defmodule Blog.Comment do
  use Blog.Web, :model

  schema "comments" do
    field :name, :string
    field :content, :string
    belongs_to :post, Blog.Post

    timestamps()
  end

  @required_fields ~w(name content post_id)
  @optional_fields ~w()
  
  @doc """
  Creates a changeset based on the `model` and `params`.
  
  If `params` are nil, an invalid changeset is returned
  with no validation performed.
  """
  def changeset(model, params \\ %{}) do
    model
    |> cast(params, @required_fields, @optional_fields)
  end
end
   

   defmodule Blog.Post do
  use Blog.Web, :model

  schema "posts" do
    field :title, :string
    field :body, :string

    has_many :comments, Blog.Comment, on_delete: :delete_all
    
    timestamps()
  end
  
  @required_fields ~w(title body)
  @optional_fields ~w()

  @doc """
  Creates a changeset based on the `model` and `params`.
  
  If `params` are nil, an invalid changeset is returned
  with no validation performed.
  """
  def changeset(model, params \\ %{}) do
    model
    |> cast(params, @required_fields, @optional_fields)
  end
  
  def count_comments(query) do
    from p in query,
      group_by: p.id,
      left_join: c in assoc(p, :comments),
      select: {p, count(c.id)}
  end
  
end
   

   defmodule Blog.Comment do
  use Blog.Web, :model

  schema "comments" do
    field :name, :string
    field :content, :string
    belongs_to :post, Blog.Post

    timestamps()
  end

  @required_fields ~w(name content post_id)
  @optional_fields ~w()
  
  @doc """
  Creates a changeset based on the `model` and `params`.
  
  If `params` are nil, an invalid changeset is returned
  with no validation performed.
  """
  def changeset(model, params \\ %{}) do
    model
    |> cast(params, @required_fields, @optional_fields)
  end
end
   

   defmodule Blog.Router do
  use Blog.Web, :router

  pipeline :browser do
    plug :accepts, ["html"]
    plug :fetch_session
    plug :fetch_flash
    plug :protect_from_forgery
    plug :put_secure_browser_headers
  end

  pipeline :api do
    plug :accepts, ["json"]
  end

  scope "/", Blog do
    pipe_through :browser # Use the default browser stack

    get "/", PageController, :index
    resources "/posts", PostController do
      post "/comment", PostController, :add_comment
    end
    
  end

  # Other scopes may use custom stacks.
  # scope "/api", Blog do
  #   pipe_through :api
  # end
end
   

   defmodule Blog.PostController do
  use Blog.Web, :controller

  alias Blog.Post
  alias Blog.Comment
  
  plug :scrub_params, "post" when action in [:create, :update]
  plug :scrub_params, "comment" when action in [:add_comment]

  def index(conn, _params) do
    posts = Post
    |> Post.count_comments
    |> Repo.all
    render(conn, "index.html", posts: posts)
  end

  def new(conn, _params) do
    changeset = Post.changeset(%Post{})
    render(conn, "new.html", changeset: changeset)
  end

  def create(conn, %{"post" => post_params}) do
    changeset = Post.changeset(%Post{}, post_params)

    if changeset.valid? do
        Repo.insert(changeset)
        
        conn
        |> put_flash(:info, "Post created successfully.")
        |> redirect(to: post_path(conn, :index))
    else
        render(conn, "new.html", changeset: changeset)
    end
  end
  
  def show(conn, %{"id" => id}) do
    post = Repo.get(Post, id) |> Repo.preload([:comments])
    changeset = Comment.changeset(%Comment{})
    render(conn, "show.html", post: post, changeset: changeset)
  end

  def edit(conn, %{"id" => id}) do
    post = Repo.get!(Post, id)
    changeset = Post.changeset(post)
    render(conn, "edit.html", post: post, changeset: changeset)
  end

  def update(conn, %{"id" => id, "post" => post_params}) do
    post = Repo.get!(Post, id)
    changeset = Post.changeset(post, post_params)

    if changeset.valid? do
        Repo.update(changeset)
        
        conn
        |> put_flash(:info, "Post updated successfully.")
        |> redirect(to: post_path(conn, :index))
    else
        render(conn, "edit.html", post: post, changeset: changeset)
    end
  end

  def delete(conn, %{"id" => id}) do
    post = Repo.get!(Post, id)
    # Here we use delete! (with a bang) because we expect
    # it to always work (and if it does not, it will raise).
    Repo.delete!(post)

    conn
    |> put_flash(:info, "Post deleted successfully.")
    |> redirect(to: post_path(conn, :index))
  end
  
  def add_comment(conn, %{"comment" => comment_params, "post_id" => post_id}) do
    changeset = Comment.changeset(%Comment{}, Map.put(comment_params, "post_id", post_id))
    post = Repo.get(Post, post_id) |> Repo.preload([:comments])

    if changeset.valid? do
      Repo.insert(changeset)

      conn
      |> put_flash(:info, "Comment added.")
      |> redirect(to: post_path(conn, :show, post))
    else
      render(conn, "show.html", post: post, changeset: changeset)
    end
  end
  
end
   

   <%= form_for @changeset, @action, fn f -> %>
  <%= if f.errors != [] do %>
    <div class="alert alert-danger">
      <p>Oops, something went wrong! Please check the errors below:</p>
      <ul>
        <%= for {attr, message} <- f.errors do %>
          <li><%= humanize(attr) %> <%= message %></li>
        <% end %>
      </ul>
    </div>
  <% end %>
 
  <div class="form-group">
    <label>Name</label>
    <%= text_input f, :name, class: "form-control" %>
  </div>

  <div class="form-group">
    <label>Content</label>
    <%= textarea f, :content, class: "form-control" %>
  </div>

  <div class="form-group">
    <%= submit "Add comment", class: "btn btn-primary" %>
  </div>
<% end %>
   

   <h2><%= @post.title %></h2>
<div>
  <%= @post.body %>
</div>

<%= render "comment_form.html", post: @post, changeset: @changeset,
                                action: post_post_path(@conn, :add_comment, @post) %>

<%= render "comments.html", post: @post %>

<%= link "Back", to: post_path(@conn, :index) %>
   

   <h3> Comments: </h3>
<table class="table">
  <thead>
    <tr>
      <th></th>
      <th></th>
    </tr>
  </thead>
  <tbody>
<%= for comment <- @post.comments do %>
    <tr>
      <td><%= comment.name %></td>
      <td><%= comment.content %></td>
    </tr>
<% end %>
  </tbody>
</table>
   

   <h2>Listing posts</h2>

<table class="table">
  <thead>
    <tr>
      <th>Title</th>
      <th>Comments</th>

      <th></th>
    </tr>
  </thead>
  <tbody>
<%= for {post, count} <- @posts do %>
    <tr>
      <td><%= post.title %></td>
      <td><%= count %></td>

      <td class="text-right">
        <%= link "Show", to: post_path(@conn, :show, post), class: "btn btn-default btn-xs" %>
        <%= link "Edit", to: post_path(@conn, :edit, post), class: "btn btn-default btn-xs" %>
        <%= link "Delete", to: post_path(@conn, :delete, post), method: :delete, class: "btn btn-danger btn-xs" %>
      </td>
    </tr>
<% end %>
  </tbody>
</table>

<%= link "New post", to: post_path(@conn, :new) %>