using System.Threading;
using System.Threading.Tasks;

namespace PayRollBLL.SAPPaySlip.Client
{
    /// <summary>
    /// Contract for the SAP ZPY_PAYSLIP_SRV HTTP client.
    ///
    /// Never throws on network or HTTP-level errors — all failures are captured in
    /// <see cref="SapPaySlipApiResultDTO"/> so the BLL can surface precise, actionable messages.
    /// Only <see cref="System.OperationCanceledException"/> propagates (caller-initiated cancellation).
    /// </summary>
    public interface ISapPaySlipApiClient
    {
        Task<SapPaySlipApiResultDTO> GetAsync(
            string employeeId,
            string fiscalYear,
            string month,
            string username,
            string password,
            string sapClient,
            CancellationToken ct);
    }

    /// <summary>
    /// Result of a single SAP PaySlip API call.
    ///
    /// When <see cref="IsSuccess"/> is false, inspect the error fields in order:
    ///   1. <see cref="StatusCode"/> == 0  → network failure; read <see cref="NetworkFailureReason"/>
    ///   2. <see cref="StatusCode"/> != 0  → HTTP error; read <see cref="SapErrorCode"/>,
    ///      <see cref="SapErrorMessage"/>, and <see cref="SapTransactionId"/>
    /// <see cref="AttemptedUri"/> is always set for debugging.
    /// </summary>
    public sealed class SapPaySlipApiResultDTO
    {
        /// <summary>True only when SAP returned HTTP 2xx with a parseable body.</summary>
        public bool IsSuccess { get; init; }

        /// <summary>
        /// HTTP status code returned by SAP.
        /// Zero (0) means a network-level failure occurred before any HTTP response was received.
        /// </summary>
        public int StatusCode { get; init; }

        /// <summary>Raw response body from SAP (may be JSON, HTML, or empty).</summary>
        public string ResponseBody { get; init; } = string.Empty;

        /// <summary>
        /// SAP OData error code parsed from the JSON error envelope
        /// (e.g. "HTTP/400", "/ZPY/PAYSLIP/001").
        /// Null when the body was empty or not a SAP OData JSON error.
        /// </summary>
        public string? SapErrorCode { get; init; }

        /// <summary>
        /// Human-readable error message from <c>error.message.value</c> in the SAP OData envelope.
        /// This is the exact text SAP sends — surface it directly to the caller.
        /// </summary>
        public string? SapErrorMessage { get; init; }

        /// <summary>
        /// SAP transaction ID from <c>error.innererror.transactionid</c>.
        /// Provide this to the SAP BASIS team to locate the server-side log entry.
        /// </summary>
        public string? SapTransactionId { get; init; }

        /// <summary>
        /// Human-readable description of the network failure, set only when
        /// <see cref="StatusCode"/> == 0. Classifies DNS failures, refused connections,
        /// TLS errors, and request timeouts precisely.
        /// </summary>
        public string? NetworkFailureReason { get; init; }

        /// <summary>Full URI that was attempted — always set for debugging and error reporting.</summary>
        public string AttemptedUri { get; init; } = string.Empty;
    }
}