#!/bin/sh

gitpack_url="https://gitpack.htlc.io"
bin_dir="$HOME/.local/bin"

cmd_help() {
  echo "Usage: gitpack <command>"
  echo ""
  echo "Commands:"
  echo "    gitpack install [app]  -  Install an app"
  echo "    gitpack remove [app]   -  Remove an app"
  echo "    gitpack run [app] %    -  Update and run an app. Additional arguments are passed through to the app"
  echo "    gitpack update         -  Update gitpack itself"
  echo ""
}

ensure_gitpack_installed() {
  # Ensure ~/.local/bin exists
  mkdir -p "$bin_dir"

  # Ensure ~/.local/bin is in PATH
  case ":$PATH:" in
  *":$bin_dir:"*) ;;
  *)
    echo "Warning: $bin_dir is not in your PATH."

    # Detect the appropriate dotfile for the user's shell
    shell_name="$(basename "$SHELL")"
    case "$shell_name" in
    zsh) dotfile="$HOME/.zshrc" ;;
    bash) dotfile="$HOME/.bashrc" ;;
    fish) dotfile="$HOME/.config/fish/config.fish" ;;
    ksh) dotfile="$HOME/.kshrc" ;;
    *) dotfile="" ;;
    esac

    if [ -n "$dotfile" ] && [ -e /dev/tty ]; then
      printf "Add %s to PATH in %s? [Y/n] " "$bin_dir" "$dotfile"
      read -r answer </dev/tty
      case "$answer" in
      [Nn]*) ;;
      *)
        if [ "$shell_name" = "fish" ]; then
          echo "fish_add_path $bin_dir" >>"$dotfile"
        else
          echo "export PATH=\"$bin_dir:\$PATH\"" >>"$dotfile"
        fi
        echo "Added. Restart your shell or run: source $dotfile"
        ;;
      esac
    else
      echo "Could not detect your shell config file. Add $bin_dir to your PATH manually."
    fi
    ;;
  esac

  # Copy gitpack itself if not already installed
  if [ ! -f "$bin_dir/gitpack" ]; then
    curl -fsSL "$gitpack_url/gitpack" -o "$bin_dir/gitpack"
    chmod +x "$bin_dir/gitpack"
  fi
}

parse_yml_field() {
  field="$1" file="$2"
  grep "^${field}:" "$file" |
    sed "s/^${field}:[[:space:]]*//" |
    sed 's/[[:space:]]*#.*//' |
    tr -d "\"'"
}

cmd_install() {
  ensure_gitpack_installed

  git_url="$1"
  if [ -z "$git_url" ]; then
    echo "Usage: gitpack install <git-url>"
    exit 1
  fi

  tmp_dir="$(mktemp -d)"

  echo "Cloning $git_url..."
  if ! git clone "$git_url" "$tmp_dir"; then
    rm -rf "$tmp_dir"
    echo "Error: Failed to clone repository."
    exit 1
  fi

  config_file="$tmp_dir/.gitpack.yml"
  if [ ! -f "$config_file" ]; then
    rm -rf "$tmp_dir"
    echo "Error: Not a valid gitpack package (missing .gitpack.yml)."
    exit 1
  fi

  app_name="$(parse_yml_field name "$config_file")"
  entrypoint="$(parse_yml_field entrypoint "$config_file")"
  setup="$(parse_yml_field setup "$config_file")"

  if [ -z "$app_name" ]; then
    rm -rf "$tmp_dir"
    echo "Error: .gitpack.yml is missing required field: name"
    exit 1
  fi

  if [ -z "$entrypoint" ]; then
    rm -rf "$tmp_dir"
    echo "Error: .gitpack.yml is missing required field: entrypoint"
    exit 1
  fi

  install_dir="$HOME/.local/share/gitpack/$app_name"
  if [ -d "$install_dir" ]; then
    rm -rf "$tmp_dir"
    echo "Error: '$app_name' is already installed. Use 'gitpack remove $app_name' first."
    exit 1
  fi

  mkdir -p "$(dirname "$install_dir")"
  mv "$tmp_dir" "$install_dir"

