defmodule DaProductApp.Settlements.Refund.CsvParserTest do
  use ExUnit.Case
  alias DaProductApp.Settlements.Refund.CsvParser

  describe "parse_file/2" do
    test "parses valid CSV with refund transactions" do
      content = """
      transactionRequestId,transactionType,fundDirection,transactionAmount,transactionCurrency
      refund_001,REFUND,DEBIT,100.50,AED
      refund_002,PAYMENT,CREDIT,200.00,AED
      refund_003,REFUND,DEBIT,75.25,AED
      """
      
      assert {:ok, result} = CsvParser.parse_file("test.csv", content)
      
      assert result.filename == "test.csv"
      assert result.total_count == 2  # Only REFUND + DEBIT transactions
      assert Decimal.equal?(result.total_amount, Decimal.new("175.75"))
      assert length(result.transactions) == 2
      
      # Check first refund transaction
      first_refund = Enum.at(result.transactions, 0)
      assert first_refund.transaction_request_id == "refund_001"
      assert first_refund.transaction_type == "REFUND"
      assert first_refund.fund_direction == "DEBIT"
      assert Decimal.equal?(first_refund.transaction_amount, Decimal.new("100.50"))
    end

    test "filters out non-refund transactions" do
      content = """
      transactionRequestId,transactionType,fundDirection,transactionAmount,transactionCurrency
      payment_001,PAYMENT,CREDIT,100.00,AED
      refund_001,REFUND,DEBIT,50.00,AED
      refund_002,REFUND,CREDIT,25.00,AED
      """
      
      assert {:ok, result} = CsvParser.parse_file("test.csv", content)
      
      assert result.total_count == 1  # Only REFUND + DEBIT
      assert length(result.transactions) == 1
      
      refund = hd(result.transactions)
      assert refund.transaction_request_id == "refund_001"
      assert refund.transaction_type == "REFUND"
      assert refund.fund_direction == "DEBIT"
    end

    test "handles empty CSV" do
      content = """
      transactionRequestId,transactionType,fundDirection,transactionAmount,transactionCurrency
      """
      
      assert {:ok, result} = CsvParser.parse_file("test.csv", content)
      
      assert result.total_count == 0
      assert result.transactions == []
      assert Decimal.equal?(result.total_amount, Decimal.new(0))
    end

    test "returns error for missing required fields" do
      content = """
      transactionId,amount,currency
      tx_001,100.00,AED
      """
      
      assert {:error, reason} = CsvParser.parse_file("test.csv", content)
      assert reason == "Missing required fields: transactionRequestId, transactionType, fundDirection"
    end

    test "handles invalid UTF-8 content" do
      invalid_content = <<0xFF, 0xFE, 0x00, 0x00>>
      
      assert {:error, "Invalid UTF-8 content"} = CsvParser.parse_file("test.csv", invalid_content)
    end

    test "handles CSV with quoted fields" do
      content = """
      "transactionRequestId","transactionType","fundDirection","transactionAmount","transactionCurrency"
      "refund_001","REFUND","DEBIT","100.50","AED"
      """
      
      assert {:ok, result} = CsvParser.parse_file("test.csv", content)
      
      assert result.total_count == 1
      refund = hd(result.transactions)
      assert refund.transaction_request_id == "refund_001"
    end
  end
end