config.py

import configparser
import sys
import os
from pprint import pprint


DEFAULT_INI=\
"""\
[server]
; base URL of the server
URL = http://dados.cta.if.ufrgs.br/emm

; board identification number (auto generated when a new board is created)
BOARD_ID =

; authentication token for the board's user
USER_HASH =

[reading]
; CSV list of sensor names/nicknames (order reflect columns on datalog files)
SENSORS = DHT22_TEMP, DHT22_AH, BMP085_PRESSURE, LDR

; time between logger cycles, in minutes
SLEEP_MINUTES = 5

; true for read board clock; if fail, or false, system's time will be used
RTC_DS1307 = true


[datalog]
; CSV delimiter for local log files (valid options:  ,  or  ;  or  \t  )
CSV_SEP = \t

; format of the datetime column
; %Y : years | %m : months | %d : days | %H : hours | %M : mins | %S : secs
DATETIME_FORMAT = %Y-%m-%d-%H-%M-%S


[arduino]
; CSV list of ports to attempt connection or blank for automatic search on
; /dev/ttyACM* and /dev/ttyUSB* (where * varies from 0 to 4)
SERIAL_PORT =
 """

DEFAULT_INI_LINES = DEFAULT_INI.splitlines()

def make_path_here(filename):
    ''' Append filename to the current __file__ path. '''
    return os.path.realpath(os.path.join(
        os.path.abspath(os.path.dirname(__file__)), filename))


class Config:
    SETTINGS_FILENAME = make_path_here('../../settings.ini')
    DATALOG_PATH = make_path_here('../../data/')
    EXECUTION_LOG_PATH = make_path_here('../logs/')
    OUTGOING_FILENAME = make_path_here('../../data/outgoing.json')

    URL_API_POST_RAWSENSORDATA = '{base}api/post/rawsensordata/{bid}'
    SERIAL_CSV_SEP = ','

    RTC_NAME = 'RTC_DS1307'
    RTC_FORMAT = '%Y-%m-%d %H:%M:%S'

    class ConfigMissingSectionError(Exception):
        def __init__(self, section, parent):
            self.message = "\nConfigurationError: At file\n    {filename}\n\n"\
                           "[{section}]\n ^\n"\
                           "Missing section!".format(
                                filename=parent.SETTINGS_FILENAME,
                                section=section)


    class ConfigMissingKeyError(Exception):
        def __init__(self, section, key, parent):
            self.message = "\nConfigurationError: At file\n    {filename}\n\n"\
                           "[{section}]\n{comment}\n{key} = \n{indicator}\n"\
                           "Missing key!".format(
                                filename=parent.SETTINGS_FILENAME,
                                comment=parent.extract_comment(key),
                                section=section, key=key.upper(),
                                indicator=' '*len(key + ' = ') + '^')

    class ConfigValueError(Exception):
        def __init__(self, section, key, message, parent):
            self.message = "\nConfigurationError: At file\n    {filename}\n\n"\
                           "[{section}]\n{comment}\n{key} = {value}\n"\
                           "{indicator}\n{msg}".format(
                                filename=parent.SETTINGS_FILENAME,
                                section=section, key=key, msg=message,
                                comment=parent.extract_comment(key),
                                value=parent[section][key.lower()],
                                indicator=' '*len(key + ' = ') + '^')

    def __init__(self):
        self.default = configparser.ConfigParser()
        self.default.read_string(DEFAULT_INI)
        try:
            self.load_settings()
        except Exception as e:
            print('Exception: {}'.format(e))
            raise e

    def __getitem__(self, key):
        return self._parser._sections[key]

    def __contains__(self, key):
        return key in self._parser._sections

    def extract_comment(self, key):
        key, comment_lines = key.upper() + ' =', []
        for i, line in enumerate(DEFAULT_INI_LINES):
            if key in line:
                j = i - 1
                while j >= 0:
                    if not DEFAULT_INI_LINES[j].startswith(';'):
                        return '\n'.join(DEFAULT_INI_LINES[k]
                                         for k in range(j+1, i))
                    j -= 1

    def assert_config_keys(self):
        for section in self.default:
            if section == 'DEFAULT':
                continue
            if section in self:
                for key in self.default[section]:
                    if not key in self[section]:
                        raise self.ConfigMissingKeyError(section, key, self)
            else:
                raise self.ConfigMissingSectionError(section, self)

    def ask_restore_settings_file(self):
        a = input("\nRestore default file now and overwrite all"
                  "current values? [y/N] ")
        if 'y' in a.lowercase():
            try:
                with open(self.SETTINGS_FILENAME, 'w') as f:
                    f.write(DEFAULT_SETTINGS)
                print("Done! Restart the application!")
                sys.exit(0)
            except:
                print("Unable to write on file\n    {}\n\nTry to run this "
                      "program from another location!".format(
                          self.SETTINGS_FILENAME))
                sys.exit(1)


    def load_settings(self):
        '''
        Load the INI configuration file onto the self._parser attribute.
        '''
        self._parser = configparser.ConfigParser()
        try:
            self._parser.read(self.SETTINGS_FILENAME)
        except:
            print("Unable to open configuration file at\n    {}".format(
                  self.SETTINGS_FILENAME))
            return

        self.assert_config_keys()

        self.validate_server()
        self.validate_reading()
        self.validate_datalog()
        self.validate_arduino()

    def validate_server(self):
        try:
            bid = int(self['server']['board_id'])
        except:
            raise Exception(
                "Invalid numeric value for the server/BOARD_ID key.\n"
                "Expected to be of type integer.\n"
                "Was given:\n   {}".format(self['server']['board_id']))

        self['server']['api_post_url'] = self.URL_API_POST_RAWSENSORDATA\
            .format(base=self['server']['url'] +
                        ('' if self['server']['url'].endswith('/') else '/'),
                    bid=bid)

    def validate_reading(self):
        self['reading']['sensors'] = [x.strip() for x in
            self['reading']['sensors'].split(',') if x.strip() != '']

        if len(self['reading']['sensors']) == 0:
            raise Exception(
                    "At least one sensor must be present on the reading/"
                    "SENSORS key.")

        if 'true' in self['reading']['rtc_ds1307'].lower():
            self['reading']['sensors'].append(self.RTC_NAME)

        self['reading']['command'] = 'read,' + ','.join(
            self['reading']['sensors'])

        try:
            self['reading']['sleep_minutes'] =\
                float(self['reading']['sleep_minutes'].replace(',', '.'))
        except:
            raise self.ConfigValueError('reading', 'SLEEP_MINUTES',
                'TypeError: Number expected!', self)


    def validate_datalog(self):
        value = self['datalog']['csv_sep']
        self['datalog']['csv_sep'] = bytes(value, 'utf8').decode(
                                           'unicode_escape')
        if not value in (',', ';', r'\t'):
            raise Exception(
                "Invalid character value for the datalog/CSV_SEP key.\n"
                "Supported values:\n    ','   ';'   '\\t'\n"
                "Was given:\n    {}".format(value))

    def validate_arduino(self):

        self['arduino']['serial_port'] = [x.strip() for x in
            self['arduino']['serial_port'].split(',') if x.strip() != '']

        if len(self['arduino']['serial_port']) == 0:
            self['arduino']['serial_port'] = []

            for i in range(5):
                self['arduino']['serial_port'].append('/dev/ttyACM{}'.format(i))
                self['arduino']['serial_port'].append('/dev/ttyUSB{}'.format(i))