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253
Prefab.Catalog/Domain/Services/PricingService.cs
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253
Prefab.Catalog/Domain/Services/PricingService.cs
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using Microsoft.EntityFrameworkCore;
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using Prefab.Catalog.Data;
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using Prefab.Catalog.Domain.Entities;
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using Prefab.Shared.Catalog.Products;
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namespace Prefab.Catalog.Domain.Services;
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/// <summary>
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/// Calculates price quotes for configured catalog products by combining base price, numeric adjustments, and percent deltas.
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/// </summary>
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public interface IPricingService
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{
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/// <summary>
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/// Produces a unit price and line-item breakdown for a shopper’s selections.
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/// </summary>
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Task<QuotePrice.Response> QuoteAsync(QuotePrice.Request request, CancellationToken cancellationToken = default);
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}
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/// <summary>
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/// Default Catalog pricing implementation that reads product/option data on demand and applies the PercentScope rules.
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/// </summary>
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public sealed class PricingService(IModuleDbReadOnly db) : IPricingService
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{
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public async Task<QuotePrice.Response> QuoteAsync(QuotePrice.Request request, CancellationToken cancellationToken = default)
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{
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ArgumentNullException.ThrowIfNull(request);
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if (request.ProductId is null && string.IsNullOrWhiteSpace(request.Sku))
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{
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throw new ArgumentException("Either ProductId or Sku must be supplied.", nameof(request));
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}
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var product = await FindProductAsync(request, cancellationToken)
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?? throw new InvalidOperationException("Product could not be located for pricing.");
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var optionsSource = product.Kind == ProductKind.Model
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? product
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: product.ParentProduct ?? throw new InvalidOperationException("Variant product is missing its model definition.");
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var optionLookup = optionsSource.Options
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.Where(o => o.DeletedOn is null)
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.ToDictionary(o => o.Id);
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var basePrice = product.Price ?? 0m;
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var numericTotal = 0m;
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var choiceAbsTotal = 0m;
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var breakdownEntries = new List<SelectionBreakdown>();
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foreach (var selection in request.Selections)
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{
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if (!optionLookup.TryGetValue(selection.OptionDefinitionId, out var option))
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{
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throw new InvalidOperationException($"Option definition '{selection.OptionDefinitionId}' was not found for product '{optionsSource.Id}'.");
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}
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switch (option.DataType)
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{
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case OptionDataType.Number:
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{
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var (delta, chosenDescription) = HandleNumber(option, selection);
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numericTotal += delta;
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breakdownEntries.Add(SelectionBreakdown.Fixed(option.Name, chosenDescription, delta));
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break;
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}
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case OptionDataType.Choice:
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{
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if (selection.OptionValueId is null)
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{
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throw new InvalidOperationException($"Selection for option '{option.Name}' must include an option value identifier.");
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}
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var value = option.Values.FirstOrDefault(v => v.DeletedOn == null && v.Id == selection.OptionValueId)
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?? throw new InvalidOperationException($"Option value '{selection.OptionValueId}' was not found for option '{option.Name}'.");
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var chosenDescription = value.Label;
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var delta = value.PriceDelta ?? 0m;
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switch (value.PriceDeltaKind)
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{
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case PriceDeltaKind.Absolute:
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choiceAbsTotal += delta;
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breakdownEntries.Add(SelectionBreakdown.Fixed(option.Name, chosenDescription, delta));
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break;
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case PriceDeltaKind.Percent:
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breakdownEntries.Add(SelectionBreakdown.Percent(option, value, chosenDescription, delta));
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break;
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default:
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throw new NotSupportedException($"Price delta kind '{value.PriceDeltaKind}' is not supported.");
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}
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break;
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}
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default:
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throw new NotSupportedException($"Option data type '{option.DataType}' is not supported.");
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}
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}
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var percentSelections = breakdownEntries.Where(e => e.Kind == BreakdownKind.Percent).ToList();
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var percentTotal = 0m;
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PercentScope? selectedScope = null;
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foreach (var entry in percentSelections)
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{
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var scope = entry.OptionDefinition.PercentScope ?? PercentScope.BaseOnly;
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if (selectedScope is null)
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{
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selectedScope = scope;
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}
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else if (selectedScope.Value != scope)
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{
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throw new InvalidOperationException("Percent options for a product must share the same percent scope.");
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}
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var scopeBase = scope switch
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{
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PercentScope.BaseOnly => basePrice,
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PercentScope.NumericOnly => numericTotal,
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PercentScope.BasePlusNumeric => basePrice + numericTotal,
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_ => basePrice
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};
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var delta = scopeBase * (entry.PercentValue / 100m);
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entry.Value = delta;
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percentTotal += delta;
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}
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var final = Math.Max(
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0m,
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Math.Round(basePrice + numericTotal + choiceAbsTotal + percentTotal, 2, MidpointRounding.AwayFromZero));
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var breakdown = breakdownEntries
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.Select(e => new QuotePrice.QuoteBreakdown(
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e.Option,
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e.Chosen,
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Math.Round(e.Value, 2, MidpointRounding.AwayFromZero)))
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.ToList();
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return new QuotePrice.Response(final, breakdown);
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}
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/// <summary>
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/// Resolves a model or variant to price, including the parent model so option metadata is always available.
