Add image generation (#2)

* Add image generation

* Optimise for minimal memory

* Added a new ui

* Add support for esp

HomeApi/Handlers/ImageGeneration.cs

@@ -0,0 +1,79 @@
+using System.Dynamic;
+using System.Reflection;
+using HomeApi.Models.Configuration;
+using MediatR;
+using Microsoft.Extensions.Options;
+using PuppeteerSharp;
+using RazorLight;
+
+namespace HomeApi.Handlers;
+
+public static class ImageGeneration
+{
+    public record Command : IRequest<Stream>;
+
+    public class Handler(
+        IWebHostEnvironment env,
+        IMediator mediator,
+        IOptions<ApiConfiguration> apiConfiguration)
+        : IRequestHandler<Command, Stream>
+    {
+        private readonly ApiConfiguration _apiConfiguration = apiConfiguration.Value;
+
+        public async Task<Stream> Handle(Command request, CancellationToken cancellationToken)
+        {
+            var weather = await mediator.Send(new Weather.Command(), cancellationToken);
+            var departureBoard = await mediator.Send(new DepartureBoard.Command(), cancellationToken);
+            
+            var model = new Models.Image
+            {
+                Weather = weather,
+                TimeTable = departureBoard
+            };
+            
+            if(weather is null)
+                throw new Exception("Weather data not found");
+            
+            var engine = new RazorLightEngineBuilder()
+                .SetOperatingAssembly(Assembly.GetExecutingAssembly())
+                .UseEmbeddedResourcesProject(typeof(ImageGeneration))
+                .UseMemoryCachingProvider()
+                .Build();
+            
+            var path = Path.Combine(env.WebRootPath, "index.cshtml");
+
+            var template = await File.ReadAllTextAsync(path, cancellationToken);
+
+            dynamic viewBag = new ExpandoObject();
+            viewBag.IsHighContrast = _apiConfiguration.EspConfiguration.IsHighContrastMode;
+            
+            var result = await engine.CompileRenderStringAsync("templateKey", template, model, viewBag: viewBag);
+
+            if (!string.IsNullOrEmpty(result)) 
+                return await CreateImage(result);
+            
+            throw new Exception("Failed to generate HTML content for image.");
+        }
+
+        private static async Task<Stream> CreateImage(string htmlContent)
+        {
+            var browserFetcher = new BrowserFetcher();
+            await browserFetcher.DownloadAsync();
+            var browser = await Puppeteer.LaunchAsync(new LaunchOptions
+            {
+                Headless = true,
+                Args = ["--disable-gpu"]
+            });
+            
+            var page = await browser.NewPageAsync();
+            await page.SetViewportAsync(new ViewPortOptions
+            {
+                Width = 800,
+                Height = 480
+            });
+            
+            await page.SetContentAsync(htmlContent, new NavigationOptions { WaitUntil = [WaitUntilNavigation.Networkidle0] });
+            return await page.ScreenshotStreamAsync(new ScreenshotOptions { Type = ScreenshotType.Jpeg, Quality = 60 });
+        }
+    }
+}