defmodule DaProductApp.Transactions.ReqPay do
  @moduledoc """
  ReqPay aggregate for UPI payment requests.

  Stores normalized data from ReqPay/RespPay with payment transaction information.
  Handles both domestic and international payment requests.
  """
  use Ecto.Schema
  import Ecto.Changeset

  alias DaProductApp.Transactions.{Transaction, TransactionEvent}
  alias DaProductApp.Partners.{Partner, Merchant}

  schema "req_pays" do
    # Core UPI fields for payment request
    field :txn_id, :string
    field :msg_id, :string
    field :org_id, :string
    field :ref_id, :string              # Reference ID for the payment
    field :ref_url, :string             # Reference URL if any
    field :payer_addr, :string
    field :payee_addr, :string
    field :payer_name, :string
    field :payee_name, :string
    field :network_inst_id, :string
    field :payment_type, :string        # "QR", "INTENT", "COLLECT"
    field :payment_purpose, :string     # Purpose of payment

    # Amount fields
    field :amount, :decimal
    field :currency, :string

    # Response fields
    field :response_code, :string
    field :response_message, :string
    field :payment_status, :string      # PENDING, SUCCESS, FAILURE, EXPIRED
    field :settlement_status, :string   # SETTLED, PENDING, FAILED
    field :npci_txn_id, :string         # NPCI generated transaction ID
    field :rrn, :string                 # Retrieval Reference Number

    # International fields
    field :corridor, :string            # "SINGAPORE", "UAE", "USA"
    field :partner_txn_id, :string      # Partner's transaction reference
    field :fx_rate, :decimal            # Exchange rate if international
    field :base_amount, :decimal        # Amount in merchant's local currency
    field :base_currency, :string       # Merchant's currency

    # QR specific fields
    field :qr_string, :string           # QR code string if QR payment
    field :qr_medium, :string           # DYNAMIC, STATIC
    field :merchant_category_code, :string
    field :merchant_vpa, :string

    # Payee account details (for RespChkTxn Ref element)
    field :payee_ifsc, :string          # Payee bank IFSC code
    field :payee_account_number, :string # Payee account number
    field :payee_account_type, :string   # SAVINGS, CURRENT
    field :invoice_number, :string       # Invoice/approval number

    # Status and tracking
    field :status, :string              # PENDING, PROCESSED, FAILED
    field :validation_type, :string     # DOMESTIC, INTERNATIONAL
    field :error_code, :string
    field :error_message, :string

    # Timestamps
    field :npci_request_received_at, :utc_datetime  # When NPCI request was received
    field :npci_response_sent_at, :utc_datetime     # When PSP response was sent
    field :processing_duration_ms, :integer         # Processing time in milliseconds
    field :paid_at, :utc_datetime                   # When payment was processed

    # Associations
    belongs_to :transaction, Transaction, foreign_key: :transaction_id
    belongs_to :partner, Partner, foreign_key: :partner_id
    belongs_to :merchant, Merchant, foreign_key: :merchant_id
    has_many :events, TransactionEvent, foreign_key: :req_pay_id

    timestamps(type: :utc_datetime)
  end

  @required ~w(msg_id org_id amount currency status validation_type)a
  @optional ~w(
    txn_id ref_id ref_url payer_addr payee_addr payer_name payee_name
    network_inst_id payment_type payment_purpose response_code response_message
    payment_status settlement_status npci_txn_id rrn corridor partner_txn_id
    fx_rate base_amount base_currency qr_string qr_medium merchant_category_code
    merchant_vpa payee_ifsc payee_account_number payee_account_type invoice_number
    error_code error_message npci_request_received_at
    npci_response_sent_at processing_duration_ms paid_at transaction_id
    partner_id merchant_id
  )a

  def changeset(struct, attrs) do
    struct
    |> cast(attrs, @required ++ @optional)
    |> validate_required(@required)
    |> validate_inclusion(:status, ~w(PENDING PROCESSED FAILED))
    |> validate_inclusion(:validation_type, ~w(DOMESTIC INTERNATIONAL))
    |> validate_inclusion(:payment_status, ~w(PENDING SUCCESS FAILURE EXPIRED DEEMED REVERSED))
    |> validate_inclusion(:payment_type, ~w(QR INTENT COLLECT REVERSAL))
    |> validate_length(:msg_id, max: 35)
    |> validate_length(:txn_id, max: 35)
    |> validate_format(:payer_addr, ~r/^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+$/, message: "Invalid UPI ID format")
    |> validate_format(:payee_addr, ~r/^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+$/, message: "Invalid UPI ID format")
    |> validate_number(:amount, greater_than_or_equal_to: 0)
    |> unique_constraint(:msg_id)
  end

  @doc """
  Changeset for international payment requests with FX validation
  """
  def international_changeset(struct, attrs) do
    struct
    |> changeset(attrs)
    |> put_change(:validation_type, "INTERNATIONAL")
    |> validate_international_fields()
  end

  @doc """
  Changeset for domestic payment requests
  """
  def domestic_changeset(struct, attrs) do
    struct
    |> changeset(attrs)
    |> put_change(:validation_type, "DOMESTIC")
    |> put_change(:corridor, nil)
    |> put_change(:fx_rate, nil)
  end

  # Private validation functions

  defp validate_international_fields(changeset) do
    changeset
    |> validate_required([:corridor])
    |> validate_inclusion(:corridor, ~w(SINGAPORE UAE USA))
    |> validate_currency_fields()
  end

  defp validate_currency_fields(changeset) do
    changeset
    |> validate_inclusion(:base_currency, ~w(USD SGD AED EUR GBP))
    |> validate_number(:fx_rate, greater_than: 0)
    |> validate_number(:base_amount, greater_than: 0)
  end

  @doc """
  Get status counts for analytics
  """
  def status_counts do
    %{
      "pending" => 0,
      "processed" => 0,
      "failed" => 0
    }
  end

  @doc """
  Get validation type counts
  """
  def validation_type_counts do
    %{
      "domestic" => 0,
      "international" => 0
    }
  end

  @doc """
  Get payment status counts
  """
  def payment_status_counts do
    %{
      "pending" => 0,
      "success" => 0,
      "failure" => 0,
      "expired" => 0,
      "deemed" => 0,
      "reversed" => 0
    }
  end
end