defmodule JSONSchemaEditor do
  @moduledoc """
  A Phoenix LiveComponent for visually editing JSON Schemas.

  It provides a rich interface for creating and modifying JSON Schemas (Draft 07), supporting
  nested structures, arrays, validation constraints, logical composition (oneOf, anyOf, allOf),
  and conditional logic (if, then, else, not).

  The component also includes a "Test Lab" for live validation of sample data and a "JSON Preview"
  with syntax highlighting.

  ## Attributes

    * `id` (required) - A unique identifier for the component instance.
    * `schema` (required) - The initial JSON Schema map to edit. Defaults to a basic schema if empty.
    * `on_save` (optional) - A 1-arity callback function invoked when the user clicks "Save".
      It receives the current schema as a map.
    * `class` (optional) - Additional CSS classes to apply to the root container.

  ## Usage

      <.live_component
        module={JSONSchemaEditor}
        id="json-editor"
        schema={@my_schema}
        on_save={fn new_schema -> send(self(), {:save_schema, new_schema}) end}
        class="my-custom-theme"
      />
  """
  use Phoenix.LiveComponent

  alias JSONSchemaEditor.{
    SchemaUtils,
    Validator,
    Components,
    SchemaGenerator,
    SimpleValidator,
    UIState,
    SchemaMutator
  }

  @types ~w(string number integer boolean object array null)

  @logic_types ~w(anyOf oneOf allOf)

  @formats ~w(email date-time date time uri uuid ipv4 ipv6 hostname)

  def update(assigns, socket) do
    known_keys = [
      :id,
      :schema,
      :on_save,
      :ui_state,
      :active_tab,
      :myself,
      :class,
      :show_import_modal,
      :import_error,
      :import_mode,
      :test_data_str,
      :test_errors
    ]

    {known_assigns, rest} = Map.split(assigns, known_keys)

    socket =
      socket
      |> assign(known_assigns)
      |> assign(:rest, Map.merge(Map.get(socket.assigns, :rest, %{}), rest))
      |> assign_new(:class, fn -> nil end)
      |> assign_new(:ui_state, fn -> %{} end)
      |> assign_new(:schema, fn -> %{} end)
      |> update(:schema, &Map.put_new(&1, "$schema", "https://json-schema.org/draft-07/schema"))
      |> assign(types: @types, formats: @formats, logic_types: @logic_types)
      |> assign_new(:active_tab, fn -> :editor end)
      |> assign_new(:show_import_modal, fn -> false end)
      |> assign_new(:import_error, fn -> nil end)
      |> assign_new(:import_mode, fn -> :schema end)
      |> assign_new(:history, fn -> [] end)
      |> assign_new(:future, fn -> [] end)
      |> assign_new(:test_data_str, fn -> "{\n  \"example\": \"value\"\n}" end)
      |> assign_new(:test_errors, fn -> [] end)
      |> validate_and_assign_errors()

    {:ok, socket}
  end

  defp validate_and_assign_errors(socket) do
    schema_errors = Validator.validate_schema(socket.assigns.schema)
    socket = assign(socket, :validation_errors, schema_errors)
    validate_test_data(socket)
  end

  defp validate_test_data(socket) do
    case JSON.decode(socket.assigns.test_data_str) do
      {:ok, data} ->
        errors = SimpleValidator.validate(socket.assigns.schema, data)
        status = if errors == [], do: :ok, else: errors
        assign(socket, :test_errors, status)

      {:error, _} ->
        assign(socket, :test_errors, ["Invalid JSON Syntax"])
    end
  end

  defp push_history(socket) do
    socket
    |> update(:history, fn h -> [socket.assigns.schema | Enum.take(h, 49)] end)
    |> assign(:future, [])
  end

  def handle_event("update_test_data", %{"value" => value}, socket) do
    {:noreply,
     socket
     |> assign(:test_data_str, value)
     |> validate_test_data()}
  end

  def handle_event("undo", _, socket) do
    case socket.assigns.history do
      [previous | rest] ->
        socket =
          socket
          |> update(:future, fn f -> [socket.assigns.schema | f] end)
          |> assign(:history, rest)
          |> assign(:schema, previous)
          |> validate_and_assign_errors()

        {:noreply, socket}

      [] ->
        {:noreply, socket}
    end
  end

  def handle_event("redo", _, socket) do
    case socket.assigns.future do
      [next | rest] ->
        socket =
          socket
          |> update(:history, fn h -> [socket.assigns.schema | h] end)
          |> assign(:future, rest)
          |> assign(:schema, next)
          |> validate_and_assign_errors()

