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

# ── Config ──────────────────────────────────────────────
REPO="TimothyYe/skm"
VERSION="${VERSION:-latest}"   # set VERSION=v0.8.7 to pin
PREFIX="$HOME/.local/bin"      # non-sudo install path

# ── Helpers ─────────────────────────────────────────────
need() { command -v "$1" >/dev/null 2>&1 || { echo "Missing dependency: $1"; exit 1; }; }
tmpdir() { mktemp -d 2>/dev/null || mktemp -d -t skm; }
cleanup() { [[ -n "${WORKDIR:-}" && -d "$WORKDIR" ]] && rm -rf "$WORKDIR"; }
trap cleanup EXIT

detect_platform() {
  local uos uarch
  uos="$(uname -s | tr '[:upper:]' '[:lower:]')"
  uarch="$(uname -m)"

  case "$uos" in
    linux) OS="linux" ;;
    darwin) OS="darwin" ;;
    *) echo "Unsupported OS: $uos"; exit 1 ;;
  esac

  case "$uarch" in
    x86_64|amd64) ARCH="amd64" ;;
    aarch64|arm64) ARCH="arm64" ;;
    i386|i686) ARCH="386" ;;
    armv7l|armv7|armv6l|armv6|armv5l|arm) ARCH="arm" ;;
    *) echo "Unsupported architecture: $uarch"; exit 1 ;;
  esac
}

# ── Fixed function ──────────────────────────────────────
get_latest_tag() {
  need curl
  local json tag
  json="$(curl -fsSL "https://api.github.com/repos/${REPO}/releases/latest")"
  tag="$(printf '%s\n' "$json" | sed -nE 's/.*"tag_name": *"([^"]+)".*/\1/p' | head -n1)"
  if [ -z "$tag" ]; then
    echo "❌ Failed to determine latest release tag from GitHub API" >&2
    exit 1
  fi
  printf '%s\n' "$tag"
}

build_url() {
  local tag="$1" os="$2" arch="$3" ver="${tag#v}"
  echo "https://github.com/${REPO}/releases/download/${tag}/skm_${ver}_${os}_${arch}.tar.gz"
}

resolve_url() {
  local tag="$1" os="$2" arch="$3"
  local url alt
  url="$(build_url "$tag" "$os" "$arch")"
  if curl -fsI "$url" >/dev/null 2>&1; then
    echo "$url"; return 0
  fi
  if [[ "$os" == "linux" && "$arch" == "arm64" ]]; then
    alt="$(build_url "$tag" "$os" "arm")"
    if curl -fsI "$alt" >/dev/null 2>&1; then
      echo "$alt"; return 0
    fi
  fi
  echo "No release asset found for ${os}/${arch} (tag ${tag})." >&2
  exit 1
}

# ── Main ────────────────────────────────────────────────
echo "→ Detecting platform..."
detect_platform
echo "   OS=${OS} ARCH=${ARCH}"

if [[ "$VERSION" == "latest" ]]; then
  echo "→ Fetching latest SKM release..."
  TAG="$(get_latest_tag)"
else
  TAG="$VERSION"
fi
echo "   Using release: $TAG"

URL="$(resolve_url "$TAG" "$OS" "$ARCH")"
echo "→ Downloading: $URL"

WORKDIR="$(tmpdir)"
cd "$WORKDIR"
FILENAME="${URL##*/}"
curl -fL --progress-bar -o "$FILENAME" "$URL"

echo "→ Extracting..."
tar -xzf "$FILENAME"

BIN="$(find . -maxdepth 2 -type f -name skm | head -n1 || true)"
[[ -n "$BIN" && -f "$BIN" ]] || { echo "Could not find skm binary"; exit 1; }

mkdir -p "$PREFIX"
mv "$BIN" "$PREFIX/skm"
chmod +x "$PREFIX/skm"

echo "→ Installed at $PREFIX/skm"

# Add to PATH if not already
if ! echo "$PATH" | grep -q "$HOME/.local/bin"; then
  echo "⚠️  $HOME/.local/bin is not in your PATH."
  echo "   Add this to your shell config (e.g. ~/.bashrc or ~/.zshrc):"
  echo "   export PATH=\"\$HOME/.local/bin:\$PATH\""
fi

echo "✅ Done. Version: $($PREFIX/skm --version)"