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/// </summary>
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private async Task<Product?> FindProductAsync(QuotePrice.Request request, CancellationToken cancellationToken)
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{
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var products = db.Products
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.Where(p => p.DeletedOn == null)
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.AsNoTracking()
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.Include(p => p.Options).ThenInclude(o => o.Values)
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.Include(p => p.Options).ThenInclude(o => o.Tiers)
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.Include(p => p.ParentProduct).ThenInclude(pp => pp!.Options).ThenInclude(o => o.Values)
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.Include(p => p.ParentProduct).ThenInclude(pp => pp!.Options).ThenInclude(o => o.Tiers);
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if (!string.IsNullOrWhiteSpace(request.Sku))
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{
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var sku = request.Sku!.Trim().ToUpperInvariant();
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return await products.FirstOrDefaultAsync(p => p.Sku != null && p.Sku.ToUpper() == sku, cancellationToken);
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}
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return await products.FirstOrDefaultAsync(p => p.Id == request.ProductId, cancellationToken);
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}
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/// <summary>
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/// Computes the price delta for numeric options with clamping, stepping, and tier evaluation.
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/// </summary>
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private static (decimal Delta, string ChosenDescription) HandleNumber(OptionDefinition option, QuotePrice.Selection selection)
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{
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if (selection.NumericValue is null)
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{
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throw new InvalidOperationException($"Selection for option '{option.Name}' must include a numeric value.");
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}
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var requested = selection.NumericValue.Value;
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var clamped = option.Min.HasValue ? Math.Max(requested, option.Min.Value) : requested;
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clamped = option.Max.HasValue ? Math.Min(clamped, option.Max.Value) : clamped;
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if (option.Step is > 0)
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{
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var step = option.Step.Value;
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clamped = Math.Round(clamped / step, MidpointRounding.AwayFromZero) * step;
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if (option.Min.HasValue)
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{
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clamped = Math.Max(clamped, option.Min.Value);
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}
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if (option.Max.HasValue)
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{
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clamped = Math.Min(clamped, option.Max.Value);
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}
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}
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var applicableTier = option.Tiers
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.Where(t => t.DeletedOn == null && clamped >= t.FromInclusive && (t.ToInclusive == null || clamped <= t.ToInclusive.Value))
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.OrderByDescending(t => t.FromInclusive)
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.FirstOrDefault();
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var rate = applicableTier?.UnitRate ?? option.PricePerUnit ?? 0m;
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var flat = applicableTier?.FlatDelta ?? 0m;
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var chosenDescription = option.Unit is { Length: > 0 }
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? $"{clamped:0.##} {option.Unit}"
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: clamped.ToString("0.##");
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return ((rate * clamped) + flat, chosenDescription);
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}
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private enum BreakdownKind
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{
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Fixed,
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Percent
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}
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private sealed class SelectionBreakdown
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{
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private SelectionBreakdown(
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string option,
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string chosen,
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BreakdownKind kind,
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OptionDefinition optionDefinition,
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OptionValue? optionValue,
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decimal value,
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decimal percentValue)
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{
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Option = option;
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Chosen = chosen;
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Kind = kind;
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OptionDefinition = optionDefinition;
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OptionValue = optionValue;
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Value = value;
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PercentValue = percentValue;
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}
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public string Option { get; }
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public string Chosen { get; }
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public BreakdownKind Kind { get; }
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public OptionDefinition OptionDefinition { get; }
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public OptionValue? OptionValue { get; }
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public decimal Value { get; set; }
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public decimal PercentValue { get; }
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public static SelectionBreakdown Fixed(string option, string chosen, decimal value) =>
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new(option, chosen, BreakdownKind.Fixed, null!, null, value, 0m);
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public static SelectionBreakdown Percent(OptionDefinition option, OptionValue value, string chosen, decimal percent) =>
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new(option.Name, chosen, BreakdownKind.Percent, option, value, 0m, percent);
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}
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}
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