"""Budget Parser"""

from collections import namedtuple

from .exceptions import BudgetParserError
from .helpers import get_sheet_of_file, is_empty_excel_value, strip_excel_value

EXPECTED_TABLE_HEADERS = [
    "Nr.",
    "Projekt",
    "Laufzeit",
    "BA",
    "Fond",
    "Budget",
    "Ausgaben",
    "Rest",
]

NUM_EXPECTED_HEADERS = len(EXPECTED_TABLE_HEADERS)

ExcelRow = namedtuple("ExcelRow", ["row", "data"])

BudgetData = namedtuple(
    "BudgetData",
    [
        "row",
        "number",
        "project_name",
        "period",
        "project",
        "fond",
        "budget",
        "expenses",
        "rest",
    ],
)


def _check_table_header(xl_row):
    fields_ignore_none = (
        ("" if c is None else c) for c in xl_row.data[:NUM_EXPECTED_HEADERS]
    )
    fields_str = (str(c) for c in fields_ignore_none)
    fields = [c.strip() for c in fields_str]
    if fields != EXPECTED_TABLE_HEADERS:
        msg = f"unexpected headers: '{xl_row.data}'"
        raise BudgetParserError(msg)


def _skip_empty_lines(rows):
    for xl_row in rows:
        first_cell = xl_row.data[0]
        if is_empty_excel_value(first_cell):
            continue
        yield xl_row


def _parse_data_table(rows):
    for xl_row in _skip_empty_lines(rows):
        data = [
            strip_excel_value(value)
            for value in xl_row.data[:NUM_EXPECTED_HEADERS]
        ]
        yield BudgetData(xl_row.row, *data)


def parse_budget_data(xls_sheet):
    """parses the budget data"""
    rows = (ExcelRow(i, v) for i, v in enumerate(xls_sheet.values, start=1))
    _check_table_header(next(rows))
    return list(_parse_data_table(rows))


def parse_budget_file(file_path):
    """parses the budget file"""
    sheet = get_sheet_of_file(file_path, sheet=None)
    return parse_budget_data(sheet)