        {:noreply, socket}

      [] ->
        {:noreply, socket}
    end
  end

  def handle_event("switch_tab", %{"tab" => tab}, socket),
    do: {:noreply, assign(socket, :active_tab, String.to_existing_atom(tab))}

  def handle_event("open_import_modal", _, socket),
    do: {:noreply, assign(socket, :show_import_modal, true) |> assign(:import_mode, :schema)}

  def handle_event("close_import_modal", _, socket),
    do: {:noreply, assign(socket, :show_import_modal, false) |> assign(:import_error, nil)}

  def handle_event("set_import_mode", %{"mode" => mode}, socket),
    do: {:noreply, assign(socket, :import_mode, String.to_existing_atom(mode))}

  def handle_event("import_schema", %{"schema_text" => text}, socket) do
    case JSON.decode(text) do
      {:ok, data} ->
        schema =
          if socket.assigns.import_mode == :json do
            SchemaGenerator.generate(data)
          else
            data
          end

        if is_map(schema) do
          socket =
            socket
            |> push_history()
            |> assign(:schema, schema)
            |> assign(:show_import_modal, false)
            |> assign(:import_error, nil)
            |> validate_and_assign_errors()

          {:noreply, socket}
        else
          {:noreply, assign(socket, :import_error, "Invalid schema: Must be a JSON object")}
        end

      {:error, _} ->
        {:noreply, assign(socket, :import_error, "Invalid JSON")}
    end
  end

  def handle_event("save", _, socket) do
    if Enum.empty?(socket.assigns.validation_errors) and socket.assigns[:on_save],
      do: socket.assigns.on_save.(socket.assigns.schema)

    {:noreply, socket}
  end

  # --- Complex Mutations (involve UI State or special logic) ---

  def handle_event("add_property", %{"path" => path}, socket) do
    {:ok, path_list} = JSON.decode(path)

    current_props =
      SchemaUtils.get_in_path(socket.assigns.schema, path_list) |> Map.get("properties", %{})

    {new_schema, new_key} = SchemaMutator.add_property(socket.assigns.schema, path)

    {:noreply,
     socket
     |> push_history()
     |> assign(:schema, new_schema)
     |> update(:ui_state, &UIState.add_property(&1, path, current_props, new_key))
     |> validate_and_assign_errors()}
  end

  def handle_event("delete_property", %{"path" => path, "key" => key}, socket) do
    {:noreply,
     socket
     |> push_history()
     |> assign(:schema, SchemaMutator.delete_property(socket.assigns.schema, path, key))
     |> update(:ui_state, &UIState.remove_property(&1, path, key))
     |> validate_and_assign_errors()}
  end

  def handle_event("rename_property", %{"path" => path, "old_key" => old, "value" => new}, socket) do
    case SchemaMutator.rename_property(socket.assigns.schema, path, old, new) do
      {:ok, new_schema} ->
        {:ok, path_list} = JSON.decode(path)

        current_props =
          SchemaUtils.get_in_path(socket.assigns.schema, path_list) |> Map.get("properties", %{})

        {:noreply,
         socket
         |> push_history()
         |> assign(:schema, new_schema)
         |> update(
           :ui_state,
           &UIState.rename_property(&1, path, current_props, old, String.trim(new))
         )
         |> validate_and_assign_errors()}

      _ ->
        {:noreply, socket}
    end
  end

  def handle_event("toggle_ui", %{"path" => p, "type" => t}, socket),
    do: {:noreply, update(socket, :ui_state, &Map.update(&1, "#{t}:#{p}", true, fn v -> !v end))}

