Add contribution payment options to registries

- Added support for single and amount-specific QR codes. - Updated `RegistrySettings` model and database schema. - Enhanced `RegistryAdmin` to configure payment options. - Introduced `RegistryContributionAmount` for partial fulfillment. - Updated `RegistryPublic` to display contribution progress. - Added new models for payment methods and QR code handling. - Improved privacy by limiting contributor visibility.
2026-05-18 23:33:06 +02:00
parent 7dd7b0342f
commit c36e04029b
14 changed files with 1211 additions and 21 deletions
@@ -247,6 +247,50 @@ else
                        </div>
                    </div>

+                    <div class="mt-3">
+                        <h3>Contribution Payment Options</h3>
+                        <div class="row g-3 mt-2">
+                            <div class="col-md-12">
+                                <label class="form-label">Single QR code URL</label>
+                                <InputText class="form-control" @bind-Value="SettingsModel.ContributionQrCodeUrl" />
+                                <small class="form-text text-muted">Optional: one QR code that donors can scan for any amount.</small>
+                            </div>
+                        </div>
+
+                        <div class="mt-3">
+                            <div class="d-flex justify-content-between align-items-center">
+                                <h4 class="mb-0">Amount-specific QR codes</h4>
+                                <button type="button" class="btn btn-outline-secondary btn-sm" @onclick="AddContributionAmountQrCode">Add QR amount</button>
+                            </div>
+
+                            @if (SettingsModel.ContributionAmountQrCodes.Count == 0)
+                            {
+                                <p class="text-muted mt-2 mb-0">No amount-specific QR codes configured.</p>
+                            }
+                            else
+                            {
+                                <div class="mt-2 d-flex flex-column gap-2">
+                                    @foreach (var amountQr in SettingsModel.ContributionAmountQrCodes)
+                                    {
+                                        <div class="row g-2 align-items-end">
+                                            <div class="col-md-3">
+                                                <label class="form-label">Amount</label>
+                                                <InputNumber class="form-control" @bind-Value="amountQr.Amount" />
+                                            </div>
+                                            <div class="col-md-7">
+                                                <label class="form-label">QR code URL</label>
+                                                <InputText class="form-control" @bind-Value="amountQr.QrCodeUrl" />
+                                            </div>
+                                            <div class="col-md-2">
+                                                <button type="button" class="btn btn-outline-danger w-100" @onclick="() => RemoveContributionAmountQrCode(amountQr)">Remove</button>
+                                            </div>
+                                        </div>
+                                    }
+                                </div>
+                            }
+                        </div>
+                    </div>
+
                    <button class="btn btn-primary mt-4" type="submit">Save settings</button>
                </EditForm>
            </section>
@@ -39,6 +39,9 @@ public partial class RegistryAdmin : ComponentBase
        builder.AddMarkupContent(3, "<span class='ql-formats'><button class='ql-link'></button><button class='ql-clean'></button></span>");
    };

+    private bool _pendingEditorLoad;
+    private string? _lastLoadedHeaderContentHtml;
+
    protected override async Task OnParametersSetAsync()
    {
        var userId = await RegistryUserContext.GetUserIdAsync(CancellationToken.None).ConfigureAwait(false);
@@ -60,14 +63,16 @@ public partial class RegistryAdmin : ComponentBase

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
-        if (!firstRender || TextEditor is null || string.IsNullOrWhiteSpace(SettingsModel.HeaderContentHtml))
+        if (TextEditor is null || !_pendingEditorLoad)
        {
            return;
        }

        try
        {
-            await TextEditor.LoadHTMLContent(SettingsModel.HeaderContentHtml).ConfigureAwait(false);
+            await TextEditor.LoadHTMLContent(SettingsModel.HeaderContentHtml ?? string.Empty).ConfigureAwait(false);
+            _lastLoadedHeaderContentHtml = SettingsModel.HeaderContentHtml ?? string.Empty;
+            _pendingEditorLoad = false;
        }
        catch (JSException)
        {
@@ -229,6 +234,17 @@ public partial class RegistryAdmin : ComponentBase
        Admins = await RegistryService.GetRegistryAdminsAsync(RegistryId, CancellationToken.None).ConfigureAwait(false);
    }

