# Development
from pprint import pprint
import csv
import sys

class StripStats:

    def __init__(self, url, output_file='out.csv', fields=None):
        self.output_file = output_file
        self.rows = self.strip_data(url)
        if fields:
            self.fields = fields
        else:
            self.fields = self.rows[0].keys

    #
    # Instance methods
    #

    # Actions
    def write_data(self):
        if not self.rows:
            raise ValueError, "'self.rows' is empty"

        is_empty = False
        if self.is_output_file_empty():
            is_empty = True
            open(self.output_file, 'w').close() #truncate whitespace

        with open(self.output_file, 'ab') as file_handle:
            writer = csv.DictWriter(
                file_handle, self.fields, extrasaction='raise', dialect='excel')
            if is_empty:
                writer.writeheader()
            for row in self.rows:
                writer.writerow(row)

    # Utility
    def is_output_file_empty(self):
        try:
            with open(self.output_file, 'r') as file_handle:
                for line in file_handle:
                    if line.strip():
                        return False
        except:
            pass
        return True

    # Abstract methods
    def strip_data(self, url):
        """Override this abstract method in derived class to. Returns an array of dictionaries
        where each dictionary's keys correspond to a particular matchup's data."""
        pass