ngryman/ribs

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

'use strict';

/**
 * Module dependencies.
 */

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

/**
 *
 * @param {string|object} params - Parameters.
 * @param {string} params.dst - Filename or stream of the destination image.
 * @param {string} params.format - Output format.
 * @param {string} params.quality - Quality (1 - 100) of the destination image, only applies to JPEG.
 * @param {boolean} params.progressive - Either the destination image is progressive or not, only applies to JPEG.
 * @param {Image} image - Image instance.
 * @param {function} next - Next function in the pipeline.
 */
function to(params, image, next) {
    // arguments type
    check('next', next, false, 'function');

    try {
        check('params', params, false, 'string', 'object', 'array');
        check('dst', params.dst, true, 'string', 'object');
        check('format', params.format, true, 'string');
        check('quality', params.quality, true, 'number');
        check('progressive', params.progressive, true, 'boolean');
        check('image', image, false, 'object');
        checkInstance('image', image, Image);

        // array to named arguments
        if (Array.isArray(params))
            params = utils.toParams(params, ['dst', 'format', 'quality', 'progressive']);

        // arguments splitting
        var dst = params.dst || params;
        var quality = params.quality || 0;
        var progressive = params.progressive || false;
        var format;

        // if dst is a path, create a writable stream
        if ('string' == typeof dst) {
            dst = fs.createWriteStream(dst);
            format = path.extname(dst.path).slice(1);
        }
        // if dst is a stream, get the output path if possible
        else if (utils.isWritableStream(dst))
            format = path.extname(dst.path).slice(1);
        // early check on dst validity
        else if (!Buffer.isBuffer(dst))
            throw new Error('invalid destination image');

        // final format
        format = params.format || format || image.originalFormat;

        // encode the image
        image.encode(format, quality, function(err, data) {
            if (err) return next(err, image);

            // dst is a stream, write to it
            if (utils.isWritableStream(dst)) {
                if (process.stdout !== dst)
                    dst.end(data);
                else
                    dst.write(data);

                dst.on('finish', function() {
                    next(null, image);
                });
                dst.on('error', function(err) {
                    next(err, image);
                });

                return;
            }

            // dst is a buffer, copy data
            data.copy(dst);

            next(null, image);
        });

        return params;
    }
    catch (err) {
        next(err, image);
        return params;
    }
}

/**
 * Register operation.
 */

Pipeline.add('to', to);

/**
 * Export.
 */

module.exports = to;