# Library Usage
How each major library is used in the application.
## Next.js
**Usage**: Web framework with App Router
**Key Features Used**:
- Server Components (default)
- Client Components (`'use client'`)
- API Routes (Route Handlers)
- Middleware for authentication
- Server-side data fetching
**Example**:
```typescript
// Server Component
export default async function Page() {
const data = await db.getData();
return <div>{data}</div>;
}
// API Route
export async function GET() {
return NextResponse.json({ data });
}
```
## React
**Usage**: UI library
**Key Features Used**:
- Server Components (Next.js)
- Client Components with hooks
- Server Actions (if used)
**Example**:
```typescript
'use client';
import { useState, useEffect } from 'react';
export default function Component() {
const [state, setState] = useState();
// ...
}
```
## NextAuth.js
**Usage**: Authentication library
**Configuration**: `equity/app/api/auth/[...nextauth]/route.ts`
**Providers**:
- Credentials (email/password)
- Google OAuth
**Session Strategy**:
- JWT for credentials
- Database for OAuth
**Usage**:
```typescript
import { getServerSession } from 'next-auth';
import { useSession } from 'next-auth/react';
// Server
const session = await getServerSession(authOptions);
// Client
const { data: session } = useSession();
```
## mysql2
**Usage**: MySQL client with connection pooling
**Location**: `equity/lib/db.ts`
**Features Used**:
- Connection pooling (10 connections)
- Prepared statements
- Transactions
**Example**:
```typescript
import { query, insert, transaction } from '@/lib/db';
const rows = await query('SELECT * FROM users WHERE id = ?', [userId]);
const id = await insert('INSERT INTO users ...', [values]);
await transaction(async (conn) => {
// Multiple operations
});
```
## KiteConnect
**Usage**: Zerodha Kite Connect SDK
**Location**: `equity/lib/kite-service.ts`, `src/index.ts`
**Features Used**:
- Authentication (login, generate session)
- Market data (quotes, OHLC, historical)
- Portfolio (holdings, positions, margins)
- Trading (place, modify, cancel orders)
**Example**:
```typescript
import { executeKiteTool } from '@/lib/kite-service';
const holdings = await executeKiteTool('get_holdings', {
account_id: 1,
user_id: 1
});
```
## Zustand
**Usage**: State management for client-side data
**Location**: `equity/store/useKiteStore.ts`
**Features Used**:
- Store for Kite account data
- Consolidation helpers
**Example**:
```typescript
import { useKiteStore } from '@/store/useKiteStore';
const { accountData, setAccountData } = useKiteStore();
```
## Tailwind CSS
**Usage**: Utility-first CSS framework
**Configuration**: `equity/postcss.config.mjs`
**Usage**: Utility classes throughout components
**Example**:
```tsx
<div className="bg-white shadow-sm border-b border-gray-200">
<div className="max-w-7xl mx-auto px-4">
{/* ... */}
</div>
</div>
```
## csv-parse
**Usage**: CSV file parsing
**Location**: `equity/app/api/import/*/route.ts`
**Example**:
```typescript
import { parse } from 'csv-parse/sync';
const records = parse(csvContent, {
columns: true,
skip_empty_lines: true
});
```
## xirr
**Usage**: XIRR calculation library
**Location**: `equity/lib/xirr-calculator.ts`
**Example**:
```typescript
import { calculateXIRR } from 'xirr';
const cashFlows = [
{ amount: -10000, when: new Date('2020-01-01') },
{ amount: 12000, when: new Date('2021-01-01') }
];
const xirr = calculateXIRR(cashFlows);
```
## bcryptjs
**Usage**: Password hashing
**Location**: `equity/app/api/register/route.ts`, `equity/app/api/auth/[...nextauth]/route.ts`
**Example**:
```typescript
import bcrypt from 'bcryptjs';
const hashed = await bcrypt.hash(password, 10);
const isValid = await bcrypt.compare(password, hashed);
```
## Resend
**Usage**: Email service API
**Location**: `equity/app/api/register/route.ts`
**Example**:
```typescript
import { Resend } from 'resend';
const resend = new Resend(process.env.RESEND_API_KEY);
await resend.emails.send({
from: process.env.EMAIL_FROM,
to: email,
subject: 'Verify your email',
html: emailContent
});
```