+    protected void AddContributionAmountQrCode()
+    {
+        SettingsModel.ContributionAmountQrCodes.Add(new ContributionAmountQrCodeModel());
+    }
+
+    protected void RemoveContributionAmountQrCode(ContributionAmountQrCodeModel model)
+    {
+        ArgumentNullException.ThrowIfNull(model);
+        SettingsModel.ContributionAmountQrCodes.Remove(model);
+    }
+
    private async Task LoadAsync()
    {
        var settings = await RegistryService.GetRegistrySettingsAsync(RegistryId, CancellationToken.None).ConfigureAwait(false);
@@ -244,6 +260,11 @@ public partial class RegistryAdmin : ComponentBase
            SettingsModel.BankAccountIban = settings.BankAccountIban;
            SettingsModel.BankAccountBic = settings.BankAccountBic;
            SettingsModel.ShowBankAccountName = settings.ShowBankAccountName;
+            SettingsModel.ContributionQrCodeUrl = settings.ContributionQrCodeUrl;
+            SettingsModel.ContributionAmountQrCodes = settings.ContributionAmountQrCodes;
+
+            var currentHeaderContent = SettingsModel.HeaderContentHtml ?? string.Empty;
+            _pendingEditorLoad = currentHeaderContent != _lastLoadedHeaderContentHtml;
        }

