from datetime import datetime
from pytask.taskapp.models import Profile, Task, Comment, Credit, Claim

def publishTask(task):
    """ set the task status to open """
    
    sub_tasks = task.subs.all()
    dependencies = task.deps.all()
    if sub_tasks or any(map(lambda t:t.status!="CM",dependencies)):
        task.status = "LO"
    else:
        task.status = "OP"
    task.save()
    return task

def addSubTask(main_task, sub_task):
    """ add the task to subs attribute of the task and update its status.
    sub task can be added only if a task is in UP/OP/LO state.
    """

    ## Shall modify after talking to pr about subtasks
    ## I think i might even remove the concept of subtasks
    main_task.subs.add(sub_task)
    sub_tasks = main_task.subs.all()
    if main_task.status == "OP":
        if any(map(lambda t:t.status!="CM",sub_tasks)):
            main_task.status = "LO"
        else:
            "CM"
    main_task.save()

def addDep(main_task, dependency):
    """ add the dependency task to deps attribute of the task.
    update the status of main_task accordingly.
    note that deps can be added only if task is in UP/OP/LO state.
    And also if the task doesn't have any subs.
    """

    main_task.deps.add(dependency)
    deps = main_task.deps.all()
    if main_task.status in ["OP", "LO"]: 
        if all(map(lambda t:t.status=="CM",deps)):
            main_task.status = "OP"
        else:
            main_task.status = "LO"
    
    main_task.save()

def addMentor(task,mentor):
    """ add the mentor to mentors list of the task """
    
    task.mentors.add(mentor)
    task.save()
    return task    
    
def createTask(title,desc,created_by,credits):
    """ creates a bare minimum task with title, description and credits.
    the creator of the task will be assigned as a mentor for the task.
    """

    try:
        task = Task.objects.get(title__iexact=title)
        return None
    except Task.DoesNotExist:
        task = Task(title=title)
    task.desc = desc
    task.created_by = created_by
    task.credits = credits
    task.creation_datetime = datetime.now()
    task.save()
    return task

def addClaim(task, message, user):
    """ add claim data to the database if it does not exist 
    and also update the claimed users field of the task.
    """
    
    task.claimed_users.add(user)
    task.save()
    claim = Claim()
    claim.message = message
    claim.task = task
    claim.user = user
    claim.creation_datetime = datetime.now()
    claim.save()
    
def assignTask(task, user):
    """ check for the status of task and assign it to the particular user """
    
    if task.status in ['OP', 'WR']:
        task.assigned_users.add(user)
        task.claimed_users.remove(user)
        task.status = "WR"
    task.save()

def getTask(tid):
    """ retreive the task from database.
    if the task has deps or subs, update its status correspondingly.
    """

    task = Task.objects.get(id=tid)
    deps = task.deps.all()
    subs = task.subs.all()

    if deps and task.status in ["OP", "LO"]:
        task.status = "OP" if all(map(lambda t:t.status=="CM",deps)) else "LO"
    if subs and task.status in ["OP", "LO", "CM"]:
        task.status = "CM" if all(map(lambda t:t.status=="CM",subs)) else "LO"

    task.save()
    return task

def updateTask(task, title=None, desc=None, credits=None, tags_field=None):
    """ update the property accordingly.
    while updating title, check for uniqueness of title.
    return None if any error. 
    """
    
    if title:
        try:
            task.title = title
            task.save()
        except Task.IntegrityError:
            return None
    if desc:task.desc = desc
    if credits:task.credits = credits
    if tags_field:task.tags_field = tags_field
    task.save()
    return task