#!/usr/bin/env bash
# gstack-relink — re-create skill symlinks based on skill_prefix config
#
# Usage:
#   gstack-relink
#
# Env overrides (for testing):
#   GSTACK_STATE_DIR   — override ~/.gstack state directory
#   GSTACK_INSTALL_DIR — override gstack install directory
#   GSTACK_SKILLS_DIR  — override target skills directory
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
GSTACK_CONFIG="${SCRIPT_DIR}/gstack-config"

# Detect install dir
INSTALL_DIR="${GSTACK_INSTALL_DIR:-}"
if [ -z "$INSTALL_DIR" ]; then
  if [ -d "$HOME/.claude/skills/gstack" ]; then
    INSTALL_DIR="$HOME/.claude/skills/gstack"
  elif [ -d "${SCRIPT_DIR}/.." ] && [ -f "${SCRIPT_DIR}/../setup" ]; then
    INSTALL_DIR="$(cd "${SCRIPT_DIR}/.." && pwd)"
  fi
fi

if [ -z "$INSTALL_DIR" ] || [ ! -d "$INSTALL_DIR" ]; then
  echo "Error: gstack install directory not found." >&2
  echo "Run: cd ~/.claude/skills/gstack && ./setup" >&2
  exit 1
fi

# Detect target skills dir
SKILLS_DIR="${GSTACK_SKILLS_DIR:-$(dirname "$INSTALL_DIR")}"
[ -d "$SKILLS_DIR" ] || mkdir -p "$SKILLS_DIR"

# Read prefix setting
PREFIX=$("$GSTACK_CONFIG" get skill_prefix 2>/dev/null || echo "false")

# Marker written into generated alias skills so a later relink can recognize
# (and clean up) an alias it created earlier, even after a prefix flip.
ALIAS_MARKER='<!-- gstack-generated-alias -->'

# Helper: remove old skill entry (symlink or real directory with symlinked SKILL.md)
_cleanup_skill_entry() {
  local entry="$1"
  if [ -L "$entry" ]; then
    rm -f "$entry"
  elif [ -d "$entry" ] && [ -L "$entry/SKILL.md" ]; then
    rm -rf "$entry"
  elif [ -d "$entry" ] && [ -f "$entry/SKILL.md" ] && grep -qF "$ALIAS_MARKER" "$entry/SKILL.md" 2>/dev/null; then
    # A generated alias holds a real SKILL.md, not a symlink, so the branch
    # above never matches it. Without this, a prefix flip leaves the old alias
    # behind and both names stay registered.
    rm -rf "$entry"
  fi
}

_link_root_skill_alias() {
  local target="$SKILLS_DIR/_gstack-command"

  [ -f "$INSTALL_DIR/SKILL.md" ] || return 0
  [ -L "$target" ] && rm -f "$target"
  mkdir -p "$target"
  ln -snf "$INSTALL_DIR/SKILL.md" "$target/SKILL.md"
}

# Backwards-compat alias: /connect-chrome → /open-gstack-browser.
#
# The alias must NOT be a symlink to the canonical skill directory. Claude Code
# keys skills on the frontmatter `name:`, so two directories sharing a name
# shadow each other and the survivor follows unsorted readdir order — meaning
# `/open-gstack-browser` (the name README, AGENTS.md, the router SKILL.md and
# the sidebar extension all tell users to run) would be registered on some
# machines and silently missing on others. Generate a thin alias skill with its
# own `name:` instead, so both commands resolve, on every machine.
_link_alias_skill() {
  local canonical="$1"
  local alias_name="$2"

  [ -f "$INSTALL_DIR/$canonical/SKILL.md" ] || return 0

  local description
  description=$(grep -m1 '^description:' "$INSTALL_DIR/$canonical/SKILL.md" 2>/dev/null |
    sed 's/^description:[[:space:]]*//')
  [ -n "$description" ] || description="Alias for /$canonical."

  # Drop the alias entry belonging to the other prefix mode, so flipping
  # skill_prefix never leaves two alias skills registered at once.
  if [ "$PREFIX" = "true" ]; then
    _cleanup_skill_entry "$SKILLS_DIR/$alias_name"
    canonical="gstack-$canonical"
    alias_name="gstack-$alias_name"
  else
    _cleanup_skill_entry "$SKILLS_DIR/gstack-$alias_name"
  fi

  local target="$SKILLS_DIR/$alias_name"
  if [ -L "$target" ]; then rm -f "$target"; fi
  mkdir -p "$target"
  if [ -L "$target/SKILL.md" ]; then rm -f "$target/SKILL.md"; fi
  cat > "$target/SKILL.md" <<EOF
---
name: $alias_name
description: Deprecated alias for /$canonical. $description
---
$ALIAS_MARKER

# /$alias_name (deprecated alias)

Kept for backwards compatibility. The skill itself lives at \`/$canonical\`.

Invoke the \`$canonical\` skill and follow it exactly. Do not restate its steps here.
EOF
}

_link_root_skill_alias

# Discover skills (directories with SKILL.md, excluding meta dirs)
SKILL_COUNT=0
for skill_dir in "$INSTALL_DIR"/*/; do
  [ -d "$skill_dir" ] || continue
  skill=$(basename "$skill_dir")
  # Skip non-skill directories. `connect-chrome` is a repo-level symlink to
  # open-gstack-browser; it is installed by _link_alias_skill below, not here,
  # so that it gets its own frontmatter name instead of the canonical one.
  case "$skill" in bin|browse|connect-chrome|design|docs|extension|lib|node_modules|scripts|test|.git|.github) continue ;; esac
  [ -f "$skill_dir/SKILL.md" ] || continue

  if [ "$PREFIX" = "true" ]; then
    # Don't double-prefix directories already named gstack-*
    case "$skill" in
      gstack-*) link_name="$skill" ;;
      *)        link_name="gstack-$skill" ;;
    esac
    # Remove old flat entry if it exists (and isn't the same as the new link)
    [ "$link_name" != "$skill" ] && _cleanup_skill_entry "$SKILLS_DIR/$skill"
  else
    link_name="$skill"
    # Don't remove gstack-* dirs that are their real name (e.g., gstack-upgrade)
    case "$skill" in
      gstack-*) ;; # Already the real name, no old prefixed link to clean
      *)        _cleanup_skill_entry "$SKILLS_DIR/gstack-$skill" ;;
    esac
  fi
  target="$SKILLS_DIR/$link_name"
  # Upgrade old directory symlinks to real directories
  [ -L "$target" ] && rm -f "$target"
  # Create real directory with symlinked SKILL.md (absolute path)
  mkdir -p "$target"
  ln -snf "$INSTALL_DIR/$skill/SKILL.md" "$target/SKILL.md"
  SKILL_COUNT=$((SKILL_COUNT + 1))
done

# Alias skills, installed after the loop so they overwrite any stale entry a
# previous relink symlinked into place.
_link_alias_skill "open-gstack-browser" "connect-chrome"

# Patch SKILL.md name: fields to match prefix setting
"$INSTALL_DIR/bin/gstack-patch-names" "$INSTALL_DIR" "$PREFIX"

if [ "$PREFIX" = "true" ]; then
  echo "Relinked $SKILL_COUNT skills as gstack-*"
else
  echo "Relinked $SKILL_COUNT skills as flat names"
fi