using Fitness_core_BE.DTOs.Auth;
using Fitness_core_BE.Exceptions;
using Fitness_core_BE.Models.IOs;
using System.Text.Json;

namespace Fitness_core_BE.Helpers
{
    // Parses AuthHex's real /api/alt|/api/user response shapes. The AuthHex gateway wraps
    // whatever the underlying handler returns in its own {success,message,data} envelope, so
    // authResponse.Data (already unwrapped once by AuthService) can itself be a SECOND envelope:
    // { "success": true, "message": "...", "data": { "referenceNumber": "REC...", "expiresAt": "2026-07-03T18:49:38Z", "recoveryType": "..." } }
    // referenceNumber is an opaque string, not a Guid, and there is no "expiresInSeconds" field -
    // it's an absolute "expiresAt" timestamp that we convert to a countdown.
    public static class AuthOtpResponseParser
    {
        public static SendOtpResult ToSendOtpResult(AuthResponse authResponse, int resendAllowedInSeconds = 60)
        {
            if (authResponse.Data == null)
                throw new BadRequestException("Auth service did not return OTP data.");

            var data = UnwrapToField(DeserializePayload.Deserialize(authResponse.Data), "referenceNumber", "ReferenceNumber");
            var referenceNumber = DataExtractor.GetRequiredStringByKeys(data, "referenceNumber");

            var expiresAt = DataExtractor.GetOptionalDateTime(data, "expiresAt");
            var expiresInSeconds = expiresAt.HasValue
                ? Math.Max(0, (int)(expiresAt.Value.ToUniversalTime() - DateTime.UtcNow).TotalSeconds)
                : DataExtractor.GetNullableInt(data, "expiresInSeconds") ?? 600;

            return new SendOtpResult(referenceNumber, expiresInSeconds, resendAllowedInSeconds);
        }

        // If the payload doesn't have any of the fields we're after but looks like another
        // {success,message,data} envelope, drop down into its "data" and try again.
        public static Dictionary<string, JsonElement> UnwrapToField(Dictionary<string, JsonElement> data, params string[] anyOfKeys)
        {
            for (var depth = 0; depth < 3; depth++)
            {
                if (anyOfKeys.Any(k => data.ContainsKey(k)))
                    return data;

                if (!data.TryGetValue("data", out var nested) || nested.ValueKind != JsonValueKind.Object)
                    return data;

                data = JsonSerializer.Deserialize<Dictionary<string, JsonElement>>(nested.GetRawText())!;
            }

            return data;
        }
    }
}