#!/usr/bin/env python

import dateutil.parser
import dateutil.tz
import datetime
import json
import logging
import time
import urllib
import urllib2
import os
import sys

API_TOKEN = os.environ.get('TODOIST_API_KEY', None)
NEXT_ACTION_LABEL = os.environ.get('TODOIST_NEXT_ACTION_LABEL', 'next_action')
SYNC_DELAY = int(os.environ.get('TODOIST_SYNC_DELAY', '5'))
INBOX_HANDLING = os.environ.get('TODOIST_INBOX_HANDLING', 'parallel')
TODOIST_VERSION = '5.3'


class TraversalState(object):
    """Simple class to contain the state of the item tree traversal."""

    def __init__(self, next_action_label_id):
        self.remove_labels = []
        self.add_labels = []
        self.found_next_action = False
        self.next_action_label_id = next_action_label_id

    def clone(self):
        """Perform a simple clone of this state object.

        For parallel traversals it's necessary to produce copies so that every
        traversal to a lower node has the same found_next_action status.
        """
        t = TraversalState(self.next_action_label_id)
        t.found_next_action = self.found_next_action
        return t

    def merge(self, other):
        """Merge clones back together.

        After parallel traversals, merge the results back into the parent state.
        """
        if other.found_next_action:
            self.found_next_action = True
        self.remove_labels += other.remove_labels
        self.add_labels += other.add_labels


class Item(object):
    def __init__(self, initial_data):
        self.parent = None
        self.children = []
        self.checked = initial_data['checked'] == 1
        self.content = initial_data['content']
        self.indent = initial_data['indent']
        self.item_id = initial_data['id']
        self.labels = initial_data['labels']
        self.priority = initial_data['priority']
        if 'due_date_utc' in initial_data and initial_data['due_date_utc'] is not None:
            p = dateutil.parser.parser()
            self.due_date_utc = p.parse(initial_data['due_date_utc'])
        else:
            # Arbitrary time in the future to always sort last
            self.due_date_utc = datetime.datetime(2100, 1, 1, tzinfo=dateutil.tz.tzutc())

    def GetItemMods(self, state):
        if self.IsSequential():
            self._SequentialItemMods(state)
        elif self.IsParallel():
            self._ParallelItemMods(state)
        if not state.found_next_action and not self.checked:
            state.found_next_action = True
            if not state.next_action_label_id in self.labels:
                state.add_labels.append(self)
        elif state.next_action_label_id in self.labels:
            state.remove_labels.append(self)

    def SortChildren(self):
        sortfunc = lambda item: [item.due_date_utc, (5 - item.priority)]
        self.children = sorted(self.children, key=sortfunc)
        for item in self.children:
            item.SortChildren()

    def GetLabelRemovalMods(self, state):
        if state.next_action_label_id in self.labels:
            state.remove_labels.append(self)
        for item in self.children:
            item.GetLabelRemovalMods(state)

    def _SequentialItemMods(self, state):
        """
        Iterate over every child, walking down the tree.
        If none of our children are the next action, check if we are.
        """
        for item in self.children:
            item.GetItemMods(state)

    def _ParallelItemMods(self, state):
        """
        Iterate over every child, walking down the tree.
        If none of our children are the next action, check if we are.
        Clone the state each time we descend down to a child.
        """
        frozen_state = state.clone()
        for item in self.children:
            temp_state = frozen_state.clone()
            item.GetItemMods(temp_state)
            state.merge(temp_state)

    def IsSequential(self):
        return not self.content.endswith('=')
        # if self.content.endswith('--') or self.content.endswith('='):
        #  return self.content.endswith('--')
        #else:
        #  return self.parent.IsSequential()

    def IsParallel(self):
        return self.content.endswith('=')
        # if self.content.endswith('--') or self.content.endswith('='):
        #  return self.content.endswith('=')
        #else:
        #  return self.parent.IsParallel()


class Project(object):
    def __init__(self, initial_data):
        self._todoist = None
        self.parent = None
        self.children = []
        self._subProjects = None
        self.itemOrder = initial_data['item_order']
        self.indent = initial_data['indent'] - 1
        self.is_archived = initial_data['is_archived'] == 1
        self.is_deleted = initial_data['is_deleted'] == 1
        self.last_updated = initial_data['last_updated']
        self.name = initial_data['name']
        # Project should act like an item, so it should have content.
        self.content = initial_data['name']
        self.project_id = initial_data['id']
        self._CreateItemTree(self.getItems())
        self.SortChildren()

    def getItems(self):
        req = urllib2.Request(
            'https://todoist.com/API/getUncompletedItems?project_id=' + str(self.project_id) + '&token=' + API_TOKEN)
        response = urllib2.urlopen(req)
        return json.loads(response.read())

