Windsurf Case Study: Solo Developer Rebuilds Legacy PHP Inventory System to Next.js in 2 Weeks
From Legacy PHP to Modern Next.js: A Solo Developer’s 2-Week Sprint with Windsurf
When a solo developer faced the daunting task of rebuilding a decade-old PHP inventory management system into a modern Next.js application, the timeline seemed impossible. Two weeks. One person. Thousands of lines of legacy code. This case study documents how Windsurf’s AI-powered development environment made it happen — covering database migration, API routes, and frontend components simultaneously through Cascade flows, multi-file editing, and intelligent code generation.
The Challenge: Legacy PHP Inventory System
The existing system was a monolithic PHP 5.6 application with direct MySQL queries, no API layer, and jQuery-based frontend templates. Key pain points included:
- Over 15,000 lines of procedural PHP with no MVC structure- Raw SQL queries scattered across 40+ files- No authentication beyond basic session handling- Zero test coverage and manual deployment via FTPThe target architecture was a Next.js 14 App Router application with Prisma ORM, PostgreSQL, NextAuth.js for authentication, and a component library built on Tailwind CSS.
Step 1: Setting Up Windsurf and Project Scaffolding
The first step was installing Windsurf and initializing the project.
# Download and install Windsurf from the official site
Then open the terminal inside Windsurf
npx create-next-app@latest inventory-pro —typescript —tailwind —app —src-dir
cd inventory-pro
npm install prisma @prisma/client next-auth @auth/prisma-adapter
npx prisma init
Inside Windsurf, the developer opened the legacy PHP project alongside the new Next.js project using the multi-root workspace feature. This allowed Cascade to reference the old codebase while generating new code.
Configuring Windsurf for the Project
A .windsurfrules file was created at the project root to guide AI behavior:
# .windsurfrules
You are helping rebuild a legacy PHP inventory system into Next.js 14.
Use App Router, Server Components by default, and Prisma for all database access.
Follow this stack: TypeScript, Tailwind CSS, Prisma, PostgreSQL, NextAuth.js.
Never use raw SQL. Always use Prisma Client methods.
Use Zod for all input validation on API routes.
Step 2: Database Migration with Cascade Flows
The developer used Windsurf's Cascade feature to analyze the legacy MySQL schema and generate a Prisma schema. By opening the old database.sql dump and prompting Cascade:
**Cascade Prompt:** *"Analyze this MySQL dump and generate a complete Prisma schema with proper relations, indexes, and enums. Map the legacy table structure to modern conventions with camelCase fields."*
Cascade produced a complete schema.prisma file:
// prisma/schema.prisma
generator client {
provider = "prisma-client-js"
}
datasource db {
provider = “postgresql”
url = env(“DATABASE_URL”)
}
model Product {
id String @id @default(cuid())
sku String @unique
name String
description String?
price Decimal @db.Decimal(10, 2)
costPrice Decimal @db.Decimal(10, 2)
quantity Int @default(0)
minStock Int @default(5)
categoryId String
category Category @relation(fields: [categoryId], references: [id])
movements StockMovement[]
createdAt DateTime @default(now())
updatedAt DateTime @updatedAt
@@index([categoryId])
@@index([sku])
}
model Category {
id String @id @default(cuid())
name String @unique
products Product[]
}
model StockMovement {
id String @id @default(cuid())
productId String
product Product @relation(fields: [productId], references: [id])
type MovementType
quantity Int
note String?
createdAt DateTime @default(now())
@@index([productId])
}
enum MovementType {
IN
OUT
ADJUSTMENT
}
Then the migration was executed:
npx prisma migrate dev —name init
npx prisma generate
Step 3: Multi-File API Route Generation
This is where Windsurf's multi-file editing became critical. The developer selected all legacy PHP endpoint files and prompted Cascade to generate corresponding Next.js API routes. Windsurf edited multiple files simultaneously — creating route handlers, validation schemas, and shared utilities in a single pass.
**Cascade Prompt:** *"Create Next.js App Router API routes for products CRUD. Include Zod validation, error handling, and pagination. Reference the Prisma schema for types."*
Windsurf generated the following across multiple files at once:
// src/app/api/products/route.ts
import { prisma } from "@/lib/prisma";
import { NextRequest, NextResponse } from "next/server";
import { z } from "zod";
const createProductSchema = z.object({
sku: z.string().min(1).max(50),
name: z.string().min(1).max(255),
description: z.string().optional(),
price: z.number().positive(),
costPrice: z.number().positive(),
quantity: z.number().int().min(0).default(0),
minStock: z.number().int().min(0).default(5),
categoryId: z.string().cuid(),
});
export async function GET(request: NextRequest) {
const { searchParams } = new URL(request.url);
const page = parseInt(searchParams.get(“page”) || “1”);
const limit = parseInt(searchParams.get(“limit”) || “20”);
const search = searchParams.get(“search”) || "";
const where = search
? { OR: [{ name: { contains: search, mode: “insensitive” as const } }, { sku: { contains: search, mode: “insensitive” as const } }] }
: {};
const [products, total] = await Promise.all([
prisma.product.findMany({
where,
include: { category: true },
skip: (page - 1) * limit,
take: limit,
orderBy: { updatedAt: “desc” },
}),
prisma.product.count({ where }),
]);
return NextResponse.json({ products, total, page, totalPages: Math.ceil(total / limit) });
}
export async function POST(request: NextRequest) {
try {
const body = await request.json();
const data = createProductSchema.parse(body);
const product = await prisma.product.create({ data, include: { category: true } });
return NextResponse.json(product, { status: 201 });
} catch (error) {
if (error instanceof z.ZodError) {
return NextResponse.json({ errors: error.errors }, { status: 400 });
}
return NextResponse.json({ error: “Internal server error” }, { status: 500 });
}
}
Step 4: Frontend Components via Cascade Flows
Cascade flows allowed chaining multiple generation steps. The developer created a flow that sequentially built the product listing table, search/filter bar, stock movement form, and dashboard summary — each step aware of the previous components.
