#!/bin/bash

set -euf -o pipefail

# This wrapper for docker client adds support for "maybepull" command
# to workaround dockerhub's limits on pull requests.  "Maybepull" command
# will look at timestamps of when images were last pulled, and will
# pull the image only when it has been over 24h from the last pull.
# Note that behavior of the usual "pull" command is not changed.
#
# We also track image last-used date to not needlessly cleanup images
# in jenkins-scripts/tcwg-cleanup-stale-containers.sh .

stamp_dir=/home/shared/docker

if ! [ -d "$stamp_dir" ]; then
    sudo mkdir -p "$stamp_dir" || mkdir -p "$stamp_dir"
    sudo chmod 0777 "$stamp_dir" || chmod 0777 "$stamp_dir"
fi

cmd="${1-}"
shift 1

image=""
case "$cmd" in
    "maybepull"|"pull")
	# Skip parameters starting with "-" and next parameter will be image.
	for opt in "$@"; do
	    case "$opt" in
		"-"*) ;;
		*)
		    image="$opt"
		    break
		    ;;
	    esac
	done
	;;
    "run")
	# "docker run" has more complex option handling than we want to deal
	# with, so find parameter that looks like a TCWG image.
	# This only affects stamp files, so is harmless if we get it wrong.
	for opt in "$@"; do
	    case "$opt" in
		"linaro/ci-"*"-tcwg-"*"-ubuntu"*)
		    image="$opt"
		    break
		    ;;
	    esac
	done
	;;
esac

if [ x"$image" != x"" ]; then
    # We use two stamp files per image:
    # - $image_stamp.pull -- time of last image pull
    # - $image_stamp.use  -- time of last image use
    image_stamp="$stamp_dir/$(echo "$image" | tr "/:" "_")"
fi

# We attempt to run all our builds using current versions of docker images.
# Unfortunately, now that dockerhub limits pull requests, we need to be more
# considerate to when we pull the image or attempt to use a local copy.
# Also note that "docker run" below will automatically pull the image if there
# is no local copy.
if [ x"$image" != x"" ] && [ x"$cmd" = x"maybepull" ]; then
    # For starters, let's try to pull images once a day.  This guarantees
    # that any change to master docker images will be deployed within a day.
    pull_if_older_than=$(($(date +%s) - 1*24*60*60))
    # Use negative comparison to handle non-existent stamp files.
    if ! [ "$(stat -c %Z "$image_stamp.pull" 2>/dev/null)" \
	       -gt $pull_if_older_than ] 2>/dev/null; then
	cmd="pull"
    else
	exit 0
    fi
fi

sudo /usr/bin/docker "$cmd" "$@"

case "$image:$cmd" in
    :*) ;;
    *:"pull")
	# Remove the stamp to avoid permission issues (we have rwx permissions
	# for all on the directory, so we can always remove a file, but only
	# owner can modify files.
	# Also touch .use stamp to compensate for inaccurate detection of
	# images from "docker run" above.
	rm -f "$image_stamp.pull" "$image_stamp.use"
	touch "$image_stamp.pull" "$image_stamp.use"
	;;
    *:"run")
	# Update the time of image use, so that we don't remove the image in
	# tcwg-cleanup-stale-containers.
	rm -f "$image_stamp.use"
	touch "$image_stamp.use"
	;;
esac