    def setTodoist(self, todoist):
        self._todoist = todoist

    def subProjects(self):
        if self._subProjects is None:
            self._subProjects = []
            initialIndent = self.indent
            initialOrder = self._todoist._orderedProjects.index(self)
            order = initialOrder + 1
            maxSize = len(self._todoist._orderedProjects)
            if order < maxSize:
                current = self._todoist._orderedProjects[order]
                while (current.indent > initialIndent) and (order < maxSize):
                    current = self._todoist._orderedProjects[order]
                    if current != None:
                        self._subProjects.append(current)
                        current.parent = self
                        order += 1

        return self._subProjects

    def IsIgnored(self):
        return self.name.startswith('Someday') or self.name.startswith('List - ')

    def IsSequential(self):
        return not self.IsIgnored() and \
            not self.IsParallel() and \
            (self.parent is None or not self.parent.IsIgnored())

    def IsParallel(self):
        return self.name.endswith('=') or (self.name == 'Inbox' and INBOX_HANDLING == 'parallel')

    SortChildren = Item.__dict__['SortChildren']

    def GetItemMods(self, state):
        if self.IsSequential():
            for item in self.children:
                item.GetItemMods(state)
        elif self.IsParallel():
            frozen_state = state.clone()
            for item in self.children:
                temp_state = frozen_state.clone()
                item.GetItemMods(temp_state)
                state.merge(temp_state)
        else:  # Remove all next_action labels in this project.
            for item in self.children:
                item.GetLabelRemovalMods(state)

    def _CreateItemTree(self, items):
        """Build a tree of items based on their indentation level."""
        parent_item = self
        previous_item = self
        for item_dict in items:
            item = Item(item_dict)
            if item.indent > previous_item.indent:
                logging.debug('pushing "%s" on the parent stack beneath "%s"',
                              previous_item.content, parent_item.content)
                parent_item = previous_item
            # walk up the tree until we reach our parent
            while parent_item.parent is not None and item.indent <= parent_item.indent:
                logging.debug('walking up the tree from "%s" to "%s"',
                              parent_item.content, (parent_item.parent if (parent_item.parent is not None) else 0))
                parent_item = parent_item.parent

            logging.debug('adding item "%s" with parent "%s"', item.content,
                          parent_item.content if (parent_item is not None) else '')
            parent_item.children.append(item)
            item.parent = parent_item
            previous_item = item


class TodoistData(object):
    """Construct an object based on a full Todoist /Get request's data"""

    def __init__(self, initial_data):
        self._SetLabelData(initial_data)
        self._projects = dict()

        for project in initial_data['Projects']:
            p = Project(project)
            p.setTodoist(self)
            self._projects[project['id']] = p

        self._orderedProjects = sorted(self._projects.values(), key=lambda project: project.itemOrder)

        for project in self._projects.values():
            project.subProjects()

    def _SetLabelData(self, label_data):
        # Store label data - we need this to set the next_action label.
        self._labels_timestamp = label_data['DayOrdersTimestamp']
        self._next_action_id = None
        for label in label_data['Labels'].values():
            if label['name'] == NEXT_ACTION_LABEL:
                self._next_action_id = label['id']
                logging.info('Found next_action label, id: %s', label['id'])
        if self._next_action_id is None:
            logging.warning('Failed to find next_action label, need to create it.')

    def GetSyncState(self):
        project_timestamps = dict()
        for project_id, project in self._projects.iteritems():
            project_timestamps[project_id] = project.last_updated
        return {'labels_timestamp': self._labels_timestamp,
                'project_timestamps': project_timestamps}

    def UpdateChangedData(self, changed_data):
        if ('DayOrdersTimestamp' in changed_data
            and changed_data['DayOrdersTimestamp'] != self._labels_timestamp):
            self._SetLabelData(changed_data)
        # delete missing projects
        if 'ActiveProjectIds' in changed_data:
            projects_to_delete = set(self._projects.keys()) - set(changed_data['ActiveProjectIds'])
            for project_id in projects_to_delete:
                logging.info("Forgetting deleted project %s", self._projects[project_id].name)
                del self._projects[project_id]
        if 'Projects' in changed_data:
            for project in changed_data['Projects']:
                logging.info("Refreshing data for project %s", project['name'])
                if project['id'] in self._projects:
                    logging.info("replacing project data, old timestamp: %s new timestamp: %s",
                                 self._projects[project['id']].last_updated, project['last_updated'])
                self._projects[project['id']] = Project(project)
        # We have already reloaded project data sent to us.
        # Now any project timestamps that have changed are due to the changes we
        # just sent to the server. Let's update our model.
        if 'ActiveProjectTimestamps' in changed_data:
            for project_id, timestamp in changed_data['ActiveProjectTimestamps'].iteritems():
                # for some reason the project id is a string and not an int here.
                project_id = int(project_id)
                if project_id in self._projects:
                    project = self._projects[project_id]
                    if project.last_updated != timestamp:
                        logging.info("Updating timestamp for project %s to %s",
                                     project.name, timestamp)
                        project.last_updated = timestamp


