#!/bin/bash

set -o pipefail # the exit status of the last failed command gets returned
set -o nounset  # exit when using undeclared variables

# Defaults
REPO=""
VERBOSE=0
PROFILE="default"
KEEP_IMAGES=3


function show_help() {
    cat > /dev/stdout << END
${0} -r <repo> [-n <number of images>] [-p <profile>] [-v] [-h]

REQUIRED ARGS:
-r - ecr repository name, eg vaola/fog (required)

OPTIONAL ARGS:
-n - number of images to keep (default=${KEEP_IMAGES})
-p - aws profile (default=${PROFILE})
-v - verbose logging (default off)
-h - show help
END
}

while getopts "h?v:n:p:r:" opt
do
    case "${opt}" in
    h|\?)
        show_help
        exit 0
        ;;
    v) VERBOSE=1 ;;
    n) KEEP_IMAGES=${OPTARG} ;;
    p) PROFILE=${OPTARG} ;;
    r) REPO=${OPTARG} ;;
    esac
done

shift "$((OPTIND-1))"

if [[ ${REPO} = "" ]]
then
    show_help
    exit 1
fi

if [[ ${VERBOSE} -gt 0 ]]
then
    set -x
fi

BUILD_DIR_BASE=$(mktemp -d "${TMPDIR:-/tmp/}$(basename $0).XXXXXXXXXXXX")
mkdir -p "${BUILD_DIR_BASE}"
RAW_FILE="${BUILD_DIR_BASE}/raw"
IMAGES_FILE="${BUILD_DIR_BASE}/images"
IMAGES_SORTED_FILE="${BUILD_DIR_BASE}/images_sorted"


function cleanup() {
    rm -fr "${BUILD_DIR_BASE}"
}

trap cleanup TERM INT QUIT

aws ecr describe-images --repository-name ${REPO} --profile ${PROFILE} --output text > $RAW_FILE

while read line; do
    rows=($line)
    if [[ "${rows[0]}" != "IMAGEDETAILS" ]]; then
        continue
    fi

    echo "${rows[2]} ${rows[5]} ${rows[1]}" >> ${IMAGES_FILE}
done < ${RAW_FILE}

sort -ro ${IMAGES_SORTED_FILE} ${IMAGES_FILE}

COUNT=0
while read line; do
    rows=($line)
    if [ "$COUNT" -ge "${KEEP_IMAGES}" ]; then
        aws ecr batch-delete-image --repository-name ${rows[1]} --profile ${PROFILE} --image-ids imageDigest=${rows[2]}
    fi
    (( COUNT++ ))
done < ${IMAGES_SORTED_FILE}

cleanup