import copy

class ctx_Controller:
  def __init__(self, c):
    self.callbacks = []
    self.context = c
    self.functions = []
    self.isProcessingQueue = False
    self.queue = []
  
  def executeFunctions(self):
    c = self.queue.pop(0)
    for f in self.functions:
      ctx = f(c)
      if ctx.recentField != "none":
        self.queue.append(ctx)

    self.context.recentField = c.recentField
    self.context.setField(c.recentField, c.field(c.recentField))
    self.reportContext()

  def processQueue(self):
    # Decline recursion.
    if self.isProcessingQueue:
      return
    self.isProcessingQueue = True
    while len(self.queue) > 0:
      self.executeFunctions()
    self.isProcessingQueue = False

  def registerCallback(self, cb):
    self.callbacks.append(cb)

  def registerFieldCallback(self, fieldName, cb):
    self.callbacks.append(lambda c: cb(c) if c.recentField == fieldName else None)

  def registerFunction(self, f):
    self.functions.append(f)

  def registerFunctions(self, funcs):
    for f in funcs:
      self.functions.append(f)

  def reportContext(self):
    for cb in self.callbacks:
      cb(self.context)

  def set(self, fieldName, value):
    c = copy.deepcopy(self.context)
    c.setField(fieldName, value)
    c.recentField = fieldName
    self.queue.append(c)
    self.processQueue()