83 lines
2.2 KiB
TypeScript
83 lines
2.2 KiB
TypeScript
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/**
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* Text file processing utilities
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* Handles text file detection, reading, and validation
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*/
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import { FileExtensionText } from '$lib/enums/files';
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/**
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* Check if a filename indicates a text file based on its extension
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* @param filename - The filename to check
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* @returns True if the filename has a recognized text file extension
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*/
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export function isTextFileByName(filename: string): boolean {
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const textExtensions = Object.values(FileExtensionText);
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return textExtensions.some((ext: FileExtensionText) => filename.toLowerCase().endsWith(ext));
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}
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/**
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* Read a file's content as text
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* @param file - The file to read
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* @returns Promise resolving to the file's text content
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*/
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export async function readFileAsText(file: File): Promise<string> {
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return new Promise((resolve, reject) => {
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const reader = new FileReader();
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reader.onload = (event) => {
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if (event.target?.result !== null && event.target?.result !== undefined) {
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resolve(event.target.result as string);
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} else {
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reject(new Error('Failed to read file'));
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}
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};
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reader.onerror = () => reject(new Error('File reading error'));
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reader.readAsText(file);
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});
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}
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/**
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* Heuristic check to determine if content is likely from a text file
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* Detects binary files by counting suspicious characters and null bytes
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* @param content - The file content to analyze
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* @returns True if the content appears to be text-based
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*/
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export function isLikelyTextFile(content: string): boolean {
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if (!content) return true;
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const sample = content.substring(0, 1000);
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let suspiciousCount = 0;
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let nullCount = 0;
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for (let i = 0; i < sample.length; i++) {
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const charCode = sample.charCodeAt(i);
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// Count null bytes
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if (charCode === 0) {
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nullCount++;
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suspiciousCount++;
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continue;
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}
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// Count suspicious control characters (excluding common ones like tab, newline, carriage return)
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if (charCode < 32 && charCode !== 9 && charCode !== 10 && charCode !== 13) {
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suspiciousCount++;
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}
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// Count replacement characters (indicates encoding issues)
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if (charCode === 0xfffd) {
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suspiciousCount++;
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}
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}
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// Reject if too many null bytes or suspicious characters
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if (nullCount > 2) return false;
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if (suspiciousCount / sample.length > 0.1) return false;
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return true;
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}
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