implement functions for iterating over metadata logs

lib/metadata.js

@@ -0,0 +1,99 @@
+var Meta = module.exports;
+
+/*  Metadata fields:
+
+    * channel <STRING>
+    * validateKey <STRING>
+    * owners <ARRAY>
+      * ADD_OWNERS
+      * RM_OWNERS
+    * expire <NUMBER>
+
+*/
+
+var commands = {};
+
+// ["ADD_OWNERS", ["7eEqelGso3EBr5jHlei6av4r9w2B9XZiGGwA1EgZ-5I="], 1561623438989]
+commands.ADD_OWNERS = function (meta, args) {
+    if (!Array.isArray(args)) {
+        throw new Error('METADATA_INVALID_OWNERS');
+    }
+    if (!Array.isArray(meta.owners)) {
+        throw new Error("METADATA_NONSENSE_OWNERS");
+    }
+
+    args.forEach(function (owner) {
+        if (meta.owners.indexOf(owner) >= 0) { return; }
+        meta.owners.push(owner);
+    });
+};
+
+// ["RM_OWNERS", ["CrufexqXcY-z+eKJlEbNELVy5Sb7E-EAAEFI8GnEtZ0="], 1561623439989]
+commands.RM_OWNERS = function (meta, args) {
+    if (!Array.isArray(args)) {
+        throw new Error('METADATA_INVALID_OWNERS');
+    }
+    if (!Array.isArray(meta.owners)) {
+        throw new Error("METADATA_NONSENSE_OWNERS");
+    }
+
+    args.forEach(function (owner) {
+        var index = meta.owners.indexOf(owner);
+        meta.owners.splice(index, 1);
+    });
+};
+
+commands.UPDATE_EXPIRATION = function () {
+
+};
+
+var handleCommand = function (meta, line) {
+    var command = line[0];
+    var args = line[1];
+    //var time = line[2];
+
+    if (typeof(commands[command]) !== 'function') {
+        throw new Error("METADATA_UNSUPPORTED_COMMAND");
+    }
+
+    commands[command](meta, args);
+};
+
+Meta.createLineHandler = function (ref, errorHandler) {
+    ref.meta = {};
+
+    errorHandler = errorHandler;
+
+    return function (err, line, index) {
+        if (err) {
+            return void errorHandler('METADATA_HANDLER_LINE_ERR', {
+                error: err,
+                index: index,
+                line: JSON.stringify(line),
+            });
+        }
+
+        if (Array.isArray(line)) {
+            try {
+                handleCommand(ref.meta, line);
+            } catch (err) {
+                errorHandler("METADATA_COMMAND_ERR", {
+                    error: err.stack,
+                    line: line,
+                });
+            }
+            return;
+        }
+
+        if (index === 0 && typeof(line) === 'object') {
+            // special case!
+            ref.meta = line;
+            return;
+        }
+
+        errorHandler("METADATA_HANDLER_WEIRDLINE", {
+            line: line,
+            index: index
+        });
+    };
+};