#!/bin/bash

GEOFABRICK_SERVER=http://download.geofabrik.de/asia/taiwan-updates
PBF_FILE=$1

# get next sequence number and store it into NEW_SEQ
NEW_SEQ=$(osmium fileinfo $PBF_FILE |\
grep osmosis_replication_sequence_number |\
cut -d'=' -f2 |\
sed 's/$/+1/' | bc)

# while server has osc file with given sequence number,
# get it and do file update
while
    SEQ_PATH=$(echo $NEW_SEQ | sed -r 's/(.{1})(.{3})/00\1\/\2/')
    STATE_URL=$GEOFABRICK_SERVER/000/$SEQ_PATH.state.txt
    echo check state file exists:
    echo $STATE_URL
    [ $(curl -o /dev/null --silent -Iw "%{http_code}" $STATE_URL) != "404" ]
do
    mkdir -p changes
    CHANGE_URL=$GEOFABRICK_SERVER/000/$SEQ_PATH.osc.gz
    echo $CHANGE_URL
    curl -o changes/$NEW_SEQ.osc.gz $CHANGE_URL && \
    osmium apply-changes $PBF_FILE changes/$NEW_SEQ.osc.gz \
        --output-header=osmosis_replication_sequence_number=$NEW_SEQ \
        --overwrite \
        --output $NEW_SEQ.osm.pbf

    mv $PBF_FILE $((NEW_SEQ-1)).osm.pbf
    mv $NEW_SEQ.osm.pbf $PBF_FILE
    (( NEW_SEQ++ ))
done

echo
echo File sequence number is $((NEW_SEQ-1)), already the latest one on Geofrbrik