        Admins = await RegistryService.GetRegistryAdminsAsync(RegistryId, CancellationToken.None).ConfigureAwait(false);
@@ -0,0 +1,75 @@
+@page "/registry/{Code}/item/{ItemId:guid}/contribution-amount"
+@rendermode InteractiveServer
+
+@using BirthList.Web.Features.Registries
+
+<PageTitle>Contribution Amount</PageTitle>
+
+@if (Registry is null || Item is null)
+{
+    <p>Item not found.</p>
+}
+else if (!IsAuthenticated)
+{
+    <p>Please log in first.</p>
+}
+else
+{
+    <div class="registry-shell @RegistryThemeService.GetCssClass(Registry.RegistryType, Registry.ThemeKey)">
+        <h1>Partially fulfill: @Item.Name</h1>
+
+        <div class="card p-3">
+            @if (RepresentableAmounts.Count == 0)
+            {
+                <p class="text-muted mb-0">No representable amount can be formed from configured QR codes up to €200.</p>
+            }
+            else
+            {
+                <label class="form-label">Select amount: €@SelectedAmount</label>
+                <input type="range"
+                       class="form-range"
+                       min="0"
+                       max="@(RepresentableAmounts.Count - 1)"
+                       step="1"
+                       @bind="SliderIndex"
+                       @bind:after="RecalculateSuggestions" />
+            }
+
+            @if (Suggestions.Count == 0)
+            {
+                <p class="text-muted mt-2">No QR combination available for this amount.</p>
+            }
+            else
+            {
+                <p class="mt-3 mb-2"><strong>Suggested QR combination:</strong></p>
+                <ul class="mb-3">
+                    @foreach (var suggestion in Suggestions)
+                    {
+                        <li>@suggestion.RepeatCount x €@suggestion.Amount</li>
+                    }
+                </ul>
+
+                <div class="d-flex flex-column gap-3">
+                    @foreach (var suggestion in Suggestions)
+                    {
+                        @for (var i = 0; i < suggestion.RepeatCount; i++)
+                        {
+                            <div>
+                                <div class="small mb-1">€@suggestion.Amount</div>
+                                <img src="@BuildQrImageUrl(suggestion.QrCodeUrl)" alt="QR code @suggestion.Amount" class="img-fluid" style="max-height: 220px;" />
+                                <div class="small text-muted text-break">
+                                    <a href="@suggestion.QrCodeUrl" target="_blank" rel="noopener noreferrer">Open payment link</a>
+                                </div>
+                            </div>
+                        }
+                    }
+                </div>
+            }
+
+            <div class="d-flex gap-2 mt-3">
+                <button class="btn btn-success" @onclick="ConfirmAsync" disabled="@(SelectedAmount <= 0)">I transferred this amount</button>
+                <button class="btn btn-outline-secondary" @onclick="BackToRegistry">Back</button>
+            </div>
+        </div>
+    </div>
+}
@@ -0,0 +1,210 @@
+using BirthList.Web.Features.Registries;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Components;
+
+namespace BirthList.Web.Components.Pages;
+
+[Authorize]
+public partial class RegistryContributionAmount : ComponentBase
+{
+    [Parameter] public string Code { get; set; } = string.Empty;
+    [Parameter] public Guid ItemId { get; set; }
+
+    [Inject] private RegistryService RegistryService { get; set; } = null!;
+    [Inject] private RegistryUserContext RegistryUserContext { get; set; } = null!;
+    [Inject] private RegistryThemeService RegistryThemeService { get; set; } = null!;
+    [Inject] private NavigationManager NavigationManager { get; set; } = null!;
+
+    protected RegistryPublicViewModel? Registry { get; private set; }
+    protected RegistryPublicItemViewModel? Item { get; private set; }
+    protected bool IsAuthenticated { get; private set; }
+    protected int SelectedAmount { get; private set; }
+    protected int SliderMin { get; private set; } = 1;
+    protected int SliderIndex { get; set; }
+    protected IReadOnlyList<int> RepresentableAmounts { get; private set; } = [];
+    protected List<QrCombinationSuggestion> Suggestions { get; private set; } = [];
+
+    protected override async Task OnParametersSetAsync()
+    {
+        var userId = await RegistryUserContext.GetUserIdAsync(CancellationToken.None).ConfigureAwait(false);
+        IsAuthenticated = !string.IsNullOrWhiteSpace(userId);
+        if (!IsAuthenticated)
+        {
+            return;
+        }
+
+        Registry = await RegistryService.GetPublicRegistryByCodeAsync(Code, userId, CancellationToken.None).ConfigureAwait(false);
+        Item = Registry?.Items.FirstOrDefault(x => x.Id == ItemId);
+
+        if (Registry is null || Item is null)
+        {
+            return;
+        }
+
+        var configuredAmounts = Registry.ContributionAmountQrCodes
+            .Select(x => (int)Math.Round(x.Amount, MidpointRounding.AwayFromZero))
+            .Where(x => x > 0)
+            .Distinct()
+            .OrderBy(x => x)
+            .ToList();
+
+        SliderMin = configuredAmounts.Count > 0 ? configuredAmounts[0] : 1;
+
+        RepresentableAmounts = Enumerable.Range(SliderMin, 201 - SliderMin)
+            .Where(x => BuildSuggestions(x).Count > 0)
+            .ToList();
+
+        if (RepresentableAmounts.Count == 0)
+        {
+            SelectedAmount = 0;
+            SliderIndex = 0;
+            Suggestions = [];
+            return;
+        }
+
+        SliderIndex = 0;
+        SelectedAmount = RepresentableAmounts[SliderIndex];
+        RecalculateSuggestions();
+    }
+
