defmodule PhoenixKit.Modules.Posts.PostComment do
  @moduledoc """
  Schema for post comments with unlimited threading depth.

  Supports nested comment threads (Reddit-style) with self-referencing parent/child
  relationships. Depth is automatically calculated based on parent chain.

  ## Comment Status

  - `published` - Comment is visible
  - `hidden` - Comment is hidden by moderator
  - `deleted` - Comment deleted (soft delete)
  - `pending` - Awaiting moderation approval

  ## Fields

  - `post_id` - Reference to the post
  - `user_id` - Reference to the commenter
  - `parent_id` - Reference to parent comment (nil for top-level)
  - `content` - Comment text
  - `status` - published/hidden/deleted/pending
  - `depth` - Nesting level (0=top, 1=reply, 2=reply-to-reply, etc.)
  - `like_count` - Denormalized counter (future feature)

  ## Examples

      # Top-level comment
      %PostComment{
        post_id: "018e3c4a-9f6b-7890-abcd-ef1234567890",
        user_id: 42,
        parent_id: nil,
        content: "Great post!",
        status: "published",
        depth: 0
      }

      # Reply to comment
      %PostComment{
        post_id: "018e3c4a-9f6b-7890-abcd-ef1234567890",
        user_id: 15,
        parent_id: "018e3c4a-1234-5678-abcd-ef1234567890",
        content: "Thanks!",
        status: "published",
        depth: 1
      }

      # Reply to reply
      %PostComment{
        post_id: "018e3c4a-9f6b-7890-abcd-ef1234567890",
        user_id: 99,
        parent_id: "018e3c4a-5678-1234-abcd-ef1234567890",
        content: "You're welcome!",
        status: "published",
        depth: 2
      }
  """
  use Ecto.Schema
  import Ecto.Changeset

  @primary_key {:id, UUIDv7, autogenerate: true}

  @type t :: %__MODULE__{
          id: UUIDv7.t() | nil,
          post_id: UUIDv7.t(),
          user_id: integer(),
          parent_id: UUIDv7.t() | nil,
          content: String.t(),
          status: String.t(),
          depth: integer(),
          like_count: integer(),
          post: PhoenixKit.Modules.Posts.Post.t() | Ecto.Association.NotLoaded.t(),
          user: PhoenixKit.Users.Auth.User.t() | Ecto.Association.NotLoaded.t(),
          parent: t() | Ecto.Association.NotLoaded.t() | nil,
          children: [t()] | Ecto.Association.NotLoaded.t(),
          inserted_at: NaiveDateTime.t() | nil,
          updated_at: NaiveDateTime.t() | nil
        }

  schema "phoenix_kit_post_comments" do
    field :content, :string
    field :status, :string, default: "published"
    field :depth, :integer, default: 0
    field :like_count, :integer, default: 0

    belongs_to :post, PhoenixKit.Modules.Posts.Post, type: UUIDv7
    belongs_to :user, PhoenixKit.Users.Auth.User, type: :integer
    belongs_to :parent, __MODULE__, type: UUIDv7

    has_many :children, __MODULE__, foreign_key: :parent_id

    timestamps(type: :naive_datetime)
  end

  @doc """
  Changeset for creating or updating a comment.

  ## Required Fields

  - `post_id` - Reference to post
  - `user_id` - Reference to commenter
  - `content` - Comment text

  ## Validation Rules

  - Content must not be empty
  - Status must be valid (published/hidden/deleted/pending)
  - Depth automatically calculated from parent
  """
  def changeset(comment, attrs) do
    comment
    |> cast(attrs, [:post_id, :user_id, :parent_id, :content, :status, :depth])
    |> validate_required([:post_id, :user_id, :content])
    |> validate_inclusion(:status, ["published", "hidden", "deleted", "pending"])
    |> validate_length(:content, min: 1, max: 10_000)
    |> foreign_key_constraint(:post_id)
    |> foreign_key_constraint(:user_id)
    |> foreign_key_constraint(:parent_id)
  end

  @doc """
  Check if comment is a reply (has parent).
  """
  def reply?(%__MODULE__{parent_id: nil}), do: false
  def reply?(%__MODULE__{}), do: true

  @doc """
  Check if comment is top-level (no parent).
  """
  def top_level?(%__MODULE__{parent_id: nil}), do: true
  def top_level?(%__MODULE__{}), do: false

  @doc """
  Check if comment is published.
  """
  def published?(%__MODULE__{status: "published"}), do: true
  def published?(_), do: false

  @doc """
  Check if comment is deleted.
  """
  def deleted?(%__MODULE__{status: "deleted"}), do: true
  def deleted?(_), do: false
end