UserTaskMatcher gets tasks with most overlapping skills to User (fixes …

…#736)

lib/code_corps/user_task_matcher.ex

@@ -0,0 +1,25 @@
+defmodule CodeCorps.UserTaskMatcher do
+  @moduledoc """
+  Find the top tasks most matching a User's skills
+  """
+
+  alias CodeCorps.{Repo, Task, User, TaskSkill}
+  import Ecto.Query
+
+  @spec match_user(User.t, number) :: [Task.t]
+  def match_user(%CodeCorps.User{} = user, tasks_count) do
+    query = from t in TaskSkill,
+      join: skill in assoc(t, :skill),
+      join: user_skill in assoc(skill, :user_skills),
+      join: user in assoc(user_skill, :user),
+      where: user.id == ^user.id,
+      group_by: t.task_id,
+      order_by: count(t.task_id),
+      limit: ^tasks_count,
+      select: t.task_id
+
+    matches = query |> Repo.all
+
+    Task |> where([t], t.id in ^matches) |> Repo.all
+  end
+end

test/lib/code_corps/user_task_matcher_test.exs

@@ -0,0 +1,32 @@
+defmodule CodeCorps.UserTaskMatcherTest do
+  use CodeCorps.ModelCase
+
+  import CodeCorps.UserTaskMatcher
+
+  test "can find top x tasks for a user's skill" do
+    coding = insert(:skill, title: "coding")
+    design = insert(:skill, title: "design")
+
+    account_page = insert(:task)
+    settings_page = insert(:task)
+    photoshop = insert(:task)
+
+    insert(:task)
+
+    insert(:task_skill, task: account_page, skill: design)
+    insert(:task_skill, task: account_page, skill: coding)
+    insert(:task_skill, task: settings_page, skill: design)
+    insert(:task_skill, task: settings_page, skill: coding)
+    insert(:task_skill, task: photoshop, skill: coding)
+
+    user = insert(:user)
+
+    insert(:user_skill, user: user, skill: design)
+    insert(:user_skill, user: user, skill: coding)
+
+    tasks = match_user(user, 2)
+
+    assert(length(tasks) == 2)
+    assert(length(match_user(user, 3)) == 3)
+  end
+end

web/models/skill.ex

@@ -12,6 +12,7 @@ defmodule CodeCorps.Skill do
     has_many :roles, through: [:role_skills, :role]
 
     has_many :project_skills, CodeCorps.ProjectSkill
+    has_many :user_skills, CodeCorps.UserSkill
     has_many :projects, through: [:project_skills, :project]
 
     timestamps()