    def GetProjectMods(self):
        mods = []
        # We need to create the next_action label
        if self._next_action_id is None:
            self._next_action_id = '$%d' % int(time.time())
            mods.append({'type': 'label_register',
                         'timestamp': int(time.time()),
                         'temp_id': self._next_action_id,
                         'args': {
                             'name': NEXT_ACTION_LABEL
                         }})
            # Exit early so that we can receive the real ID for the label.
            # Otherwise we end up applying the label two different times, once with
            # the temporary ID and once with the real one.
            # This makes adding the label take an extra round through the sync
            # process, but that's fine since this only happens on the first ever run.
            logging.info("Adding next_action label")
            return mods
        for project in self._projects.itervalues():
            state = TraversalState(self._next_action_id)
            project.GetItemMods(state)
            if len(state.add_labels) > 0 or len(state.remove_labels) > 0:
                logging.info("For project %s, the following mods:", project.name)
            for item in state.add_labels:
                # Intentionally add the next_action label to the item.
                # This prevents us from applying the label twice since the sync
                # interface does not return our changes back to us on GetAndSync.
                item.labels.append(self._next_action_id)
                mods.append({'type': 'item_update',
                             'timestamp': int(time.time()),
                             'args': {
                                 'id': item.item_id,
                                 'labels': item.labels
                             }})
                logging.info("add next_action to: %s", item.content)
            for item in state.remove_labels:
                item.labels.remove(self._next_action_id)
                mods.append({'type': 'item_update',
                             'timestamp': int(time.time()),
                             'args': {
                                 'id': item.item_id,
                                 'labels': item.labels
                             }})
                logging.info("remove next_action from: %s", item.content)
        return mods


def GetResponse():
    values = {'api_token': API_TOKEN, 'resource_types': ['labels']}
    data = urllib.urlencode(values)
    req = urllib2.Request('https://api.todoist.com/TodoistSync/v' + TODOIST_VERSION + '/get', data)
    return urllib2.urlopen(req)


def GetLabels():
    req = urllib2.Request('https://todoist.com/API/getLabels?token=' + API_TOKEN)
    return urllib2.urlopen(req)


def GetProjects():
    req = urllib2.Request('https://todoist.com/API/getProjects?token=' + API_TOKEN)
    return urllib2.urlopen(req)


def DoSync(items_to_sync):
    values = {'api_token': API_TOKEN,
              'items_to_sync': json.dumps(items_to_sync)}
    logging.info("posting %s", values)
    data = urllib.urlencode(values)
    req = urllib2.Request('https://api.todoist.com/TodoistSync/v' + TODOIST_VERSION + '/sync', data)
    return urllib2.urlopen(req)


def DoSyncAndGetUpdated(items_to_sync, sync_state):
    values = {'api_token': API_TOKEN,
              'items_to_sync': json.dumps(items_to_sync)}
    for key, value in sync_state.iteritems():
        values[key] = json.dumps(value)
    logging.debug("posting %s", values)
    data = urllib.urlencode(values)
    req = urllib2.Request('https://api.todoist.com/TodoistSync/v' + TODOIST_VERSION + '/syncAndGetUpdated', data)
    return urllib2.urlopen(req)


def main():
    if os.environ.get('TODOIST_DEBUG', None):
        log_level = logging.DEBUG
    else:
        log_level = logging.INFO
    logging.basicConfig(level=log_level)
    if not API_TOKEN:
        logging.error('No API key set, exiting...')
        sys.exit(1)
    response = GetResponse()
    json_data = json.loads(response.read())
    while True:
        response = GetLabels()
        json_data['Labels'] = json.loads(response.read())
        response = GetProjects()
        json_data['Projects'] = json.loads(response.read())
        logging.debug("Got initial data: %s", json_data)
        logging.info("*** Retrieving Data")
        singleton = TodoistData(json_data)
        logging.info("*** Data built")
        mods = singleton.GetProjectMods()
        if len(mods) == 0:
            time.sleep(SYNC_DELAY)
        else:
            logging.info("* Modifications necessary - skipping sleep cycle.")
        logging.info("** Beginning sync")
        sync_state = singleton.GetSyncState()
        changed_data = DoSyncAndGetUpdated(mods, sync_state).read()
        logging.debug("Got sync data %s", changed_data)
        changed_data = json.loads(changed_data)
        logging.info("* Updating model after receiving sync data")
        singleton.UpdateChangedData(changed_data)
        logging.info("* Finished updating model")
        logging.info("** Finished sync")


if __name__ == '__main__':
    main()