My chart

MainCategoryChart.swift

import Charts
import SwiftData
import SwiftUI

struct MainCategoryChart: View {
    
    @AppStorage("preferedCurrencyCode") private var preferedCurrencyCode = Currency.preview.first!.code
    
    @Query private var subscriptions: [Subscription]
    @Query private var categories: [Category]
    
    @State var selectedPrices: Double? = nil
    @Binding var timeFrame: TimeFrame
    
    var updatedCategories: [Category] {
        return categories.sorted(by: { $0.name.lowercased() < $1.name.lowercased() })
    }
    
    private var cumulativePricesRangesForCategories: [(category: Category, range: Range<Double>)] {
        var cumulative = 0.0
        return updatedCategories.map { category in
            let totalCost = category.getSubscriptionsCost(timeFrame: timeFrame, preferredCurrency: Currency.preview.first(where: { $0.code == preferedCurrencyCode })!)
            let newCumulative = cumulative + totalCost
            let result = (category: category, range: cumulative..<newCumulative)
            cumulative = newCumulative
            return result
        }
    }
    
    var selectedCategory: Category? {
        if let selectedPrices,
           let selectedIndex = cumulativePricesRangesForCategories
            .firstIndex(where: { $0.range.contains(selectedPrices) }) {
            return updatedCategories[selectedIndex]
        }
        return nil
    }
    
    var body: some View {
        Chart(updatedCategories, id: \.name) { element in
            SectorMark(
                angle: .value("Price", element.getSubscriptionsCost(timeFrame: timeFrame, preferredCurrency: Currency.preview.first(where: { $0.code == preferedCurrencyCode })!)),
                innerRadius: .ratio(0.618),
                angularInset: 1.5
            )
            .cornerRadius(5.0)
            .foregroundStyle(by: .value("Name", element.name))
            .opacity(selectedCategory == nil ? 1 : element.name == (selectedCategory?.name ?? "") ? 1 : 0.3)
        }
        .chartLegend(alignment: .center, spacing: 18)
        .chartAngleSelection(value: $selectedPrices)
        .scaledToFit()
#if os(macOS)
        .transaction {
            $0.animation = nil // Do not animate on macOS
        }
#endif
        .chartBackground { chartProxy in
            GeometryReader { geometry in
                let frame = geometry[chartProxy.plotFrame!]
                VStack {
                    Text(timeFrame == .days ? "Monthly" : "Yearly")
                        .font(.callout)
                        .foregroundStyle(.secondary)
                        .opacity(selectedCategory == nil ? 1 : 0)
                    if let selectedCat = selectedCategory {
                        Text(selectedCat.getSubscriptionsCost(timeFrame: timeFrame, preferredCurrency: Currency.preview.first(where: { $0.code == preferedCurrencyCode })!), format: .currency(code: Currency.preview.first(where: { $0.code == preferedCurrencyCode })!.code).precision(.fractionLength(2)).presentation(.narrow))
                            .font(.title2.bold())
                            .foregroundStyle(Color.primary)
                    } else {
                        Text(totalCost(), format: .currency(code: Currency.preview.first(where: { $0.code == preferedCurrencyCode })!.code).precision(.fractionLength(2)).presentation(.narrow))
                            .font(.title2.bold())
                            .foregroundStyle(Color.primary)
                    }
                    Text(selectedCategory == nil ? String(localized: "Average", comment: "Average monthly/yearly total subscription cost") : selectedCategory?.name ?? "???")
                        .font(.callout)
                        .foregroundStyle(Color.secondary)
                }
                .position(x: frame.midX, y: frame.midY)
            }
        }
    }
    
    func totalCost() -> Double {
        if timeFrame == .days {
            return subscriptions.reduce(0) { $0 + $1.costPerMonth(preferredCurrency: Currency.preview.first(where: { $0.code == preferedCurrencyCode })!) }
        } else {
            return subscriptions.reduce(0) { $0 + $1.costPerYear(preferredCurrency: Currency.preview.first(where: { $0.code == preferedCurrencyCode })!) }
        }
    }
}