mitgliederverwaltung/lib/mv_web/live/member_live/index.ex

defmodule MvWeb.MemberLive.Index do
  @moduledoc """
  LiveView for displaying and managing the member list.

  ## Features
  - Full-text search across member profiles using PostgreSQL tsvector
  - Sortable columns (name, email, address fields)
  - Bulk selection for future batch operations
  - Real-time updates via LiveView
  - Bookmarkable URLs with query parameters

  ## URL Parameters
  - `query` - Search query string for full-text search
  - `sort_field` - Field to sort by (e.g., :first_name, :email, :join_date)
  - `sort_order` - Sort direction (:asc or :desc)

  ## Events
  - `delete` - Remove a member from the database
  - `select_member` - Toggle individual member selection
  - `select_all` - Toggle selection of all visible members

  ## Implementation Notes
  - Search uses PostgreSQL full-text search (plainto_tsquery)
  - Sort state is synced with URL for bookmarkability
  - Components communicate via `handle_info` for decoupling
  """
  use MvWeb, :live_view
  import Ash.Expr
  import Ash.Query

  @doc """
  Initializes the LiveView state.

  Sets up initial assigns for page title, search query, sort configuration,
  and member selection. Actual data loading happens in `handle_params/3`.
  """
  @impl true
  def mount(_params, _session, socket) do
    socket =
      socket
      |> assign(:page_title, gettext("Members"))
      |> assign(:query, "")
      |> assign_new(:sort_field, fn -> :first_name end)
      |> assign_new(:sort_order, fn -> :asc end)
      |> assign(:selected_members, [])

    # We call handle params to use the query from the URL
    {:ok, socket}
  end

  # -----------------------------------------------------------------
  # Handle Events
  # -----------------------------------------------------------------

  @doc """
  Handles member-related UI events.

  ## Supported events:
  - `"delete"` - Removes a member from the database
  - `"select_member"` - Toggles individual member selection
  - `"select_all"` - Toggles selection of all visible members
  """
  @impl true
  def handle_event("delete", %{"id" => id}, socket) do
    member = Ash.get!(Mv.Membership.Member, id)
    Ash.destroy!(member)

    updated_members = Enum.reject(socket.assigns.members, &(&1.id == id))
    {:noreply, assign(socket, :members, updated_members)}
  end

  @impl true
  def handle_event("select_member", %{"id" => id}, socket) do
    selected =
      if id in socket.assigns.selected_members do
        List.delete(socket.assigns.selected_members, id)
      else
        [id | socket.assigns.selected_members]
      end

    {:noreply, assign(socket, :selected_members, selected)}
  end

  @impl true
  def handle_event("select_all", _params, socket) do
    members = socket.assigns.members

    all_ids = Enum.map(members, & &1.id)

    selected =
      if Enum.sort(socket.assigns.selected_members) == Enum.sort(all_ids) do
        []
      else
        all_ids
      end

    {:noreply, assign(socket, :selected_members, selected)}
  end

  # -----------------------------------------------------------------
  # Handle Infos from Child Components
  # -----------------------------------------------------------------

  @doc """
  Handles messages from child components.

  ## Supported messages:
  - `{:sort, field}` - Sort event from SortHeaderComponent. Updates sort field/order and syncs URL
  - `{:search_changed, query}` - Search event from SearchBarComponent. Filters members and syncs URL
  """
  @impl true
  def handle_info({:sort, field_str}, socket) do
    field = String.to_existing_atom(field_str)
    {new_field, new_order} = determine_new_sort(field, socket)

    socket
    |> update_sort_components(socket.assigns.sort_field, new_field, new_order)
    |> push_sort_url(new_field, new_order)
  end

  @impl true
  def handle_info({:search_changed, q}, socket) do
    socket = load_members(socket, q)

    existing_field_query = socket.assigns.sort_field
    existing_sort_query = socket.assigns.sort_order

    # Build the URL with queries
    query_params = %{
      "query" => q,
      "sort_field" => existing_field_query,
      "sort_order" => existing_sort_query
    }

    # Set the new path with params
    new_path = ~p"/members?#{query_params}"

    # Push the new URL
    {:noreply,
     push_patch(socket,
       to: new_path,
       replace: true
     )}
  end

  # -----------------------------------------------------------------
  # Handle Params from the URL
  # -----------------------------------------------------------------
  @doc """
  Handles URL parameter changes.

