Adds the CRUD API plugin. Closes #437 (#445)

Author: waldekmastykarz

dev-proxy-plugins/MockResponses/CrudApiDefinitionLoader.cs

@@ -0,0 +1,114 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Microsoft.DevProxy.Abstractions;
+using System.Text.Json;
+
+namespace Microsoft.DevProxy.Plugins.MockResponses;
+
+internal class CrudApiDefinitionLoader : IDisposable
+{
+    private readonly ILogger _logger;
+    private readonly CrudApiConfiguration _configuration;
+
+    public CrudApiDefinitionLoader(ILogger logger, CrudApiConfiguration configuration)
+    {
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _configuration = configuration ?? throw new ArgumentNullException(nameof(configuration));
+    }
+
+    private FileSystemWatcher? _watcher;
+
+    public void LoadApiDefinition()
+    {
+        if (!File.Exists(_configuration.ApiFile))
+        {
+            _logger.LogWarn($"File {_configuration.ApiFile} not found. CRUD API will be disabled");
+            return;
+        }
+
+        try
+        {
+            using (FileStream stream = new FileStream(_configuration.ApiFile, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
+            {
+                using (StreamReader reader = new StreamReader(stream))
+                {
+                    var apiDefinitionString = reader.ReadToEnd();
+                    var apiDefinitionConfig = JsonSerializer.Deserialize<CrudApiConfiguration>(apiDefinitionString);
+                    _configuration.BaseUrl = apiDefinitionConfig?.BaseUrl ?? string.Empty;
+                    _configuration.DataFile = apiDefinitionConfig?.DataFile ?? string.Empty;
+
+                    IEnumerable<CrudApiAction>? configResponses = apiDefinitionConfig?.Actions;
+                    if (configResponses is not null)
+                    {
+                        _configuration.Actions = configResponses;
+                        foreach (var action in _configuration.Actions)
+                        {
+                            if (string.IsNullOrEmpty(action.Method))
+                            {
+                                action.Method = action.Action switch
+                                {
+                                    CrudApiActionType.Create => "POST",
+                                    CrudApiActionType.GetAll => "GET",
+                                    CrudApiActionType.GetOne => "GET",
+                                    CrudApiActionType.Merge => "PATCH",
+                                    CrudApiActionType.Update => "PUT",
+                                    CrudApiActionType.Delete => "DELETE",
+                                    _ => throw new InvalidOperationException($"Unknown action type {action.Action}")
+                                };
+                            }
+                        }
+                        _logger.LogInfo($"{configResponses.Count()} actions for CRUD API loaded from {_configuration.ApiFile}");
+                    }
+                }
+            }
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError($"An error has occurred while reading {_configuration.ApiFile}:");
+            _logger.LogError(ex.Message);
+        }
+    }
+
+    public void InitApiDefinitionWatcher()
+    {
+        if (_watcher is not null)
+        {
+            return;
+        }
+
+        string path = Path.GetDirectoryName(_configuration.ApiFile) ?? throw new InvalidOperationException($"{_configuration.ApiFile} is an invalid path");
+        if (!File.Exists(_configuration.ApiFile))
+        {
+            _logger.LogWarn($"File {_configuration.ApiFile} not found. No CRUD API will be provided");
+            _configuration.Actions = Array.Empty<CrudApiAction>();
+            return;
+        }
+
+        _watcher = new FileSystemWatcher(Path.GetFullPath(path))
+        {
+            NotifyFilter = NotifyFilters.CreationTime
+                             | NotifyFilters.FileName
+                             | NotifyFilters.LastWrite
+                             | NotifyFilters.Size,
+            Filter = Path.GetFileName(_configuration.ApiFile),
+            EnableRaisingEvents = true
+        };
+        _watcher.Changed += ApiDefinitionFile_Changed;
+        _watcher.Created += ApiDefinitionFile_Changed;
+        _watcher.Deleted += ApiDefinitionFile_Changed;
+        _watcher.Renamed += ApiDefinitionFile_Changed;
+
+        LoadApiDefinition();
+    }
+
+    private void ApiDefinitionFile_Changed(object sender, FileSystemEventArgs e)
+    {
+        LoadApiDefinition();
+    }
+
+    public void Dispose()
+    {
+        _watcher?.Dispose();
+    }
+}