#!/usr/bin/env bash
set -euo pipefail

SKILL_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
TEMPLATES_DIR="$SKILL_DIR/../assets/templates"

usage() {
  cat <<EOF
Usage: new-skill.sh <skill-name> <destination-dir>

Create a new skill scaffold by copying annotated templates to the destination.

Arguments:
  skill-name       Kebab-case skill identifier (e.g. my-tool, data-analyzer).
                   Must match the directory name exactly.
  destination-dir  Parent directory to create the skill in.
                   Examples: ~/.agents/skills/  plugins/myplugin/skills/

Output:
  Creates <destination-dir>/<skill-name>/ with annotated templates ready to fill in.

Exit codes:
  0  Scaffold created successfully
  1  Invalid arguments or destination already exists
EOF
}

if [[ "${1:-}" == "--help" || "${1:-}" == "-h" ]]; then
  usage
  exit 0
fi

if [[ $# -lt 2 ]]; then
  echo "Error: skill-name and destination-dir are required." >&2
  echo "" >&2
  usage >&2
  exit 1
fi

SKILL_NAME="$1"
DEST_DIR="$2"

# Validate skill name format
if ! echo "$SKILL_NAME" | grep -qE '^[a-z0-9]+(-[a-z0-9]+)*$'; then
  echo "Error: skill-name must use lowercase letters, numbers, and hyphens only." >&2
  echo "       No leading, trailing, or consecutive hyphens." >&2
  echo "       Received: '$SKILL_NAME'" >&2
  exit 1
fi

# Validate templates directory exists
if [[ ! -d "$TEMPLATES_DIR" ]]; then
  echo "Error: templates directory not found at '$TEMPLATES_DIR'." >&2
  echo "       Run this script from its original location inside the skill-write skill." >&2
  exit 1
fi

# Validate destination exists
if [[ ! -d "$DEST_DIR" ]]; then
  echo "Error: destination directory '$DEST_DIR' does not exist." >&2
  exit 1
fi

TARGET="$DEST_DIR/$SKILL_NAME"

# Refuse to overwrite existing directory
if [[ -d "$TARGET" ]]; then
  echo "Error: '$TARGET' already exists." >&2
  echo "       Remove it first or choose a different name." >&2
  exit 1
fi

# Copy templates to destination
cp -r "$TEMPLATES_DIR" "$TARGET"

# Set skill name in templates
sed -i "s/SKILL_NAME/$SKILL_NAME/g" "$TARGET/SKILL.md"
sed -i "s/SKILL_NAME/$SKILL_NAME/g" "$TARGET/README.md"

echo "Scaffold created: $TARGET"
echo ""
echo "Next steps:"
echo "  1. Fill in $TARGET/SKILL.md — replace all FILL IN: placeholders"
echo "  2. Add scripts to scripts/ if needed (or delete the directory)"
echo "  3. Add docs to references/ if needed (or delete the directory)"
echo "  4. Add resources to assets/ if needed (or delete the directory)"
echo "  5. Validate: run /skill-audit on $TARGET"