#!/usr/bin/env bash

# set -x
set -e

#
# Source the environment variables
#
if [[ -f .env ]]; then
    source .env
elif [[ -f /etc/azure-dns-update/.env ]]; then
    source /etc/azure-dns-update/.env
else
#if [[ ! -f .env ]]; then
    echo "MISSING .env FILE!"
    exit -1
fi

#
# Logging
# 
write_log() {
    logLevel='DEBUG'
    if [[ ! -z $2 ]]; then
        echo "$1: $2"
    else
        echo "logLevel: $1"
    fi
}
write_message() {
    write_log 'INFO' "$1"
}


# 
# CURL to get the bearer token for the following calls
#
get_token() {
    curl -s -X POST \
        -d "grant_type=client_credentials&client_id=$CLIENT_ID&client_secret=$CLIENT_SECRET&resource=https%3A%2F%2Fmanagement.azure.com%2F" \
        https://login.microsoftonline.com/$TENANT_ID/oauth2/token | jq --raw-output '.access_token'
}

#
# CURL to get the recordset
#
get_recordset() {
    curl -s -X GET \
        -H "Authorization: Bearer $access_token" \
        -H "Content-Type: application/json" \
        https://management.azure.com/subscriptions/$SUBSCRIPTION_ID/resourceGroups/$resource_group/providers/Microsoft.Network/dnsZones/$zone_name/$RECORD_TYPE/$RELATIVE_RECORD_SET_NAME?api-version=2018-05-01 \
        | jq '.'
}

#
# Parses the IPv4 IP Address from the Record Set response
#
get_recordset_address() {
    get_recordset | jq --raw-output '.properties.ARecords[].ipv4Address'
}

#
# Updates and formats the record set to be used in the PUT request body
#
update_recordset() {
    echo $azure_recordset | jq -r ".properties.ARecords[].ipv4Address = \"$1\" | del(.name,.type,.id,.properties.fqdn,.properties.provisioningState) | @text"
}

#
# CURL to PUT the updated record set 
#
put_recordset() {
    curl -s -X PUT \
        -H "Authorization: Bearer $access_token" \
        -H "Content-Type: application/json" \
        --data-raw "$1" \
        https://management.azure.com/subscriptions/$SUBSCRIPTION_ID/resourceGroups/$resource_group/providers/Microsoft.Network/dnsZones/$zone_name/$RECORD_TYPE/$RELATIVE_RECORD_SET_NAME?api-version=2018-05-01
}

resource_group_list=($RESOURCE_GROUP_NAMES)
zone_list=($ZONE_NAMES)

write_message "======================================="
write_message "======================================="
for i in "${!resource_group_list[@]}"; do
    resource_group="${resource_group_list[i]}"
    zone_name="${zone_list[i]}"
    access_token=$(get_token)

    # Get the Record Set
    azure_recordset=$(get_recordset)
    write_message "Azure Record Set: $zone_name"

    # Parse the Record Set
    azure_ip_address=$(get_recordset_address $azure_recordset)
    write_message "Azure IP: $azure_ip_address"

    # Get the currently assigned Public IP
    isp_ip_address=$(dig +short myip.opendns.com @resolver1.opendns.com)
    write_message "ISP IP: $isp_ip_address"

    # If the currently assigned public IP doesn't match the configured IP address in Azure...
    #  update the Azure record set.
    if [ $azure_ip_address != $isp_ip_address ]; then
        write_message "IP ADDRESSES DON'T MATCH. UPDATING..."

        # Prepare the request content
        azure_recordset_UPDATE=$(update_recordset $isp_ip_address)
        write_message $azure_recordset_UPDATE

        # Perform the Update
        AZURE_PUT_RESPONSE=$(put_recordset $azure_recordset_UPDATE)
        write_message "Azure PUT Response: $AZURE_PUT_RESPONSE"

	write_message "======================================="
        write_message $'Azure IP Address updated successfully\n'
	write_message "======================================="
    else
	write_message "======================================="
        write_message $'IP Address is up to date.\n'
	write_message "======================================="
    fi
done

write_message "======================================="
write_message "======================================="