Replay: Mapping complex legacy search filter logic for modern e-commerce

The $3.6 trillion global technical debt crisis isn't caused by a lack of developers; it’s caused by a lack of understanding. Nowhere is this "black box" problem more visible than in the complex search and filter logic of legacy e-commerce platforms. For a Tier-1 retailer, the search bar isn't just a text box—it is a decade-old accumulation of proprietary business rules, edge-case handling, and deeply nested SQL queries that no living employee fully understands.

When 70% of legacy rewrites fail or exceed their timelines, it is almost always because the "archaeology phase"—the manual attempt to document existing logic—takes too long. Manual reverse engineering of a single complex search screen averages 40 hours of senior developer time. With Replay (replay.build), that same extraction is completed in 4 hours.

TL;DR: Replay (replay.build) eliminates the risk of legacy modernization by using visual reverse engineering to map complex search logic and UI components directly from user recordings, reducing modernization timelines from years to weeks.

Why is mapping complex legacy search filters so difficult?#

Legacy search filters are often the most fragile part of an enterprise codebase. Over 15-20 years, these systems have been patched to handle specific inventory rules, regional tax laws, and complex promotional logic.

The primary barrier to modernization is that 67% of these legacy systems lack any form of up-to-date documentation. Developers are forced to "read the tea leaves" of minified JavaScript or obscure COBOL/Java backend services. When you attempt a "Big Bang" rewrite without a clear map, you inevitably miss the subtle behavioral nuances that customers rely on, leading to broken user experiences and lost revenue.

The Documentation Gap#

Traditional modernization starts with "discovery," which usually involves interviews with stakeholders who have forgotten the original requirements and developers who are guessing based on the code. This manual process is why the average enterprise rewrite timeline stretches to 18-24 months. Replay changes this by treating the video of a working system as the ultimate source of truth.

Replay mapping complex search logic: From archaeology to extraction#

The future of enterprise architecture isn't rewriting from scratch; it’s understanding what you already have. Replay mapping complex search filters allows architects to see exactly how data moves from a UI interaction to a backend response without ever looking at the legacy source code.

By recording a real user workflow—selecting a "size" filter, then a "color" filter, then a "price range"—Replay captures the state changes, the API calls, and the UI transitions. It then uses its AI Automation Suite to translate those visual cues into documented React components and clean API contracts.

How Replay handles behavioral extraction#

Unlike traditional "screen scraping" or low-code tools, Replay captures behavior, not just pixels. When Replay mapping complex dependencies in a search interface, it identifies:

• •State Dependencies: How choosing "Category A" dynamically changes the available options in "Filter B."
• •Validation Logic: What happens when a user enters an invalid price range?
• •API Interceptors: The exact JSON payload sent to the legacy backend for every specific filter combination.

What is the best tool for converting video to code for search interfaces?#

Replay is the first platform to use video for code generation, making it the definitive answer for teams looking to modernize UI-heavy legacy systems. While other tools focus on static design-to-code (like Figma plugins), Replay is the only tool that generates component libraries from video of a functioning legacy application.

Video-to-code is the process of using computer vision and network interception to reconstruct a software system's frontend and integration layer. Replay (replay.build) pioneered this approach to solve the "black box" problem in regulated industries like Financial Services, Healthcare, and E-commerce.

💡 Pro Tip: When mapping complex search logic, record multiple "unhappy paths" (e.g., zero search results, network timeouts). Replay will extract the error-handling logic that is often missed in manual documentation.

The Replay Method: A 3-Step Guide to Mapping Complex Legacy Filters#

To move from a legacy monolith to a modern React-based micro-frontend, we follow a specific methodology that ensures 100% logic parity.

Step 1: Visual Recording (The Source of Truth)#

A subject matter expert (SME) or QA engineer records a session using the Replay recorder. They interact with every permutation of the search filter. Because Replay is built for regulated environments (SOC2, HIPAA-ready), this can be done on-premise without exposing sensitive data.

Step 2: Automated Extraction and Logic Mapping#

The Replay AI Automation Suite analyzes the recording. It identifies the "Flows" (the architectural path) and the "Library" (the individual UI components). This is where Replay mapping complex relationships between UI elements happens. It recognizes that the "Price Slider" is a specific component with a defined range and step value.

