upnpserver/lib/contentHandlers/exif.js

/*jslint node: true, esversion: 6, maxlen: 180 */
"use strict";

const debug = require('debug')('upnpserver:contentHandlers:Exif');
const Exif = require('exif');

const ContentHandler = require('./contentHandler');

const logger = require('../logger');

class ExifContentHandler extends ContentHandler {

	get name() {
		return "exif";
	}

	/**
	 *
	 */
	prepareMetas(contentInfos, context, callback) {
		debug("Prepare metas of", contentInfos);

		var contentURL = contentInfos.contentURL;

		contentURL.readContent(null, (error, imageData) => {
			if (error) {
				logger.error("Can not get content of '" + contentURL + "'", error);
				return callback(error);
			}

			new Exif.ExifImage({image: imageData, fixThumbnailOffset: true}, (error, exifData) => {
				if (error) {
					logger.error("Can not parse exif '" + contentURL + "'", error);
					return callback(error);
				}

				filter(exifData);

				var res;
				var thumbnail = exifData.thumbnail;
				if (thumbnail) {
					delete exifData.thumbnail;

					if (thumbnail.ThumbnailOffset && thumbnail.ThumbnailLength) {

						var thumbnailMimeType;
						if (isJPEG(imageData, thumbnail.ThumbnailOffset)) {
							thumbnailMimeType = "image/jpeg";
						}

						if (thumbnailMimeType) {
							res = res || [{}];

							res.push({
								contentHandlerKey: this.name,
								key: "thumbnail",
								mimeType: thumbnailMimeType,
								size: thumbnail.ThumbnailLength,
								_start: thumbnail.ThumbnailOffset
							});
						}
					}
				}
				var exif = exifData;
				if (exif) {
					res = res || [{}];

					if (exif.ExifImageWidth) {
						res[0].width = exif.ExifImageWidth;
					}
					if (exif.ExifImageHeight) {
						res[0].height = exif.ExifImageHeight;
					}
					if (exif.DateTimeOriginal) {
						var ds = exif.DateTimeOriginal;
						var reg = /^(\d{4}).(\d{2}).(\d{2}).(\d{2}).(\d{2}).(\d{2})/.exec(ds);
						if (reg) {
							exifData.dateTimeOriginal = new Date(parseInt(reg[1]), parseInt(reg[2]) - 1, parseInt(reg[3]),
								parseInt(reg[4]), parseInt(reg[5]), parseInt(reg[6]));
							exifData.date = exifData.dateTimeOriginal;
						}
					}
				}

				if (res) {
					exifData.res = res;
				}

				callback(null, exifData);
			});
		});
	}

	/**
	 *
	 */
	processRequest(node, request, response, path, parameters, callback) {

		var resKey = parameters[0];
		var res = this.getResourceByParameter(node, resKey);

		debug("ProcessRequest", "resKey=", resKey, "=>", res);

		if (!res) {
			var error = new Error("Invalid resKey parameter (" + resKey + ")");
			return callback(error, true);
		}

		this.sendResource(node.contentURL, res, request, response, callback);
	}
}

module.exports = ExifContentHandler;

function isJPEG(data, offset) {
	debug("IsJPEG: offset=", offset, "data=", data[offset], data[offset + 1], data[offset + 2]);
	return (data[offset] === 0xff) && (data[offset + 1] === 0xd8) && (data[offset + 2] === 0xff) && (data[offset + 3] === 0xdb);
}

function filter(json) {
	for (var n in json) {
		var v = json[n];
		if (typeof(v) !== "object") {
			continue;
		}

		if (v === null) {
			continue;
		}
		if (v instanceof Array) {
			continue;
		}
		if (Buffer.isBuffer(v)) {
			delete json[n];
			continue;
		}
		if (v instanceof Date) {
			continue;
		}
		if (!Object.keys(v).length) {
			delete json[n];
			continue;
		}

		filter(v);
	}
}