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index.js
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index.js
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var _ = require("underscore");
var buildTags = function(metas, prefix,ignorePrefix) {
var tags = "";
var links = metas[prefix].meta;
prefix = ignorePrefix ? '' : prefix+':';
for (var i in links) {
var link = links[i];
var keys = Object.keys(link);
for (var j in keys) {
var key = keys[j];
tags += '<meta name="'+ prefix + key + '" content="' + link[key] + '">\n';
}
return tags;
}
};
var injectMetaOptions = function(str, options, prefix,ignorePrefix) {
return str.replace(/<head>((?:.|\n|\r)+?)<\/head>/i, "<head>$1" + buildTags(options, prefix, ignorePrefix)+"</head>");
};
var Meta = function(prefix, ignorePrefix){
return function(originalPlatforms) {
return function(req, res, next) {
var platforms = [];
res._metas = res._metas || {};
if (_.isFunction(originalPlatforms)) {
platforms = originalPlatforms(req, res);
} else {
platforms = originalPlatforms;
}
if (!_.isArray(platforms)) {
platforms = [ platforms ];
}
var htmlMetaHeaders = req.headers["prefer-html-meta-tags"] || "";
var preferMetas = _.some(htmlMetaHeaders.split(","), function(value) {
return value.trim() === prefix;
});
if (preferMetas) {
// Always returns html
res.set("Content-Type", "text/html");
}
// Only modify the render function once in case app links
// is defined multiple times
if (!res._metas[prefix]) {
var render = res.render;
res.render = function(view, options, finishCallback) {
options = options || {};
// Support callback function as second arg
if (_.isFunction(options)) {
finishCallback = options, options = {};
}
var self = this;
var defaultCallback = function(err, str) {
if (err) {
return req.next(err);
}
self.send(str);
};
if (!_.isFunction(finishCallback)) {
finishCallback = defaultCallback;
}
if (res._metas[prefix].preferMetas) {
// If we prefer App Links, let's render simple HTML
str = "<html><head></head><body></body><html>";
str = injectMetaOptions(str, res._metas, prefix, ignorePrefix);
res.send(str);
} else {
render.call(res, view, options, function(err, str) {
str = injectMetaOptions(str, res._metas, prefix,ignorePrefix);
// remove _appLinks object from response
delete res._metas[prefix];
finishCallback(err, str);
});
}
};
}
// Inject app links meta to response object
res._metas = res._metas || {};
res._metas[prefix] = res._metas[prefix] || {};
res._metas[prefix].meta = res._metas[prefix].meta || [];
// Render more specific meta tag first
res._metas[prefix].meta = platforms.concat(res._metas[prefix].meta);
res._metas[prefix].preferAppLinks = preferMetas;
next();
};
}
}
module.exports = Meta;