defmodule PhiaUi.Components.Dialog do
  @moduledoc """
  Accessible Dialog (Modal) component following the WAI-ARIA Dialog pattern.

  Uses `Phoenix.LiveView.JS` for open/close transitions and the `PhiaDialog`
  JavaScript Hook for focus trap, keyboard navigation, and scroll locking.

  ## Registration in app.js

  After running `mix phia.add dialog`, register the hook in your LiveSocket:

      import PhiaDialog from "./phia_hooks/dialog.js"

      let liveSocket = new LiveSocket("/live", Socket, {
        hooks: { PhiaDialog, ...yourOtherHooks }
      })

  ## Example

      <.dialog id="confirm-delete">
        <.dialog_trigger for="confirm-delete">
          <.button variant={:destructive}>Delete</.button>
        </.dialog_trigger>

        <.dialog_content id="confirm-delete">
          <.dialog_header>
            <.dialog_title id="confirm-delete-title">Delete Item</.dialog_title>
            <.dialog_description id="confirm-delete-description">
              This action cannot be undone.
            </.dialog_description>
          </.dialog_header>
          <.dialog_footer>
            <.dialog_close for="confirm-delete">Cancel</.dialog_close>
            <.button variant={:destructive} phx-click="delete">Delete</.button>
          </.dialog_footer>
        </.dialog_content>
      </.dialog>

  ## Sub-components

  | Function              | Purpose                                      |
  |-----------------------|----------------------------------------------|
  | `dialog/1`            | Hook anchor, outer container                 |
  | `dialog_trigger/1`    | Opens the dialog via JS.remove_class         |
  | `dialog_content/1`    | Overlay + panel (hidden by default)          |
  | `dialog_header/1`     | Title + description layout container         |
  | `dialog_title/1`      | `<h2>` heading (set id for ARIA linkage)     |
  | `dialog_description/1`| `<p>` supporting text (set id for ARIA)      |
  | `dialog_footer/1`     | Action row (close button, confirmations)     |
  | `dialog_close/1`      | Closes the dialog via JS.add_class           |
  """

  use Phoenix.Component

  import PhiaUi.ClassMerger, only: [cn: 1]

  alias Phoenix.LiveView.JS

  # ---------------------------------------------------------------------------
  # dialog/1
  # ---------------------------------------------------------------------------

  @doc """
  Outer container for the Dialog. Binds the `PhiaDialog` JavaScript Hook.

  Must wrap both `dialog_trigger/1` and `dialog_content/1`.
  """
  attr(:id, :string, required: true, doc: "Unique ID used as the hook anchor")
  attr(:class, :string, default: nil, doc: "Additional CSS classes")
  slot(:inner_block, required: true)

  def dialog(assigns) do
    ~H"""
    <div id={@id} phx-hook="PhiaDialog" class={cn(["relative", @class])}>
      <%= render_slot(@inner_block) %>
    </div>
    """
  end

  # ---------------------------------------------------------------------------
  # dialog_trigger/1
  # ---------------------------------------------------------------------------

  @doc """
  Opens the dialog by calling `JS.remove_class("hidden")` on `#dialog-{for}`.
  """
  attr(:for, :string, required: true, doc: "ID of the dialog to open (matches dialog/1's :id)")
  attr(:class, :string, default: nil)
  attr(:rest, :global)
  slot(:inner_block, required: true)

  def dialog_trigger(assigns) do
    ~H"""
    <div
      phx-click={
        JS.remove_class("hidden", to: "#dialog-#{@for}")
        |> JS.add_class("opacity-100 scale-100", to: "#dialog-#{@for} [data-dialog-panel]")
      }
      class={cn(["cursor-pointer inline-block", @class])}
      {@rest}
    >
      <%= render_slot(@inner_block) %>
    </div>
    """
  end

  # ---------------------------------------------------------------------------
  # dialog_content/1
  # ---------------------------------------------------------------------------

  @doc """
  The dialog surface: renders the overlay backdrop and the modal panel.

  Hidden by default. Shown by `dialog_trigger/1` via `JS.remove_class("hidden")`.

  The outer container id is `"dialog-{id}"` (prefixed) so that
  `dialog_trigger/1` and `dialog_close/1` can target it.

