src/lib/api/README.md

# Centralized API Calls with Axios Interceptors

This directory contains the implementation of a centralized API client using Axios with interceptors for the PM Tool application.

## Structure

- `axios-instance.ts`: Contains the core Axios instance with configured interceptors for authentication, error handling, etc.
- `api-utils.ts`: Contains utility functions for common HTTP methods (GET, POST, PUT, PATCH, DELETE) with standardized error handling and response formatting.
- `index.ts`: Exports all API functionality for easier importing.

## Features

- **Authentication**: Automatically adds authentication tokens to each request
- **Error Handling**: Centralized error handling with custom error messages
- **Response Formatting**: Standardized response format for all API calls
- **Token Refresh**: Support for token refresh flow (to be implemented)
- **File Uploads**: Special handling for file uploads with progress tracking

## Usage

### Basic API Calls

Import the API functions from the library:

```typescript
import { get, getList, post, put, patch, del } from '../lib/api/api-utils';
```

Then use them in your service:

```typescript
// GET a single item
const response = await get<User>('/api/users/1');

// GET a list of items
const response = await getList<User>('/api/users');

// POST to create a new item
const response = await post<User, UserCreateRequest>('/api/users', newUser);

// PUT to update an item
const response = await put<User, UserUpdateRequest>('/api/users/1', updatedUser);

// PATCH to partially update an item
const response = await patch<User>('/api/users/1', { name: 'Updated Name' });

// DELETE an item
const response = await del('/api/users/1');
```

### File Uploads

```typescript
import { uploadFile } from '../lib/api/api-utils';

// Upload a file with progress tracking
const response = await uploadFile(
  '/api/documents',
  file,
  { documentType: 'invoice' },
  (progress) => {
    console.log(`Upload progress: ${progress}%`);
  }
);
```

### Direct Access to Axios Instance

If you need more control, you can import the Axios instance directly:

```typescript
import { apiClient } from '../lib/api';

// Use it directly
const response = await apiClient.get('/api/custom-endpoint');
```

## Response Format

All API calls return a standardized response format:

```typescript
interface ResponseData<T> {
  data: T;           // The actual response data
  success: boolean;  // Whether the request was successful
  message: string;   // A message describing the result
}
```

## Error Handling

Errors are automatically handled and transformed into the same response format with:
- `success` set to `false`
- `data` set to a default value (empty object or array)
- `message` containing the error message

## Authentication

The API client automatically adds the authentication token to each request if available in localStorage.