git-dot

#!/usr/bin/env ruby

class Grapher
  class << self

    Props = {
      :branch   => '[shape=box,style=filled,fillcolor="#ccffcc",color="#003300"]',
      :commit   => '[style=filled,fillcolor="#ffffcc",color="#663333"]',
      :ref     => '',
      :relation => '[dir=back,color="#545443"]',
      :current  =>  '[shape=box,style=filled,fillcolor="#ffcccc",color="#330000"]'
    }

    def refs
      branches.inject({}) {|h,b|
        h.tap { h[b] = `git log -1 #{b} --pretty=format:"%h"` }
      }
    end

    def branches
      @branches ||= cmd("git branch") {|b| b[2..-1] }
    end

    def commits
      @commits ||= cmd("git log --pretty=format:\"%h\" #{@args.join ' '}")
    end

    def relations
      @rels ||= cmd("git log --pretty=format:\"%h %p\" #{@args.join ' '}") { |l|
        c, *parents = l.split
        parents.map {|p| [p, c] }
      }.flatten(1)
    end

    def run(*args)
      @args = args
      puts "digraph G {"
      puts "node [fontsize=8,fontname=\"Monaco bold\"," +
           "height=0.3,fontcolor=\"#333333\"];"

      puts "\n// Commits"
      commits.each   {|c|
        puts %("#{c}" #{Props[:commit]};)
      }

      puts "\n// Branches"
      puts %("#{current_branch}" #{Props[:current]};)
      (branches - [current_branch]).each  {|b|
        puts %("#{b}" #{Props[:branch]};) if commits.member?(refs[b])
      }

      puts "\n// Relations"
      relations.each {|p,c|
        puts %("#{c}" -> "#{p}" #{Props[:relation]};)
      }

      puts "\n// Refs"
      refs.each {|r,c|
        puts %("#{r}" -> "#{c}" #{Props[:ref]};) if commits.member?(c)
      }
      puts "}"
    end

    def current_branch
      cmd("git branch").select {|l| l =~ /^\*/ }.first.strip[2..-1]
    end

    private

    def cmd(c, &blk)
      `#{c}`.split($/).map(&blk || proc {|a| a })
    end

  end
end

Grapher.run(*ARGV)