+    protected void RecalculateSuggestions()
+    {
+        if (RepresentableAmounts.Count == 0)
+        {
+            Suggestions = [];
+            SelectedAmount = 0;
+            return;
+        }
+
+        var maxIndex = RepresentableAmounts.Count - 1;
+        if (SliderIndex < 0)
+        {
+            SliderIndex = 0;
+        }
+        else if (SliderIndex > maxIndex)
+        {
+            SliderIndex = maxIndex;
+        }
+
+        SelectedAmount = RepresentableAmounts[SliderIndex];
+        Suggestions = BuildSuggestions(SelectedAmount);
+    }
+
+    protected async Task ConfirmAsync()
+    {
+        var userId = await RegistryUserContext.GetUserIdAsync(CancellationToken.None).ConfigureAwait(false);
+        if (string.IsNullOrWhiteSpace(userId) || Item is null || SelectedAmount <= 0)
+        {
+            return;
+        }
+
+        await RegistryService.AddContributionAsync(Item.Id, userId, SelectedAmount, $"Participation for item: {Item.Name}", CancellationToken.None).ConfigureAwait(false);
+        BackToRegistry();
+    }
+
+    protected void BackToRegistry()
+    {
+        NavigationManager.NavigateTo($"/registry/{Code}");
+    }
+
+    private List<QrCombinationSuggestion> BuildSuggestions(decimal requestedAmount)
+    {
+        if (Registry is null || requestedAmount <= 0)
+        {
+            return [];
+        }
+
+        var target = (int)Math.Round(requestedAmount, MidpointRounding.AwayFromZero);
+
+        var options = Registry.ContributionAmountQrCodes
+            .Where(x => x.Amount > 0 && !string.IsNullOrWhiteSpace(x.QrCodeUrl))
+            .Select(x => new
+            {
+                Amount = (int)Math.Round(x.Amount, MidpointRounding.AwayFromZero),
+                QrCodeUrl = x.QrCodeUrl.Trim()
+            })
+            .Where(x => x.Amount > 0)
+            .DistinctBy(x => x.Amount)
+            .OrderByDescending(x => x.Amount)
+            .ToList();
+
+        if (options.Count == 0 || target <= 0)
+        {
+            return [];
+        }
+
+        var max = int.MaxValue / 4;
+        var minCoins = Enumerable.Repeat(max, target + 1).ToArray();
+        var choice = Enumerable.Repeat(-1, target + 1).ToArray();
+        minCoins[0] = 0;
+
+        for (var amount = 1; amount <= target; amount++)
+        {
+            for (var i = 0; i < options.Count; i++)
+            {
+                var option = options[i];
+                if (option.Amount > amount)
+                {
+                    continue;
+                }
+
+                var candidate = minCoins[amount - option.Amount];
+                if (candidate == max)
+                {
+                    continue;
+                }
+
+                candidate += 1;
+                if (candidate < minCoins[amount])
+                {
+                    minCoins[amount] = candidate;
+                    choice[amount] = i;
+                }
+            }
+        }
+
+        if (minCoins[target] == max)
+        {
+            return [];
+        }
+
+        var counts = new Dictionary<int, int>();
+        var current = target;
+
+        while (current > 0)
+        {
+            var optionIndex = choice[current];
+            if (optionIndex < 0)
+            {
+                return [];
+            }
+
+            var optionAmount = options[optionIndex].Amount;
+            counts[optionIndex] = counts.TryGetValue(optionIndex, out var count) ? count + 1 : 1;
+            current -= optionAmount;
+        }
+
+        return counts
+            .Select(x => new QrCombinationSuggestion
+            {
+                Amount = options[x.Key].Amount,
+                QrCodeUrl = options[x.Key].QrCodeUrl,
+                RepeatCount = x.Value
+            })
+            .OrderBy(x => x.Amount)
+            .ToList();
+    }
+
+    protected static string BuildQrImageUrl(string paymentLink)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(paymentLink);
+        return $"https://api.qrserver.com/v1/create-qr-code/?size=320x320&data={Uri.EscapeDataString(paymentLink)}";
+    }
+
+    protected sealed class QrCombinationSuggestion
+    {
+        public int Amount { get; init; }
+        public string QrCodeUrl { get; init; } = string.Empty;
+        public int RepeatCount { get; init; }
+    }
+}
@@ -64,14 +64,17 @@ else
                        {
                            <p class="card-text item-description-text">@item.Description</p>
                        }
-                        <p class="mb-1"><strong>Qty:</strong> @item.PurchasedQuantity/@item.DesiredQuantity purchased</p>
+                        @if (item.DesiredQuantity > 1)
+                        {
+                            <p class="mb-1"><strong>Qty:</strong> @item.PurchasedQuantity/@item.DesiredQuantity purchased</p>
+                        }
                        @if (item.PriceAmount.HasValue)
                        {
                            <p class="mb-1"><strong>Price:</strong> @item.PriceAmount.Value.ToString("0.00") @item.CurrencyCode</p>
                        }
-                        @if (item.ParticipationAllowed && item.ParticipationTargetAmount.HasValue)
+                        @if (item.ParticipationAllowed && GetParticipationTotalAmount(item).HasValue)
                        {
-                            <p class="mb-2"><strong>Participation:</strong> @item.MoneyFulfilledAmount.ToString("0.00") / @item.ParticipationTargetAmount.Value.ToString("0.00") @item.CurrencyCode</p>
+                            <p class="mb-2"><strong>Participation:</strong> €@item.MoneyFulfilledAmount.ToString("0.00") out of €@GetParticipationTotalAmount(item)!.Value.ToString("0.00") fulfilled</p>
                        }

