From dfe3113910ff7bc7600151e3345a6584ffe93272 Mon Sep 17 00:00:00 2001
From: Jonathan Hodgson <git@jonathanh.co.uk>
Date: Wed, 29 Jul 2020 17:32:38 +0100
Subject: [PATCH] Adds git-to-tikz script

---
 bin/.bin/git/git-to-tikz | 149 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 149 insertions(+)
 create mode 100755 bin/.bin/git/git-to-tikz

diff --git a/bin/.bin/git/git-to-tikz b/bin/.bin/git/git-to-tikz
new file mode 100755
index 00000000..06ba1093
--- /dev/null
+++ b/bin/.bin/git/git-to-tikz
@@ -0,0 +1,149 @@
+#!/usr/bin/env ruby
+
+# A small ruby script to extract a git history to a tikz picture
+# Author: Michael Hauspie <Michael.Hauspie@lifl.fr>
+#
+# Not clean code, not always working well, but does its job in most of the cases I needed :)
+
+# A commit object
+class Commit
+  attr_accessor :hash
+  attr_accessor :children
+  attr_accessor :parents
+  attr_accessor :message
+  attr_reader   :node_pos
+  
+  # Construct a commit from a line
+  # A line is commit_hash [child1_hash ... childN_hash] message
+  def initialize()
+    @hash = nil
+    @children = Hash.new()
+    @parents = Hash.new()
+    @message = ""
+    @node_pos = 0
+    @message_pos = 0
+  end
+  def build(line)
+    # Parse each word to match a hash or the commmit message
+    pos=0
+    line.split(" ").each do |word|
+      if word =~ /[a-f0-9]{7}/ &&  @message == "" # match a short sha-1 commit tag
+        if ! @hash
+          @hash = word
+        else
+          @parents[word] = nil
+        end
+      elsif word == '*' # Position of the node
+        @node_pos = pos
+      elsif word =~ /[^|\/\\]/
+        @message_pos = pos
+        @message << " #{word}"
+      end
+      pos = pos + 1
+    end
+    @message.delete!("!")
+    @message.lstrip!()
+    if !@hash
+      return false
+    end
+    return true
+  end
+
+  # sets a child object
+  def set_parent(c)
+    @parents[c.hash] = c
+    c.children[@hash] = self
+  end
+
+  def export_to_tikz(ypos)
+    puts "\\node[commit] (#{@hash}) at (#{0.5*@node_pos},#{ypos}) {};"
+    puts "\\node[right,xshift=#{@message_pos*0.5}] (label_#{@hash}) at (#{@hash}.east) {\\verb!#{@hash} #{@message}!};"
+    @children.each_value do |child|
+      puts "\\draw[->] (#{@hash}) -- (#{child.hash});"
+    end
+  end
+
+  def to_s()
+    "#{@hash}: #{@message} #{@node_pos} #{@message_pos}"
+  end
+end
+
+class Branch
+  attr_accessor :name
+  attr_accessor :hash
+  attr_accessor :commit
+
+  def initialize(line)
+    words = line.split(" ")
+    @name = words[0]
+    @hash = words[1]
+    @commit = nil
+  end
+end
+
+# A repository, which is a collection of commit objects and branches
+class Repository
+  def initialize()
+    @commits = Hash.new()
+    @branches = Array.new()
+  end
+  
+  def add_commit(commit)
+    @commits[commit.hash] = commit
+  end
+
+  def add_branch(branch)
+    if ! @commits.has_key?(branch.hash)
+      return false
+    end
+    c = @commits.fetch(branch.hash)
+    branch.commit = c
+    @branches << branch
+    return true
+  end
+
+  # This iterates other commits and resolves its parents
+  def resolve_parents()
+    @commits.each_value do |commit|
+      commit.parents.keys.each do |parent_hash|
+        c = @commits.fetch(parent_hash)
+        commit.set_parent(c) # Link the commit object to its parent
+      end
+    end
+  end
+
+  def export_to_tikz
+    puts "\\begin{tikzpicture}"
+    ypos=0
+    ystep=-0.5
+    @commits.each_value do |commit|
+      commit.export_to_tikz(ypos)
+      ypos = ypos + ystep
+    end
+    @branches.each do |branch|
+      puts "\\node[branch,right,xshift=.1] (#{branch.name}) at (label_#{branch.hash}.east) {\\texttt{#{branch.name}}};"
+    end
+    puts "\\end{tikzpicture}"
+  end
+end
+
+
+
+
+r = Repository.new()
+
+# Extract commits
+`git log --graph --branches --oneline --parents`.lines().each do |line|
+  c = Commit.new()
+  if c.build(line)
+    r.add_commit(c)
+  end
+end
+r.resolve_parents()
+
+# Extract branches
+`git branch -av | cut -b 3-`.lines().each do |line|
+  r.add_branch(Branch.new(line))
+end
+
+r.export_to_tikz()