  ## Size variants

  | Value       | Max width                  |
  |-------------|----------------------------|
  | `"sm"`      | `max-w-sm`                 |
  | `"default"` | `max-w-lg` (default)       |
  | `"lg"`      | `max-w-2xl`                |
  | `"xl"`      | `max-w-4xl`                |
  | `"full"`    | `max-w-[calc(100vw-2rem)]` |
  """
  attr(:id, :string, required: true, doc: "ID matching the parent dialog/1's :id")

  attr(:size, :string,
    default: "default",
    values: ~w(sm default lg xl full),
    doc: "Width of the dialog panel"
  )

  attr(:show_close_button, :boolean,
    default: true,
    doc: "Render the default X close button in the top-right corner of the panel"
  )

  attr(:scrollable, :boolean,
    default: false,
    doc: "Add overflow-y-auto to the panel for content that may overflow the viewport"
  )

  attr(:full_screen_mobile, :boolean,
    default: false,
    doc: """
    When `true`, the dialog panel fills the entire screen on mobile viewports
    (`fixed inset-0 rounded-none`) and reverts to its normal centered behavior
    on `sm:` and wider screens (`sm:relative sm:inset-auto sm:rounded-lg`).
    Ideal for complex forms or content that benefits from full viewport space
    on small devices.
    """
  )

  attr(:class, :string, default: nil, doc: "Additional classes for the panel")
  slot(:inner_block, required: true)

  def dialog_content(assigns) do
    ~H"""
    <div id={"dialog-#{@id}"} class="fixed inset-0 z-50 hidden" data-dialog-content>
      <%!-- Overlay — fade-in via backdrop-blur and bg --%>
      <div
        class="fixed inset-0 z-50 bg-black/80 backdrop-blur-sm"
        data-dialog-overlay
        aria-hidden="true"
      ></div>
      <%!-- Panel — scale-in transition from opacity-0 scale-95 to opacity-100 scale-100 --%>
      <div
        role="dialog"
        aria-modal="true"
        aria-labelledby={"#{@id}-title"}
        aria-describedby={"#{@id}-description"}
        class={cn([
          "fixed left-[50%] top-[50%] z-50 grid w-full translate-x-[-50%] translate-y-[-50%]",
          "gap-4 border bg-background p-6 shadow-lg sm:rounded-lg",
          "transition-all ease-out duration-300 opacity-0 scale-95",
          dialog_content_size(@size),
          @scrollable && "overflow-y-auto max-h-[calc(100vh-8rem)]",
          @full_screen_mobile &&
            "max-sm:inset-0 max-sm:rounded-none max-sm:translate-x-0 max-sm:translate-y-0 max-sm:left-0 max-sm:top-0 max-sm:max-w-none max-sm:h-full",
          @class
        ])}
        data-dialog-panel
      >
        <%= if @show_close_button do %>
          <button
            type="button"
            aria-label="Close dialog"
            phx-click={
              JS.remove_class("opacity-100 scale-100", to: "#dialog-#{@id} [data-dialog-panel]")
              |> JS.add_class("opacity-0 scale-95", to: "#dialog-#{@id} [data-dialog-panel]")
              |> JS.add_class("hidden", to: "#dialog-#{@id}")
            }
            class="absolute right-4 top-4 inline-flex h-9 w-9 items-center justify-center rounded-sm opacity-70 ring-offset-background transition-opacity hover:opacity-100 focus:outline-none focus:ring-2 focus:ring-ring focus:ring-offset-2"
          >
            <svg
              class="h-4 w-4"
              viewBox="0 0 24 24"
              fill="none"
              stroke="currentColor"
              stroke-width="2"
              stroke-linecap="round"
              stroke-linejoin="round"
              aria-hidden="true"
            >
              <path d="M18 6 6 18M6 6l12 12" />
            </svg>
            <span class="sr-only">Close</span>
          </button>
        <% end %>
        <%= render_slot(@inner_block) %>
      </div>
    </div>
    """
  end

  # ---------------------------------------------------------------------------
  # dialog_header/1
  # ---------------------------------------------------------------------------

  @doc """
  Layout container for the dialog title and description.

  Renders a `<div>` with `flex flex-col space-y-1.5 text-center sm:text-left`.
  On mobile viewports the content is centred; on `sm` and wider it aligns
  to the left, matching the standard modal convention for each form factor.

  Wrap `dialog_title/1` and `dialog_description/1` inside this component.
  Both must have their `:id` set (to `"{dialog-id}-title"` and
  `"{dialog-id}-description"`) so the panel's `aria-labelledby` and
  `aria-describedby` attributes resolve correctly.