                        @if (item.Purchasers.Count > 0 || item.Contributors.Count > 0)
@@ -110,13 +113,39 @@ else
                                @if (item.Contributors.Count > 0)
                                {
                                    <div class="mb-2">
-                                        <strong class="text-sm">Contributed by:</strong>
-                                        <div class="contributor-list">
-                                            @foreach (var contributor in item.Contributors)
+                                        @if (Registry.IsAdmin)
+                                        {
+                                            <strong class="text-sm">Contributed by:</strong>
+                                            <div class="contributor-list">
+                                                @foreach (var contributor in item.Contributors)
+                                                {
+                                                    <span class="contributor-badge">@contributor.DisplayName (@contributor.Amount.ToString("0.00") @item.CurrencyCode)</span>
+                                                }
+                                            </div>
+                                        }
+                                        else if (!string.IsNullOrWhiteSpace(Registry.CurrentUserId))
+                                        {
+                                            var currentUserContribution = item.Contributors.FirstOrDefault(x => x.UserId == Registry.CurrentUserId);
+                                            if (currentUserContribution is not null)
                                            {
-                                                <span class="contributor-badge">@contributor.DisplayName (@contributor.Amount.ToString("0.00") @item.CurrencyCode)</span>
+                                                <strong class="text-sm">Contributed by:</strong>
+                                                <div class="contributor-list">
+                                                    <span class="contributor-badge">@currentUserContribution.DisplayName (@currentUserContribution.Amount.ToString("0.00") @item.CurrencyCode)</span>
+                                                    @if (item.Contributors.Count > 1)
+                                                    {
+                                                        <span class="contributor-badge">and others</span>
+                                                    }
+                                                </div>
                                            }
-                                        </div>
+                                            else
+                                            {
+                                                <span class="text-muted small">Contributed</span>
+                                            }
+                                        }
+                                        else
+                                        {
+                                            <span class="text-muted small">Contributed</span>
+                                        }
                                    </div>
                                }
                            </div>
@@ -147,7 +176,7 @@ else
                                }
                                @if (item.ParticipationAllowed)
                                {
-                                    <button class="btn btn-secondary btn-sm" @onclick="() => OpenContributionPrompt(item.Id)">I transferred money</button>
+                                    <button class="btn btn-secondary btn-sm" @onclick="() => OpenContributionPrompt(item.Id)">Partially fulfill</button>
                                }
                            </div>
                        }
@@ -219,3 +248,91 @@ else
        </div>
    </div>
 }
+
+@if (ShowPartialFulfillWizard)
+{
+    <div class="prompt-overlay">
+        <div class="prompt-card">
+            <h3>Partially fulfill item</h3>
+
+            @if (PartialFulfillStep == 1)
+            {
+                <p>Select how you want to donate:</p>
+
+                <div class="d-flex flex-column gap-2">
+                    @if (HasIbanPaymentOption())
+                    {
+                        <button class="btn btn-outline-primary text-start" @onclick="() => SelectPaymentMethod(ContributionPaymentMethodType.Iban)">
+                            IBAN transfer
+                        </button>
+                    }
+                    @if (HasSingleQrPaymentOption())
+                    {
+                        <button class="btn btn-outline-primary text-start" @onclick="() => SelectPaymentMethod(ContributionPaymentMethodType.SingleQrCode)">
+                            Single QR code
+                        </button>
+                    }
+                    @if (HasAmountSpecificQrPaymentOption())
+                    {
+                        <button class="btn btn-outline-primary text-start" @onclick="() => SelectPaymentMethod(ContributionPaymentMethodType.AmountSpecificQrCode)">
+                            QR code per amount
+                        </button>
+                    }
+                </div>
+
+                @if (SelectedPaymentMethod == ContributionPaymentMethodType.Iban && !string.IsNullOrWhiteSpace(Registry?.BankAccountIban))
+                {
+                    <div class="alert alert-secondary mt-3 mb-0">
+                        <strong>IBAN:</strong> @Registry.BankAccountIban
+                        @if (!string.IsNullOrWhiteSpace(Registry.BankAccountBic))
+                        {
+                            <span> | <strong>BIC:</strong> @Registry.BankAccountBic</span>
+                        }
+                    </div>
+                }
+
+                @if (!string.IsNullOrWhiteSpace(SelectedPaymentQrCodeUrl))
+                {
+                    <div class="mt-3 text-center">
+                        <img src="@BuildQrImageUrl(SelectedPaymentQrCodeUrl)" alt="Payment QR code" class="img-fluid" style="max-height: 240px;" />
+                        <div class="mt-2">
+                            <a href="@SelectedPaymentQrCodeUrl" target="_blank" rel="noopener noreferrer">Open payment link</a>
+                        </div>
+                    </div>
+                }
+
+                <div class="d-flex gap-2 mt-3">
+                    <button class="btn btn-primary" @onclick="ContinueContributionWizard" disabled="@(SelectedPaymentMethod is null)">Next</button>
+                    <button class="btn btn-outline-secondary" @onclick="CloseContributionPrompt">Cancel</button>
+                </div>
+            }
+            else if (PartialFulfillStep == 2)
+            {
+                <p>How much did you add for this item?</p>
+                <InputNumber class="form-control" @bind-Value="ContributionAmount" @bind-Value:after="OnContributionAmountChanged" />
+                <p class="mt-2">Message: @ContributionMessage</p>
+
+                @if (SelectedPaymentMethod == ContributionPaymentMethodType.AmountSpecificQrCode && ContributionAmount > 0 && string.IsNullOrWhiteSpace(SelectedPaymentQrCodeUrl))
+                {
+                    <p class="text-muted mt-2 mb-0">No QR code configured for this exact amount.</p>
+                }
+
+                @if (!string.IsNullOrWhiteSpace(SelectedPaymentQrCodeUrl))
+                {
+                    <div class="mt-3 text-center">
+                        <img src="@BuildQrImageUrl(SelectedPaymentQrCodeUrl)" alt="Payment QR code" class="img-fluid" style="max-height: 240px;" />
+                        <div class="mt-2">
+                            <a href="@SelectedPaymentQrCodeUrl" target="_blank" rel="noopener noreferrer">Open payment link</a>
+                        </div>
+                    </div>
+                }
+
+                <div class="d-flex gap-2 mt-3">
+                    <button class="btn btn-success" @onclick="ConfirmContributionAsync">Confirm</button>
+                    <button class="btn btn-outline-secondary" @onclick="BackContributionWizard">Back</button>
+                    <button class="btn btn-outline-secondary" @onclick="CloseContributionPrompt">Cancel</button>
+                </div>
+            }
+        </div>
+    </div>
+}
@@ -27,6 +27,11 @@ public partial class RegistryPublic : ComponentBase
    protected string? PurchaseItemUrl { get; private set; }
    protected IReadOnlyList<ItemContributorViewModel> PurchasersToUnmark { get; private set; } = [];

