require 'rugged'

module Technologist
  class GitRepository
    attr_reader :repository

    def initialize(repository_path)
      @repository = Rugged::Repository.new(repository_path)
    end

    def root_tree
      repository.head.target.tree
    end

    # Recursively searches for the blob identified by `blob_name`
    # in all subdirectories in the repository. A blob is usually either
    # a file or a directory.
    #
    # @param blob_name [String] the blob name
    # @param current_tree [Rugged::Tree] the git directory tree in which to look for the blob.
    #   Defaults to the root tree (see `#root_tree`).
    #
    # @yield [Rugged::Blob] Yields the found blob to an optional block.
    #   If the block returns `true` it means that the file is found and
    #   recursion is stopped. If the return value is `false`, the resursion continues.
    #
    # @return [Rugged::Blob] The blob blob or nil if it cannot be found.
    def find_blob(blob_name, current_tree = root_tree, &block)
      blob = current_tree[blob_name]

      if blob
        blob = repository.lookup(blob[:oid])
        if !block_given? || yield(blob)
          return blob
        end
      end

      # recurse
      current_tree.each_tree do |sub_tree|
        blob = find_blob(blob_name, repository.lookup(sub_tree[:oid]), &block)
        break blob if blob
      end
    end

    # Looks for a directory and returns true when the directory
    # can be found.
    #
    # @param directory_name [String] the directory name
    #
    # @return [Boolean] true if the directory can be found.
    def directory_exists?(directory_name)
      !!find_blob(directory_name)
    end

    # Looks for a file and returns true when the file
    # can be found.
    #
    # @param file_name [String] the file name
    #
    # @return [Boolean] true if the file can be found.
    def file_exists?(file_name)
      !!find_blob(file_name)
    end

    # Looks for a file and yields the file content to
    # the block (if the file can be found). The block's
    # return value is used to determine if we're done
    # searching. If the return value is `false`, we
    # keep searching for the file.
    #
    # @param file_name [String] the file name
    #
    # @return [Boolean] true if the file can be found.
    def file_with_content_exists?(file_name)
      !!find_blob(file_name) do |file|
        yield file.content
      end
    end
  end
end