import os, sys
import random
import yaml
import json
import sqlite3
from datetime import datetime

# my code
import questions
import database

# ===========================================================================
def read_configuration(filename, debug=False, show_points=False, show_hints=False, practice=False, save_answers=False, show_ref=False):
    # FIXME validar se ficheiros e directorios existem???
    if not os.path.isfile(filename):
        print('  * Cannot find file "%s"' % filename)
        sys.exit(1)

    try:
        with open(filename, 'r') as f:
            test = yaml.load(f)
    except:
        print('  * Error reading yaml file "{0}".'.format(filename))
        raise

    # defaults:
    test['ref'] = str(test.get('ref', filename))
    test['title'] = str(test.get('title', ''))
    test['show_hints'] = bool(test.get('show_hints', show_hints))
    test['show_points'] = bool(test.get('show_points', show_points))
    test['practice'] = bool(test.get('practice', practice))
    test['debug'] = bool(test.get('debug', debug))
    test['show_ref'] = bool(test.get('show_ref', show_ref))
    test['path'] = str(test.get('path', '.'))  # questions dir  FIXME use os.path
    # FIXME check that the directory exists
    if not os.path.exists(test['path']):
        print('  * Questions path "{0}" does not exist. Fix it in "{1}".'.format(test['path'], filename))
        sys.exit(1)
    test['save_answers'] = bool(test.get('save_answers', save_answers))
    if test['save_answers']:
        if 'answers_dir' not in test:
            raise exception('Missing "answers_dir" in the test configuration.')
        if not os.path.isdir(test['answers_dir']):
            print('  * Directory "%s" does not exist. Creating...' % test['answers_dir'])
            os.mkdir(test['answers_dir'])

    if 'database' not in test:
        print('  * Missing database in the test configuration.')
        sys.exit(1)
    if not os.path.exists(test['database']):
        print('  * Database "{0}" not found.'.format(test['database']))
        sys.exit(1)


    if isinstance(test['files'], str):
        test['files'] = [test['files']]

    # replace ref,points by actual questions from pool
    pool = questions.QuestionsPool()
    pool.add_from_files(files=
        test['files'], path=test['path'])

    for i, q in enumerate(test['questions']):
        # each question is a list of alternative versions, even if the list
        # contains only one element
        if isinstance(q, str):
            # normalize question to a dict
            #       - some_ref
            # becomes
            #       - ref: some_ref
            #         points: 1.0
            test['questions'][i] = [pool[q]]  # list with just one question
            test['questions'][i][0]['points'] = 1.0
            # Note: at this moment we do not know the questions types.
            # Some questions, like information, should have default points
            # set to 0. That must be done later when the question is
            # instantiated.

        elif isinstance(q, dict):
            if 'ref' not in q:
                print('  * Found a question without a "ref" key in the test "{}"'.format(filename))
                print('    Dictionary contents:', q)
                sys.exit(1)

            if isinstance(q['ref'], str):
                q['ref'] = [q['ref']]       # ref is always a list
            p = float(q.get('points', 1.0)) # default points is 1.0

            # create list of alternatives, normalized
            l = []
            for r in q['ref']:
                try:
                    qq = pool[r]
                except KeyError:
                    print('  * question "{0}" in test "{1}" not found in the pool. Ignoring...'.format(r, test['ref']))
                    continue
                qq['points'] = p
                l.append(qq)

            # add question (i.e. list of alternatives) to the test
            test['questions'][i] = l

    return test

# ===========================================================================
class Test(dict):
    # -----------------------------------------------------------------------
    def __init__(self, d):
        super().__init__(d)

        qlist = []
        for i, qq in enumerate(self['questions']):
            q = random.choice(qq)  # select from alternative versions
            qlist.append(questions.create_question(q))  # create instance
        self['questions'] = qlist
        self['start_time'] = datetime.now()

    # -----------------------------------------------------------------------
    def update_answers(self, ans):
        '''given a dictionary ans={'ref':'some answer'} updates the answers
        of the test.  FIXME: check if answer is to be corrected or not
        '''
        for q in self['questions']:
            q['answer'] = ans[q['ref']] if q['ref'] in ans else None

    # -----------------------------------------------------------------------
    def correct(self):
        '''Corrects all the answers and computes the final grade.'''

        self['finish_time'] = datetime.now()

        total_points = 0.0
        final_grade = 0.0
        for q in self['questions']:
            final_grade += q.correct() * q['points']
            total_points += q['points']

        final_grade = 20.0 * max(final_grade / total_points, 0.0)

        self['grade'] = final_grade
        return final_grade

    # -----------------------------------------------------------------------
    def save_json(self, path):
        filename = ' -- '.join((str(self['number']), self['ref'],
                               str(self['finish_time']))) + '.json'
        filepath = os.path.abspath(os.path.join(path, filename))
        with open(filepath, 'w') as f:
            json.dump(self, f, indent=2, default=str)
            # HACK default=str is required for datetime objects