1 files changed, 75 insertions, 0 deletions
diff --git a/lib/modifiers/summary/mergeAtLevel.js b/lib/modifiers/summary/mergeAtLevel.js
new file mode 100644
index 0000000..9a95ffc
--- /dev/null
+++ b/lib/modifiers/summary/mergeAtLevel.js
@@ -0,0 +1,75 @@
+
+/**
+    Edit a list of articles
+
+    @param {List<Article>} articles
+    @param {String} level
+    @param {Article} newArticle
+    @return {List<Article>}
+*/
+function editArticleInList(articles, level, newArticle) {
+    return articles.map(function(article) {
+        var articleLevel = article.getLevel();
+
+        if (articleLevel === level) {
+            // it is the article to edit
+            return article.merge(newArticle);
+        } else if (level.indexOf(articleLevel) === 0) {
+            // it is a parent
+            var articles = editArticleInList(article.getArticles(), level, newArticle);
+            return article.set('articles', articles);
+        } else {
+            // This is not the article you are looking for
+            return article;
+        }
+    });
+}
+
+
+/**
+    Edit an article in a part
+
+    @param {Part} part
+    @param {String} level
+    @param {Article} newArticle
+    @return {Part}
+*/
+function editArticleInPart(part, level, newArticle) {
+    var articles = part.getArticles();
+    articles = editArticleInList(articles, level, newArticle);
+
+    return part.set('articles', articles);
+}
+
+
+/**
+    Edit an article, or a part, in a summary. Does a shallow merge.
+
+    @param {Summary} summary
+    @param {String} level
+    @param {Article|Part} newValue
+    @return {Summary}
+*/
+function mergeAtLevel(summary, level, newValue) {
+    var levelParts = level.split('.');
+    var partIndex = Number(levelParts[0]) -1;
+
+    var parts = summary.getParts();
+    var part = parts.get(partIndex);
+    if (!part) {
+        return summary;
+    }
+
+    var isEditingPart = levelParts.length < 2;
+    if (isEditingPart) {
+        part = part.merge(newValue);
+    } else {
+        part = editArticleInPart(part, level, newValue);
+    }
+
+    parts = parts.set(partIndex, part);
+    return summary.set('parts', parts);
+}
+
+
+module.exports = mergeAtLevel;