#!/usr/bin/env bash
# Usage: ./update_docker_images.sh [--prune] [--build] [compose-directory]
# By default, pull non-buildable images and update services without pruning or building.
# Continue after project failures; report them and exit nonzero at the end.
# WARNING: Pruning removes stopped containers, unused images, build cache,
# and unused anonymous volumes.
set -euo pipefail

usage() {
    printf 'Usage: %s [--prune] [--build] [compose-directory]\n' "$0"
    printf '%s\n' \
        '  --prune  Remove unused Docker resources before updating (including volumes).' \
        '  --build  Build images with --pull before updating services.' \
        '  -h, --help  Show this help.' \
        'Default: pull images for services without build definitions and update services.' \
        'Services with build definitions keep their local images unless --build is used.' \
        'Project failures are reported at the end; other projects are still updated.'
}

prune=false
build=false
positional=()
while (( $# )); do
    case "$1" in
        --prune) prune=true ;;
        --build) build=true ;;
        -h|--help) usage; exit 0 ;;
        --) shift; positional+=("$@"); break ;;
        -*) printf 'Unknown option: %s\n' "$1" >&2; usage >&2; exit 2 ;;
        *) positional+=("$1") ;;
    esac
    shift
done
if (( ${#positional[@]} > 1 )); then
    usage >&2
    exit 2
fi

compose_root=${positional[0]:-/etc/docker/compose}
if [[ ! -d "$compose_root" ]]; then
    printf 'Compose directory not found: %s\n' "$compose_root" >&2
    exit 1
fi

created_builder=
cleanup() {
    local status=$?
    trap - EXIT
    if [[ -n "$created_builder" ]]; then
        if ! docker buildx rm "$created_builder"; then
            printf 'Could not remove builder: %s\n' "$created_builder" >&2
            if (( status == 0 )); then
                status=1
            fi
        fi
    fi
    exit "$status"
}
trap cleanup EXIT
trap 'exit 130' INT
trap 'exit 143' TERM

if "$prune"; then
    docker system df
    docker system prune -a --volumes -f
    docker system df
fi

if "$build"; then
    # Select an existing container builder, not merely check whether one exists.
    # Capture the list separately so a failed Docker command stops the script.
    builders=$(docker buildx ls --format '{{.Name}} {{.Driver}}')
    builder=
    while read -r name driver; do
        if [[ "$driver" == docker-container ]]; then
            builder=$name
            break
        fi
    done <<< "$builders"
    if [[ -z "$builder" ]]; then
        # Bootstrap separately so cleanup can run if startup fails.
        created_builder=$(docker buildx create \
            --buildkitd-config /etc/docker/buildx/buildkit.toml \
            --driver docker-container \
            --driver-opt 'network=treehouse')
        builder=$created_builder
    fi

    # Select the builder for this script without changing the user's default.
    export BUILDX_BUILDER="$builder"
    docker buildx inspect "$builder" --bootstrap
fi

failed_projects=()
for directory in "$compose_root"/*; do
    [[ -d "$directory" ]] || continue
    [[ -f "$directory/docker-compose.yml" ]] || continue
    # Manually update Minecraft, so we're not always on the cutting edge
    [[ "$directory" == *minecraft* ]] && continue

    printf '\nUpdating %s\n' "$directory"
    # A subshell restores the working directory even when a command fails.
    # Because it is tested by 'if', explicitly stop on each failed command;
    # Bash does not apply 'set -e' inside this conditional subshell.
    if (
        cd -- "$directory" || exit "$?"
        docker compose pull --ignore-buildable || exit "$?"
        if "$build"; then
            docker compose build --pull || exit "$?"
        fi
        # Do not let Compose implicitly build images when starting services.
        docker compose up -d --no-build
    ); then
        printf 'Updated %s\n' "$directory"
    else
        status=$?
        printf 'Update failed for %s (exit %s); continuing.\n' "$directory" "$status" >&2
        failed_projects+=("$directory")
    fi
done

if (( ${#failed_projects[@]} )); then
    printf '\nFailed projects:\n' >&2
    printf '  %s\n' "${failed_projects[@]}" >&2
    exit 1
fi