#!/usr/bin/env bash
#  examine result
# docker run --rm -it -v webawesome-3.2.1:/volume alpine sh
set -euo pipefail  # strict error handling

# Usage message
usage() {
    echo "Usage: $0 <volume_name> [source_dir]"
    echo "  volume_name   Name of the Docker volume to create/populate"
    echo "  source_dir    Source directory (default: current directory)"
    exit 1
}

# Check args
[[ $# -lt 1 ]] && usage

VOLUME_NAME="$1"
SOURCE_DIR="${2:-.}"

# Resolve source dir to absolute path (handles relative paths, symlinks via readlink)
if ! SOURCE_DIR=$(cd "$SOURCE_DIR" && pwd); then
    echo "❌ Error: Source directory '$2' does not exist or is not readable." >&2
    exit 1
fi

echo "📦 Populating Docker volume '$VOLUME_NAME' from: $SOURCE_DIR"

# Create the volume (safe: no-op if exists)
docker volume create "$VOLUME_NAME" >/dev/null 2>&1 || true

# Use Alpine Linux container to copy contents into the volume
# - --rm: auto-cleanup after exit
# - read-only source for safety
# - cp -a preserves all metadata (symlinks, perms, timestamps)
# - /source/. → copies *contents* of source dir into target root
docker run --rm \
  -v "$SOURCE_DIR:/source:ro" \
  -v "$VOLUME_NAME:/target" \
  alpine:latest \
  sh -c 'cp -a /source/. /target/' || {
    echo "❌ Error copying files. Is Docker running?" >&2
    exit 1
}

echo "✅ Volume '$VOLUME_NAME' is now populated from '$SOURCE_DIR'"