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a7476ec | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 | # Code Review & Refactoring Report
## Overview
This report analyzes the current codebase (`sockets` project) and provides actionable feedback to improve maintainability, performance, and structure. The project uses **Express** and **ws** for a simple WebSocket server with room management.
---
## 1. Architectural Improvements
### Issue: specialized "Service" instantiated per message
Currently, a new `MessageService` instance is created for every single incoming message.
```typescript
// src/index.ts
new MessageService({ msg: msg.toString(), ... })
```
This is inefficient and semantically incorrect for a "Service". A Service should ideally be a singleton or a static utility that handles logic, rather than an ephemeral object representing a single request.
**Recommendation:**
Refactor `MessageService` to contain static methods or be a singleton instance that accepts the message and socket as arguments to a `handleMessage` method.
### Issue: Tight Coupling and Logic in Constructor
Critical business logic (parsing, routing, executing side effects) happens inside the `constructor` of `MessageService`.
```typescript
// src/services/MessageService.ts
constructor(...) {
// ... logic ...
if(action === 'join') ...
}
```
Constructors should primarily initialize state. Side effects (like broadcasting messages) should happen in explicit methods.
**Recommendation:**
Move logic out of the constructor. Create a `handleIncomingMessage(data: string, socket: WebSocket)` method.
---
## 2. Robustness and Error Handling
### Issue: Unsafe `JSON.parse`
If a client sends an invalid JSON string, `JSON.parse(msg)` inside `MessageService` will throw an error. Since this is not wrapped in a `try-catch` block, it could crash the application or unexpectedly terminate the socket connection.
**Recommendation:**
Wrap the parsing logic in a `try-catch` block. If parsing fails, send an error response to the sender and abort processing.
### Issue: Missing Input Validation
The code assumes `room_id`, `username`, and `action` always exist in the parsed payload.
```typescript
this.room_id = layers['room_id'] // Could be undefined
```
Accessing properties on undefined or unexpected data types can lead to runtime errors.
**Recommendation:**
Use a schema validation library (like **Zod**) or manual checks to ensure incoming data matches the expected structure (Interface) before processing.
---
## 3. Type Safety and TypeScript Best Practices
### Issue: `any` types implicitly
`JSON.parse` returns `any`. You should define an interface for your message structure.
```typescript
interface WebSocketMessage {
room_id: string
username: string
message: string
action: 'join' | 'leave' | 'message'
}
```
### Issue: Encapsulation
In `RoomServices`, the `map` property is public.
```typescript
map: Map<string, Map<string, WebSocket>>
```
This allows external code to modify the state directly, bypassing helper methods like `leaveRoom`.
**Recommendation:**
Make `map` private: `private map: Map<...>`.
---
## 4. Code Cleanliness & Manageability
### Magic Strings
Strings like `'join'` and `'leave'` are hardcoded in multiple places.
**Recommendation:** use an `enum` or constants for Action types.
```typescript
enum SocketAction {
JOIN = 'join',
LEAVE = 'leave',
MESSAGE = 'message',
}
```
### Duplicate Logic
In `MessageService.broadcast`, the check for room existence is repeated redundant calls.
---
## Proposed Refactored Structure
### `src/types.ts`
Define shared interfaces and enums here.
### `src/services/RoomManager.ts` (Renamed from RoomServices)
Keep it focused on state management (add, remove, get users). Ensure data is private.
### `src/handlers/MessageHandler.ts` (Renamed from MessageService)
A stateless function or class that:
1. Parses the message (safely).
2. Validates the schema.
3. Calls the appropriate action on `RoomServices`.
### `src/index.ts`
Initialize the `App` and pass the singletons/handlers to the WebSocket event listener.
---
## Summary of Next Steps
1. **Safety**: Add `try-catch` around JSON parsing.
2. **Organization**: Separate "Data Types" from "Logic".
3. **Pattern**: Stop `new MessageService(...)` pattern. Use `MessageController.handle(...)`.
4. **Resilience**: Validate all inputs before using them.
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