cesr/dist/encoding-base64.js

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const B64_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_".split("");
function getBase64Index(char) {
    if (char === "=") {
        return 0;
    }
    const code = B64_ALPHABET.indexOf(char);
    if (code === -1) {
        throw new Error(`Invalid base64 character '${char}'`);
    }
    return code;
}
export function decodeBase64Int(str) {
    let result = 0;
    for (let i = str.length - 1; i >= 0; i--) {
        const character = str.charAt(i);
        const index = getBase64Index(character);
        const factor = 64 ** (str.length - i - 1);
        result += factor * index;
    }
    return result;
}
export function encodeBase64Int(value, length) {
    if (length !== undefined && value >= 64 ** length) {
        throw new Error(`value ${value} too big for base64 length ${length}`);
    }
    let remainder = value;
    let result = "";
    while (remainder !== 0) {
        result = B64_ALPHABET[remainder % 64] + result;
        remainder = Math.floor(remainder / 64);
    }
    return result.padStart(length ?? 1, "A");
}
export function encodeBase64Url(uint8) {
    // CREDIT: https://github.com/denoland/std/blob/main/encoding/base64.ts
    // CREDIT: https://gist.github.com/enepomnyaschih/72c423f727d395eeaa09697058238727
    let result = "";
    let i;
    const l = uint8.length;
    for (i = 2; i < l; i += 3) {
        result += B64_ALPHABET[uint8[i - 2] >> 2];
        result += B64_ALPHABET[((uint8[i - 2] & 0x03) << 4) | (uint8[i - 1] >> 4)];
        result += B64_ALPHABET[((uint8[i - 1] & 0x0f) << 2) | (uint8[i] >> 6)];
        result += B64_ALPHABET[uint8[i] & 0x3f];
    }
    if (i === l + 1) {
        // 1 octet yet to write
        result += B64_ALPHABET[uint8[i - 2] >> 2];
        result += B64_ALPHABET[(uint8[i - 2] & 0x03) << 4];
    }
    if (i === l) {
        // 2 octets yet to write
        result += B64_ALPHABET[uint8[i - 2] >> 2];
        result += B64_ALPHABET[((uint8[i - 2] & 0x03) << 4) | (uint8[i - 1] >> 4)];
        result += B64_ALPHABET[(uint8[i - 1] & 0x0f) << 2];
    }
    return result;
}
export function decodeBase64Url(input) {
    if (typeof input !== "string") {
        throw new Error(`input must be a string`);
    }
    if (input.length === 0) {
        return new Uint8Array(0);
    }
    const remainder = input.length % 4;
    const padSize = remainder > 0 ? 4 - remainder : remainder;
    const str = input.padEnd(padSize + input.length, "=");
    const result = new Uint8Array(3 * (str.length / 4));
    for (let i = 0, j = 0; i < str.length; i += 4, j += 3) {
        const sixtet0 = getBase64Index(str.charAt(i)) << 18;
        const sixtet1 = getBase64Index(str.charAt(i + 1)) << 12;
        const sixtet2 = getBase64Index(str.charAt(i + 2)) << 6;
        const sixtet3 = getBase64Index(str.charAt(i + 3));
        const chunk = sixtet0 | sixtet1 | sixtet2 | sixtet3;
        result[j] = chunk >> 16;
        result[j + 1] = (chunk >> 8) & 0xff;
        result[j + 2] = chunk & 0xff;
    }
    return result.slice(0, result.length - padSize);
}