  # --- Simple Mutations (Schema update only) ---

  def handle_event(event, params, socket) do
    case get_mutation(event, params) do
      {func, args} ->
        {:noreply,
         socket
         |> push_history()
         |> assign(:schema, apply(SchemaMutator, func, [socket.assigns.schema | args]))
         |> validate_and_assign_errors()}

      nil ->
        {:noreply, socket}
    end
  end

  defp get_mutation("change_type", %{"path" => p, "type" => t}), do: {:change_type, [p, t]}
  defp get_mutation("toggle_required", %{"path" => p, "key" => k}), do: {:toggle_required, [p, k]}

  defp get_mutation("set_default_schema", _),
    do: {:update_field, ["[]", "$schema", "https://json-schema.org/draft-07/schema"]}

  defp get_mutation("change_schema", %{"value" => v}), do: {:update_field, ["[]", "$schema", v]}

  defp get_mutation("change_format", %{"path" => p, "value" => v}),
    do: {:update_field, [p, "format", v]}

  defp get_mutation("change_title", %{"path" => p, "value" => v}),
    do: {:update_field, [p, "title", String.trim(v)]}

  defp get_mutation("change_description", %{"path" => p, "value" => v}),
    do: {:update_field, [p, "description", String.trim(v)]}

  defp get_mutation("update_constraint", %{"path" => p, "field" => f, "value" => v}),
    do: {:update_constraint, [p, f, v]}

  defp get_mutation("update_const", %{"path" => p, "value" => v}), do: {:update_const, [p, v]}

  defp get_mutation("toggle_additional_properties", %{"path" => p}),
    do: {:toggle_additional_properties, [p]}

  defp get_mutation("add_enum_value", %{"path" => p}), do: {:add_enum_value, [p]}

  defp get_mutation("remove_enum_value", %{"path" => p, "index" => i}),
    do: {:remove_enum_value, [p, i]}

  defp get_mutation("update_enum_value", %{"path" => p, "index" => i, "value" => v}),
    do: {:update_enum_value, [p, i, v]}

  defp get_mutation("add_logic_branch", %{"path" => p, "type" => t}),
    do: {:add_logic_branch, [p, t]}

  defp get_mutation("remove_logic_branch", %{"path" => p, "type" => t, "index" => i}),
    do: {:remove_logic_branch, [p, t, i]}

  defp get_mutation("add_child", %{"path" => p, "key" => k}), do: {:add_child, [p, k]}
  defp get_mutation("remove_child", %{"path" => p, "key" => k}), do: {:remove_child, [p, k]}
  defp get_mutation(_, _), do: nil

