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

# skills-link — Symlink k8s-agent-skills to agent skill directories
#
# Auto-update: Uses SYMLINKS, so skill CONTENT always reflects the latest
# source. git pull / npm update = instant update. Stale symlinks (skills
# removed from package) are cleaned up automatically. Only re-run when
# NEW skills are added to the package (--check detects this).
#
# Usage:
#   skills-link                    # link to ~/.agents/skills/ (OpenCode default)
#   skills-link --agents           # ~/.agents/skills/
#   skills-link --opencode         # ~/.config/opencode/skills/
#   skills-link --claude           # ~/.claude/skills/
#   skills-link --codex            # ~/.codex/skills/
#   skills-link --cursor           # ~/.cursor/skills/
#   skills-link --global           # all above
#   skills-link --all              # alias for --global
#   skills-link --check            # verify all skills linked, exit 1 if not
#   skills-link --dry-run          # preview without linking

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
PKG_DIR="$(cd "$SCRIPT_DIR/.." && pwd)"
SKILLS_DIR="$PKG_DIR/skills"

if [ ! -d "$SKILLS_DIR" ]; then
  echo "ERROR: skills/ not found at $SKILLS_DIR" >&2
  echo "Run this script from within the k8s-agent-skills package." >&2
  exit 1
fi

# All known agent skill directories
ALL_TARGETS=(
  "$HOME/.agents/skills"
  "$HOME/.config/opencode/skills"
  "$HOME/.claude/skills"
  "$HOME/.codex/skills"
  "$HOME/.cursor/skills"
)

declare -a TARGETS
DRY_RUN=false
CHECK=false

# Default: ~/.agents/skills only
TARGETS+=("$HOME/.agents/skills")

while [[ $# -gt 0 ]]; do
  case "$1" in
    --agents)   TARGETS+=("$HOME/.agents/skills")              ;;
    --opencode) TARGETS+=("$HOME/.config/opencode/skills")     ;;
    --claude)   TARGETS+=("$HOME/.claude/skills")              ;;
    --codex)    TARGETS+=("$HOME/.codex/skills")               ;;
    --cursor)   TARGETS+=("$HOME/.cursor/skills")              ;;
    --global|--all)
      for t in "${ALL_TARGETS[@]}"; do TARGETS+=("$t"); done
      ;;
    --check)    CHECK=true; DRY_RUN=true                      ;;
    --dry-run)  DRY_RUN=true                                   ;;
    --help|-h)
      echo "Usage: skills-link [--agents] [--opencode] [--claude] [--codex] [--cursor] [--global|--all] [--check] [--dry-run]"
      echo ""
      echo "  Default:  ~/.agents/skills/ (OpenCode agent skills)"
      echo "  --global  Link to all known agent directories:"
      for t in "${ALL_TARGETS[@]}"; do echo "              $t"; done
      echo "  --check   Verify all skills linked (exit 1 if drift found)"
      exit 0
      ;;
    *)
      echo "Unknown option: $1" >&2
      echo "Usage: skills-link [--agents] [--opencode] [--claude] [--codex] [--cursor] [--global|--all] [--check] [--dry-run]" >&2
      exit 1
      ;;
  esac
  shift
done

# Deduplicate (preserve order)
declare -a UNIQUE
for t in "${TARGETS[@]}"; do
  seen=false
  for u in "${UNIQUE[@]}"; do
    [ "$u" = "$t" ] && seen=true && break
  done
  $seen || UNIQUE+=("$t")
done

EXIT_CODE=0

for TARGET in "${UNIQUE[@]}"; do
  mkdir -p "$TARGET"

  # Cleanup stale symlinks (skills removed from package)
  broken=0
  while IFS= read -r -d '' link; do
    if [ ! -e "$link" ]; then
      $DRY_RUN && echo "  [dry-run] rm $link" || rm -f "$link"
      broken=$((broken + 1))
    fi
  done < <(find "$TARGET" -maxdepth 1 -type l -name '*' -print0 2>/dev/null || true)

  missing=0
  linked=0
  skipped=0
  migrated=0
  for skill_dir in "$SKILLS_DIR"/*/; do
    [ -d "$skill_dir" ] || continue
    skill_name="$(basename "$skill_dir")"
    link_path="$TARGET/$skill_name"
    expect_target="$(readlink -f "$skill_dir")"

    # Already points to the right place
    if [ -L "$link_path" ] && [ "$(readlink "$link_path")" = "$skill_dir" ]; then
      skipped=$((skipped + 1))
      continue
    fi

    # Check mode: symlink is missing or wrong
    if $CHECK; then
      if [ ! -e "$link_path" ] && [ ! -L "$link_path" ]; then
        echo "  MISSING: $link_path → $skill_dir"
        missing=$((missing + 1))
      elif [ -L "$link_path" ]; then
        echo "  WRONG: $link_path → $(readlink "$link_path") (expected $skill_dir)"
        missing=$((missing + 1))
      elif [ -d "$link_path" ]; then
        echo "  COPY (not symlink): $link_path"
        missing=$((missing + 1))
      fi
      continue
    fi

    # Handle existing entry
    if [ -e "$link_path" ] || [ -L "$link_path" ]; then
      if [ -L "$link_path" ]; then
        $DRY_RUN && echo "  [dry-run] rm $link_path" || rm -f "$link_path"
      elif [ -d "$link_path" ] && [ -f "$link_path/SKILL.md" ]; then
        $DRY_RUN && echo "  [dry-run] rm -rf $link_path (old copy)" || rm -rf "$link_path"
        migrated=$((migrated + 1))
      else
        echo "  WARN: $link_path exists and is not a symlink — skipping" >&2
        continue
      fi
    fi

    if $DRY_RUN; then
      echo "  [dry-run] ln -sf $skill_dir $link_path"
      linked=$((linked + 1))
    else
      ln -sf "$skill_dir" "$link_path"
      linked=$((linked + 1))
    fi
  done

  if $CHECK; then
    if [ "$missing" -gt 0 ]; then
      echo "[$TARGET] $missing skill(s) missing or wrong — run 'skills-link --global' to fix"
      EXIT_CODE=1
    else
      echo "[$TARGET] all $skipped skill(s) up-to-date ✓"
    fi
  else
    action=$($DRY_RUN && echo "would link" || echo "linked")
    echo "[$TARGET] $action $linked skill(s), $skipped up-to-date, $migrated migrated, $broken stale symlink(s) removed"
  fi
done

exit $EXIT_CODE