  Parses query parameters for search query, sort field, and sort order,
  then loads members accordingly. This enables bookmarkable URLs and
  browser back/forward navigation.
  """
  @impl true
  def handle_params(params, _url, socket) do
    socket =
      socket
      |> maybe_update_search(params)
      |> maybe_update_sort(params)
      |> load_members(params["query"])

    {:noreply, socket}
  end

  # -------------------------------------------------------------
  # FUNCTIONS
  # -------------------------------------------------------------

  # Determines new sort field and order based on current state
  defp determine_new_sort(field, socket) do
    if socket.assigns.sort_field == field do
      {field, toggle_order(socket.assigns.sort_order)}
    else
      {field, :asc}
    end
  end

  # Updates both the active and old SortHeader components
  defp update_sort_components(socket, old_field, new_field, new_order) do
    active_id = :"sort_#{new_field}"
    old_id = :"sort_#{old_field}"

    # Update the new SortHeader
    send_update(MvWeb.Components.SortHeaderComponent,
      id: active_id,
      sort_field: new_field,
      sort_order: new_order
    )

    # Reset the current SortHeader
    send_update(MvWeb.Components.SortHeaderComponent,
      id: old_id,
      sort_field: new_field,
      sort_order: new_order
    )

    socket
  end

  # Builds sort URL and pushes navigation patch
  defp push_sort_url(socket, field, order) do
    query_params = %{
      "query" => socket.assigns.query,
      "sort_field" => Atom.to_string(field),
      "sort_order" => Atom.to_string(order)
    }

    new_path = ~p"/members?#{query_params}"

    {:noreply,
     push_patch(socket,
       to: new_path,
       replace: true
     )}
  end

  # Load members eg based on a query for sorting
  defp load_members(socket, search_query) do
    query =
      Mv.Membership.Member
      |> Ash.Query.new()
      |> Ash.Query.select([
        :id,
        :first_name,
        :last_name,
        :email,
        :street,
        :house_number,
        :postal_code,
        :city,
        :phone_number,
        :join_date
      ])

    # Apply the search filter first
    query = apply_search_filter(query, search_query)

    # Apply sorting based on current socket state
    query = maybe_sort(query, socket.assigns.sort_field, socket.assigns.sort_order)

    members = Ash.read!(query)
    assign(socket, :members, members)
  end

  # -------------------------------------------------------------
  # Helper Functions
  # -------------------------------------------------------------

  # Function to apply search query
  defp apply_search_filter(query, search_query) do
    if search_query && String.trim(search_query) != "" do
      query
      |> filter(expr(fragment("search_vector @@ plainto_tsquery('simple', ?)", ^search_query)))
    else
      query
    end
  end

  # Functions to toggle sorting order
  defp toggle_order(:asc), do: :desc
  defp toggle_order(:desc), do: :asc
  defp toggle_order(nil), do: :asc

  # Function to sort the column if needed
  defp maybe_sort(query, nil, _), do: query

  defp maybe_sort(query, field, :asc) when not is_nil(field),
    do: Ash.Query.sort(query, [{field, :asc}])

  defp maybe_sort(query, field, :desc) when not is_nil(field),
    do: Ash.Query.sort(query, [{field, :desc}])

  defp maybe_sort(query, _, _), do: query

  # Validate that a field is sortable
  defp valid_sort_field?(field) when is_atom(field) do
    valid_fields = [
      :first_name,
      :last_name,
      :email,
      :street,
      :house_number,
      :postal_code,
      :city,
      :phone_number,
      :join_date
    ]

    field in valid_fields
  end

  defp valid_sort_field?(_), do: false

  # Function to maybe update the sort
  defp maybe_update_sort(socket, %{"sort_field" => sf, "sort_order" => so}) do
    field = determine_field(socket.assigns.sort_field, sf)
    order = determine_order(socket.assigns.sort_order, so)

    socket
    |> assign(:sort_field, field)
    |> assign(:sort_order, order)
  end

  defp maybe_update_sort(socket, _), do: socket

  defp determine_field(default, sf) do
    case sf do
      "" ->
        default

      nil ->
        default

      sf when is_binary(sf) ->
        sf
        |> String.to_existing_atom()
        |> handle_atom_conversion(default)

      sf when is_atom(sf) ->
        handle_atom_conversion(sf, default)

      _ ->
        default
    end
  end

  defp handle_atom_conversion(val, default) when is_atom(val) do
    if valid_sort_field?(val), do: val, else: default
  end

  defp handle_atom_conversion(_, default), do: default

  defp determine_order(default, so) do
    case so do
      "" -> default
      nil -> default
      so when so in ["asc", "desc"] -> String.to_atom(so)
      _ -> default
    end
  end

  # Function to update search parameters
  defp maybe_update_search(socket, %{"query" => query}) when query != "" do
    assign(socket, :query, query)
  end

  defp maybe_update_search(socket, _params) do
    # Keep the previous search query if no new one is provided
    socket
  end
end