+    protected bool ShowPartialFulfillWizard { get; private set; }
+    protected int PartialFulfillStep { get; private set; } = 1;
+    protected ContributionPaymentMethodType? SelectedPaymentMethod { get; set; }
+    protected string? SelectedPaymentQrCodeUrl { get; private set; }
+
    protected override async Task OnParametersSetAsync()
    {
        var userId = await RegistryUserContext.GetUserIdAsync(CancellationToken.None).ConfigureAwait(false);
@@ -97,27 +102,95 @@ public partial class RegistryPublic : ComponentBase
        ContributionMessage = Registry?.Items.FirstOrDefault(x => x.Id == itemId) is { } item
            ? $"Participation for item: {item.Name}"
            : string.Empty;
-        ShowContributionPrompt = true;
+        ShowPartialFulfillWizard = true;
+        PartialFulfillStep = 1;
+        SelectedPaymentMethod = null;
+        SelectedPaymentQrCodeUrl = null;
    }

    protected void CloseContributionPrompt()
    {
-        ShowContributionPrompt = false;
+        ShowPartialFulfillWizard = false;
+        PartialFulfillStep = 1;
+        SelectedPaymentMethod = null;
+        SelectedPaymentQrCodeUrl = null;
        ActiveItemId = Guid.Empty;
        ContributionMessage = string.Empty;
    }

