module ExtractsPath

Assigns common instance variables for views working with Git tree-ish objects

Assignments are:

• @id - A string representing the joined ref and path

• @ref - A string representing the ref (e.g., the branch, tag, or commit SHA)

• @path - A string representing the filesystem path

• @commit - A CommitDecorator representing the commit from the given ref

• @tree - A TreeDecorator representing the tree at the given ref/path

If the :id parameter appears to be requesting a specific response format, that will be handled as well.

Automatically renders `not_found!` if a valid tree path could not be resolved (e.g., when a user inserts an invalid path or ref).

# File lib/extracts_path.rb, line 94
def assign_ref_vars
  # Handle formats embedded in the id
  if params[:id].ends_with?('.atom')
    params[:id].gsub!(%r\.atom$/, '')
    request.format = :atom
  end

  @ref, @path = extract_ref(params[:id])

  @id = File.join(@ref, @path)

  @commit = CommitDecorator.decorate(@project.commit(@ref))

  @tree = Tree.new(@commit.tree, @project, @ref, @path)
  @tree = TreeDecorator.new(@tree)

  raise InvalidPathError if @tree.invalid?
rescue NoMethodError, InvalidPathError
  not_found!
end

Given a string containing both a Git tree-ish, such as a branch or tag, and a filesystem path joined by forward slashes, attempts to separate the two.

Expects a @project instance variable to contain the active project. This is used to check the input against a list of valid repository refs.

Examples

# No @project available
extract_ref('master')
# => ['', '']

extract_ref('master')
# => ['master', '']

extract_ref("f4b14494ef6abf3d144c28e4af0c20143383e062/CHANGELOG")
# => ['f4b14494ef6abf3d144c28e4af0c20143383e062', 'CHANGELOG']

extract_ref("v2.0.0/README.md")
# => ['v2.0.0', 'README.md']

extract_ref('issues/1234/app/models/project.rb')
# => ['issues/1234', 'app/models/project.rb']

# Given an invalid branch, we fall back to just splitting on the first slash
extract_ref('non/existent/branch/README.md')
# => ['non', 'existent/branch/README.md']

Returns an Array where the first value is the tree-ish and the second is the path

# File lib/extracts_path.rb, line 45
def extract_ref(input)
  pair = ['', '']

  return pair unless @project

  if input.match(%r^([[:alnum:]]{40})(.+)/)
    # If the ref appears to be a SHA, we're done, just split the string
    pair = $~.captures
  else
    # Otherwise, attempt to detect the ref using a list of the project's
    # branches and tags

    # Append a trailing slash if we only get a ref and no file path
    id = input
    id += '/' unless id.ends_with?('/')

    valid_refs = @project.ref_names
    valid_refs.select! { |v| id.start_with?("#{v}/") }

    if valid_refs.length != 1
      # No exact ref match, so just try our best
      pair = id.match(%r([^\/]+)(.*)/).captures
    else
      # Partition the string into the ref and the path, ignoring the empty first value
      pair = id.partition(valid_refs.first)[1..-1]
    end
  end

  # Remove ending slashes from path
  pair[1].gsub!(%r^\/|\/$/, '')

  pair
end