#!/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> <path>

Create a new skill scaffold by copying annotated templates to the resolved
destination. <path> is any existing path inside or at the target — a
package or a standalone location. It does not have to be a package root
itself.

The script walks up from <path> to pick one of two modes:

  Package mode:
    If an apm.yml with a top-level 'type:' field (instructions, skill,
    hybrid, or prompts) is found at or above <path>, the skill is
    scaffolded into <package-root>/.apm/skills/<skill-name>/ — not under
    <path> itself. An apm.yml with no 'type:' field is a marketplace-only
    manifest, not a package; it is skipped and the walk continues upward.

  Standalone mode:
    If the walk reaches a '.git' directory or the filesystem root without
    finding a type-bearing apm.yml, the skill is scaffolded directly into
    <path>/<skill-name>/, exactly as <path> was given.

Arguments:
  skill-name  Kebab-case skill identifier (e.g. my-tool, data-analyzer).
              Must match the directory name exactly.
  path        Any existing path inside/at the target. Used to locate the
              package (package mode) or as the literal parent directory
              (standalone mode). Must already exist.
              Examples: ~/.agents/skills/  packages/my-pkg/some/subdir/

Output:
  Package mode:    <package-root>/.apm/skills/<skill-name>/
  Standalone mode: <path>/<skill-name>/

Exit codes:
  0  Scaffold created successfully, or destination already exists (no-op)
  1  Invalid arguments, missing path, or templates not found
EOF
}

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

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

SKILL_NAME="$1"
TARGET_INPUT="$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-author skill." >&2
  exit 1
fi

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

# ---------------------------------------------------------------------------
# Walk up from <path> looking for a type-bearing apm.yml (package mode) or a
# .git boundary / filesystem root (standalone mode). An apm.yml with no
# top-level 'type:' field is a marketplace-only manifest — skip it and keep
# walking up. Prints two lines: the resolved root, then the mode.
# ---------------------------------------------------------------------------
find_package_root() {
  local current
  current="$(cd "$1" && pwd)"
  while true; do
    if [[ -f "$current/apm.yml" ]]; then
      if grep -qE '^type:[[:space:]]*(instructions|skill|hybrid|prompts)\b' "$current/apm.yml"; then
        echo "$current"
        echo "package"
        return 0
      fi
      # apm.yml exists but has no type: field — marketplace-only manifest.
      # Not a package match; keep walking up.
    fi
    if [[ -d "$current/.git" ]]; then
      echo "$current"
      echo "no-package"
      return 0
    fi
    local parent
    parent="$(dirname "$current")"
    if [[ "$parent" == "$current" ]]; then
      echo "$current"
      echo "no-package"
      return 0
    fi
    current="$parent"
  done
}

# `mapfile`/`readarray` are bash 4.0+ builtins with no fallback on macOS's
# stock /bin/bash 3.2 — read the two output lines individually instead.
WALK_OUTPUT="$(find_package_root "$TARGET_INPUT")"
PKG_ROOT="$(echo "$WALK_OUTPUT" | sed -n '1p')"
MODE="$(echo "$WALK_OUTPUT" | sed -n '2p')"

if [[ "$MODE" == "package" ]]; then
  TARGET="$PKG_ROOT/.apm/skills/$SKILL_NAME"
else
  TARGET="$TARGET_INPUT/$SKILL_NAME"
fi

# Destination already exists — treat as a no-op so retries are safe
if [[ -d "$TARGET" ]]; then
  echo "Scaffold already exists at '$TARGET' — nothing to do." >&2
  exit 0
fi

mkdir -p "$(dirname "$TARGET")"

# 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"
sed -i "s/SKILL_NAME/$SKILL_NAME/g" "$TARGET/tests/README.md"

if [[ "$MODE" == "package" ]]; then
  echo "Mode: package — type-bearing apm.yml found at '$PKG_ROOT'" >&2
  echo "Scaffold created: $TARGET" >&2
  echo "" >&2
  echo "Note: if '$PKG_ROOT/apm.yml' has an explicit 'includes:' list (not 'auto')," >&2
  echo "      add '.apm/skills/$SKILL_NAME/' to it." >&2
else
  echo "Mode: standalone — no type-bearing apm.yml found above '$TARGET_INPUT'" >&2
  echo "Scaffold created: $TARGET" >&2
fi
echo "" >&2
echo "Next steps:" >&2
echo "  1. Fill in $TARGET/SKILL.md — replace all FILL IN: placeholders" >&2
echo "  2. Add scripts to scripts/ if needed (or delete the directory)" >&2
echo "  3. Add docs to references/ if needed (or delete the directory)" >&2
echo "  4. Add resources to assets/ if needed (or delete the directory)" >&2
echo "  5. Add tests to tests/ if the skill has scripts (or delete the directory)" >&2
echo "  6. Populate references/sources.md with research sources, or delete it" >&2
echo "  7. Validate: run /skill-audit on $TARGET" >&2