  def render(assigns) do
    ~H"""
    <div id={@id} class={["jse-host", @class]} {@rest}>
      <div class="jse-container">
        <div class="jse-header">
          <div class="jse-tabs">
            <button
              class={["jse-tab-btn", @active_tab == :editor && "active"]}
              phx-click="switch_tab"
              phx-value-tab="editor"
              phx-target={@myself}
            >
              Visual Editor
            </button>
            <button
              class={["jse-tab-btn", @active_tab == :preview && "active"]}
              phx-click="switch_tab"
              phx-value-tab="preview"
              phx-target={@myself}
            >
              JSON Preview
            </button>
            <button
              class={["jse-tab-btn", @active_tab == :test && "active"]}
              phx-click="switch_tab"
              phx-value-tab="test"
              phx-target={@myself}
            >
              Test Lab
            </button>
          </div>
          <div class="jse-schema-selector">
            <label for={"#{@id}-schema-uri"}>$schema</label>
            <div class="jse-input-group">
              <input
                type="text"
                id={"#{@id}-schema-uri"}
                value={Map.get(@schema, "$schema")}
                phx-blur="change_schema"
                phx-target={@myself}
                placeholder="Schema URI..."
              />
              <%= if Map.get(@schema, "$schema") in [nil, ""] do %>
                <button
                  class="jse-btn jse-btn-xs jse-btn-secondary jse-default-schema-btn"
                  phx-click="set_default_schema"
                  phx-target={@myself}
                  title="Set default schema"
                >
                  Default
                </button>
              <% end %>
            </div>
          </div>
          <div class="jse-actions">
            <button
              class="jse-btn jse-btn-icon"
              phx-click="undo"
              phx-target={@myself}
              disabled={Enum.empty?(@history)}
              title="Undo"
            >
              <Components.icon name={:undo} />
            </button>
            <button
              class="jse-btn jse-btn-icon"
              phx-click="redo"
              phx-target={@myself}
              disabled={Enum.empty?(@future)}
              title="Redo"
            >
              <Components.icon name={:redo} />
            </button>
            <button
              class="jse-btn jse-btn-secondary"
              phx-click="open_import_modal"
              phx-target={@myself}
            >
              <span>Import</span> <Components.icon name={:import} />
            </button>
            <button
              class="jse-btn jse-btn-primary"
              phx-click="save"
              phx-target={@myself}
              disabled={not Enum.empty?(@validation_errors)}
            >
              <span>Save</span> <Components.icon name={:save} />
            </button>
          </div>
        </div>
        <div class="jse-content-area">
          <%= if @active_tab == :editor do %>
            <div class="jse-editor-pane">
              <Components.render_node
                node={@schema}
                path={[]}
                ui_state={@ui_state}
                validation_errors={@validation_errors}
                types={@types}
                logic_types={@logic_types}
                formats={@formats}
                myself={@myself}
              />
            </div>
          <% end %>
          <%= if @active_tab == :preview do %>
            <div class="jse-preview-panel">
              <div class="jse-preview-header">
                <span>Current Schema</span>
                <button
                  class="jse-btn-copy"
                  id={"#{@id}-copy-btn"}
                  phx-hook="JSONSchemaEditorClipboard"
                  data-content={JSON.encode!(@schema)}
                >
                  <span>Copy to Clipboard</span>
                </button>
              </div>
              <div class="jse-preview-content">
                <JSONSchemaEditor.Viewer.render json={@schema} />
              </div>
            </div>
          <% end %>
          <%= if @active_tab == :test do %>
            <div class="jse-test-lab">
              <div class="jse-test-input-section">
                <div class="jse-preview-header">
                  <span>Sample JSON Data</span>
                </div>
                <textarea
                  class="jse-test-textarea"
                  phx-keyup="update_test_data"
                  phx-target={@myself}
                  spellcheck="false"
                >{@test_data_str}</textarea>
              </div>
              <div class="jse-test-results">
                <div class="jse-preview-header">
                  <span>Validation Results</span>
                  <%= if @test_errors == :ok do %>
                    <Components.badge class="jse-badge-success">Valid</Components.badge>
                  <% else %>
                    <Components.badge class="jse-badge-error">Invalid</Components.badge>
                  <% end %>
                </div>
                <div class="jse-test-output">
                  <%= if @test_errors == :ok do %>
                    <div class="jse-test-success-message">
                      <Components.icon name={:check} class="jse-icon-lg" />
                      <span>Data matches the schema!</span>
                    </div>
                  <% else %>
                    <div class="jse-error-list">
                      <%= for error <- @test_errors do %>
                        <div class="jse-error-item">
                          <%= if is_binary(error) do %>
                            {error}
                          <% else %>
                            <span class="jse-error-path">{elem(error, 1)}</span>
                            <span class="jse-error-desc">{elem(error, 0)}</span>
                          <% end %>
                        </div>
                      <% end %>
                    </div>
                  <% end %>
                </div>
              </div>
            </div>
          <% end %>
        </div>
      </div>

      <%= if @show_import_modal do %>
        <div class="jse-modal-overlay">
          <div class="jse-modal">
            <div class="jse-modal-header">
              <div class="jse-tabs">
                <button
                  type="button"
                  class={["jse-tab-btn", @import_mode == :schema && "active"]}
                  phx-click="set_import_mode"
                  phx-value-mode="schema"
                  phx-target={@myself}
                >
                  Import Schema
                </button>
                <button
                  type="button"
                  class={["jse-tab-btn", @import_mode == :json && "active"]}
                  phx-click="set_import_mode"
                  phx-value-mode="json"
                  phx-target={@myself}
                >
                  Generate from JSON
                </button>
              </div>
              <button class="jse-btn-icon" phx-click="close_import_modal" phx-target={@myself}>
                <Components.icon name={:close} class="jse-icon-sm" />
              </button>
            </div>
            <form phx-submit="import_schema" phx-target={@myself}>
              <div class="jse-modal-body">
                <%= if @import_error do %>
                  <div class="jse-modal-error">{@import_error}</div>
                <% end %>
                <textarea
                  name="schema_text"
                  class="jse-modal-textarea"
                  placeholder={
                    if @import_mode == :schema,
                      do: "Paste your JSON Schema here...",
                      else: "Paste a JSON object to generate a schema..."
                  }
                  autofocus
                ></textarea>
              </div>
              <div class="jse-modal-footer">
                <button
                  type="button"
                  class="jse-btn jse-btn-secondary"
                  phx-click="close_import_modal"
                  phx-target={@myself}
                >
                  Cancel
                </button>
                <button type="submit" class="jse-btn jse-btn-primary">
                  {if @import_mode == :schema, do: "Import", else: "Generate"}
                </button>
              </div>
            </form>
          </div>
        </div>
      <% end %>
    </div>
    """
  end
end