-    protected async Task ConfirmContributionAsync()
+    protected bool HasIbanPaymentOption()
    {
-        var userId = await RegistryUserContext.GetUserIdAsync(CancellationToken.None).ConfigureAwait(false);
-        if (string.IsNullOrWhiteSpace(userId) || ActiveItemId == Guid.Empty || ContributionAmount <= 0)
+        return Registry is not null && !string.IsNullOrWhiteSpace(Registry.BankAccountIban);
+    }
+
+    protected bool HasSingleQrPaymentOption()
+    {
+        return Registry is not null && !string.IsNullOrWhiteSpace(Registry.ContributionQrCodeUrl);
+    }
+
+    protected bool HasAmountSpecificQrPaymentOption()
+    {
+        return Registry is not null && Registry.ContributionAmountQrCodes.Count > 0;
+    }
+
+    protected void SelectPaymentMethod(ContributionPaymentMethodType method)
+    {
+        SelectedPaymentMethod = method;
+        SelectedPaymentQrCodeUrl = method switch
        {
-            return;
+            ContributionPaymentMethodType.SingleQrCode => Registry?.ContributionQrCodeUrl,
+            ContributionPaymentMethodType.AmountSpecificQrCode => FindAmountSpecificQrCode(ContributionAmount),
+            _ => null
+        };
+    }
+
+    protected void ContinueContributionWizard()
+    {
+        if (PartialFulfillStep == 1)
+        {
+            if (SelectedPaymentMethod is null)
+            {
+                return;
+            }
+
+            if (SelectedPaymentMethod == ContributionPaymentMethodType.AmountSpecificQrCode && ActiveItemId != Guid.Empty)
+            {
+                ShowPartialFulfillWizard = false;
+                NavigationManager.NavigateTo($"/registry/{Code}/item/{ActiveItemId}/contribution-amount");
+                return;
+            }
+
+            PartialFulfillStep = 2;
+        }
+    }
+
+    protected void BackContributionWizard()
+    {
+        if (PartialFulfillStep > 1)
+        {
+            PartialFulfillStep--;
+        }
+    }
+
+    protected void OnContributionAmountChanged()
+    {
+        if (SelectedPaymentMethod == ContributionPaymentMethodType.AmountSpecificQrCode)
+        {
+            SelectedPaymentQrCodeUrl = FindAmountSpecificQrCode(ContributionAmount);
+        }
+    }
+
+    private string? FindAmountSpecificQrCode(decimal amount)
+    {
+        if (Registry is null || amount <= 0)
+        {
+            return null;
        }

-        await RegistryService.AddContributionAsync(ActiveItemId, userId, ContributionAmount, ContributionMessage, CancellationToken.None).ConfigureAwait(false);
-        ShowContributionPrompt = false;
-        Registry = await RegistryService.GetPublicRegistryByCodeAsync(Code, userId, CancellationToken.None).ConfigureAwait(false);
+        var match = Registry.ContributionAmountQrCodes
+            .FirstOrDefault(x => x.Amount == amount);
+
+        return match?.QrCodeUrl;
    }

    protected async Task UnmarkPurchaseAsync(Guid itemId)
@@ -184,4 +257,32 @@ public partial class RegistryPublic : ComponentBase
        ShowPurchaserSelectionPrompt = false;
        Registry = await RegistryService.GetPublicRegistryByCodeAsync(Code, userId, CancellationToken.None).ConfigureAwait(false);
    }
+
+    protected async Task ConfirmContributionAsync()
+    {
+        var userId = await RegistryUserContext.GetUserIdAsync(CancellationToken.None).ConfigureAwait(false);
+        if (string.IsNullOrWhiteSpace(userId) || ActiveItemId == Guid.Empty || ContributionAmount <= 0)
+        {
+            return;
+        }
+
+        await RegistryService.AddContributionAsync(ActiveItemId, userId, ContributionAmount, ContributionMessage, CancellationToken.None).ConfigureAwait(false);
+        ShowPartialFulfillWizard = false;
+        PartialFulfillStep = 1;
+        SelectedPaymentMethod = null;
+        SelectedPaymentQrCodeUrl = null;
+        Registry = await RegistryService.GetPublicRegistryByCodeAsync(Code, userId, CancellationToken.None).ConfigureAwait(false);
+    }
+
+    protected static decimal? GetParticipationTotalAmount(RegistryPublicItemViewModel item)
+    {
+        ArgumentNullException.ThrowIfNull(item);
+        return item.ParticipationTargetAmount ?? item.PriceAmount;
+    }
+
+    protected static string BuildQrImageUrl(string paymentLink)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(paymentLink);
+        return $"https://api.qrserver.com/v1/create-qr-code/?size=320x320&data={Uri.EscapeDataString(paymentLink)}";
+    }
 }