“use strict”; var Buffer = require(“safer-buffer”).Buffer;

// UTF-7 codec, according to tools.ietf.org/html/rfc2152 // See also below a UTF-7-IMAP codec, according to tools.ietf.org/html/rfc3501#section-5.1.3

exports.utf7 = Utf7Codec; exports.unicode11utf7 = 'utf7'; // Alias UNICODE-1-1-UTF-7 function Utf7Codec(codecOptions, iconv) {

this.iconv = iconv;

};

Utf7Codec.prototype.encoder = Utf7Encoder; Utf7Codec.prototype.decoder = Utf7Decoder; Utf7Codec.prototype.bomAware = true;

// – Encoding

var nonDirectChars = /[^A-Za-z0-9'(),-./:? nrt]+/g;

function Utf7Encoder(options, codec) {

this.iconv = codec.iconv;

}

Utf7Encoder.prototype.write = function(str) {

// Naive implementation.
// Non-direct chars are encoded as "+<base64>-"; single "+" char is encoded as "+-".
return Buffer.from(str.replace(nonDirectChars, function(chunk) {
    return "+" + (chunk === '+' ? '' : 
        this.iconv.encode(chunk, 'utf16-be').toString('base64').replace(/=+$/, '')) 
        + "-";
}.bind(this)));

}

Utf7Encoder.prototype.end = function() { }

// – Decoding

function Utf7Decoder(options, codec) {

this.iconv = codec.iconv;
this.inBase64 = false;
this.base64Accum = '';

}

var base64Regex = /[A-Za-z0-9/+]/; var base64Chars = []; for (var i = 0; i < 256; i++)

base64Chars[i] = base64Regex.test(String.fromCharCode(i));

var plusChar = '+'.charCodeAt(0),

minusChar = '-'.charCodeAt(0),
andChar = '&'.charCodeAt(0);

Utf7Decoder.prototype.write = function(buf) {

var res = "", lastI = 0,
    inBase64 = this.inBase64,
    base64Accum = this.base64Accum;

// The decoder is more involved as we must handle chunks in stream.

for (var i = 0; i < buf.length; i++) {
    if (!inBase64) { // We're in direct mode.
        // Write direct chars until '+'
        if (buf[i] == plusChar) {
            res += this.iconv.decode(buf.slice(lastI, i), "ascii"); // Write direct chars.
            lastI = i+1;
            inBase64 = true;
        }
    } else { // We decode base64.
        if (!base64Chars[buf[i]]) { // Base64 ended.
            if (i == lastI && buf[i] == minusChar) {// "+-" -> "+"
                res += "+";
            } else {
                var b64str = base64Accum + buf.slice(lastI, i).toString();
                res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
            }

            if (buf[i] != minusChar) // Minus is absorbed after base64.
                i--;

            lastI = i+1;
            inBase64 = false;
            base64Accum = '';
        }
    }
}

if (!inBase64) {
    res += this.iconv.decode(buf.slice(lastI), "ascii"); // Write direct chars.
} else {
    var b64str = base64Accum + buf.slice(lastI).toString();

    var canBeDecoded = b64str.length - (b64str.length % 8); // Minimal chunk: 2 quads -> 2x3 bytes -> 3 chars.
    base64Accum = b64str.slice(canBeDecoded); // The rest will be decoded in future.
    b64str = b64str.slice(0, canBeDecoded);

    res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
}

this.inBase64 = inBase64;
this.base64Accum = base64Accum;

return res;

}

Utf7Decoder.prototype.end = function() {

var res = "";
if (this.inBase64 && this.base64Accum.length > 0)
    res = this.iconv.decode(Buffer.from(this.base64Accum, 'base64'), "utf16-be");

this.inBase64 = false;
this.base64Accum = '';
return res;

}

// UTF-7-IMAP codec. // RFC3501 Sec. 5.1.3 Modified UTF-7 (tools.ietf.org/html/rfc3501#section-5.1.3) // Differences: // * Base64 part is started by “&” instead of “+” // * Direct characters are 0x20-0x7E, except “&” (0x26) // * In Base64, “,” is used instead of “/” // * Base64 must not be used to represent direct characters. // * No implicit shift back from Base64 (should always end with '-') // * String must end in non-shifted position. // * “-&” while in base64 is not allowed.

exports.utf7imap = Utf7IMAPCodec; function Utf7IMAPCodec(codecOptions, iconv) {

this.iconv = iconv;

};

Utf7IMAPCodec.prototype.encoder = Utf7IMAPEncoder; Utf7IMAPCodec.prototype.decoder = Utf7IMAPDecoder; Utf7IMAPCodec.prototype.bomAware = true;

// – Encoding

function Utf7IMAPEncoder(options, codec) {

this.iconv = codec.iconv;
this.inBase64 = false;
this.base64Accum = Buffer.alloc(6);
this.base64AccumIdx = 0;

