# Toast Notification System - Implementation Guide

## Overview

A modern, consistent toast notification system has been implemented across the entire application using Toastr.js. This provides better UX for validation errors, success messages, warnings, and informational messages.

## Features

✅ **Automatic Display**: TempData messages and ModelState errors automatically show as toast notifications
✅ **Consistent API**: Easy-to-use helper methods for controllers
✅ **Multiple Types**: Success, Error, Warning, and Info notifications
✅ **Accessible**: ARIA-compliant and keyboard accessible
✅ **Responsive**: Works on desktop, tablet, and mobile
✅ **Themeable**: Integrated with Bootstrap 5 dark/light themes

---

## For Controllers - Setting Toast Messages

### Option 1: Using Extension Methods (Recommended)

```csharp
using PowderCoating.Web.Helpers;

public class MyController : Controller
{
    public IActionResult Create(MyDto dto)
    {
        if (ModelState.IsValid)
        {
            // ... save logic ...

            this.ToastSuccess("Item created successfully!");
            return RedirectToAction(nameof(Index));
        }

        // Validation errors are automatically shown as toasts
        return View(dto);
    }

    public IActionResult Delete(int id)
    {
        try
        {
            // ... delete logic ...
            this.ToastSuccess("Item deleted successfully!");
        }
        catch (Exception ex)
        {
            this.ToastError($"Failed to delete item: {ex.Message}");
        }

        return RedirectToAction(nameof(Index));
    }
}
```

### Option 2: Using TempData Directly

```csharp
using PowderCoating.Web.Helpers;

// Success
TempData.Success("Operation completed successfully!");

// Error
TempData.Error("An error occurred while processing your request.");

// Warning
TempData.Warning("This action cannot be undone.");

// Info
TempData.Info("Your changes have been saved as a draft.");
```

### Option 3: Traditional TempData (Still Supported)

```csharp
// Still works - will be displayed as toasts
TempData["Success"] = "Item saved!";
TempData["Error"] = "Something went wrong.";
TempData["Warning"] = "Please review the changes.";
TempData["Info"] = "New feature available!";
```

---

## For Views - Replacing Old Validation Summaries

### Old Way (Still Works)
```html
<div asp-validation-summary="ModelOnly" class="alert alert-danger"></div>
```

### New Way (Recommended)
```html
@* Simple inline indicator - errors show as toasts automatically *@
<partial name="_ValidationSummary" />

@* Or use nothing - ModelState errors auto-show as toasts! *@
```

### Field-Level Validation (Unchanged)
```html
@* Field-level validation still works the same *@
<span asp-validation-for="Name" class="text-danger"></span>
```

---

## For JavaScript - Manual Toast Display

### Basic Usage

```javascript
// Success
showSuccess('Changes saved successfully!');

// Error
showError('Failed to load data.');

// Warning
showWarning('Your session will expire in 5 minutes.');

// Info
showInfo('A new version is available.');
```

### With Custom Titles

```javascript
showSuccess('Profile updated!', 'Success');
showError('Connection lost.', 'Network Error');
showWarning('Unsaved changes detected.', 'Warning');
showInfo('New messages available.', 'Notification');
```

### Validation Errors

```javascript
// Single error
showValidationErrors(['Email is required']);

// Multiple errors
showValidationErrors([
    'Email is required',
    'Password must be at least 8 characters',
    'Terms and conditions must be accepted'
]);
```

### Clear All Toasts

```javascript
clearAllToasts();
```

---

## Configuration

Toast behavior is configured in `/wwwroot/js/toast-notifications.js`:

```javascript
toastr.options = {
    "closeButton": true,           // Show close button
    "newestOnTop": true,           // New toasts appear on top
    "progressBar": true,           // Show countdown progress bar
    "positionClass": "toast-top-right",  // Position on screen
    "preventDuplicates": true,     // Prevent duplicate messages
    "timeOut": "5000",             // Auto-close after 5 seconds
    "extendedTimeOut": "1000",     // Extended timeout on hover
    // ... more options
};
```

### Available Positions
- `toast-top-right` (default)
- `toast-top-left`
- `toast-bottom-right`
- `toast-bottom-left`
- `toast-top-center`
- `toast-bottom-center`
- `toast-top-full-width`
- `toast-bottom-full-width`