// src/components/products/product-table.tsx
"use client";
import { useState } from "react";
import { useRouter } from "next/navigation";
interface Product {
id: string;
sku: string;
name: string;
quantity: number;
minStock: number;
price: number;
category: { name: string };
}
export function ProductTable({ products }: { products: Product[] }) {
const router = useRouter();
return (
{products.map((product) => (
router.push(`/products/${product.id}`)} className="cursor-pointer hover:bg-gray-50">
))}
SKU
Name
Category
Stock
Price
{product.sku}
{product.name}
{product.category.name}
{product.quantity}
${product.price.toFixed(2)}
);
}
Results: 2-Week Outcome
| Metric | Legacy PHP | New Next.js |
|---|---|---|
| Codebase Size | 15,000+ lines | 4,200 lines |
| Page Load Time | 3.2 seconds | 0.4 seconds |
| API Response (avg) | 850ms | 120ms |
| Test Coverage | 0% | 78% |
| Deployment | Manual FTP | Vercel CI/CD |
| Development Time | Original: 6 months | Rebuild: 2 weeks |
.windsurfrules file updated as your architecture solidifies. Cascade references it on every prompt, so adding schema constraints and naming conventions here saves correction cycles.- **Use multi-file edits for refactors:** When renaming a model field, select all files that reference it and ask Cascade to rename in one pass. This avoids broken imports and type errors.- **Chain Cascade flows for full features:** Prompt the API route first, then the server component, then the client component in sequence. Each step gets the context of the previous output, producing coherent end-to-end features.- **Leverage Supercomplete for Prisma queries:** Start typing a Prisma method like prisma.product.findMany( and let Supercomplete fill in the include, where, and orderBy clauses based on your schema.- **Pin legacy files as context:** When rewriting a specific PHP file, pin it in the editor tab so Cascade always sees the original logic while generating the replacement.
## Troubleshooting Common Issues
Cascade generates outdated Next.js patterns (Pages Router)
If Cascade produces getServerSideProps or pages/api patterns, add this to your .windsurfrules:
Always use Next.js 14 App Router. Never use Pages Router, getServerSideProps, or getStaticProps.
Use server components by default. Use route handlers in app/api/ directory.
### Prisma Client not reflecting schema changes
After editing schema.prisma, you must regenerate the client:
npx prisma generate
# If types still don't update in Windsurf, restart the TypeScript server:
# Cmd/Ctrl + Shift + P → "TypeScript: Restart TS Server"
### Multi-file edit applies changes to wrong files
This typically happens when multiple files have similar names. Close unrelated tabs and explicitly mention file paths in your Cascade prompt: *"Edit src/app/api/products/route.ts and src/app/api/products/[id]/route.ts only."*
Environment variables not loaded in API routes
Ensure your .env file is at the project root and variables are formatted correctly:
DATABASE_URL=“postgresql://user:password@localhost:5432/inventory_db”
NEXTAUTH_SECRET=“YOUR_SECRET_KEY”
NEXTAUTH_URL=“http://localhost:3000”
Frequently Asked Questions
Can Windsurf handle database migration from MySQL to PostgreSQL directly?
Windsurf's Cascade can generate the Prisma schema by analyzing your legacy SQL dump or PHP database code, but the actual data migration requires a separate tool like pgloader or a custom script. Cascade excels at translating schema structures, generating the Prisma models, and creating seed scripts — but you will need to run the data transfer outside the IDE. A common workflow is to prompt Cascade to generate a migration script that reads from your MySQL export and writes Prisma seed commands for PostgreSQL.
How does Windsurf’s multi-file editing compare to Cursor or GitHub Copilot?
Windsurf’s Cascade flows are specifically designed for coordinated multi-file changes where edits in one file depend on the content of another. Unlike single-file inline completions, Cascade maintains a working context across all open and pinned files, so generating an API route, its types, and the consuming frontend component happens in one coherent pass. This is particularly powerful for full-stack refactors where a schema change cascades through the data layer, API, and UI simultaneously.
Is Windsurf free to use for a project like this?
Windsurf offers a free tier that includes access to the editor and basic AI completions. For the heavy Cascade flow usage described in this case study — including multi-file generation, long-context analysis of legacy code, and chained prompts — a Pro subscription is recommended. The Pro tier provides significantly more Cascade credits and access to faster models, which made the 2-week timeline feasible for this rebuild.