defmodule Mix.Tasks.AddNavigation do
@doc """
## Usage
Run the `mix add_navigation` task to automatically add navigation.
Sections for navigation should be included in the notebook using the following comments:
```md
```
`livebook_utils` can update your navigation whenever your index file changes. You also have control over where navigation goes.
## Template Example
Typically, we recommend putting a navigation section at the top and the bottom of the file.
Here's an example template livebook file with navigation at the top and bottom of the file.
```md
# Title
## Navigation
## SubTitle
## Navigation
```
You must have two or more notebooks in your index file with valid paths and titles to add navigation.
## Styling
Currently, we don't provide any control over styling the navigation section. Here's how navigation looks out of the box:
"""
use Mix.Task
require Logger
def run(_args) do
Logger.info("Adding Navigation")
index_path = Application.get_env(:livebook_utils, :index_path)
notebooks_path = Application.get_env(:livebook_utils, :notebooks_path)
index = File.read!(index_path)
notebooks = get_notebooks(index, notebooks_path)
if Enum.count(notebooks) <= 1 do
raise "Cannot add navigation with one or fewer books"
else
write_navigation_sections!(notebooks, notebooks_path)
end
end
defp get_notebooks(index, notebooks_path) do
Regex.scan(~r/\[(.*)\]\((.*)\)/, index)
|> Enum.map(fn [_, title, path] -> %{path: path, title: title} end)
|> Enum.filter(fn %{path: path, title: title} ->
String.contains?(path, ".livemd") and File.exists?(Path.join(notebooks_path, path)) and
title != ""
end)
end
defp write_navigation_sections!(notebooks, notebooks_path) do
List.flatten([nil, notebooks])
|> Enum.chunk_every(3, 1, [nil])
|> Enum.map(fn
[prev, current, next] ->
file = File.read!(Path.join(notebooks_path, current.path))
file_with_nav =
Regex.replace(
~r/(?:.|\n)*?/,
file,
nav_snippet(prev, current, next)
)
File.write!("#{notebooks_path}/#{current.path}", file_with_nav)
end)
end
defp nav_snippet(prev, _, next) do
"""
#{if prev, do: prev_snippet(prev)}
#{if next, do: next_snippet(next)}
"""
end
defp next_snippet(next) do
"""
"""
end
defp prev_snippet(prev) do
"""
"""
end
end