#!/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}"

get_date() {
    printf '%s' "$(date +'%Y.%m.%d_%H:%M:%S')"
}

# 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)
# - finally_hook :: gets executed after (and also only if) the final result has been written to disk

if [ -f "${TEMPLATE_SRC}" ]
then
    source "${TEMPLATE_SRC}"
    if [ -z "${TEMPLATE}" ]
    then
        printf '%s | [ERR]: Template "%s" does define a template string.\n' "$(get_date)" "${TEMPLATE_SRC}"
        exit 1
    fi
else
    printf '%s | [ERR]: No such File "%s".\n' "$(get_date)" "${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 type finally_hook 2>/dev/null | grep -q "finally_hook is a function"
then
    RUN_FINALLY_HOOK=true
else
    RUN_FINALLY_HOOK=false
fi


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

for row in $(jq -r '.[] | @base64' <<< "${DOCKER_DATA}")
do
    CONTAINER_DATA=$(base64 -d <<< "${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

    # 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 ${RUN_TEMPLATE_HOOK}
    then
        if template_hook
        then
            # FIX with printf
            RESULT=$(printf '%s' "${RESULT}" "${RESULT:+$SEPARATOR}" "${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
        unset "${var}"
    done
done

RESULT="$(printf "%s" "${WRAP_START}" "${RESULT}" "${WRAP_END}")"

if [ -z "${OUT}" ]
then
    printf "%b" "${RESULT}";
else
    if [ "$(cat "${OUT}")" != "$(printf '%b'"${RESULT}")" ]
    then
        printf "%s | Template Task: '%s' has been written to: '%s'\n" "$(get_date)" "${TEMPLATE_SRC}" "${OUT}"
        printf "%b" "${RESULT}" > "${OUT}";
        if ${RUN_FINALLY_HOOK}
        then
            finally_hook
        fi
    fi
fi