#-*- coding:utf-8 -*-
"""
====================================
Utilities to help with using CSV IO
====================================


Example usage
-------------

Code that used to do this::

    writer = csv.writer(open('/path/to/file.csv'))

Can now do this to work with Unicode::

    writer = UnicodeWriter(open('/path/to/file.csv'))

----

.. seealso::

    * `Python csv docs <http://docs.python.org/2/library/csv.html#csv-examples>`_
    * https://gist.github.com/ewalstad/8325465
"""


import csv, codecs, cStringIO


class UTF8Recoder:
    """
    Iterator that reads an encoded stream and reencodes the input to UTF-8
    """
    def __init__(self, f, encoding):
        self.reader = codecs.getreader(encoding)(f)

    def __iter__(self):
        return self

    def next(self):
        return self.reader.next().encode("utf-8")


class UnicodeReader:
    """
    A CSV reader which will iterate over lines in the CSV file "f",
    which is encoded in the given encoding.
    """

    def __init__(self, f, dialect=csv.excel, encoding="utf-8", **kwds):
        f = UTF8Recoder(f, encoding)
        self.reader = csv.reader(f, dialect=dialect, **kwds)

    def next(self):
        row = self.reader.next()
        return [unicode(s, "utf-8") for s in row]

    def __iter__(self):
        return self

    @property
    def line_num(self):
        """The number of lines read from the source iterator. This is not the
        same as the number of records returned, as records can span multiple
        lines."""
        return self.reader.line_num

    @property
    def dialect(self):
        """A read-only description of the dialect in use by the parser."""
        return self.reader.dialect


class UnicodeWriter:
    """
    A CSV writer which will write rows to CSV file "f",
    which is encoded in the given encoding.
    """

    def __init__(self, f, dialect=csv.excel, encoding="utf-8", **kwds):
        # Redirect output to a queue
        self.queue = cStringIO.StringIO()
        self.writer = csv.writer(self.queue, dialect=dialect, **kwds)
        self.stream = f
        self.encoder = codecs.getincrementalencoder(encoding)()

    def writerow(self, row):
        self.writer.writerow([s.encode("utf-8") for s in row])
        # Fetch UTF-8 output from the queue ...
        data = self.queue.getvalue()
        data = data.decode("utf-8")
        # ... and reencode it into the target encoding
        data = self.encoder.encode(data)
        # write to the target stream
        self.stream.write(data)
        # empty queue
        self.queue.truncate(0)

    def writerows(self, rows):
        for row in rows:
            self.writerow(row)