  ## Example

      <.dialog_header>
        <.dialog_title id="confirm-delete-title">
          Delete project?
        </.dialog_title>
        <.dialog_description id="confirm-delete-description">
          All data will be permanently removed. This cannot be undone.
        </.dialog_description>
      </.dialog_header>
  """
  attr(:class, :string, default: nil)
  attr(:rest, :global)
  slot(:inner_block, required: true)

  def dialog_header(assigns) do
    ~H"""
    <div class={cn(["flex flex-col space-y-1.5 text-center sm:text-left", @class])} {@rest}>
      <%= render_slot(@inner_block) %>
    </div>
    """
  end

  # ---------------------------------------------------------------------------
  # dialog_title/1
  # ---------------------------------------------------------------------------

  @doc """
  Dialog heading (`<h2>`). Set `:id` to `"{dialog-id}-title"` for ARIA linkage.
  """
  attr(:id, :string, default: nil)
  attr(:class, :string, default: nil)
  attr(:rest, :global)
  slot(:inner_block, required: true)

  def dialog_title(assigns) do
    ~H"""
    <h2
      id={@id}
      class={cn(["text-lg font-semibold leading-none tracking-tight", @class])}
      {@rest}
    >
      <%= render_slot(@inner_block) %>
    </h2>
    """
  end

  # ---------------------------------------------------------------------------
  # dialog_description/1
  # ---------------------------------------------------------------------------

  @doc """
  Supporting text below the title. Set `:id` to `"{dialog-id}-description"` for ARIA linkage.
  """
  attr(:id, :string, default: nil)
  attr(:class, :string, default: nil)
  attr(:rest, :global)
  slot(:inner_block, required: true)

  def dialog_description(assigns) do
    ~H"""
    <p id={@id} class={cn(["text-sm text-muted-foreground", @class])} {@rest}>
      <%= render_slot(@inner_block) %>
    </p>
    """
  end

  # ---------------------------------------------------------------------------
  # dialog_footer/1
  # ---------------------------------------------------------------------------

  @doc """
  Action row at the bottom of the dialog for confirmation and close buttons.

  Renders a `<div>` with `flex flex-col-reverse sm:flex-row sm:justify-end sm:space-x-2`.

  **Responsive stacking behaviour:**
  - On mobile (`< sm`): buttons stack vertically in reverse DOM order, so
    the primary action (last in the template) appears visually at the top —
    thumb-friendly and consistent with mobile modal conventions.
  - On `sm`+ screens: buttons arrange horizontally, aligned to the right,
    with `space-x-2` (8px) gaps.

  Place the cancel/close action first in the template and the primary
  (submit/confirm) action last. The CSS reversal puts the primary action
  at the top on mobile automatically:

  ## Example

      <.dialog_footer>
        <%!-- Cancel appears second on desktop, first (top) on mobile --%>
        <.dialog_close for="confirm-delete">Cancel</.dialog_close>
        <%!-- Primary action appears first on desktop (rightmost), top on mobile --%>
        <.button variant={:destructive} phx-click="delete_item">
          Delete
        </.button>
      </.dialog_footer>
  """
  attr(:class, :string, default: nil)
  attr(:rest, :global)
  slot(:inner_block, required: true)

  def dialog_footer(assigns) do
    ~H"""
    <div
      class={cn(["flex flex-col-reverse sm:flex-row sm:justify-end sm:space-x-2", @class])}
      {@rest}
    >
      <%= render_slot(@inner_block) %>
    </div>
    """
  end

  # ---------------------------------------------------------------------------
  # dialog_close/1
  # ---------------------------------------------------------------------------

  @doc """
  Closes the dialog via `JS.add_class("hidden")` on `#dialog-{for}`.
  The Escape key is also handled by the `PhiaDialog` JS Hook.
  """
  attr(:for, :string, required: true, doc: "ID of the dialog to close (matches dialog/1's :id)")
  attr(:class, :string, default: nil)
  attr(:rest, :global)
  slot(:inner_block, required: true)

  def dialog_close(assigns) do
    ~H"""
    <button
      type="button"
      phx-click={
        JS.remove_class("opacity-100 scale-100", to: "#dialog-#{@for} [data-dialog-panel]")
        |> JS.add_class("opacity-0 scale-95", to: "#dialog-#{@for} [data-dialog-panel]")
        |> JS.add_class("hidden", to: "#dialog-#{@for}")
      }
      class={cn([
        "inline-flex items-center justify-center rounded-md text-sm font-medium",
        "ring-offset-background transition-colors focus-visible:outline-none",
        "focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2",
        @class
      ])}
      {@rest}
    >
      <%= render_slot(@inner_block) %>
    </button>
    """
  end

  # ---------------------------------------------------------------------------
  # Private helpers
  # ---------------------------------------------------------------------------

  defp dialog_content_size("sm"), do: "max-w-sm"
  defp dialog_content_size("default"), do: "max-w-lg"
  defp dialog_content_size("lg"), do: "max-w-2xl"
  defp dialog_content_size("xl"), do: "max-w-4xl"
  defp dialog_content_size("full"), do: "max-w-[calc(100vw-2rem)]"
end