# -*- coding: utf-8 -*-
"""Convert the Yelp Dataset Challenge dataset from json format to csv.
For more information on the Yelp Dataset Challenge please visit http://yelp.com/dataset_challenge
"""
import argparse
import codecs
import collections
import csv
import simplejson as json


def read_and_write_file(json_file_path, csv_file_path, column_names):
    """Read in the json dataset file and write it out to a csv file, given the column names."""
    with open(csv_file_path, 'wb+') as fout:
        csv_file = csv.writer(fout)
        csv_file.writerow(list(column_names))
        with open(json_file_path) as fin:
            for line in fin:
                print line
                line_contents = json.loads(line)
                csv_file.writerow(get_row(line_contents, column_names))

def get_superset_of_column_names_from_file(json_file_path):
    """Read in the json dataset file and return the superset of column names."""
    column_names = set()
    with open(json_file_path) as fin:
        for line in fin:
            print line
            line_contents = json.loads(line)
            column_names.update(
                    set(get_column_names(line_contents).keys())
                    )
    return column_names

def get_review_rating_from_file(json_file_path, limit=None):
    """Read in the json dataset file and return the reviews and ratings."""
    reviews = []
    num_processed = 0
    with open(json_file_path) as fin:
        for line in fin:
            num_processed += 1
            reviews.append(json.loads(line))
            if limit is not None and limit <= num_processed:
                break
    return reviews

def write_file(reviews, reviews_csv_file_path, ratings_csv_file_path):
    """Read in the json dataset file and write it out to a csv file, given the column names."""
    with open(reviews_csv_file_path, 'wb+') as reviews_out:
        with open(ratings_csv_file_path, 'wb+') as ratings_out:
            reviews_out.writelines([get_row(review, ['text'])[0]+'\n' for review in reviews])
            ratings_out.writelines([get_row(review, ['stars'])[0]+'\n' for review in reviews])


def get_column_names(line_contents, parent_key=''):
    """Return a list of flattened key names given a dict.
    Example:
        line_contents = {
            'a': {
                'b': 2,
                'c': 3,
                },
        }
        will return: ['a.b', 'a.c']
    These will be the column names for the eventual csv file.
    """
    column_names = []
    for k, v in line_contents.iteritems():
        column_name = "{0}.{1}".format(parent_key, k) if parent_key else k
        if isinstance(v, collections.MutableMapping):
            column_names.extend(
                    get_column_names(v, column_name).items()
                    )
        else:
            column_names.append((column_name, v))
    return dict(column_names)

def get_nested_value(d, key):
    """Return a dictionary item given a dictionary `d` and a flattened key from `get_column_names`.

    Example:
        d = {
            'a': {
                'b': 2,
                'c': 3,
                },
        }
        key = 'a.b'
        will return: 2

    """
    if '.' not in key:
        if key not in d:
            return None
        return d[key]
    base_key, sub_key = key.split('.', 1)
    if base_key not in d:
        return None
    sub_dict = d[base_key]
    return get_nested_value(sub_dict, sub_key)

def get_row(line_contents, column_names):
    """Return a csv compatible row given column names and a dict."""
    row = []
    for column_name in column_names:
        line_value = get_nested_value(
                        line_contents,
                        column_name,
                        )
        if isinstance(line_value, unicode):
            row.append('{0}'.format(line_value.encode('utf-8')))
        elif line_value is not None:
            if column_name == 'stars':
                line_value = (line_value - 1)* 0.25
            row.append('{0}'.format(line_value))
        else:
            row.append('')
    row = [s.replace('\n', '').replace('\r', '') for s in row]
    return row


def get_review_rating(json_file, limit=None):
    review_csv_file = '{0}_review.txt'.format(json_file.split('.json')[0])
    rating_csv_file = '{0}_rating.txt'.format(json_file.split('.json')[0])
    reviews = get_review_rating_from_file(json_file, limit)
    write_file(reviews, review_csv_file, rating_csv_file)


if __name__ == '__main__':
    """Convert a yelp dataset file from json to csv."""

    parser = argparse.ArgumentParser(
            description='Convert Yelp Dataset Challenge data from JSON format to CSV.',
            )

    parser.add_argument(
            'json_file',
            type=str,
            help='The json file to convert.',
            )

    parser.add_argument(
        'limit',
        type=int,
        help='Limit of reviews to process',
        default=None,
        nargs='?',
    )

    args = parser.parse_args()

    json_file = args.json_file
    limit = args.limit
    get_review_rating(json_file, limit)

    # read_and_write_file(json_file, csv_file, column_names)
