#!/usr/bin/env python

from datetime import datetime

from imiptools.config import STORE_DIR, PUBLISH_DIR

from os.path import abspath, commonprefix, exists, isfile, join, split

from os import chmod, listdir, makedirs

from vCalendar import iterwrite

def check_dir(base, dir):

    return commonprefix([base, abspath(dir)]) == base

def fix_permissions(filename):

    try:

        chmod(filename, 0660)

    except OSError:

        pass

def make_calendar(fragment, method=None):

    """

    Return a complete calendar item wrapping the given 'fragment' and employing

    the given 'method', if indicated.

    """

    return ("VCALENDAR", {},

            (method and [("METHOD", {}, method)] or []) +

            [("VERSION", {}, "2.0")] +

            fragment

           )

def to_stream(out, fragment, encoding="utf-8"):

    iterwrite(out, encoding=encoding).append(fragment)

class FileBase:

    "Basic filesystem operations."

    def __init__(self, store_dir=STORE_DIR):

        self.store_dir = store_dir

        if not exists(self.store_dir):

            makedirs(self.store_dir)

    def get_file_object(self, base, *parts):

        pathname = join(base, *parts)

        return check_dir(base, pathname) and pathname or None

    def get_object_in_store(self, *parts):

        """

        Return the name of any valid object stored within a hierarchy specified

        by the given 'parts'.

        """

        parent = expected = self.store_dir

        for part in parts:

            filename = self.get_file_object(expected, part)

            if not filename:

                return False

            parent = expected

            expected = filename

        if not exists(parent):

            makedirs(parent)

        return filename

class FileStore(FileBase):

    "A file store of tabular free/busy data and objects."

    def get_events(self, user):

        "Return a list of event identifiers."

        filename = self.get_object_in_store(user, "objects")

        if not filename or not exists(filename):

            return None

        return [name for name in listdir(filename) if isfile(join(filename, name))]

    def get_event(self, user, uid):

        "Get the event for the given 'user' with the given 'uid'."

        filename = self.get_object_in_store(user, "objects", uid)

        if not filename or not exists(filename):

            return None

        return open(filename) or None

    def set_event(self, user, uid, node):

        "Set an event for 'user' having the given 'uid' and 'node'."

        filename = self.get_object_in_store(user, "objects", uid)

        if not filename:

            return False

        f = open(filename, "w")

        try:

            to_stream(f, node)

        finally:

            f.close()

            fix_permissions(filename)

        return True

    def get_freebusy(self, user):

        "Get free/busy details for the given 'user'."

        filename = self.get_object_in_store(user, "freebusy")

        if not filename or not exists(filename):

            return None

        else:

            return self._get_freebusy(filename)

    def get_freebusy_for_other(self, user, other):

        "For the given 'user', get free/busy details for the 'other' user."

        filename = self.get_object_in_store(user, "freebusy-other", other)

        if not filename:

            return None

        else:

            return self._get_freebusy(filename)

    def _get_freebusy(self, filename):

        f = open(filename)

        try:

            l = []

            for line in f.readlines():

                l.append(tuple(line.strip().split("\t")))

            return l

        finally:

            f.close()

    def set_freebusy(self, user, freebusy):

        "For the given 'user', set 'freebusy' details."

        filename = self.get_object_in_store(user, "freebusy")

        if not filename:

            return False

        self._set_freebusy(filename, freebusy)

        return True

    def set_freebusy_for_other(self, user, freebusy, other):

        "For the given 'user', set 'freebusy' details for the 'other' user."

        filename = self.get_object_in_store(user, "freebusy-other", other)

        if not filename:

            return False

        self._set_freebusy(filename, freebusy)

        return True

    def _set_freebusy(self, filename, freebusy):

        f = open(filename, "w")

        try:

            for item in freebusy:

                f.write("\t".join([(value or "OPAQUE") for value in item]) + "\n")

        finally:

            f.close()

            fix_permissions(filename)

    def get_requests(self, user):

        "Get requests for the given 'user'."

        filename = self.get_object_in_store(user, "requests")

        if not filename or not exists(filename):

            return None

        f = open(filename)

        try:

            return [line.strip() for line in f.readlines()]

        finally:

            f.close()

    def set_requests(self, user, requests):

        "For the given 'user', set the list of queued 'requests'."

        filename = self.get_object_in_store(user, "requests")

        if not filename:

            return False

        f = open(filename, "w")

        try:

            for request in requests:

                print >>f, request

        finally:

            f.close()

            fix_permissions(filename)

        return True

    def set_request(self, user, request):

        "For the given 'user', set the queued 'request'."

        filename = self.get_object_in_store(user, "requests")

        if not filename:

            return False

        f = open(filename, "a")

        try:

            print >>f, request

        finally:

            f.close()

            fix_permissions(filename)

        return True

    def queue_request(self, user, uid):

        "Queue a request for 'user' having the given 'uid'."

        requests = self.get_requests(user) or []

        if uid not in requests:

            return self.set_request(user, uid)

        return False

    def dequeue_request(self, user, uid):

        "Dequeue a request for 'user' having the given 'uid'."

        requests = self.get_requests(user) or []

        try:

            requests.remove(uid)

            self.set_requests(user, requests)

        except ValueError:

            return False

        else:

            return True

class FilePublisher(FileBase):

    "A publisher of objects."

    def __init__(self, store_dir=PUBLISH_DIR):

        FileBase.__init__(self, store_dir)

    def set_freebusy(self, user, freebusy):

        "For the given 'user', set 'freebusy' details."

        filename = self.get_object_in_store(user, "freebusy")

        if not filename:

            return False

        record = []

        rwrite = record.append

        rwrite(("ORGANIZER", {}, user))

        rwrite(("UID", {}, user))

        rwrite(("DTSTAMP", {}, datetime.utcnow().strftime("%Y%m%dT%H%M%SZ")))

        for start, end, uid, transp in freebusy:

            if not transp or transp == "OPAQUE":

                rwrite(("FREEBUSY", {"FBTYPE" : "BUSY"}, "/".join([start, end])))

        f = open(filename, "w")

        try:

            to_stream(f, make_calendar([("VFREEBUSY", {}, record)], "PUBLISH"))

        finally:

            f.close()

            fix_permissions(filename)

        return True

# vim: tabstop=4 expandtab shiftwidth=4