defmodule Mv.Membership.CustomField do
  @moduledoc """
  Ash resource defining the schema for custom member fields.

  ## Overview
  CustomFields define the "schema" for custom fields in the membership system.
  Each CustomField specifies the name, data type, and behavior of a custom field
  that can be attached to members via CustomFieldValue resources.

  ## Attributes
  - `name` - Unique identifier for the custom field (e.g., "phone_mobile", "birthday")
  - `value_type` - Data type constraint (`:string`, `:integer`, `:boolean`, `:date`, `:email`)
  - `description` - Optional human-readable description
  - `immutable` - If true, custom field values cannot be changed after creation
  - `required` - If true, all members must have this custom field (future feature)

  ## Supported Value Types
  - `:string` - Text data (unlimited length)
  - `:integer` - Numeric data (64-bit integers)
  - `:boolean` - True/false flags
  - `:date` - Date values (no time component)
  - `:email` - Validated email addresses

  ## Relationships
  - `has_many :custom_field_values` - All custom field values of this type

  ## Constraints
  - Name must be unique across all custom fields
  - Cannot delete a custom field that has existing custom field values (RESTRICT)

  ## Examples
      # Create a new custom field
      CustomField.create!(%{
        name: "phone_mobile",
        value_type: :string,
        description: "Mobile phone number"
      })

      # Create a required custom field
      CustomField.create!(%{
        name: "emergency_contact",
        value_type: :string,
        required: true
      })
  """
  use Ash.Resource,
    domain: Mv.Membership,
    data_layer: AshPostgres.DataLayer

  postgres do
    table "custom_fields"
    repo Mv.Repo
  end

  actions do
    defaults [:create, :read, :update, :destroy]
    default_accept [:name, :value_type, :description, :immutable, :required]
  end

  attributes do
    uuid_primary_key :id

    attribute :name, :string, allow_nil?: false, public?: true

    attribute :value_type, :atom,
      constraints: [one_of: [:string, :integer, :boolean, :date, :email]],
      allow_nil?: false,
      description: "Defines the datatype `CustomFieldValue.value` is interpreted as"

    attribute :description, :string, allow_nil?: true, public?: true

    attribute :immutable, :boolean,
      default: false,
      allow_nil?: false

    attribute :required, :boolean,
      default: false,
      allow_nil?: false
  end

  relationships do
    has_many :custom_field_values, Mv.Membership.CustomFieldValue
  end

  identities do
    identity :unique_name, [:name]
  end
end