const UNDEFINED_CODE_POINTS = new Set([
    0xff_fe, 0xff_ff, 0x1_ff_fe, 0x1_ff_ff, 0x2_ff_fe, 0x2_ff_ff, 0x3_ff_fe, 0x3_ff_ff, 0x4_ff_fe, 0x4_ff_ff, 0x5_ff_fe,
    0x5_ff_ff, 0x6_ff_fe, 0x6_ff_ff, 0x7_ff_fe, 0x7_ff_ff, 0x8_ff_fe, 0x8_ff_ff, 0x9_ff_fe, 0x9_ff_ff, 0xa_ff_fe,
    0xa_ff_ff, 0xb_ff_fe, 0xb_ff_ff, 0xc_ff_fe, 0xc_ff_ff, 0xd_ff_fe, 0xd_ff_ff, 0xe_ff_fe, 0xe_ff_ff, 0xf_ff_fe,
    0xf_ff_ff, 0x10_ff_fe, 0x10_ff_ff,
]);

export const REPLACEMENT_CHARACTER = '\uFFFD';

export enum CODE_POINTS {
    EOF = -1,
    NULL = 0x00,
    TABULATION = 0x09,
    CARRIAGE_RETURN = 0x0d,
    LINE_FEED = 0x0a,
    FORM_FEED = 0x0c,
    SPACE = 0x20,
    EXCLAMATION_MARK = 0x21,
    QUOTATION_MARK = 0x22,
    NUMBER_SIGN = 0x23,
    AMPERSAND = 0x26,
    APOSTROPHE = 0x27,
    HYPHEN_MINUS = 0x2d,
    SOLIDUS = 0x2f,
    DIGIT_0 = 0x30,
    DIGIT_9 = 0x39,
    SEMICOLON = 0x3b,
    LESS_THAN_SIGN = 0x3c,
    EQUALS_SIGN = 0x3d,
    GREATER_THAN_SIGN = 0x3e,
    QUESTION_MARK = 0x3f,
    LATIN_CAPITAL_A = 0x41,
    LATIN_CAPITAL_F = 0x46,
    LATIN_CAPITAL_X = 0x58,
    LATIN_CAPITAL_Z = 0x5a,
    RIGHT_SQUARE_BRACKET = 0x5d,
    GRAVE_ACCENT = 0x60,
    LATIN_SMALL_A = 0x61,
    LATIN_SMALL_F = 0x66,
    LATIN_SMALL_X = 0x78,
    LATIN_SMALL_Z = 0x7a,
    REPLACEMENT_CHARACTER = 0xff_fd,
}

export const SEQUENCES = {
    DASH_DASH: '--',
    CDATA_START: '[CDATA[',
    DOCTYPE: 'doctype',
    SCRIPT: 'script',
    PUBLIC: 'public',
    SYSTEM: 'system',
};

//Surrogates
export function isSurrogate(cp: number): boolean {
    return cp >= 0xd8_00 && cp <= 0xdf_ff;
}

export function isSurrogatePair(cp: number): boolean {
    return cp >= 0xdc_00 && cp <= 0xdf_ff;
}

export function getSurrogatePairCodePoint(cp1: number, cp2: number): number {
    return (cp1 - 0xd8_00) * 0x4_00 + 0x24_00 + cp2;
}

//NOTE: excluding NULL and ASCII whitespace
export function isControlCodePoint(cp: number): boolean {
    return (
        (cp !== 0x20 && cp !== 0x0a && cp !== 0x0d && cp !== 0x09 && cp !== 0x0c && cp >= 0x01 && cp <= 0x1f) ||
        (cp >= 0x7f && cp <= 0x9f)
    );
}

export function isUndefinedCodePoint(cp: number): boolean {
    return (cp >= 0xfd_d0 && cp <= 0xfd_ef) || UNDEFINED_CODE_POINTS.has(cp);
}