WIP: First stab at git post-commit hook

The post-commit hook parses the state of the code after each commit to the
`master` branch, builds a tree of method definition "files" using ri-style
naming, and adds a corresponding commit to the orphan `method-log` branch.

* This code assumes the `method-log` branch already exists.

* I've not thought about what happens if the history on `master` is re-written.

* There is no explicit reference between the commits on `master` and those on
the `method-log` branch.

* I'm not sure how tenable it is to use a `Gemfile` and bundler for this hook.
Maybe an in-line `Gemfile` [1] might be better.

* I've duplicated some code from elsewhere in the repo, e.g. `#unindent`.

* I've used `instance_variable_get` on the instance of `MethodFinder`, but it
would be easy to surface this as a public attribute reader method.

[1]: http://bundler.io/whats_new.html#inline

hooks/Gemfile

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+source 'https://rubygems.org'
+
+gem 'parser'
+gem 'method_log'

hooks/post-commit

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+#!/usr/bin/env bash
+
+cd .git/hooks
+bundle exec ruby post_commit.rb

hooks/post_commit.rb

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+require 'bundler/setup'
+
+require 'method_log/repository'
+require 'method_log/method_finder'
+require 'method_log/source_file'
+
+def unindent(code)
+  lines = code.split($/)
+  indent = lines.reject { |l| l.strip.length == 0 }.map { |l| l[/^ */].length }.min
+  lines.map { |l| l.sub(Regexp.new(' ' * indent), '') }.join($/)
+end
+
+repository_path = File.expand_path('../..')
+rugged_repository = Rugged::Repository.new(repository_path)
+exit unless rugged_repository.head.name == 'refs/heads/master'
+last_commit_sha = rugged_repository.last_commit.oid
+
+repository = MethodLog::Repository.new(repository_path)
+last_commit = repository.build_commit(last_commit_sha)
+
+rugged_repository.checkout('method-log')
+begin
+  new_commit = repository.build_commit
+  last_commit.source_files.each do |source_file|
+    next if source_file.path[%r{^(vendor|test)}]
+    begin
+      method_finder = MethodLog::MethodFinder.new(source_file)
+      method_finder.instance_variable_get('@methods').each do |method_signature, method_definition|
+        _, namespace, name = method_signature.match(/^(.*)([#.].*)$/).to_a
+        path = namespace.split('::').push(name).join(File::SEPARATOR) + '.rb'
+        new_commit.add(MethodLog::SourceFile.new(path: path, source: unindent(method_definition.source) + $/))
+      end
+    rescue Parser::SyntaxError => e
+      p e
+    end
+  end
+  new_commit.apply(user: last_commit.author, message: last_commit.message)
+  rugged_repository.reset('HEAD', :hard)
+ensure
+  rugged_repository.checkout('master')
+end