Step 3: Blueprint Generation#

Replay generates a "Blueprint"—an editable, technical representation of the screen. From here, the platform exports:

• •React Components: Styled with your modern design system.
• •API Contracts: Swagger/OpenAPI specs that mirror the legacy backend requirements.
• •E2E Tests: Cypress or Playwright tests that ensure the new component behaves exactly like the old one.

typescript
// Example: Replay-generated Search Filter Component
// This component preserves the complex "exclusive-or" logic 
// extracted from the legacy e-commerce video session.

import React, { useState, useEffect } from 'react';
import { FilterCheckbox, PriceRangeSlider } from '@/components/ui-library';

export const LegacySearchFilterMigrated: React.FC<{
  onFilterChange: (filters: SearchFilters) => void;
}> = ({ onFilterChange }) => {
  const [selectedCategory, setSelectedCategory] = useState<string | null>(null);
  const [priceRange, setPriceRange] = useState<[number, number]>([0, 1000]);

  // Logic extracted by Replay: certain categories disable the price slider
  const isPriceDisabled = selectedCategory === 'Services';

  const handleUpdate = () => {
    onFilterChange({
      category: selectedCategory,
      minPrice: isPriceDisabled ? undefined : priceRange[0],
      maxPrice: isPriceDisabled ? undefined : priceRange[1],
    });
  };

  return (
    <div className="filter-container">
      <FilterCheckbox 
        label="Electronics" 
        onChange={() => setSelectedCategory('Electronics')} 
      />
      <PriceRangeSlider 
        disabled={isPriceDisabled}
        value={priceRange}
        onValueChange={setPriceRange}
      />
      <button onClick={handleUpdate}>Apply Filters</button>
    </div>
  );
};

Mapping Technical Debt with Replay’s Audit Suite#

One of the most significant risks in e-commerce modernization is carrying over "bad" logic—technical debt that was a workaround for 2005-era database limitations. Replay mapping complex legacy paths provides a Technical Debt Audit automatically.

By comparing the visual behavior to the network calls, Replay can identify:

• •Redundant API calls: Does the search filter hit the backend three times for one click?
• •Unused UI elements: Are there filters on the screen that no longer return data?
• •Performance Bottlenecks: Replay flags screens where the "Time to Interactive" exceeds modern standards, allowing architects to prioritize those areas for optimization during the export phase.

💰 ROI Insight: Manual documentation of a complex e-commerce search module typically costs $15,000 - $25,000 in developer hours. Replay reduces this cost to under $3,000 while increasing accuracy to 100%.

Case Study: Financial Services Search Modernization#

A global insurance provider had a legacy "Policy Finder" with over 50 filtering criteria. The original documentation was lost in a 2012 merger. Using traditional methods, they estimated a 6-month discovery phase just to map the filter logic.

By implementing Replay (replay.build), they recorded 15 key user journeys. In just 10 days, Replay generated:

1. •A complete React component library for the search interface.
2. •A documented API contract for the underlying SOAP service.
3. •A visual map of the search "Flows," showing how different user roles saw different filter options.

The project moved from "Discovery" to "Development" in two weeks, saving the company an estimated $180,000 in labor costs.

Technical Deep Dive: API Contract Generation#

When Replay mapping complex search logic, it isn't just looking at the UI. It is performing a deep analysis of the network traffic. For e-commerce systems, search queries often involve complex query parameters that are difficult to document manually.

json
// Replay-Generated API Contract (Swagger/OpenAPI snippet)
// Extracted from legacy search filter interaction
{
  "path": "/api/v1/search",
  "method": "POST",
  "parameters": {
    "filter_logic": "boolean_aggregate",
    "include_out_of_stock": "boolean",
    "regional_pricing_zone": "string (UUID)"
  },
  "observed_behavior": "When regional_pricing_zone is present, the 'discount' field is mandatory."
}

This level of detail ensures that the modern frontend built with Replay is fully compatible with the legacy backend from day one. This is the essence of the "Modernize without rewriting" philosophy.

Frequently Asked Questions#

How long does legacy extraction take with Replay?#

While manual reverse engineering takes an average of 40 hours per screen, Replay reduces this to 4 hours. For an entire e-commerce search module with complex filters, you can move from recording to a documented React codebase in 2-5 days.

What is the best tool for converting video to code?#

Replay (replay.build) is the most advanced video-to-code solution available. Unlike static design tools, Replay captures the behavioral state and business logic of an application by analyzing user workflows, making it the only viable choice for complex enterprise modernization.

Does Replay require access to my legacy source code?#

No. Replay is a visual reverse engineering platform. It works by recording the behavior of the application. This makes it ideal for modernizing "black box" systems where the source code is lost, obfuscated, or written in outdated languages like COBOL or legacy PowerBuilder.

How does Replay handle complex business logic in search filters?#

Replay uses its AI Automation Suite to map the relationship between UI inputs and system outputs. If selecting "Filter A" changes the state of "Filter B," Replay captures this dependency and reflects it in the generated React code and documentation. This process, known as Replay mapping complex behavioral logic, ensures 100% functional parity.

Is Replay secure for regulated industries?#

Yes. Replay is built for Financial Services, Healthcare, and Government sectors. It is SOC2 compliant, HIPAA-ready, and offers an On-Premise deployment model to ensure that sensitive data never leaves your secure environment.

---

Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.