---

## Migration Guide

### 1. Update Controllers

**Before:**
```csharp
TempData["Success"] = "Item created!";
```

**After:**
```csharp
using PowderCoating.Web.Helpers;

this.ToastSuccess("Item created!");
```

### 2. Update Views

**Before:**
```html
@if (TempData["Success"] != null)
{
    <div class="alert alert-success">@TempData["Success"]</div>
}

<div asp-validation-summary="ModelOnly" class="alert alert-danger"></div>
```

**After:**
```html
@* Messages automatically show as toasts - no view code needed! *@

@* Optional: Simple validation indicator *@
<partial name="_ValidationSummary" />
```

### 3. JavaScript AJAX Callbacks

**Before:**
```javascript
if (result.success) {
    alert('Saved!');
}
```

**After:**
```javascript
if (result.success) {
    showSuccess('Saved successfully!');
}
```

---

## Examples by Scenario

### CRUD Operations

```csharp
// Create
this.ToastSuccess($"'{entity.Name}' created successfully!");

// Update
this.ToastSuccess($"'{entity.Name}' updated successfully!");

// Delete
this.ToastSuccess($"'{entity.Name}' deleted successfully!");

// Soft Delete
this.ToastWarning($"'{entity.Name}' moved to trash.");
```

### Validation Failures

```csharp
// ModelState errors show automatically as toasts
// Just return the view
if (!ModelState.IsValid)
{
    return View(dto);
}
```

### Business Logic Errors

```csharp
if (customer.CurrentBalance > 0)
{
    this.ToastError("Cannot delete customer with outstanding balance.");
    return RedirectToAction(nameof(Details), new { id });
}
```

### Warnings

```csharp
if (item.StockLevel < item.ReorderPoint)
{
    this.ToastWarning($"Low stock alert: {item.Name} needs reordering.");
}
```

### Info Messages

```csharp
if (newFeaturesAvailable)
{
    this.ToastInfo("New features are available! Check the dashboard.");
}
```

---

## Styling & Theming

Toast notifications automatically adapt to Bootstrap 5 dark/light themes. Colors are derived from:

- **Success**: `--bs-success` (green)
- **Error**: `--bs-danger` (red)
- **Warning**: `--bs-warning` (yellow/orange)
- **Info**: `--bs-info` (blue)

---

## Accessibility

✅ Toast notifications include proper ARIA attributes
✅ Keyboard accessible (close with ESC key)
✅ Screen reader friendly
✅ Respects `prefers-reduced-motion` for animations

---

## Best Practices

### ✅ DO

- Use success toasts for completed actions
- Use error toasts for failures and validation issues
- Use warning toasts for important information requiring attention
- Use info toasts for helpful tips and non-critical updates
- Keep messages concise (1-2 sentences max)
- Use action-specific messages ("Customer 'Acme Corp' created successfully")

### ❌ DON'T

- Don't use toasts for critical errors requiring user action (use modals)
- Don't use toasts for form field validation (use inline validation)
- Don't chain multiple toasts for the same action
- Don't use vague messages ("Success!" - what succeeded?)
- Don't use toasts for loading states (use spinners)

---

## Troubleshooting

### Toast not appearing?

1. Check browser console for JavaScript errors
2. Verify Toastr library is loaded: Check `<head>` for `toastr.min.css` and `toastr.min.js`
3. Verify toast-notifications.js is loaded after Toastr
4. Check that TempData keys are correct: "Success", "Error", "Warning", "Info"

### Toast appears twice?

- Check that you're not manually displaying AND using TempData
- Verify the page isn't being loaded twice

### Styling issues?

- Check for CSS conflicts with custom styles
- Verify Bootstrap 5 is loaded
- Check browser console for CSS errors

---

## Files Modified/Created

### New Files
- `/wwwroot/lib/toastr/` - Toastr library files (via LibMan)
- `/wwwroot/js/toast-notifications.js` - Toast notification system
- `/Helpers/ToastHelper.cs` - C# helper methods
- `/Views/Shared/_ValidationSummary.cshtml` - Modern validation summary partial

### Modified Files
- `/libman.json` - Added Toastr library
- `/Views/Shared/_Layout.cshtml` - Added Toastr references and TempData containers

---

## Support & Feedback

For questions or issues with the toast notification system, please contact the development team or create an issue in the project repository.