const EMPTY = new Uint8Array([0x03]);

function isAscii(s: string): boolean {
    for (let i = 0; i < s.length; i++) if (s.charCodeAt(i) > 0x7f) return false;
    return true;
}

export function encodeDevicesql(s: string): Uint8Array {
    if (!s) return EMPTY;
    if (isAscii(s) && s.length < 127) {
        const ascii = new TextEncoder().encode(s);
        const length = ascii.length + 1;
        const lengthAndKind = ((length << 1) | 1) & 0xff;
        const out = new Uint8Array(1 + ascii.length);
        out[0] = lengthAndKind;
        out.set(ascii, 1);
        return out;
    }
    const utf16 = new Uint8Array(s.length * 2);
    for (let i = 0; i < s.length; i++) {
        const c = s.charCodeAt(i);
        utf16[i * 2] = c & 0xff;
        utf16[i * 2 + 1] = (c >> 8) & 0xff;
    }
    const totalLength = utf16.length + 4;
    const out = new Uint8Array(4 + utf16.length);
    out[0] = 0x90;
    out[1] = totalLength & 0xff;
    out[2] = (totalLength >> 8) & 0xff;
    out[3] = 0x00;
    out.set(utf16, 4);
    return out;
}