.6 for info.

    """
    # Reading request
    root = ET.fromstring(xml_request.encode("utf8"))

    prop_element = root.find(_tag("D", "prop"))
    props = [prop.tag for prop in prop_element]

    if calendar:
        if root.tag == _tag("C", "calendar-multiget"):
            # Read rfc4791-7.9 for info
            hreferences = set(
                href_element.text for href_element
                in root.findall(_tag("D", "href")))
        else:
            hreferences = (path,)
    else:
        hreferences = ()

    # Writing answer
    multistatus = ET.Element(_tag("D", "multistatus"))

    for hreference in hreferences:
        # Check if the reference is an item or a calendar
        name = name_from_path(hreference, calendar)
        if name:
            # Reference is an item
            path = "/".join(hreference.split("/")[:-1]) + "/"
            items = (item for item in calendar.items if item.name == name)
        else:
            # Reference is a calendar
            path = hreference
            items = calendar.components

        for item in items:
            response = ET.Element(_tag("D", "response"))
            multistatus.append(response)

            href = ET.Element(_tag("D", "href"))
            href.text = path + item.name
            response.append(href)

            propstat = ET.Element(_tag("D", "propstat"))
            response.append(propstat)

            prop = ET.Element(_tag("D", "prop"))
            propstat.append(prop)

            for tag in props:
                element = ET.Element(tag)
                if tag == _tag("D", "getetag"):
                    element.text = item.etag
                elif tag == _tag("C", "calendar-data"):
                    if isinstance(item, (ical.Event, ical.Todo, ical.Journal)):
                        element.text = ical.serialize(
                            calendar.headers, calendar.timezones + [item])
                prop.append(element)

            status = ET.Element(_tag("D", "status"))
            status.text = _response(200)
            propstat.append(status)

    return _pretty_xml(multistatus)