gistfile1.txt

require 'awesome_print'
require 'pp'

input = <<TEXT
2       1       app/assets/javascripts/bar.js
16      25      app/assets/javascripts/baz.js.coffee
1       1       app/assets/javascripts/foo.js.coffee
4       9       app/controllers/bar_controller.rb
3       2       app/controllers/baz_controller.rb
11      0       app/controllers/foo_controller.rb
3       2       db/schema.rb
41      1       lib/foobar.rb
12      7       lib/tasks/cache.rake
5       13      lib/tasks/import.rake
TEXT

# totals: add: 98, del: 61
expected =
[
 { name: "app",
   add: 37,
   del: 38,
   children: [
     {name: "assets", add: 19, del: 27, children: [
         {name: "javascripts", add: 19, del: 27, children: [
             {name: "bar.js", add: 2, del: 1},
             {name: "baz.js.coffee", add: 16, del: 25},
             {name: "foo.js.coffee", add: 1, del: 1}
           ]
         },
       ]
     },
     {name: "controllers", add: 18, del: 11, children: [
         {name: "bar_controller.rb", add: 4, del: 9},
         {name: "baz_controller.rb", add: 3, del: 2},
         {name: "foo_controller.rb", add: 11, del: 0},
       ]
     },
   ]
 },

 { add: 3,
   del: 2,
   name: "db",
   children: [ {name: "schema.rb", add: 3, del: 2} ]
 },

 { add: 58,
   del: 21,
   name: "lib",
   children: [
     {name: "foobar.rb", add: 41, del: 1},
     {name: "tasks", add: 17, del: 20, children:
       [ {name: "cache.rake", add: 12, del: 7},
         {name: "import.rake", add: 5, del: 13} ] }
   ]
 }
]


def git_group lines, root = 'root'
  if lines.count == 1 and lines[0][:name].empty? then
    return {
      name: root,
      add: lines.map { |l| l[:add] }.reduce(0, :+),
      del: lines.map { |l| l[:del] }.reduce(0, :+),
    }
  end

  lines = lines.group_by { |line| line[:name].shift }
               .map { |key, value| git_group(value, key) }

  return {
    name: root,
    add: lines.map { |l| l[:add] }.reduce(0, :+),
    del: lines.map { |l| l[:del] }.reduce(0, :+),
    children: lines
  }
end

def to_git_diffnum_tree(txt)
  data = txt.split("\n")
    .map { |line| line.split() }
    .map { |line| {add: line[0].to_i, del: line[1].to_i, name: line[2].split('/')} }
    .sort_by { |item| item[:name] }

  git_group(data)[:children]
end

out = to_git_diffnum_tree(input)
puts; ap out; puts

puts; puts "Expected result:"; puts expected.inspect
puts; puts "Actual result: ";  puts out.inspect
puts; puts "Are expected and actual results identical: #{expected == out}"