from django.http import Http404

from pytask.taskapp.models import Task, Map

def getTask(tid):

    """ retreive the task from database.

    if the task has deps or subs, update its status correspondingly.

    """

    try:

        task = Task.objects.get(id=tid)

    except Task.DoesNotExist:

        raise Http404

    try:

        mapobj = Map.objects.get(main=task)

    except Map.DoesNotExist:

        mapobj = Map()

        mapobj.main = task

        mapobj.save()

    task_subs = mapobj.subs.all()

    if task.sub_type == "D":

        task.deps, task.subs = task_subs, []

    elif task.sub_type == "S":

        task.subs, task.deps = task_subs, []

    deps, subs = task.deps, task.subs

    if deps and task.status in ["OP", "LO"]:

        task.status = "OP" if all(map(lambda t:t.status=="CM",deps)) else "LO"

    ## a task with subs will remain in "LO" and will be made "OP" only if all subs are removed.

    if subs and task.status in ["OP", "LO"]:

        task.status = "LO"

    task.save()

    return task