#!/usr/bin/env bash
# Export Variables so they can be picked up by envsubst
set -ae
TEMPLATE_SRC=$1;
DOCKER_DATA=$2;

NETWORK_NAME="${NETWORK_NAME:-proxy}"

# "NetworkSettings"

# Import Template
# Required Variables:
# - TEMPLATE :: The template string which will be read by envsubst
# Optional Variables:
# - WRAP_START :: String to prepend in front of the mapped template result
# - WRAP_END :: String to append to the mapped template result
# - SEPARATOR :: String/Charater to separate TEMPLATE lines (DEFAULT: \n)
# - OUT :: if set the result will be written to $OUT instead of stdout
# Optional Functions:
# - label_hook :: modify/override label query results
# - template_hook :: hook to verify/modify template rsults (0 => OK; 1 => SKIP)

if [ -f "${TEMPLATE_SRC}" ]
then
    source "${TEMPLATE_SRC}"
    if [ -z "${TEMPLATE}" ]
    then
        echo "[ERR]: Template \"${TEMPLATE_SRC}\" does define a template string."
        exit 1
    fi
else
    echo "[ERR]: No such File \"${TEMPLATE_SRC}\".";
    exit 1
fi

# Check Hooks
if type label_hook 2>/dev/null | grep -q "label_hook is a function"
then
    RUN_LABEL_HOOK=true
else
    RUN_LABEL_HOOK=false
fi

if type template_hook 2>/dev/null | grep -q "template_hook is a function"
then
    RUN_TEMPLATE_HOOK=true
else
    RUN_TEMPLATE_HOOK=false
fi

if [ -z "${SEPARATOR+.}" ]
then
    SEPARATOR='\n'
fi

for row in $(jq -r '.[] | @base64' <<< "${DOCKER_DATA}")
do
    CONTAINER_DATA=$(base64 --decode <<< "${row}");
    # Set non Label values
    if [ -z "${LOCAL_IP}" ]
    then
        LOCAL_IP=$(jq -r '.NetworkSettings.Networks | if has($ENV.NETWORK_NAME) then .[$ENV.NETWORK_NAME].IPAddress else first(.[].IPAddress) end' <<< "${CONTAINER_DATA}");
    fi
    # export LOCAL_IP

    # Read Label values
    CONTAINER_LABELS=$(jq '.Labels' <<< "${CONTAINER_DATA}");
    for var in $(envsubst -v "${TEMPLATE}")
    do
        if [ -z "${!var}" ]
        then
            VAR_LABEL=$(tr '[:upper:]_' '[:lower:].' <<< "${var}")
            LABEL_VAL=$(jq --arg KEY "${VAR_LABEL}" -r 'if has($KEY) then .[$KEY] else "" end' <<< "${CONTAINER_LABELS}")

            if [ -n "${LABEL_VAL}" ]
            then
                declare "${var}"="${LABEL_VAL}";
            fi
        fi
    done

    if ${RUN_LABEL_HOOK}
    then
        label_hook
    fi

    PARTIAL_RESULT="$(envsubst <<< "${TEMPLATE}")";
    # Verify template result if check_template is defined
    if ${RUN_TEMPLATE_HOOK}
    then
        if template_hook
        then
            # FIX with printf
            RESULT+="${PARTIAL_RESULT}"
        fi
    else
        RESULT=$(printf '%s' "${RESULT}" "${RESULT:+$SEPARATOR}" "${PARTIAL_RESULT}")
    fi

    # Unset label-environment variables for next container
    for var in $(envsubst -v "${TEMPLATE}")
    do
        if [ "${var}" != "LOCAL_IP" ]
        then
            unset "${!var}"
        fi
    done
done

RESULT="${WRAP_START}${RESULT}${WRAP_END}"


if [ -z "${OUT}" ]
then
    printf "%b\n" "${RESULT}";
else
    if ! diff --brief "${OUT}" - > /dev/null 2>&1 <<< "${RESULT}"
    then
        printf "Template Task: '%s' has been written to: '%s'\n" "${TEMPLATE_SRC}" "${OUT}"
        printf "%b\n" "${RESULT}" > "${OUT}";
    fi
fi