Implemented theme import and export

Moonlight.Api/Http/Controllers/Admin/Themes/TransferController.cs

@@ -0,0 +1,76 @@
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using Moonlight.Api.Database;
+using Moonlight.Api.Database.Entities;
+using Moonlight.Api.Mappers;
+using Moonlight.Api.Models;
+using Moonlight.Shared;
+using Moonlight.Shared.Http.Responses.Admin.Themes;
+using VYaml.Serialization;
+
+namespace Moonlight.Api.Http.Controllers.Admin.Themes;
+
+[ApiController]
+[Route("api/admin/themes")]
+[Authorize(Policy = Permissions.Themes.View)]
+public class TransferController : Controller
+{
+    private readonly DatabaseRepository<Theme> ThemeRepository;
+
+    public TransferController(DatabaseRepository<Theme> themeRepository)
+    {
+        ThemeRepository = themeRepository;
+    }
+
+    [HttpGet("{id:int}/export")]
+    public async Task<ActionResult> ExportAsync([FromRoute] int id)
+    {
+        var theme = await ThemeRepository
+            .Query()
+            .FirstOrDefaultAsync(x => x.Id == id);
+
+        if (theme == null)
+            return Problem("No theme with that id found", statusCode: 404);
+
+        var yml = YamlSerializer.Serialize(new ThemeTransferModel()
+        {
+            Name = theme.Name,
+            Author = theme.Author,
+            CssContent = theme.CssContent,
+            Version = theme.Version
+        });
+
+        return File(yml.ToArray(), "text/yaml", $"{theme.Name}.yml");
+    }
+
+    [HttpPost("import")]
+    public async Task<ActionResult<ThemeDto>> ImportAsync()
+    {
+        var themeToImport = await YamlSerializer.DeserializeAsync<ThemeTransferModel>(Request.Body);
+
+        var existingTheme = await ThemeRepository
+            .Query()
+            .FirstOrDefaultAsync(x => x.Name == themeToImport.Name && x.Author == themeToImport.Author);
+
+        if (existingTheme == null)
+        {
+            var finalTheme = await ThemeRepository.AddAsync(new Theme()
+            {
+                Name = themeToImport.Name,
+                Author = themeToImport.Author,
+                CssContent = themeToImport.CssContent,
+                Version = themeToImport.Version
+            });
+
+            return ThemeMapper.ToDto(finalTheme);
+        }
+
+        existingTheme.CssContent = themeToImport.CssContent;
+        existingTheme.Version = themeToImport.Version;
+
+        await ThemeRepository.UpdateAsync(existingTheme);
+
+        return ThemeMapper.ToDto(existingTheme);
+    }
+}