// Copyright 2015 Joyent, Inc.

module.exports = {

read: read,
write: write

};

var assert = require('assert-plus'); var utils = require('../utils'); var Key = require('../key'); var PrivateKey = require('../private-key');

var pem = require('./pem'); var ssh = require('./ssh'); var rfc4253 = require('./rfc4253');

function read(buf, options) {

if (typeof (buf) === 'string') {
        if (buf.trim().match(/^[-]+[ ]*BEGIN/))
                return (pem.read(buf, options));
        if (buf.match(/^\s*ssh-[a-z]/))
                return (ssh.read(buf, options));
        if (buf.match(/^\s*ecdsa-/))
                return (ssh.read(buf, options));
        buf = new Buffer(buf, 'binary');
} else {
        assert.buffer(buf);
        if (findPEMHeader(buf))
                return (pem.read(buf, options));
        if (findSSHHeader(buf))
                return (ssh.read(buf, options));
}
if (buf.readUInt32BE(0) < buf.length)
        return (rfc4253.read(buf, options));
throw (new Error('Failed to auto-detect format of key'));

}

function findSSHHeader(buf) {

var offset = 0;
while (offset < buf.length &&
    (buf[offset] === 32 || buf[offset] === 10 || buf[offset] === 9))
        ++offset;
if (offset + 4 <= buf.length &&
    buf.slice(offset, offset + 4).toString('ascii') === 'ssh-')
        return (true);
if (offset + 6 <= buf.length &&
    buf.slice(offset, offset + 6).toString('ascii') === 'ecdsa-')
        return (true);
return (false);

}

function findPEMHeader(buf) {

var offset = 0;
while (offset < buf.length &&
    (buf[offset] === 32 || buf[offset] === 10))
        ++offset;
if (buf[offset] !== 45)
        return (false);
while (offset < buf.length &&
    (buf[offset] === 45))
        ++offset;
while (offset < buf.length &&
    (buf[offset] === 32))
        ++offset;
if (offset + 5 > buf.length ||
    buf.slice(offset, offset + 5).toString('ascii') !== 'BEGIN')
        return (false);
return (true);

}

function write(key, options) {

throw (new Error('"auto" format cannot be used for writing'));

}