  # Write a launcher script that delegates to `gitpack run`
  launcher="$bin_dir/$app_name"
  printf '#!/bin/sh\nexec gitpack run %s "$@"\n' "$app_name" >"$launcher"
  chmod +x "$launcher"

  if [ -n "$setup" ]; then
    setup_path="$install_dir/$setup"
    if [ -f "$setup_path" ]; then
      echo "Running setup..."
      chmod +x "$setup_path"
      "$setup_path"
    else
      echo "Warning: setup script '$setup' not found in repository."
    fi
  fi

  echo ""
  echo "📦 $app_name installed successfully!"
}

cmd_remove() {
  app_name="$1"

  if [ -z "$app_name" ]; then
    echo "Usage: gitpack remove <app>"
    exit 1
  fi

  install_dir="$HOME/.local/share/gitpack/$app_name"
  if [ ! -d "$install_dir" ]; then
    echo "Error: '$app_name' is not installed."
    exit 1
  fi

  rm -rf "$install_dir"
  rm -f "$bin_dir/$app_name"
  echo "$app_name removed."
}

cmd_run() {
  app_name="$1"
  shift

  if [ -z "$app_name" ]; then
    echo "Usage: gitpack run <app>"
    exit 1
  fi

  install_dir="$HOME/.local/share/gitpack/$app_name"
  if [ ! -d "$install_dir" ]; then
    echo "Error: '$app_name' is not installed."
    exit 1
  fi

  config_file="$install_dir/.gitpack.yml"

  # Fetch remote and check if we're behind before attempting a merge
  git -C "$install_dir" fetch origin --quiet
  local_rev="$(git -C "$install_dir" rev-parse HEAD)"
  remote_rev="$(git -C "$install_dir" rev-parse @{u} 2>/dev/null)"

  if [ -n "$remote_rev" ] && [ "$local_rev" != "$remote_rev" ]; then
    echo "[📦 gitpack] Update for $app_name is available. Fetching..."
    echo ""

    if ! git -C "$install_dir" merge --ff-only --quiet; then
      echo "Warning: Could not fast-forward $app_name. Skipping update."
    fi

    setup="$(parse_yml_field setup "$config_file")"
    if [ -n "$setup" ]; then
      setup_path="$install_dir/$setup"
      if [ -f "$setup_path" ]; then
        chmod +x "$setup_path"
        "$setup_path"
      fi
    fi
  fi

  entrypoint="$(parse_yml_field entrypoint "$config_file")"

  if [ -z "$entrypoint" ]; then
    echo "Error: .gitpack.yml is missing required field: entrypoint"
    exit 1
  fi

  entrypoint_path="$install_dir/$entrypoint"
  if [ ! -f "$entrypoint_path" ]; then
    echo "Error: entrypoint '$entrypoint' not found in repository."
    exit 1
  fi

  chmod +x "$entrypoint_path"
  exec "$entrypoint_path" "$@"
}

cmd_update() {
  target="$bin_dir/gitpack"
  tmp="$(mktemp)"
  echo "Updating gitpack..."
  if curl -fsSL "$gitpack_url/gitpack" -o "$tmp"; then
    chmod +x "$tmp"
    mv "$tmp" "$target"
    echo "gitpack updated."
  else
    rm -f "$tmp"
    echo "Error: Failed to download update."
    exit 1
  fi
}

case "$1" in
help) cmd_help ;;
install) cmd_install "$2" ;;
remove) cmd_remove "$2" ;;
run) shift; cmd_run "$@" ;;
update) cmd_update ;;
*)
  echo "Unknown command: $1"
  echo "Run gitpack help for usage instructions"
  exit 1
  ;;
esac