#!/bin/bash

#    Geotag images
#    Copyright (C) 2017  Pekka Helenius
#
#    This program is free software; you can redistribute it and/or
#    modify it under the terms of the GNU General Public License
#    as published by the Free Software Foundation; either version 2
#    of the License, or (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program; if not, write to the Free Software
#    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
###############################################

# TODO Coordinate threshold = Grid size is 30x30m?
# TODO Find API for ASTER DEM v2 (better data)

USERNAME=Fincer #For API (data request)

############################

INTERNET_TEST=$(ping -c 3 nominatim.openstreetmap.org 2>&1 | grep -c "unknown host") #Ping Github three times and look for string 'unknown host'

if [[ ! $INTERNET_TEST -eq 0 ]]; then #If 'unknown host' string is found, then
    echo -e "\nCan't connect to geoservice provider (Nominatim). Please check your internet connection and try again.\n"
    exit 1
fi

############################

for IMAGE in $(echo "${@}"); do

    IMAGE_BASENAME=$(basename "${IMAGE}" | cut -f 1 -d '.')
    IMAGE_EXTENSION=$(echo $(basename "${IMAGE}" | cut -f 2 -d '.' | sed '/^\s*$/d'))

    if [[ $(exiftool -n -p '$GPSLatitude,$GPSLongitude' "${IMAGE}" | awk -F ',' '{print NF}') != 2 ]]; then
        echo -e "$IMAGE_BASENAME: Missing coordinates. Are you sure you have geotagged the photo?\n"
        exit
    
    else
    
        LATITUDE=$(exiftool -n -p '$GPSLatitude' "${IMAGE}")
        LONGITUDE=$(exiftool -n -p '$GPSLongitude' "${IMAGE}")

        # Clear previous geonames information
        exiftool -Location= -LocationShownCity= -LocationShownCountryName= -LocationShownProvinceState= -LocationShownSublocation= -Country-PrimaryLocationName= -Sub-location= -Country= -City= -State= -Province-State= -GPSAltitude= "${IMAGE}" -overwrite_original

        #if [[ $(exiftool -p '$Country-PrimaryLocationName' "${IMAGE}" | awk '{print NF}') != 1 ]]; then
        echo -e "$IMAGE_BASENAME: retrieving country information.\n"
        reversegeo "${IMAGE}"
        #fi

        # Reference: http://www.geonames.org/export/web-services.html
        # Get elevation by retrieving a ASTER DEM value from GeoNames API server, grid size 30x30m
        # There are several error factors:
            # DEM Grid size
            # General inaccurancies in DEM model
            # Geoid model & projection errors
            # Coordinate errors
            # Variations in (estimated) height values

        # So the retrieved elevation value is just a rough estimation here

        ALTITUDE=$(curl -s "http://api.geonames.org/astergdem?lat=$LATITUDE&lng=$LONGITUDE&username=$USERNAME")

        # IF successful answer, then
        if [[ $ALTITUDE =~ '^[0-9]+$' ]]; then

            exiftool -GPSAltitude=$ALTITUDE "${IMAGE}" -overwrite_original
            echo -e "$IMAGE_BASENAME: Altitude value updated.\n"

        else
        # TODO IF NOT successful, try again for 2 times, then abort

            echo -e "$IMAGE_BASENAME: Couldn't retrieve altitude value.\n"

done