anolson/git_diff

# frozen_string_literal: true

module GitDiff
  class File
    attr_reader :a_path, :a_blob, :b_path, :b_blob, :b_mode, :hunks, :binary

    def self.from_string(string)
      if path_info = %r{^diff --git(?: a/(\S+))?(?: b/(\S+))?}.match(string)
        File.new(
          a_path: path_info.captures[0] || "/dev/null",
          b_path: path_info.captures[1] || "/dev/null"
        )
      end
    end

    def initialize(a_path: "/dev/null", b_path: "/dev/null")
      @hunks = []
      @a_path = a_path
      @b_path = b_path
    end

    def <<(string)
      return if extract_diff_meta_data(string)

      if (range_info = RangeInfo.from_string(string))
        add_hunk Hunk.new(range_info)
      else
        append_to_current_hunk string
      end
    end

    def stats
      @stats ||= Stats.total(collector)
    end

    private

    attr_accessor :current_hunk

    def collector
      GitDiff::StatsCollector::Rollup.new(hunks)
    end

    def add_hunk(hunk)
      self.current_hunk = hunk
      hunks << current_hunk
      @binary = false
    end

    def append_to_current_hunk(string)
      current_hunk << string
    end

    def extract_diff_meta_data(string)
      if a_path_info = %r{^[-]{3} /dev/null(.*)$}.match(string)
        @a_path = "/dev/null"
      elsif a_path_info = %r{^[-]{3} "?a/(.*)$}.match(string)
        @a_path = a_path_info[1]
      elsif b_path_info = %r{^[+]{3} /dev/null(.*)$}.match(string)
        @b_path = "/dev/null"
      elsif b_path_info = %r{^[+]{3} "?b/(.*)$}.match(string)
        @b_path = b_path_info[1]
      elsif blob_info = /^index ([0-9A-Fa-f]+)\.\.([0-9A-Fa-f]+) ?(.+)?$/.match(string)
        @a_blob, @b_blob, @b_mode = *blob_info.captures
      elsif /^new file mode [0-9]{6}$/.match(string)
        @a_path = "/dev/null"
      elsif /^deleted file mode [0-9]{6}$/.match(string)
        @b_path = "/dev/null"
      elsif mode_info = /^(old|new) mode ([0-9]{6})$/.match(string)
        if mode_info.captures[0] == "old"
          @a_mode = mode_info.captures[1]
        else
          @b_mode = mode_info.captures[1]
        end
      elsif copy_rename_info = /^(copy|rename) (from|to) (.*)$/.match(string)
        if copy_rename_info.captures[1] == "from"
          @a_path = copy_rename_info.captures[2]
        else
          @b_path = copy_rename_info.captures[2]
        end
      elsif binary_info = %r{^Binary files (?:/dev/null|"?a/(.*)) and (?:/dev/null|"?b/(.*)) differ$}.match(string)
        @binary = true
        @a_path ||= binary_info[1] || "/dev/null"
        @b_path ||= binary_info[2] || "/dev/null"
      elsif /^similarity/.match(string)
        # trash
        true
      end
    end
  end
end