camo: support URL encoding option

src/camo.js

@@ -24,8 +24,14 @@ export function camoify(camoConfig: CamoConfig, url: string): string {
     const hmac = crypto.createHmac('sha1', camoConfig.getKey());
     hmac.update(url);
     const digest = hmac.digest('hex');
-    const hexUrl = Buffer.from(url, 'utf8').toString('hex');
-    return `${camoConfig.getServer()}/${digest}/${hexUrl}`;
+    // https://github.com/atmos/camo#url-formats
+    if (camoConfig.getEncoding() === 'hex') {
+        const hexUrl = Buffer.from(url, 'utf8').toString('hex');
+        return `${camoConfig.getServer()}/${digest}/${hexUrl}`;
+    } else {
+        const encoded = encodeURIComponent(url);
+        return `${camoConfig.getServer()}/${digest}?url=${encoded}`;
+    }
 }
 
 export function transformImgTags(camoConfig: CamoConfig, tagName: string, attribs: Object) {

src/configuration/camoconfig.js

@@ -4,6 +4,14 @@ class CamoConfig {
         if (this.config.server) {
             this.config.server = this.config.server.replace(/\/+$/, '');
         }
+        this.validate();
+    }
+
+    validate() {
+        if (this.config.encoding
+                && !~['url', 'hex'].indexOf(this.config.encoding)) {
+            throw new Error(`Value for key 'encoding' must be either 'url' or 'hex', not '${this.config.encoding}'`);
+        }
     }
 
     isEnabled() {
@@ -21,6 +29,10 @@ class CamoConfig {
     getWhitelistedDomains() {
         return this.config['whitelisted-domains'] || [];
     }
+
+    getEncoding() {
+        return this.config.encoding || 'url';
+    }
 }
 
 export { CamoConfig };