defmodule ComponentsElixir.Inventory do
  @moduledoc """
  The Inventory context for managing components and categories.
  """

  import Ecto.Query, warn: false
  alias ComponentsElixir.Repo

  alias ComponentsElixir.Inventory.{Category, Component}

  ## Categories

  @doc """
  Returns the list of categories.
  """
  def list_categories do
    Category
    |> order_by([c], [asc: c.name])
    |> preload(:parent)
    |> Repo.all()
  end

  @doc """
  Returns the list of root categories (no parent).
  """
  def list_root_categories do
    Category
    |> where([c], is_nil(c.parent_id))
    |> order_by([c], [asc: c.name])
    |> Repo.all()
  end

  @doc """
  Returns the list of child categories for a given parent.
  """
  def list_child_categories(parent_id) do
    Category
    |> where([c], c.parent_id == ^parent_id)
    |> order_by([c], [asc: c.name])
    |> Repo.all()
  end

  @doc """
  Gets a single category.
  """
  def get_category!(id) do
    Category
    |> preload(:parent)
    |> Repo.get!(id)
  end

  @doc """
  Creates a category.
  """
  def create_category(attrs \\ %{}) do
    %Category{}
    |> Category.changeset(attrs)
    |> Repo.insert()
  end

  @doc """
  Updates a category.
  """
  def update_category(%Category{} = category, attrs) do
    category
    |> Category.changeset(attrs)
    |> Repo.update()
  end

  @doc """
  Deletes a category.
  """
  def delete_category(%Category{} = category) do
    Repo.delete(category)
  end

  @doc """
  Returns an `%Ecto.Changeset{}` for tracking category changes.
  """
  def change_category(%Category{} = category, attrs \\ %{}) do
    Category.changeset(category, attrs)
  end

  @doc """
  Returns the count of components in a specific category.
  """
  def count_components_in_category(category_id) do
    Component
    |> where([c], c.category_id == ^category_id)
    |> Repo.aggregate(:count, :id)
  end

  ## Components

  @doc """
  Returns the list of components with optional filtering and pagination.
  """
  def list_components(opts \\ []) do
    Component
    |> apply_component_filters(opts)
    |> preload(:category)
    |> order_by([c], [asc: c.category_id, asc: c.name])
    |> Repo.all()
  end

  @doc """
  Returns paginated components with search and filtering.
  """
  def paginate_components(opts \\ []) do
    limit = Keyword.get(opts, :limit, 20)
    offset = Keyword.get(opts, :offset, 0)

    query =
      Component
      |> apply_component_filters(opts)
      |> preload(:category)
      |> order_by([c], [asc: c.category_id, asc: c.name])

    components =
      query
      |> limit(^limit)
      |> offset(^offset)
      |> Repo.all()

    total_count = Repo.aggregate(query, :count, :id)

    %{
      components: components,
      total_count: total_count,
      has_more: total_count > offset + length(components)
    }
  end

  defp apply_component_filters(query, opts) do
    Enum.reduce(opts, query, fn
      {:search, search}, query when is_binary(search) and search != "" ->
        if String.length(search) > 3 do
          # Use full-text search for longer queries
          where(query, [c],
            fragment("to_tsvector('english', ? || ' ' || coalesce(?, '') || ' ' || coalesce(?, '')) @@ plainto_tsquery(?)",
              c.name, c.description, c.keywords, ^search))
        else
          # Use ILIKE for shorter queries
          search_term = "%#{search}%"
          where(query, [c],
            ilike(c.name, ^search_term) or
            ilike(c.description, ^search_term) or
            ilike(c.keywords, ^search_term))
        end

      {:category_id, category_id}, query when is_integer(category_id) ->
        where(query, [c], c.category_id == ^category_id)

      {:sort_criteria, "name"}, query ->
        order_by(query, [c], [asc: c.name])

      {:sort_criteria, "description"}, query ->
        order_by(query, [c], [asc: c.description])

      {:sort_criteria, "id"}, query ->
        order_by(query, [c], [asc: c.id])

      {:sort_criteria, "category_id"}, query ->
        order_by(query, [c], [asc: c.category_id, asc: c.name])

      _, query ->
        query
    end)
  end

  @doc """
  Gets a single component.
  """
  def get_component!(id) do
    Component
    |> preload(:category)
    |> Repo.get!(id)
  end

  @doc """
  Creates a component.
  """
  def create_component(attrs \\ %{}) do
    %Component{}
    |> Component.changeset(attrs)
    |> Repo.insert()
  end

  @doc """
  Updates a component.
  """
  def update_component(%Component{} = component, attrs) do
    component
    |> Component.changeset(attrs)
    |> Repo.update()
  end

  @doc """
  Updates a component's count.
  """
  def update_component_count(%Component{} = component, count) when is_integer(count) do
    component
    |> Component.count_changeset(%{count: count})
    |> Repo.update()
  end

  @doc """
  Increments a component's count.
  """
  def increment_component_count(%Component{} = component) do
    update_component_count(component, component.count + 1)
  end

  @doc """
  Decrements a component's count (minimum 0).
  """
  def decrement_component_count(%Component{} = component) do
    new_count = max(0, component.count - 1)
    update_component_count(component, new_count)
  end

  @doc """
  Updates a component's image filename.
  """
  def update_component_image(%Component{} = component, image_filename) do
    component
    |> Component.image_changeset(%{image_filename: image_filename})
    |> Repo.update()
  end

  @doc """
  Deletes a component.
  """
  def delete_component(%Component{} = component) do
    Repo.delete(component)
  end

  @doc """
  Returns an `%Ecto.Changeset{}` for tracking component changes.
  """
  def change_component(%Component{} = component, attrs \\ %{}) do
    Component.changeset(component, attrs)
  end

  @doc """
  Returns component statistics.
  """
  def component_stats do
    total_components = Repo.aggregate(Component, :count, :id)
    total_stock = Repo.aggregate(Component, :sum, :count) || 0
    categories_with_components =
      Component
      |> select([c], c.category_id)
      |> distinct(true)
      |> Repo.aggregate(:count, :category_id)

    %{
      total_components: total_components,
      total_stock: total_stock,
      categories_with_components: categories_with_components
    }
  end
end