#!/usr/bin/env bash
# TerraFin skill installer — symlink skills/terrafin into the skill dirs of
# every AI coding host you have installed (or a specific one via --host).
#
# Usage:
#   ./setup                         # auto: install to every detected host
#   ./setup --host claude           # just Claude Code
#   ./setup --host codex            # just Codex CLI
#   ./setup --host opencode         # just opencode
#   ./setup -q                      # quiet (errors only)
#
# Idempotent: re-running overwrites the symlink. `git pull` propagates
# upgrades to every host because the target is a live symlink to the repo
# checkout — no re-copy needed.
#
# Install pattern (single-file ./setup at repo root, --host auto mode,
# inclusive detection via `command -v`, idempotent symlinks) is adapted
# from gstack's installer — https://github.com/garrytan/gstack — which
# pioneered the multi-host skill-drop-in shape for Anthropic Skills.

set -euo pipefail

HOST="auto"
QUIET=0

while [ "$#" -gt 0 ]; do
  case "$1" in
    --host) HOST="$2" ; shift 2 ;;
    --host=*) HOST="${1#*=}" ; shift ;;
    -q|--quiet) QUIET=1 ; shift ;;
    -h|--help)
      sed -n '2,14p' "$0" | sed 's/^# \{0,1\}//' ; exit 0 ;;
    *)
      echo "unknown flag: $1" >&2 ; exit 2 ;;
  esac
done

case "$HOST" in
  auto|claude|codex|opencode) ;;
  *) echo "--host must be one of: auto, claude, codex, opencode (got: $HOST)" >&2 ; exit 2 ;;
esac

REPO_ROOT="$(cd "$(dirname "$0")" && pwd)"
SKILL_SRC="$REPO_ROOT/skills/terrafin"

if [ ! -f "$SKILL_SRC/SKILL.md" ]; then
  echo "missing $SKILL_SRC/SKILL.md — run ./setup from the TerraFin repo root" >&2
  exit 1
fi

log() { [ "$QUIET" -eq 1 ] || echo "$@" ; }

install_one() {
  local host="$1" detect_cmd="$2" target_dir="$3"
  if [ "$HOST" != "auto" ] && [ "$HOST" != "$host" ]; then
    return 0
  fi
  if [ "$HOST" = "auto" ] && ! command -v "$detect_cmd" >/dev/null 2>&1; then
    return 0
  fi
  mkdir -p "$target_dir"
  local link="$target_dir/terrafin"
  # `ln -snf` replaces an existing symlink atomically; if a real directory
  # already exists at the target (e.g. a previous `cp -r`), bail loudly so
  # we don't clobber it.
  if [ -e "$link" ] && [ ! -L "$link" ]; then
    echo "refusing to overwrite existing directory: $link" >&2
    echo "  (likely a leftover from 'cp -r skills/terrafin'; remove it and re-run ./setup)" >&2
    return 1
  fi
  ln -snf "$SKILL_SRC" "$link"
  log "installed: $host → $link"
  INSTALLED=$((INSTALLED + 1))
}

INSTALLED=0

install_one claude   claude   "$HOME/.claude/skills"
install_one codex    codex    "$HOME/.codex/skills"
install_one opencode opencode "$HOME/.config/opencode/skills"

if [ "$INSTALLED" -eq 0 ]; then
  if [ "$HOST" = "auto" ]; then
    # No host detected on PATH — fall back to Claude (the canonical target)
    # so `./setup` is never a no-op. Matches gstack's default.
    log "no AI host detected on PATH — defaulting to Claude Code"
    mkdir -p "$HOME/.claude/skills"
    link="$HOME/.claude/skills/terrafin"
    if [ -e "$link" ] && [ ! -L "$link" ]; then
      echo "refusing to overwrite existing directory: $link" >&2
      exit 1
    fi
    ln -snf "$SKILL_SRC" "$link"
    log "installed: claude → $link"
  else
    echo "host '$HOST' not installed on PATH" >&2
    exit 1
  fi
fi

log ""
log "Done. Open a new session in your AI host and type 'terrafin' to invoke."