// for embedded scripts, quoted and modified from https://github.com/swansontec/rfc4648.js by William Swanson
'use strict';
var base64url = base64url || {};
(function(base64url) {

    function parse (string, encoding, opts = {}) {
        // Build the character lookup table:
        if (!encoding.codes) {
              encoding.codes = {};
              for (let i = 0; i < encoding.chars.length; ++i) {
                  encoding.codes[encoding.chars[i]] = i;
              }
        }

        // The string must have a whole number of bytes:
        if (!opts.loose && (string.length * encoding.bits) & 7) {
            throw new SyntaxError('Invalid padding');
        }

        // Count the padding bytes:
        let end = string.length;
        while (string[end - 1] === '=') {
            --end;

            // If we get a whole number of bytes, there is too much padding:
            if (!opts.loose && !(((string.length - end) * encoding.bits) & 7)) {
                throw new SyntaxError('Invalid padding');
            }
        }

        // Allocate the output:
        const out = new (opts.out || Uint8Array)(((end * encoding.bits) / 8) | 0);

        // Parse the data:
        let bits = 0; // Number of bits currently in the buffer
        let buffer = 0; // Bits waiting to be written out, MSB first
        let written = 0; // Next byte to write
        for (let i = 0; i < end; ++i) {
            // Read one character from the string:
            const value = encoding.codes[string[i]];
            if (value === void 0) {
                throw new SyntaxError('Invalid character ' + string[i]);
            }

            // Append the bits to the buffer:
            buffer = (buffer << encoding.bits) | value;
            bits += encoding.bits;

            // Write out some bits if the buffer has a byte's worth:
            if (bits >= 8) {
                bits -= 8;
                out[written++] = 0xff & (buffer >> bits);
            }
        }

        // Verify that we have received just enough bits:
        if (bits >= encoding.bits || 0xff & (buffer << (8 - bits))) {
            throw new SyntaxError('Unexpected end of data');
        }

        return out
    }

    function stringify (data, encoding, opts = {}) {
        const { pad = true } = opts;
        const mask = (1 << encoding.bits) - 1;
        let out = '';

        let bits = 0; // Number of bits currently in the buffer
        let buffer = 0; // Bits waiting to be written out, MSB first
        for (let i = 0; i < data.length; ++i) {
            // Slurp data into the buffer:
            buffer = (buffer << 8) | (0xff & data[i]);
            bits += 8;

            // Write out as much as we can:
            while (bits > encoding.bits) {
                bits -= encoding.bits;
                out += encoding.chars[mask & (buffer >> bits)];
            }
        }

        // Partial character:
        if (bits) {
            out += encoding.chars[mask & (buffer << (encoding.bits - bits))];
        }

        // Add padding characters until we hit a byte boundary:
        if (pad) {
            while ((out.length * encoding.bits) & 7) {
                out += '=';
            }
        }

        return out
    }

    const encoding = {
        chars: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_',
        bits: 6
    }

    base64url.decode = function (string, opts) {
        return parse(string, encoding, opts);
    }

    base64url.encode = function (data, opts) {
        return stringify(data, encoding, opts)
    }

    return base64url;
}(base64url));