// Copyright 2018 Joyent, Inc.

module.exports = {

read: read,
write: write

};

var assert = require('assert-plus'); var Buffer = require('safer-buffer').Buffer; var rfc4253 = require('./rfc4253'); var Key = require('../key');

var errors = require('../errors');

function read(buf, options) {

var lines = buf.toString('ascii').split(/[\r\n]+/);
var found = false;
var parts;
var si = 0;
while (si < lines.length) {
        parts = splitHeader(lines[si++]);
        if (parts &&
            parts[0].toLowerCase() === 'putty-user-key-file-2') {
                found = true;
                break;
        }
}
if (!found) {
        throw (new Error('No PuTTY format first line found'));
}
var alg = parts[1];

parts = splitHeader(lines[si++]);
assert.equal(parts[0].toLowerCase(), 'encryption');

parts = splitHeader(lines[si++]);
assert.equal(parts[0].toLowerCase(), 'comment');
var comment = parts[1];

parts = splitHeader(lines[si++]);
assert.equal(parts[0].toLowerCase(), 'public-lines');
var publicLines = parseInt(parts[1], 10);
if (!isFinite(publicLines) || publicLines < 0 ||
    publicLines > lines.length) {
        throw (new Error('Invalid public-lines count'));
}

var publicBuf = Buffer.from(
    lines.slice(si, si + publicLines).join(''), 'base64');
var keyType = rfc4253.algToKeyType(alg);
var key = rfc4253.read(publicBuf);
if (key.type !== keyType) {
        throw (new Error('Outer key algorithm mismatch'));
}
key.comment = comment;
return (key);

}

function splitHeader(line) {

var idx = line.indexOf(':');
if (idx === -1)
        return (null);
var header = line.slice(0, idx);
++idx;
while (line[idx] === ' ')
        ++idx;
var rest = line.slice(idx);
return ([header, rest]);

}

function write(key, options) {

assert.object(key);
if (!Key.isKey(key))
        throw (new Error('Must be a public key'));

var alg = rfc4253.keyTypeToAlg(key);
var buf = rfc4253.write(key);
var comment = key.comment || '';

var b64 = buf.toString('base64');
var lines = wrap(b64, 64);

lines.unshift('Public-Lines: ' + lines.length);
lines.unshift('Comment: ' + comment);
lines.unshift('Encryption: none');
lines.unshift('PuTTY-User-Key-File-2: ' + alg);

return (Buffer.from(lines.join('\n') + '\n'));

}

function wrap(txt, len) {

var lines = [];
var pos = 0;
while (pos < txt.length) {
        lines.push(txt.slice(pos, pos + 64));
        pos += 64;
}
return (lines);

}