#!/bin/bash
# cleanup.docker.images.sh
#
# Removes old Docker images, keeping only the newest image per repository.
# Images are sorted by creation date, and only the most recent per repo is retained.
#
# Usage:
#   ./cleanup.docker.images.sh [--dryrun]
#
# Options:
#   --dryrun    Show what would be deleted without actually deleting
#
# Returns:
#   0 on success
#   1 on error

set -euo pipefail

DRYRUN=false

# Parse arguments
for arg in "$@"; do
    case $arg in
        --dryrun)
            DRYRUN=true
            shift
            ;;
        --help|-h)
            echo "Usage: $0 [--dryrun]"
            echo ""
            echo "Removes old Docker images, keeping only the newest per repository."
            echo ""
            echo "Options:"
            echo "  --dryrun    Show what would be deleted without actually deleting"
            echo "  --help      Show this help message"
            exit 0
            ;;
        *)
            echo "Unknown option: $arg"
            echo "Use --help for usage information"
            exit 1
            ;;
    esac
done

# Get images to delete: all but the newest per repository
# Format: repository|tag|id|created
# Sort by repo, then by date descending (newest first)
# Skip the first (newest) for each repo, output the rest
get_images_to_delete() {
    docker images --format '{{.Repository}}|{{.Tag}}|{{.ID}}|{{.CreatedAt}}' | \
        grep -v '<none>' | \
        sort -t'|' -k1,1 -k4r | \
        awk -F'|' 'seen[$1]++ {print $1"|"$2"|"$3}'
}

# Get unique image IDs from the list
get_unique_ids() {
    awk -F'|' '{print $3}' | sort -u
}

echo "Scanning Docker images..."
echo ""

IMAGES_TO_DELETE=$(get_images_to_delete)

if [ -z "$IMAGES_TO_DELETE" ]; then
    echo "No old images to clean up. Each repository has only one image."
    exit 0
fi

# Count images
IMAGE_COUNT=$(echo "$IMAGES_TO_DELETE" | wc -l | tr -d ' ')
UNIQUE_IDS=$(echo "$IMAGES_TO_DELETE" | get_unique_ids)
UNIQUE_COUNT=$(echo "$UNIQUE_IDS" | wc -l | tr -d ' ')

if [ "$DRYRUN" = true ]; then
    echo "=== DRY RUN MODE ==="
    echo "The following images would be deleted ($IMAGE_COUNT tags, $UNIQUE_COUNT unique images):"
    echo ""
    printf "%-50s %-35s %s\n" "REPOSITORY" "TAG" "IMAGE ID"
    printf "%-50s %-35s %s\n" "----------" "---" "--------"
    echo "$IMAGES_TO_DELETE" | while IFS='|' read -r repo tag id; do
        printf "%-50s %-35s %s\n" "$repo" "$tag" "$id"
    done
    echo ""
    echo "Run without --dryrun to delete these images."
else
    echo "Deleting $IMAGE_COUNT image tags ($UNIQUE_COUNT unique images)..."
    echo ""

    DELETED=0
    FAILED=0

    for id in $UNIQUE_IDS; do
        if docker rmi "$id" 2>/dev/null; then
            ((DELETED++)) || true
        else
            # Try force removal if normal removal fails
            if docker rmi -f "$id" 2>/dev/null; then
                ((DELETED++)) || true
            else
                echo "Warning: Could not delete image $id (may be in use)"
                ((FAILED++)) || true
            fi
        fi
    done

    echo ""
    echo "Cleanup complete: $DELETED deleted, $FAILED failed/skipped"
fi