}

Utf7IMAPEncoder.prototype.write = function(str) {

var inBase64 = this.inBase64,
    base64Accum = this.base64Accum,
    base64AccumIdx = this.base64AccumIdx,
    buf = Buffer.alloc(str.length*5 + 10), bufIdx = 0;

for (var i = 0; i < str.length; i++) {
    var uChar = str.charCodeAt(i);
    if (0x20 <= uChar && uChar <= 0x7E) { // Direct character or '&'.
        if (inBase64) {
            if (base64AccumIdx > 0) {
                bufIdx += buf.write(base64Accum.slice(0, base64AccumIdx).toString('base64').replace(/\//g, ',').replace(/=+$/, ''), bufIdx);
                base64AccumIdx = 0;
            }

            buf[bufIdx++] = minusChar; // Write '-', then go to direct mode.
            inBase64 = false;
        }

        if (!inBase64) {
            buf[bufIdx++] = uChar; // Write direct character

            if (uChar === andChar)  // Ampersand -> '&-'
                buf[bufIdx++] = minusChar;
        }

    } else { // Non-direct character
        if (!inBase64) {
            buf[bufIdx++] = andChar; // Write '&', then go to base64 mode.
            inBase64 = true;
        }
        if (inBase64) {
            base64Accum[base64AccumIdx++] = uChar >> 8;
            base64Accum[base64AccumIdx++] = uChar & 0xFF;

            if (base64AccumIdx == base64Accum.length) {
                bufIdx += buf.write(base64Accum.toString('base64').replace(/\//g, ','), bufIdx);
                base64AccumIdx = 0;
            }
        }
    }
}

this.inBase64 = inBase64;
this.base64AccumIdx = base64AccumIdx;

return buf.slice(0, bufIdx);

}

Utf7IMAPEncoder.prototype.end = function() {

var buf = Buffer.alloc(10), bufIdx = 0;
if (this.inBase64) {
    if (this.base64AccumIdx > 0) {
        bufIdx += buf.write(this.base64Accum.slice(0, this.base64AccumIdx).toString('base64').replace(/\//g, ',').replace(/=+$/, ''), bufIdx);
        this.base64AccumIdx = 0;
    }

    buf[bufIdx++] = minusChar; // Write '-', then go to direct mode.
    this.inBase64 = false;
}

return buf.slice(0, bufIdx);

}

// – Decoding

function Utf7IMAPDecoder(options, codec) {

this.iconv = codec.iconv;
this.inBase64 = false;
this.base64Accum = '';

}

var base64IMAPChars = base64Chars.slice(); base64IMAPChars = true;

Utf7IMAPDecoder.prototype.write = function(buf) {

var res = "", lastI = 0,
    inBase64 = this.inBase64,
    base64Accum = this.base64Accum;

// The decoder is more involved as we must handle chunks in stream.
// It is forgiving, closer to standard UTF-7 (for example, '-' is optional at the end).

for (var i = 0; i < buf.length; i++) {
    if (!inBase64) { // We're in direct mode.
        // Write direct chars until '&'
        if (buf[i] == andChar) {
            res += this.iconv.decode(buf.slice(lastI, i), "ascii"); // Write direct chars.
            lastI = i+1;
            inBase64 = true;
        }
    } else { // We decode base64.
        if (!base64IMAPChars[buf[i]]) { // Base64 ended.
            if (i == lastI && buf[i] == minusChar) { // "&-" -> "&"
                res += "&";
            } else {
                var b64str = base64Accum + buf.slice(lastI, i).toString().replace(/,/g, '/');
                res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
            }

            if (buf[i] != minusChar) // Minus may be absorbed after base64.
                i--;

            lastI = i+1;
            inBase64 = false;
            base64Accum = '';
        }
    }
}

if (!inBase64) {
    res += this.iconv.decode(buf.slice(lastI), "ascii"); // Write direct chars.
} else {
    var b64str = base64Accum + buf.slice(lastI).toString().replace(/,/g, '/');

    var canBeDecoded = b64str.length - (b64str.length % 8); // Minimal chunk: 2 quads -> 2x3 bytes -> 3 chars.
    base64Accum = b64str.slice(canBeDecoded); // The rest will be decoded in future.
    b64str = b64str.slice(0, canBeDecoded);

    res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
}

this.inBase64 = inBase64;
this.base64Accum = base64Accum;

return res;

}

Utf7IMAPDecoder.prototype.end = function() {

var res = "";
if (this.inBase64 && this.base64Accum.length > 0)
    res = this.iconv.decode(Buffer.from(this.base64Accum, 'base64'), "utf16-be");

this.inBase64 = false;
this.base64Accum = '';
return res;

}