step3/api/QuestionsApi/Models/AccessModels.cs

using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;

namespace QuestionsApi.Models;

public static class AccessCatalog
{
    public const int FreeQuestionLimit = 20;
    public const int CreditEarningLimit = 20;
    public const int DayPassCreditCost = 100;

    public static readonly IReadOnlyDictionary<string, AccessProduct> Products =
        new Dictionary<string, AccessProduct>(StringComparer.Ordinal)
        {
            ["access_day_1"] = new("access_day_1", "One-day QBank token", 100, "usd", AccessGrant.DayToken),
            ["access_week_1"] = new("access_week_1", "Seven-day QBank token", 500, "usd", AccessGrant.WeekToken),
            ["access_month_1"] = new("access_month_1", "Thirty-day QBank token", 2000, "usd", AccessGrant.MonthToken),
            ["exam_token_1"] = new("exam_token_1", "Exam simulation token", 199, "usd", AccessGrant.ExamToken),
            ["qbank_reset_1"] = new("qbank_reset_1", "QBank reset token", 499, "usd", AccessGrant.ResetToken)
        };
}

public static class AccessGrant
{
    public const string DayToken = "day_token";
    public const string WeekToken = "week_token";
    public const string MonthToken = "month_token";
    public const string ExamToken = "exam_token";
    public const string ResetToken = "reset_token";
}

public sealed record AccessProduct(string Sku, string Name, long AmountCents, string Currency, string Grant);

public sealed class AccessEvent
{
    public string Id { get; set; } = "";
    public string SubjectId { get; set; } = "";
    public DateTime CreatedUtc { get; set; }
}

public sealed class UserAccessAccount
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string? Id { get; set; }
    public string UserId { get; set; } = "";
    public int Credits { get; set; }
    public int DayTokens { get; set; }
    public int WeekTokens { get; set; }
    public int MonthTokens { get; set; }
    public int ExamTokens { get; set; }
    public int ResetTokens { get; set; }
    public int BankCycle { get; set; }
    public DateTime? UnlimitedUntilUtc { get; set; }
    public List<AccessEvent> RecentUsage { get; set; } = [];
    public List<AccessEvent> RecentCredits { get; set; } = [];
    public List<string> AppliedOperationIds { get; set; } = [];
    public int Revision { get; set; }
    public DateTime UpdatedUtc { get; set; } = DateTime.UtcNow;
}

public sealed class AccessStatusResponse
{
    public int FreeQuestionLimit { get; set; } = AccessCatalog.FreeQuestionLimit;
    public int QuestionsUsed { get; set; }
    public int QuestionsRemaining { get; set; }
    public DateTime? NextQuestionAvailableUtc { get; set; }
    public int Credits { get; set; }
    public int DayPassCreditCost { get; set; } = AccessCatalog.DayPassCreditCost;
    public int DayTokens { get; set; }
    public int WeekTokens { get; set; }
    public int MonthTokens { get; set; }
    public int ExamTokens { get; set; }
    public int ResetTokens { get; set; }
    public int BankCycle { get; set; }
    public bool Unlimited { get; set; }
    public DateTime? UnlimitedUntilUtc { get; set; }
    public List<AccessProduct> Products { get; set; } = [];
}

public sealed class ActivateAccessTokenRequest
{
    public string Token { get; set; } = "";
    public string OperationId { get; set; } = "";
}

public sealed class RedeemCreditsRequest
{
    public string OperationId { get; set; } = "";
}

public sealed class ResetQBankRequest
{
    public string Confirmation { get; set; } = "";
    public string OperationId { get; set; } = "";
}

public sealed class CreateAccessCheckoutRequest
{
    public string Sku { get; set; } = "";
}

public sealed class AccessCheckoutResponse
{
    public string PurchaseId { get; set; } = "";
    public string CheckoutUrl { get; set; } = "";
    public string Sku { get; set; } = "";
    public long AmountCents { get; set; }
}

public static class AccessPurchaseStatus
{
    public const string Pending = "pending";
    public const string Paid = "paid";
    public const string Failed = "failed";
    public const string Expired = "expired";
    public const string Refunded = "refunded";
}

public sealed class AccessPurchase
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string? Id { get; set; }
    public string UserId { get; set; } = "";
    public string Sku { get; set; } = "";
    public long AmountCents { get; set; }
    public string Currency { get; set; } = "usd";
    public string Status { get; set; } = AccessPurchaseStatus.Pending;
    public string Provider { get; set; } = "stripe";
    public string ProviderSessionId { get; set; } = "";
    public string ProviderPaymentId { get; set; } = "";
    public List<string> ProviderEventIds { get; set; } = [];
    public bool GrantApplied { get; set; }
    public DateTime CreatedUtc { get; set; } = DateTime.UtcNow;
    public DateTime UpdatedUtc { get; set; } = DateTime.UtcNow;
}

public sealed class AccessPurchaseStatusResponse
{
    public string PurchaseId { get; set; } = "";
    public string Sku { get; set; } = "";
    public long AmountCents { get; set; }
    public string Currency { get; set; } = "";
    public string Status { get; set; } = "";
}