import eikon as ek


def check_eikon_data_download(error):
    if error is not None:
        ValueError('Could not download Eikon data! Something went wrong in Request!')


def get_eikon_data_for_index(universe, dt, eikon_key=None, ric_codes=None, fund_flds=None, fperiod=None,
                             isin=False, xl_name=None):

    if sum(x is None for x in [fund_flds, fperiod]) == 1:
        ValueError('Fundamental fields and list must both be defined!')

    if eikon_key is None:
        eikon_key = 'Need to set own key here...'
    ek.set_app_key(eikon_key)

    if ric_codes is None:
        static_flds = ['TR.IndexConstituentRIC', 'TR.IndexConstituentName']
        inst_list, err_const = ek.get_data(instruments=universe, fields=static_flds,
                                           parameters={'SDate': dt, 'EDate': dt})
    else:
        inst_list = ric_codes

    # get the list of stocks within the STOXX 600 universe...
    if isin:
        isin_list, err_isin = ek.get_data(instruments=inst_list.loc[:, 'Constituent RIC'].tolist(),
                                     fields=['TR.ISINCode', 'TR.SEDOL'])
        inst_list[isin_list.columns[1:]] = isin_list.iloc[:, 1:]

    if fperiod is not None:
        fund_data, err_fund = ek.get_data(instruments=inst_list.loc[:, 'Constituent RIC'].tolist(),
                                          fields=fund_flds,
                                          parameters={'SDate': dt, 'Period': fperiod})
    else:
        fund_data, err_fund = ek.get_data(instruments=inst_list.loc[:, 'Constituent RIC'].tolist(),
                                          fields=fund_flds,
                                          parameters={'SDate': dt})
    inst_list[fund_data.columns[1:]] = fund_data.iloc[:, 1:]

    # write this over into a spreadsheet
    if xl_name is not None:
        inst_list.to_excel(xl_name)

    return inst_list


if __name__== '__main__':

    date = '2017-01-15'
    univ = ['.STOXX']

    # get some fundamentals here...
    fund_fields = ['TR.EPSMean', 'TR.OperatingMarginPercent']
    f_per = 'FY0'
    fund_data = get_eikon_data_for_index(univ, date, fund_flds=fund_fields, fperiod=f_per, isin=True)

    # get dividend yield data...
    div_yld = ['TR.DPSMeanYield']
    f_per = 'FY1'
    div_yld = get_eikon_data_for_index(univ, date, ric_codes=fund_data.loc[:, ['Constituent RIC']], fund_flds=div_yld,
                                       fperiod=f_per, isin=False)

    # get Net Debt/EBITDA data...
    n_d_to_ebitda = ['TR.NetDebtToEBITDA']
    net_debt_to_ebitda = get_eikon_data_for_index(univ, date, ric_codes=fund_data.loc[:, ['Constituent RIC']],
                                                  fund_flds=n_d_to_ebitda, isin=False)

    #combine data...
    fund_data[div_yld.columns[1:]] = div_yld.iloc[:, 1:]
    fund_data[net_debt_to_ebitda.columns[1:]] = net_debt_to_ebitda.iloc[:, 1:]

    # write to excel...
    fund_data.to_excel('test_point-in-time.xlsx')