"""Read accounting run files from the local filesystem."""

from accounting.models.statement import Statement


def read_exchange_rate_file(filename):
    """Read the lines of the exchange rates file into a list of dicts."""
    header = True
    rows = []
    with open(filename, 'r', encoding='utf-8') as lines:
        for line in lines:
            if header:
                header = False
                continue
            if not line:
                continue
            rate_row = line.strip().split('\t')
            rows.append({
                'period_id': int(rate_row[0]),
                'currency_from_id': int(rate_row[1]),
                'currency_to_id': int(rate_row[2]),
                'exchange_rate': float(rate_row[3])})
    return rows


def read_statement_file(filename):
    """Read the lines of the statement TSV into an array of dicts.

    Args:
        filename (str): valid local filepath of a tsv file.

    Yields:
        dict: a dict representation of a line from the file.

    """
    header = True
    with open(filename, 'r', encoding='utf-8') as lines:
        for line in lines:
            if header:
                header = False
                continue

            yield build_dict(
                Statement.fields.keys(), line.strip().split('\t'))


def read_transaction_file(filename):
    """Read the lines of the digital sales TSV into an array of dicts.

    Args:
        filename (str): valid local filepath of a tsv file.

    Yields:
        dict: a dict representation of a line from the file.

    """
    mapped_fields = [
        'statement_id',
        'date',
        'upc',
        'cd',
        'track_id',
        'isrc',
        'track_name',
        'qty',
        'unit_price',
        'total',
        'trans_type',
        'retail_price',
        'original_price',
        'discount'
    ]
    with open(filename, 'r', encoding='utf-8') as lines:
        for line in lines:
            txn = build_dict(mapped_fields, line.strip().split('\t'))
            del txn['track_name']
            del txn['isrc']
            yield txn


def build_dict(headers, values):
    """Combine a list of keys and a list of values into a dict.

    String stripping is performed to sanitize the input.

    Args:
        headers (List): Ordered keys for a dict.
        values (List): Ordered values for a dict.

    Returns:
        dict: A dict representation of combined headers and values.

    """
    for idx, value in enumerate(values):
        values[idx] = value.strip('\"')

    return dict(zip(headers, values))