Upload 4.7

part4/bloglist/utils/list_helper.js

@@ -0,0 +1,37 @@
+const dummy = (blogs) => {
+  return 1
+}
+
+const sumLikes = (blogs) => {
+  return blogs.reduce((sum, blog) => sum + blog.likes, 0)
+}
+
+const favoriteBlog = (blogs) => {
+  return blogs.reduce((max, blog) => max.likes > blog.likes ? max : blog)
+}
+
+const mostBlogs = (blogs) => {
+  const authors = blogs.map(blog => blog.author)
+  const uniqueAuthors = [...new Set(authors)]
+  const authorBlogs = uniqueAuthors.map(author => {
+    return { author: author, blogs: authors.filter(a => a === author).length }
+  })
+  return authorBlogs.reduce((max, author) => max.blogs > author.blogs ? max : author)
+}
+
+const mostLikes = (blogs) => {
+  const authors = blogs.map(blog => blog.author)
+  const uniqueAuthors = [...new Set(authors)]
+  const authorLikes = uniqueAuthors.map(author => {
+    return { author: author, likes: blogs.filter(blog => blog.author === author).reduce((sum, blog) => sum + blog.likes, 0) }
+  })
+  return authorLikes.reduce((max, author) => max.likes > author.likes ? max : author)
+}
+
+module.exports = {
+  dummy,
+  sumLikes,
+  favoriteBlog,
+  mostBlogs,
+  mostLikes
+}