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

usage() {
  cat <<'EOF'
Usage:
  bash scripts/install-skill.sh fix-title
  bash scripts/install-skill.sh --all

Options:
  --force                 Back up and replace existing installed Skill
  --install-claude-link   Create/update .claude/skills link to .agents/skills
EOF
}

skill=""
install_all=0
force=0
install_claude_link=0

while [[ $# -gt 0 ]]; do
  case "$1" in
    --all)
      install_all=1
      shift
      ;;
    --force)
      force=1
      shift
      ;;
    --install-claude-link)
      install_claude_link=1
      shift
      ;;
    -h|--help)
      usage
      exit 0
      ;;
    -*)
      echo "Unknown option: $1" >&2
      usage
      exit 2
      ;;
    *)
      if [[ -n "$skill" ]]; then
        echo "Only one Skill name may be provided." >&2
        usage
        exit 2
      fi
      skill="$1"
      shift
      ;;
  esac
done

if [[ "$install_all" -eq 1 && -n "$skill" ]] || [[ "$install_all" -eq 0 && -z "$skill" ]]; then
  usage
  exit 2
fi

script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
repo_root="$(cd "$script_dir/.." && pwd)"
skills_root="$repo_root/skills"
registry_path="$repo_root/registry/skills-index.md"

if [[ -n "${USERPROFILE:-}" ]]; then
  home_dir="$USERPROFILE"
else
  home_dir="$HOME"
fi

install_root="${SKILLS_VAULT_INSTALL_ROOT:-$home_dir/.agents/skills}"
claude_skills_root="${SKILLS_VAULT_CLAUDE_SKILLS_ROOT:-$home_dir/.claude/skills}"

registry_meta() {
  local name="$1"
  [[ -f "$registry_path" ]] || return 1
  grep -E "^\|[[:space:]]*\`$name\`[[:space:]]*\|" "$registry_path" | head -n 1 || true
}

registry_cell() {
  local line="$1"
  local index="$2"
  printf '%s\n' "$line" | awk -F'|' -v i="$index" '{gsub(/^ +| +$/, "", $(i + 1)); gsub(/`/, "", $(i + 1)); print $(i + 1)}'
}

all_default_skills() {
  local allowed_statuses=" tested installable installed "
  for dir in "$skills_root"/*; do
    [[ -d "$dir" ]] || continue
    [[ -f "$dir/SKILL.md" ]] || continue
    local name
    name="$(basename "$dir")"
    local line
    line="$(registry_meta "$name")"
    if [[ -z "$line" ]]; then
      echo "Skipping $name: no registry row" >&2
      continue
    fi
    local status policy
    status="$(registry_cell "$line" 4)"
    policy="$(registry_cell "$line" 5)"
    if [[ "$allowed_statuses" != *" $status "* ]]; then
      echo "Skipping $name: status is $status" >&2
      continue
    fi
    if [[ "$policy" != "default" ]]; then
      echo "Skipping $name: install policy is $policy" >&2
      continue
    fi
    printf '%s\n' "$name"
  done
}

backup_existing_path() {
  local path="$1"
  local stamp
  stamp="$(date +%Y%m%d%H%M%S)"
  local backup="$path.backup-$stamp"
  mv "$path" "$backup"
  printf '%s\n' "$backup"
}

copy_skill_directory() {
  local source="$1"
  local target="$2"
  mkdir -p "$target"
  shopt -s dotglob nullglob
  for item in "$source"/*; do
    local base
    base="$(basename "$item")"
    case "$base" in
      manual-test|__pycache__|.pytest_cache)
        continue
        ;;
    esac
    cp -a "$item" "$target/"
  done
  shopt -u dotglob nullglob
}

create_claude_link() {
  local name="$1"
  local target="$2"
  local link="$claude_skills_root/$name"
  mkdir -p "$claude_skills_root"
  if [[ -e "$link" || -L "$link" ]]; then
    if [[ "$force" -ne 1 ]]; then
      echo "Claude Skill link/path already exists: $link. Re-run with --force to back it up and replace it." >&2
      exit 1
    fi
    local backup
    backup="$(backup_existing_path "$link")"
    echo "Backed up existing Claude path to $backup"
  fi

  if [[ "${OS:-}" == "Windows_NT" ]]; then
    cmd.exe /c mklink /J "$(cygpath -w "$link")" "$(cygpath -w "$target")" >/dev/null
  else
    ln -s "$target" "$link"
  fi
  echo "Linked Claude Skill $link -> $target"
}

install_one_skill() {
  local name="$1"
  if [[ ! "$name" =~ ^[a-z0-9][a-z0-9-]*$ ]]; then
    echo "Invalid Skill name: $name" >&2
    exit 1
  fi

  local source="$skills_root/$name"
  if [[ ! -f "$source/SKILL.md" ]]; then
    echo "Skill source not found: $source/SKILL.md" >&2
    exit 1
  fi

  local line
  line="$(registry_meta "$name")"
  if [[ -n "$line" ]]; then
    local policy
    policy="$(registry_cell "$line" 5)"
    if [[ "$policy" == "disabled" && "$force" -ne 1 ]]; then
      echo "Skill $name has install policy disabled. Use --force only if you intentionally want to install it." >&2
      exit 1
    fi
  fi

  local target="$install_root/$name"
  mkdir -p "$install_root"
  if [[ -e "$target" || -L "$target" ]]; then
    if [[ "$force" -ne 1 ]]; then
      echo "Installed Skill already exists: $target. Re-run with --force to back it up and replace it." >&2
      exit 1
    fi
    local backup
    backup="$(backup_existing_path "$target")"
    echo "Backed up existing Skill to $backup"
  fi

  copy_skill_directory "$source" "$target"
  echo "Installed $name to $target"

  if [[ "$install_claude_link" -eq 1 ]]; then
    create_claude_link "$name" "$target"
  fi
}

if [[ "$install_all" -eq 1 ]]; then
  mapfile -t skills < <(all_default_skills)
  if [[ "${#skills[@]}" -eq 0 ]]; then
    echo "No default installable Skills found."
    exit 0
  fi
  for name in "${skills[@]}"; do
    install_one_skill "$name"
  done
else
  install_one_skill "$skill"
fi