import os
import yaml


class QuestionException(Exception):
	""" Exception to be thrown when there is something wrong with
	    the question file. """
	pass

class Questions(object):
	""" Object holding all the questions """

	QUESTION_TYPES = ["Text", "Image", "Music", "Code"]
	QUESTION_KEYS = ["Name", "Question", "Answer", "Type", "Double-Jeopardy"]

	def __init__(self, qfile):
		self.qfile = qfile
		self._questions = None
		self._read_questions()

	def get_sections(self):
		return [s["Section"] for s in self._questions]

	def get_questions(self, section):
		sec = filter(lambda s: s["Section"] ==  section, self._questions)
		if len(sec) < 1:
			raise ValueError("Section %s does not exist" % (section,))
		return sec[0]["Questions"]

	def get_question(self, section, question):
		if type(question) != int or question < 1 or question > 5:
			raise ValueError("question parameter needs to be an integer between 1 and 5")
		return self.get_questions(section)[question-1]

	def get_number_from_section(self, section):
		for i,s in enumerate(self._questions, 1):
			if s["Section"] == section:
				return i
		raise ValueError("Section '%s' does not exist" % section)

	def _read_questions(self):
		f = None

		# open file
		try:
			f = open(self.qfile)
		except OSError as e:
			raise QuestionException("Could not read question file: %s" % e)

		# load yaml
		ysrc = None
		try:
			ysrc = yaml.load(f.read())
		except Exception as e:
			raise QuestionException("Error parsing question file %s: %s" % (self.qfile, e))

		# now to check the integrity of the question file
		if type(ysrc) is not list:
			raise QuestionException("The questionfile has to be a list of question")
		
		for i, sec in enumerate(ysrc, 1):
			if not "Section" in sec.keys() or not "Questions" in sec.keys():
				raise QuestionException("Section %d needs to have the keys 'Section' and 'Question' (case-sensitive)" % i)

			for j, q in enumerate(sec["Questions"], 1):
				# check for keys we need in each question
				if any([x not in q.keys() for x in ["Question", "Answer", "Type"]]):
					raise QuestionException("Question %d from section %d (%s) is missing one of the keywords Question, Answer or Type" % (j, i, sec["Section"]))

				# check for keys we do not know
				for key in q.keys():
					if key not in self.QUESTION_KEYS:
						raise QuestionException("Qestion %d from section %d (%s) has invalid keyword '%s'" % (j, i, sec["Section"], key))

				# check Double-Jeopardy is a bool and is set to false it non-existant
				if "Double-Jeopardy" not in q.keys():
					q["Double-Jeopardy"] = False
				elif type(q["Double-Jeopardy"]) != bool:
					raise QuestionException("The Double-Jeopardy key from question %d from section %d (%s) must be either true or false" % (j, i, sec["Section"]))

				# check for broken question types
				if q["Type"] not in self.QUESTION_TYPES:
					raise QuestionException("Question %d from Section %d (%s) has an invalid type '%s' (valid types are %s)" % (j, i, sec["Section"], q["Type"], ", ".join(self.VALID_TYPES)))

				# check if file for music/image questions exist
				if q["Type"] in ("Music", "Image"):
					if not os.path.isfile(q["Question"]):
						raise QuestionException("File for question %d, section %d (%s) not found" % (j, i, sec["Section"]))

			# check if this section has enough questions
			if j != 5:
				raise QuestionException("Section %d (%s) needs to have exactly %d questions (has %d)" % (i, sec["Section"], 5, j))

		# check for only having unique section names
		sections = [s["Section"] for s in ysrc]
		if len(sections) != len(set(sections)):
			raise QuestionException("All section names must be unique")

		# done, save yaml src to _questions
		self._questions = ysrc

		return True

if __name__ == '__main__':
	q = Questions("questions/template.q")
	print(q.get_sections())
	print(q.get_questions("A"))
	print(q.get_question("A", 1))