add backlinks

lib/memex/contexts.ex

@@ -88,6 +88,42 @@ defmodule Memex.Contexts do
     )
   end
 
+  @doc """
+  Returns the list of contexts that link to a particular slug.
+
+  ## Examples
+
+      iex> backlink(%User{id: 123})
+      [%Context{}, ...]
+
+      iex> backlink("[other-context]", %User{id: 123})
+      [%Context{content: "[other-context]"}, ...]
+
+  """
+  @spec backlink(String.t(), User.t()) :: [Context.t()]
+  def backlink(link, %{id: user_id}) when user_id |> is_binary() do
+    link = link |> String.replace("[", "\\[") |> String.replace("]", "\\]")
+    link_regex = "(^|[^\[])#{link}($|[^\]])"
+
+    Repo.all(
+      from c in Context,
+        where: fragment("? ~ ?", c.content, ^link_regex),
+        order_by: c.slug
+    )
+  end
+
+  def backlink(link, _invalid_user) do
+    link = link |> String.replace("[", "\\[") |> String.replace("]", "\\]")
+    link_regex = "(^|[^\[])#{link}($|[^\]])"
+
+    Repo.all(
+      from c in Context,
+        where: fragment("? ~ ?", c.content, ^link_regex),
+        where: c.visibility == :public,
+        order_by: c.slug
+    )
+  end
+
   @doc """
   Gets a single context.
 

lib/memex/notes.ex

@@ -86,6 +86,42 @@ defmodule Memex.Notes do
     )
   end
 
+  @doc """
+  Returns the list of notes that link to a particular slug.
+
+  ## Examples
+
+      iex> backlink(%User{id: 123})
+      [%Note{}, ...]
+
+      iex> backlink("[other-note]", %User{id: 123})
+      [%Note{content: "[other-note]"}, ...]
+
+  """
+  @spec backlink(String.t(), User.t()) :: [Note.t()]
+  def backlink(link, %{id: user_id}) when user_id |> is_binary() do
+    link = link |> String.replace("[", "\\[") |> String.replace("]", "\\]")
+    link_regex = "(^|[^\[])#{link}($|[^\]])"
+
+    Repo.all(
+      from n in Note,
+        where: fragment("? ~ ?", n.content, ^link_regex),
+        order_by: n.slug
+    )
+  end
+
+  def backlink(link, _invalid_user) do
+    link = link |> String.replace("[", "\\[") |> String.replace("]", "\\]")
+    link_regex = "(^|[^\[])#{link}($|[^\]])"
+
+    Repo.all(
+      from n in Note,
+        where: fragment("? ~ ?", n.content, ^link_regex),
+        where: n.visibility == :public,
+        order_by: n.slug
+    )
+  end
+
   @doc """
   Gets a single note.
 

lib/memex/pipelines.ex

@@ -142,6 +142,50 @@ defmodule Memex.Pipelines do
     )
   end
 
+  @doc """
+  Returns the list of pipelines that link to a particular slug.
+
+  ## Examples
+
+      iex> backlink(%User{id: 123})
+      [%Pipeline{}, ...]
+
+      iex> backlink("[other-pipeline]", %User{id: 123})
+      [%Pipeline{description: "[other-pipeline]"}, ...]
+
+  """
+  @spec backlink(String.t(), User.t()) :: [Pipeline.t()]
+  def backlink(link, %{id: user_id}) when user_id |> is_binary() do
+    link = link |> String.replace("[", "\\[") |> String.replace("]", "\\]")
+    link_regex = "(^|[^\[])#{link}($|[^\]])"
+
+    Repo.all(
+      from p in Pipeline,
+        left_join: s in assoc(p, :steps),
+        where:
+          fragment("? ~ ?", p.description, ^link_regex) or
+            fragment("? ~ ?", s.content, ^link_regex),
+        distinct: true,
+        order_by: p.slug
+    )
+  end
+
+  def backlink(link, _invalid_user) do
+    link = link |> String.replace("[", "\\[") |> String.replace("]", "\\]")
+    link_regex = "(^|[^\[])#{link}($|[^\]])"
+
+    Repo.all(
+      from p in Pipeline,
+        left_join: s in assoc(p, :steps),
+        where:
+          fragment("? ~ ?", p.description, ^link_regex) or
+            fragment("? ~ ?", s.content, ^link_regex),
+        where: p.visibility == :public,
+        distinct: true,
+        order_by: p.slug
+    )
+  end
+
   @doc """
   Creates a pipeline.