#!/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")

# #2569: rendered :user variants (brain-aware blocks) live in an UNTRACKED
# out-dir instead of the tracked install checkout. When a render exists for a
# skill, relink serves it — otherwise a config change would silently flip
# every skill back to the canonical (blockless) source.
RENDER_DIR="${GSTACK_USER_RENDER_DIR:-${GSTACK_HOME:-$HOME/.gstack}/render/claude}"

# ─── Ownership gate ───────────────────────────────────────────────────────────
# relink runs on every ./setup and used to `rm -rf` any same-name entry with a
# symlinked SKILL.md and `ln -snf` over any existing SKILL.md — so a user's own
# skill that happened to share a name (a personal `qa`, a fork under another
# path) was deleted or had its SKILL.md replaced by a symlink into gstack
# (#2119; Linux replaces a real file with `ln -snf`, macOS refuses by accident).
# setup:1040 and gstack-uninstall:204 already gate on readlink; this is the
# same rule for the one remaining unguarded deleter.
#
# An entry is OURS when:
#   - it is a symlink resolving into $INSTALL_DIR or $RENDER_DIR, or
#   - it is a real dir whose SKILL.md is a symlink resolving into either, or
#   - it is a real dir carrying the .gstack-owned marker setup writes for
#     Windows copy installs (no symlinks there to read).
# Anything else — a foreign symlink, a real dir with a real SKILL.md and no
# marker, or an entry whose readlink fails — is FOREIGN: never deleted, never
# linked over, reported on stderr.
_target_is_ours() {
  # $1 = a path that readlink resolved; ours when it lives under our roots.
  case "$1" in
    "$INSTALL_DIR"/*|"$RENDER_DIR"/*) return 0 ;;
    *) return 1 ;;
  esac
}

_entry_is_ours() {
  local entry="$1" dest
  if [ -L "$entry" ]; then
    dest="$(readlink "$entry" 2>/dev/null || true)"
    [ -n "$dest" ] || return 1
    _target_is_ours "$dest"
    return $?
  fi
  if [ -d "$entry" ]; then
    [ -f "$entry/.gstack-owned" ] && return 0
    if [ -L "$entry/SKILL.md" ]; then
      dest="$(readlink "$entry/SKILL.md" 2>/dev/null || true)"
      [ -n "$dest" ] || return 1
      _target_is_ours "$dest"
      return $?
    fi
    return 1
  fi
  return 1
}

FOREIGN_SKIPPED=()
_report_foreign() {
  echo "  skipped $1: not a gstack-managed entry (foreign skill with the same name) — left untouched" >&2
  FOREIGN_SKIPPED+=("$1")
}

# Helper: remove an OLD skill entry from the opposite prefix mode. Only entries
# we can prove are ours are removed; anything else is reported and kept.
_cleanup_skill_entry() {
  local entry="$1"
  [ -e "$entry" ] || [ -L "$entry" ] || return 0
  if ! _entry_is_ours "$entry"; then
    _report_foreign "$entry"
    return 0
  fi
  if [ -L "$entry" ]; then
    rm -f "$entry"
  elif [ -d "$entry" ]; then
    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"
  # Copy-then-rewrite, never a symlink (#2511): a symlinked alias re-serves
  # the canonical `name: gstack`, Claude Code sees a duplicate skill name,
  # and drops the ENTIRE personal-skills set. sed reads the source and writes
  # a fresh copy — remove any prior symlink first so the redirect can never
  # write through it into the generated source.
  rm -f "$target/SKILL.md"
  sed "1,/^---\$/ s/^name:[[:space:]].*/name: _gstack-command/" "$INSTALL_DIR/SKILL.md" > "$target/SKILL.md"
}

_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
  # Skip symlinked skill dirs (connect-chrome → open-gstack-browser): linking
  # one under the symlink's basename would duplicate the canonical frontmatter
  # name and collide in Claude Code's skill registry (#2201). setup owns the
  # rewritten-copy alias for those.
  [ -L "${skill_dir%/}" ] && continue
  skill=$(basename "$skill_dir")
  # Skip non-skill directories
  case "$skill" in bin|browse|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"
  # A destination that already exists and is NOT ours is a foreign skill that
  # shares our name. Never `ln -snf` over its SKILL.md (on Linux that replaces
  # a real file with a symlink into gstack) and never mkdir into it — skip
  # loudly and leave registration of that one name to the user.
  if { [ -e "$target" ] || [ -L "$target" ]; } && ! _entry_is_ours "$target"; then
    _report_foreign "$target"
    continue
  fi
  # Upgrade old directory symlinks to real directories
  [ -L "$target" ] && rm -f "$target"
  # Create real directory with symlinked SKILL.md (absolute path)
  mkdir -p "$target"
  skill_md_src="$INSTALL_DIR/$skill/SKILL.md"
  [ -f "$RENDER_DIR/$skill/SKILL.md" ] && skill_md_src="$RENDER_DIR/$skill/SKILL.md"
  ln -snf "$skill_md_src" "$target/SKILL.md"
  SKILL_COUNT=$((SKILL_COUNT + 1))
done

# Patch SKILL.md name: fields to match prefix setting. When a gbrain render
# is active the loop above links SKILL.md from RENDER_DIR — the file the host
# actually serves — so patch THAT tree too or skill_prefix=true is a no-op
# for every brain-aware skill (#2738). gstack-patch-names takes an arbitrary
# root, skips already-prefixed names (idempotent), and the render dir is
# user-owned and untracked, so patching it never dirties a checkout.
"$INSTALL_DIR/bin/gstack-patch-names" "$INSTALL_DIR" "$PREFIX"
[ -d "$RENDER_DIR" ] && "$INSTALL_DIR/bin/gstack-patch-names" "$RENDER_DIR" "$PREFIX"

if [ "$PREFIX" = "true" ]; then
  echo "Relinked $SKILL_COUNT skills as gstack-*"
else
  echo "Relinked $SKILL_COUNT skills as flat names"
fi
if [ ${#FOREIGN_SKIPPED[@]} -gt 0 ]; then
  echo "Skipped ${#FOREIGN_SKIPPED[@]} foreign entr$( [ ${#FOREIGN_SKIPPED[@]} -eq 1 ] && echo y || echo ies) (not gstack-managed, left untouched): ${FOREIGN_SKIPPED[*]}"
fi