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

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

from datetime import datetime, timedelta
import os
import shutil
from fractions import Fraction
import pyexiv2

class Radiation:
    '''
    Reiceives values vom CSV file and creates a list of the relevant data

    Arguments:
    timestamp: Date/time string from CSV as string
    radiation: Radiation from CSV in CP/M as float
    local_timezone: timezone for timezone-unware CSV / Photo, if GPX is timezone aware
    si_factor: CP/M to (µS/h) conversion factor - specific to GMC-tube
    
    Returns:
    timestamp: timestamp of CSV value als datetime object
    radiation: radiation in µS/h as str (for Exif comment, UTF-8)
    '''

    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 = float(radiation) * si_factor
        return radiation

class Photo:
    '''
    Reads Exif metadata.

    Arguments:
    photo: source photo ()
    local_timezone: timezone for timezone-unware CSV / Photo, if GPX is timezone aware
    dest_dir: destination directory where the photo is going to be copied to.
    dry_run: whether to acutally write (True / False)

    Returns:
    get_date: timestamp of photo als datetime object
    get_photo_filename: full path to photo file to work on
    get_photo_basename: only filename (e. g. for print output)
    '''

    def __init__(self, photo, local_timezone, dest_dir, dry_run):
        self.get_date = self._get_creation_date(photo, local_timezone)
        self.get_photo_filename = self._copy_photo(photo, dest_dir, dry_run)[1]
        self.get_photo_basename = self._copy_photo(photo, dest_dir, dry_run)[0]

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

    def _copy_photo(self, photo, dest_dir, dry_run):
        # Determine where to work on photo and copy it there if needed.
        
        # Get image file name out of path
        photo_basename = os.path.basename(photo)
        # be os aware and use the correct directory delimiter for dest_photo
        dest_photo = os.path.join(dest_dir, photo_basename)

        # Copy photo to dest_dir and return its (new) filename
        # if not in dry_run mode or if dest_dir is different from src_dir.
        if dry_run is True:
            return photo_basename, photo
        if dest_dir != '.':
            shutil.copy(photo, dest_photo)
            return photo_basename, dest_photo
        return photo_basename, photo

    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

class Match:
    '''
    Receives lists of time / radiation and GPS data and compares it to timestamp.
    Then returns relevant values matching to time - or None

    Arguments:
    photo_time: timestamp of photo
    radiation_list: list of timestamp / radiation values
    position_list: list of timestamp / position / elevation values
    
    Returns:
    minimal timedelta: as timedelta object
    best matching values
    '''

    def __init__(self, photo_time, radiation_list, position_list):
        self.radiation_value = self._find_radiation_match(photo_time, radiation_list)[1]
        self.radiation_delta = self._find_radiation_match(photo_time, radiation_list)[0]
        self.position_delta = self._find_position_match(photo_time, position_list)[0]
        self.position_latitude = self._find_position_match(photo_time, position_list)[1][1]
        self.position_longitude = self._find_position_match(photo_time, position_list)[1][2]
        self.position_altitude = self._find_position_match(photo_time, position_list)[1][3]

    def __repr__(self):
        if self.radiation_value:
            radiation = round(self.radiation_value, 2)
        else:
            radiation = None

        if self.position_altitude:
            altitude = round(self.position_altitude)
        else:
            altitude = None
        return 'Radiation: %s µS/h (Δt %s) \nPosition: Lat: %s, Long: %s, Alt: %sm (Δt %s)' % \
                (str(radiation), str(self.radiation_delta), str(self.position_latitude), \
                str(self.position_longitude), altitude, str(self.position_delta))

    def _find_radiation_match(self, photo_time, list):
        valuelist = []
        for row in list:
            # Define timedelta and define timedelta datetime object.
            delta = timedelta(seconds=60)
            if row.timestamp:
                time_delta = abs(row.timestamp - photo_time)
            # datetime objects should match with 1 minute precision.
            if time_delta < delta:
                element = (time_delta, row)
                valuelist.append(element)
        # Return the list item with the lowest timedelta in column 0.
        # Column 2 contains the source objects untouched.
        if valuelist:
            result = min(valuelist, key=lambda x: x[0])
            return result[0], result[1].radiation
        # Return a tuple of 2x None, if there was no match.
        return None, None

    def _find_position_match(self, photo_time, list):
        valuelist = []
        for row in list:
            # Define timedelta and define timedelta datetime object.
            delta = timedelta(seconds=300)
            if row[0]:
                time_delta = abs(row[0] - photo_time)
            # datetime objects should match with 5 minute precision.
            if time_delta < delta:
                element = (time_delta, row)
                valuelist.append(element)
        # Return the list item with the lowest timedelta in column 0.
        # Column 2 contains the source objects untouched.
        if valuelist:
            #print(min(valuelist, key=lambda x: x[0]))
            return min(valuelist, key=lambda x: x[0])
        # Return Nones in the same cascaded manner as if it matched.
        return [None, [None, None, None, None]]

class Exif:
    '''
    Converts, compiles and writes Exif/ITPC/XMP-Tags from given arguments. 
    
