ngryman/ribs

/*!
 * ribs
 * Copyright (c) 2013-2014 Nicolas Gryman <ngryman@gmail.com>
 * LGPL Licensed
 */

'use strict';

/**
 * Module dependencies.
 */

var fs = require('fs'),
    Image = require('../image'),
    Pipeline = require('../pipeline'),
    utils = require('../utils'),
    check = utils.checkType;

/**
 *
 * @param {object|string|Buffer|Readable} src - Source image.
 * @param {function} next - Next function in the pipeline.
 */
function from(src, next) {
    check('next', next, false, 'function');

    try {
        check('params', src, false, 'string', 'object', 'array');

        // array to named arguments
        if (Array.isArray(src))
            src = src[0];

        // src is a path, create a readable stream
        if ('string' == typeof src) {
            src = fs.createReadStream(src);
        }

        // src is a stream, read it, then decode it
        if (utils.isReadableStream(src)) {
            var buffers = [];

            src.on('data', buffers.push.bind(buffers));
            src.on('end', function() {
                if (0 === buffers.length)
                    return next(new Error('empty file: ' + src.path), null);

                Image.decode(Buffer.concat(buffers), next);
            });
            src.on('error', function(err) {
                // indirection for curry
                next(err, null);
            });
        }
        // src is a buffer, decode it directly
        else if (Buffer.isBuffer(src)) {
            Image.decode(src, next);
        }
        else
            throw new Error('invalid source image');

        return src;
    }
    catch (err) {
        next(err, undefined);
        return src;
    }
}

/**
 * Register operation.
 */

Pipeline.add('from', from);

/**
 * Export.
 */

module.exports = from;