PluginLoader.js

/**
 * Copyright (C) 2012-2015 KO GmbH <copyright@kogmbh.com>
 *
 * @licstart
 * This file is part of ViewerJS.
 *
 * ViewerJS is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Affero General Public License (GNU AGPL)
 * as published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * ViewerJS is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with ViewerJS.  If not, see <http://www.gnu.org/licenses/>.
 * @licend
 *
 * @source: http://viewerjs.org/
 * @source: http://github.com/kogmbh/ViewerJS
 */

/*global document, window, Viewer, ODFViewerPlugin, PDFViewerPlugin*/

(function () {
    "use strict";

    var css,
        pluginRegistry = [
        (function() {
            var odfMimetypes = [
                'application/vnd.oasis.opendocument.text',
                'application/vnd.oasis.opendocument.text-flat-xml',
                'application/vnd.oasis.opendocument.text-template',
                'application/vnd.oasis.opendocument.presentation',
                'application/vnd.oasis.opendocument.presentation-flat-xml',
                'application/vnd.oasis.opendocument.presentation-template',
                'application/vnd.oasis.opendocument.spreadsheet',
                'application/vnd.oasis.opendocument.spreadsheet-flat-xml',
                'application/vnd.oasis.opendocument.spreadsheet-template'];
            var odfFileExtensions = [
                'odt',
                'fodt',
                'ott',
                'odp',
                'fodp',
                'otp',
                'ods',
                'fods',
                'ots'];

            return {
                supportsMimetype: function(mimetype) {
                    return (odfMimetypes.indexOf(mimetype) !== -1);
                },
                supportsFileExtension: function(extension) {
                    return (odfFileExtensions.indexOf(extension) !== -1);
                },
                path: "./ODFViewerPlugin",
                getClass: function() { return ODFViewerPlugin; }
            };
        }()),
        {
            supportsMimetype: function(mimetype) {
                return (mimetype === 'application/pdf');
            },
            supportsFileExtension: function(extension) {
                return (extension === 'pdf');
            },
            path: "./PDFViewerPlugin",
            getClass: function() { return PDFViewerPlugin; }
        }
    ];


    function estimateTypeByHeaderContentType(documentUrl, cb) {
        var xhr = new XMLHttpRequest();
        xhr.onreadystatechange = function() {
            var mimetype, matchingPluginData;
            if (xhr.readyState === 4) {
                if ((xhr.status >= 200 && xhr.status < 300) || xhr.status === 0) {
                    mimetype = xhr.getResponseHeader('content-type');

                    if (mimetype) {
                        pluginRegistry.some(function(pluginData) {
                            if (pluginData.supportsMimetype(mimetype)) {
                                matchingPluginData = pluginData;
                                console.log('Found plugin by mimetype and xhr head: ' + mimetype);
                                return true;
                            }
                            return false;
                        });
                    }
                }
                cb(matchingPluginData);
            }
        };
        xhr.open("HEAD", documentUrl, true);
        xhr.send();
    }


    function doEstimateTypeByFileExtension(extension) {
        var matchingPluginData;

        pluginRegistry.some(function(pluginData) {
            if (pluginData.supportsFileExtension(extension)) {
                matchingPluginData = pluginData;
                return true;
            }
            return false;
        });

        return matchingPluginData;
    }


    function estimateTypeByFileExtension(extension) {
        var matchingPluginData = doEstimateTypeByFileExtension(extension)

        if (matchingPluginData) {
            console.log('Found plugin by parameter type: ' + extension);
        }

        return matchingPluginData;
    }


    function estimateTypeByFileExtensionFromPath(documentUrl) {
        // See to get any path from the url and grep what could be a file extension
        var documentPath = documentUrl.split('?')[0],
            extension = documentPath.split('.').pop(),
            matchingPluginData = doEstimateTypeByFileExtension(extension)

        if (matchingPluginData) {
            console.log('Found plugin by file extension from path: ' + extension);
        }

        return matchingPluginData;
    }


    function parseSearchParameters(location) {
        var parameters = {},
            search = location.search || "?";

        search.substr(1).split('&').forEach(function (q) {
            // skip empty strings
            if (!q) {
                return;
            }
            // if there is no '=', have it handled as if given key was set to undefined
            var s = q.split('=', 2);
            parameters[decodeURIComponent(s[0])] = decodeURIComponent(s[1]);
        });

        return parameters;
    }


    window.onload = function () {
        var viewer,
            documentUrl = document.location.hash.substring(1),
            parameters = parseSearchParameters(document.location),
            Plugin;

        if (documentUrl) {
            // try to guess the title as filename from the location, if not set by parameter
            if (!parameters.title) {
                parameters.title = documentUrl.replace(/^.*[\\\/]/, '');
            }

            parameters.documentUrl = documentUrl;

            // trust the server most
            estimateTypeByHeaderContentType(documentUrl, function(pluginData) {
                if (!pluginData) {
                    if (parameters.type) {
                        pluginData = estimateTypeByFileExtension(parameters.type);
                    } else {
                        // last ressort: try to guess from path
                        pluginData = estimateTypeByFileExtensionFromPath(documentUrl);
                    }
                }

                if (pluginData) {
                    if (String(typeof loadPlugin) !== "undefined") {
                        loadPlugin(pluginData.path, function () {
                            Plugin = pluginData.getClass();
                            viewer = new Viewer(new Plugin(), parameters);
                        });
                    } else {
                        Plugin = pluginData.getClass();
                        viewer = new Viewer(new Plugin(), parameters);
                    }
                } else {
                    viewer = new Viewer();
                }
            });
        } else {
            viewer = new Viewer();
        }
    };

    css = /**@type{!HTMLStyleElement}*/(document.createElementNS(document.head.namespaceURI, 'style'));
    css.setAttribute('media', 'screen');
    css.setAttribute('type', 'text/css');
    css.appendChild(document.createTextNode(viewer_css));
    document.head.appendChild(css);

    css = /**@type{!HTMLStyleElement}*/(document.createElementNS(document.head.namespaceURI, 'style'));
    css.setAttribute('media', 'only screen and (max-device-width: 800px) and (max-device-height: 800px)');
    css.setAttribute('type', 'text/css');
    css.setAttribute('viewerTouch', '1');
    css.appendChild(document.createTextNode(viewerTouch_css));
    document.head.appendChild(css);

}());