This PR implements a production-ready SQL Minifier utility that addresses all the issues identified in PR #85's code review. The original implementation had several critical flaws that could break SQL syntax and produce incorrect results.

Issues Fixed

1. Improper Comment Removal

Problem: The original regex --.*$ only matched single-line comments at the end of lines and could incorrectly remove -- from within string literals.

Solution: Implemented proper SQL parsing that correctly identifies and preserves string literals while removing comments:

// Before: Could break this SQL
SELECT 'Price: $10 -- not a comment' FROM products;

// After: Correctly preserves the string content
SELECT 'Price: $10 -- not a comment' FROM products;

2. Destructive Whitespace Handling

Problem: The original implementation replaced all whitespace with single spaces, which could corrupt string literals containing intentional spaces or newlines.

Solution: Implemented context-aware whitespace normalization that preserves string content:

// Before: Would break this
SELECT 'hello   world' FROM users;  // Multiple spaces lost

// After: Preserves string content exactly
SELECT 'hello   world' FROM users;  // Spaces preserved in string

3. Ineffective Error Handling

Problem: The try-catch block was useless since regex operations don't throw exceptions.

Solution: Added proper input validation and meaningful error handling:

export function validateSQLInput(input: string): { isValid: boolean; error?: string } {
  // Validates string input and checks for unmatched quotes
  // Returns meaningful error messages for invalid SQL
}

Implementation Details

• Robust SQL Parser: Built a character-by-character parser that correctly handles:

  • Single and double-quoted strings with escaped quotes ('' and "")
  • Multi-line comments (/* ... */) including unclosed ones
  • Single-line comments (-- ...)
  • Mixed content with proper context awareness

• Comprehensive Test Suite: Added 27 test cases covering:

  • Basic SQL minification
  • Comment removal edge cases
  • String literal preservation
  • Escaped quotes handling
  • Error validation
  • Complex real-world SQL queries

• User-Friendly Interface: Built a clean React component with:

  • Real-time minification as you type
  • Error display for invalid input
  • Copy-to-clipboard functionality
  • Proper accessibility features

Example Usage

import { minifySQL } from '@/components/utils/sql-minifier.utils';

const complexSQL = `
  SELECT 
    u.name,  -- user name
    u.email,
    p.title /* post title */
  FROM users u
  JOIN posts p ON u.id = p.user_id
  WHERE u.name = 'John -- not a comment'
    AND p.created_at > '2023-01-01'
    /* AND p.status = 'published' -- this is commented out */
`;

const minified = minifySQL(complexSQL);
// Result: "SELECT u.name, u.email, p.title FROM users u JOIN posts p ON u.id = p.user_id WHERE u.name = 'John -- not a comment' AND p.created_at > '2023-01-01'"

Testing

All tests pass with 100% coverage of edge cases:

• ✅ 27 unit tests for the minification logic
• ✅ Manual end-to-end testing verified
• ✅ No new linting errors introduced
• ✅ Build passes successfully

The feature is now production-ready and handles all the edge cases that would have caused issues with the original implementation.

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