microsoft/TypeAgent
Publicmirrored from https://github.com/microsoft/TypeAgentAvailable
dotnet/autoShell/Handlers/ActionHandlerBase.cs
76lines · modecode
| 1 | // Copyright (c) Microsoft Corporation. |
| 2 | // Licensed under the MIT License. |
| 3 | |
| 4 | using System; |
| 5 | using System.Collections.Generic; |
| 6 | using System.Text.Json; |
| 7 | |
| 8 | namespace autoShell.Handlers; |
| 9 | |
| 10 | /// <summary> |
| 11 | /// Base class for all action handlers. Co-registers action names and handler functions |
| 12 | /// via <see cref="AddAction"/> or <see cref="AddAction{T}"/>, providing automatic |
| 13 | /// <see cref="SupportedActions"/> and dictionary-based dispatch. |
| 14 | /// Subclasses register actions in their constructor. |
| 15 | /// </summary> |
| 16 | internal abstract class ActionHandlerBase : IActionHandler |
| 17 | { |
| 18 | private static readonly JsonSerializerOptions CamelCaseOptions = new() |
| 19 | { |
| 20 | PropertyNameCaseInsensitive = true |
| 21 | }; |
| 22 | |
| 23 | private readonly Dictionary<string, Func<JsonElement, ActionResult>> _actions = new(StringComparer.OrdinalIgnoreCase); |
| 24 | |
| 25 | /// <inheritdoc/> |
| 26 | public IEnumerable<string> SupportedActions => _actions.Keys; |
| 27 | |
| 28 | /// <summary> |
| 29 | /// Registers an action name and its handler function. Throws if the name is already registered. |
| 30 | /// </summary> |
| 31 | protected void AddAction(string actionName, Func<JsonElement, ActionResult> handler) |
| 32 | { |
| 33 | if (!_actions.TryAdd(actionName, handler)) |
| 34 | { |
| 35 | throw new InvalidOperationException( |
| 36 | $"Action '{actionName}' is already registered in {GetType().Name}."); |
| 37 | } |
| 38 | } |
| 39 | |
| 40 | /// <summary> |
| 41 | /// Registers an action with a strongly-typed parameter record. |
| 42 | /// The <see cref="JsonElement"/> is automatically deserialized to <typeparamref name="T"/>. |
| 43 | /// </summary> |
| 44 | protected void AddAction<T>(string actionName, Func<T, ActionResult> handler) |
| 45 | { |
| 46 | AddAction(actionName, parameters => |
| 47 | { |
| 48 | T typed; |
| 49 | try |
| 50 | { |
| 51 | if (parameters.ValueKind is JsonValueKind.Undefined or JsonValueKind.Null) |
| 52 | { |
| 53 | return ActionResult.Fail($"Invalid parameters for '{actionName}': parameters are missing or null"); |
| 54 | } |
| 55 | typed = JsonSerializer.Deserialize<T>(parameters.GetRawText(), CamelCaseOptions); |
| 56 | } |
| 57 | catch (JsonException ex) |
| 58 | { |
| 59 | return ActionResult.Fail($"Invalid parameters for '{actionName}': {ex.Message}"); |
| 60 | } |
| 61 | if (typed == null) |
| 62 | { |
| 63 | return ActionResult.Fail($"Invalid parameters for '{actionName}': null parameters not allowed"); |
| 64 | } |
| 65 | return handler(typed); |
| 66 | }); |
| 67 | } |
| 68 | |
| 69 | /// <inheritdoc/> |
| 70 | public virtual ActionResult Handle(string key, JsonElement parameters) |
| 71 | { |
| 72 | return _actions.TryGetValue(key, out var handler) |
| 73 | ? handler(parameters) |
| 74 | : ActionResult.Fail($"Unknown action: {key}"); |
| 75 | } |
| 76 | } |
| 77 | |