    Arguments:
    photo: file name of photo to modify
    radiation: radiation levels float
    latitude: latitude as float
    longitude: longitude as float
    elevation: elevation as float
    dry_run: whether to acutally write (True / False)

    Returns:
    Latitude / Longitude: in degrees
    Exif-Comment: that has been written (incl. radiation)
    '''

    def __init__(self, photo, dry_run, radiation, latitude, longitude, elevation):
        self.write_exif = self._write_exif(photo, dry_run, radiation, latitude,
                                           longitude, elevation)
 
    def __repr__(self):
        return 'Position: %s, %s: %s ' % self.write_exif

    def _to_degree(self, value, loc):
        if value < 0:
            loc_value = loc[0]
        elif value > 0:
            loc_value = loc[1]
        else:
            loc_value = ""
        abs_value = abs(value)
        deg = int(abs_value)
        t1 = (abs_value - deg) * 60
        minute = int(t1)
        second = round((t1 - minute) * 60, 5)
        return (deg, minute, second, loc_value) 

    def _write_exif(self, photo, dry_run, radiation, latitude, longitude, elevation):

        metadata = pyexiv2.ImageMetadata(photo)
        metadata.read()

        if latitude and longitude:
            latitude_degree = self._to_degree(latitude, ["S", "N"])
            longitude_degree = self._to_degree(longitude, ["W", "E"])

            # convert decimal coordinates into fractions required for pyexiv2
            exiv2_latitude = (Fraction(latitude_degree[0] * 60 + latitude_degree[1], 60),
                              Fraction(int(round(latitude_degree[2] * 100, 0)), 6000),
                              Fraction(0, 1))
            exiv2_longitude = (Fraction(longitude_degree[0] * 60 + longitude_degree[1], 60),
                               Fraction(int(round(longitude_degree[2] * 100, 0)), 6000),
                               Fraction(0, 1))

            # Exif tags to write
            metadata['Exif.GPSInfo.GPSLatitude'] = exiv2_latitude
            metadata['Exif.GPSInfo.GPSLatitudeRef'] = latitude_degree[3]
            metadata['Exif.GPSInfo.GPSLongitude'] = exiv2_longitude
            metadata['Exif.GPSInfo.GPSLongitudeRef'] = longitude_degree[3]
            metadata['Exif.Image.GPSTag'] = 654
            metadata['Exif.GPSInfo.GPSMapDatum'] = "WGS-84"
            metadata['Exif.GPSInfo.GPSVersionID'] = '2 0 0 0'

            if not elevation:
                metadata['Exif.GPSInfo.GPSAltitude'] = Fraction(elevation)
                metadata['Exif.GPSInfo.GPSAltitudeRef'] = '0'
        else:
            latitude_degree = None
            longitude_degree = None

        if radiation:
            # Set new UserComment
            new_comment = 'Radiation ☢ : %s µS/h' % str(round(radiation, 2))

            metadata['Exif.Photo.UserComment'] = new_comment
            metadata['Exif.Image.ImageDescription'] = new_comment
            metadata['Iptc.Application2.Caption'] = [new_comment]
            metadata['Xmp.dc.description'] = new_comment
        else:
            new_comment = None

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

        return latitude_degree, longitude_degree, new_comment

class Output:
    '''
    Receives values to be printed, formats them and returns a string for printing.

    Arguments:
    radiation: radiation as float
    latitude: latitude as float
    longitude: longitude as float
    elevation: elevation as float

    Returns:
    A String that can be printed in output
    '''

    def __init__(self, radiation, latitude, longitude, altitude):
        self.get_string = self._get_string(radiation, latitude, longitude, altitude)

    def __repr__(self):
        return self.get_string

    def _get_string(self, radiation, latitude, longitude, altitude):
        # Convert values to styled strings
        if radiation:
            rad = '☢: %sµS/h ' % str(round(radiation, 2))
        else:
            rad = '☢: N/A '

        if latitude and longitude:
            latlon = 'Lat.: %s Long.: %s ' % (str(latitude), str(longitude))
        else:
            latlon = 'Lat.: N/A, Long.: N/A '

        if altitude:
            alt = 'Alt.: %sm' % str(round(altitude, 1))
        else:
            alt = 'Alt.: N/A'

        data = rad + latlon + alt

        # Return data string
        return data