/**
* @license
* Copyright 2026 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
/**
* Converts a given string to snake_case.
* This function handles camelCase, PascalCase, and acronyms, including transitions between letters and numbers.
* It uses Unicode-aware regular expressions (`\p{L}`, `\p{N}`, `\p{Lu}`, `\p{Ll}` with the `u` flag)
* to correctly process letters and numbers from various languages.
*
* @param text The input string to convert to snake_case.
* @returns The snake_case version of the input string.
*/
export function toSnakeCase(text: string): string {
if (!text) {
return '';
}
// First, handle case-based transformations to insert underscores correctly.
// 1. Add underscore between a letter and a number.
// e.g., "version2" -> "version_2"
// 2. Add underscore between an uppercase letter sequence and a following uppercase+lowercase sequence.
// e.g., "APIFlags" -> "API_Flags"
// 3. Add underscore between a lowercase/number and an uppercase letter.
// e.g., "lastName" -> "last_Name", "version_2Update" -> "version_2_Update"
// 4. Replace sequences of non-alphanumeric with a single underscore
// 5. Remove any leading or trailing underscores.
const result = text
.replace(/(\p{L})(\p{N})/gu, '$1_$2') // 1
.replace(/(\p{Lu}+)(\p{Lu}\p{Ll})/gu, '$1_$2') // 2
.replace(/(\p{Ll}|\p{N})(\p{Lu})/gu, '$1_$2') // 3
.toLowerCase()
.replace(/[^\p{L}\p{N}]+/gu, '_') // 4
.replace(/^_|_$/g, ''); // 5
return result;
}
