#!/usr/bin/env python
# -*- coding: utf-8 -*-

''' Classes used by main program. '''

from datetime import datetime
import pyexiv2

class Radiation:
    ''' Handles CSV processing.'''
    def __init__(self, timestamp, radiation, local_timezone, si_factor):
        self.timestamp = self._time_conversion(timestamp, local_timezone)
        self.radiation = self._radiation_conversion(radiation, si_factor)

    def __repr__(self):
        return '%s %f µS/h' % (str(self.timestamp), self.radiation)

    def _time_conversion(self, timestamp, local_timezone):
        csv_naive_time = datetime.fromisoformat(timestamp)
        # Set timezone
        csv_aware_time = csv_naive_time.astimezone(local_timezone)
        return csv_aware_time

    def _radiation_conversion(self, radiation, si_factor):
        # Convert CP/M to µS/h using si_factor
        radiation = round(float(radiation) * si_factor, 2)
        return radiation

class Photo:
    ''' Reads and writes Exif metadata'''
    def __init__(self, photo, local_timezone):
        self.get_date = self._get_creation_date(photo, local_timezone)
        self.photo = photo

    def __repr__(self):
        return 'Photo Creation Date: %s' % str(self.get_date)

    def _get_creation_date(self, photo, local_timezone):
        # Load Exif data from photo
        metadata = pyexiv2.ImageMetadata(photo)
        metadata.read()
        date = metadata['Exif.Photo.DateTimeOriginal']
        # date.value creates datetime object in pic_naive_time
        pic_naive_time = date.value
        # Set timezone
        pic_aware_time = pic_naive_time.astimezone(local_timezone)
        return pic_aware_time

    def write_exif(self, radiation, latitude, longitude, dry_run):

        ''' UNTESTED ! '''

        metadata = pyexiv2.ImageMetadata(self.photo)
        
        # Set new UserComment
        new_comment = 'Radiation ☢ ' + str(radiation) + ' µS/h'
        # Exif tags to write
        keys = ['Exif.Photo.UserComment', 'Exif.Photo.latitude', 'Exif.Photo.longitude']
        # Values to write
        values = [new_comment, latitude, longitude]
        
        # Create metadata object with all data to write
        for key, value in zip(keys, values):
            # Only create object if there is anything to fill with
            if value is not None:
                metadata[key] = pyexiv2.ExifTag(key, value)

        # Write Exif tags to file, if not in dry-run mode
        if dry_run == 'True':
            metadata.write()
        return new_comment