function filterFiles(files: string[], suffix: string): string[] {
    return files.filter(file => {
        const fileName = file.toLowerCase();
        return (fileName.includes(suffix) || fileName.includes('_v3')) &&
               (fileName.endsWith(suffix) || fileName.endsWith('_v3'));
    });
}

// Változó értéke
const suffix = "sa";

// Teszteset:
const files = ["weapons.txt", "weapons_sa.txt", "weapons_v3.txt", "something_v3_else_sa.txt", "file_v4.txt"];
const filteredFiles = filterFiles(files, suffix);
console.log(filteredFiles);