Add Installer to perform installation

This writes a repo-specific 'overcommit.yml' based on a combination of
the specified template (or the 'default' template) and the command-line
specified 'exclude's.

The last piece of the puzzle is to make the hook runner respect this
YAML file.

Change-Id: Id7d78bbf7141d75bb75fde8fe796623ab15d6530
Reviewed-on: https://gerrit.causes.com/22695
Reviewed-by: Aiden Scandella <aiden@causes.com>
Tested-by: Aiden Scandella <aiden@causes.com>

Author: Aiden Scandella

config/templates.yml

@@ -1,3 +1,4 @@
+---
 default:
   excludes:
     pre_commit:
@@ -6,3 +7,5 @@ default:
       - restricted_paths
     commit_msg:
       - change_id
+all:
+  excludes:

lib/overcommit.rb

@@ -2,6 +2,7 @@
 require 'overcommit/console_methods'
 require 'overcommit/git_hook'
 require 'overcommit/hook_specific_check'
+require 'overcommit/installer'
 require 'overcommit/reporter'
 require 'overcommit/utils'
 require 'overcommit/version'

lib/overcommit/cli.rb

@@ -2,7 +2,6 @@
 
 module Overcommit
   class CLI
-
     def initialize(arguments = [])
       @arguments = arguments
       @options   = {}
@@ -20,6 +19,38 @@ def parse_arguments
           puts VERSION
           exit 0
         end
+
+        opts.on('-a', '--all', 'Include all git hooks') do
+          @options[:template] = 'all'
+        end
+
+        opts.on('-t', '--template template',
+                'Specify a template of hooks') do |template|
+          @options[:template] = template
+        end
+
+        opts.on('-e', '--exclude hook_name,...', Array,
+                'Exclude hooks from installation') do |excludes|
+          # Transform from:
+          #
+          #   pre_commit/test_history,commit_msg/change_id
+          #
+          # Into:
+          #
+          #   {
+          #     'commit_msg' => ['change_id'],
+          #     'pre_commit' => ['test_history']
+          #   }
+          @options[:excludes] = excludes.inject({}) do |memo, exclude|
+            parts = exclude.split(%r{[:/.]})
+            next memo unless parts.size == 2
+
+            memo[parts.first] ||= []
+            memo[parts.first] << parts.last
+
+            memo
+          end
+        end
       end
 
       begin
@@ -33,7 +64,24 @@ def parse_arguments
     end
 
     def run
-      raise NotImplementedError, 'Nothing to see here yet'
+      if @options[:targets].nil? || @options[:targets].empty?
+        puts 'You must supply at least one directory to install into.'
+        puts 'For example:', ''
+        puts "  #{File.basename($0)} <target directory>"
+        exit 2
+      end
+
+      installer = Installer.new(@options)
+
+      @options[:targets].each do |target|
+        installer.install(target)
+      end
+
+      puts 'Installation complete.'
+
+    rescue ArgumentError => ex
+      puts "Installation failed: #{ex}"
+      exit 3
     end
 
   private

lib/overcommit/configuration.rb

@@ -8,8 +8,7 @@ class Configuration
     attr_reader :templates
 
     def initialize
-      @templates = YAML::load_file(File.join(File.dirname(
-        File.expand_path(__FILE__)), '..', '..', 'config', 'templates.yml'))
+      @templates = YAML::load_file(Utils.absolute_path('config/templates.yml'))
     end
   end
 

lib/overcommit/installer.rb

@@ -0,0 +1,59 @@
+require 'fileutils'
+require 'yaml'
+
+module Overcommit
+  class Installer
+    def initialize(options = {})
+      @options = options
+    end
+
+    def install(target)
+      absolute_target = File.expand_path(target)
+      unless File.directory?(File.join(absolute_target, '.git'))
+
+        raise ArgumentError, "#{target} does not appear to be a git repository"
+      end
+
+      puts "Installing hooks into #{target}"
+      hook_path = File.join(absolute_target, '.git/hooks')
+
+      install_scripts(hook_path)
+      install_hooks(hook_path)
+      write_configuration(hook_path)
+    end
+
+  private
+
+    # Make helper scripts available locally inside the repo
+    def install_scripts(target)
+      FileUtils.cp_r Utils.absolute_path('bin/scripts'), target
+    end
+
+    # Install all available git hooks into the repo
+    def install_hooks(target)
+      Dir[Utils.absolute_path('bin/hooks/*')].each do |hook|
+        FileUtils.cp hook, File.join(target, File.basename(hook))
+      end
+    end
+
+    # Dump a YAML document containing requested configuration
+    def write_configuration(target)
+      template = @options.fetch(:template, 'default')
+      base_config = Overcommit.config.templates[template]
+      if base_config.nil?
+        raise ArgumentError, "No such template '#{template}'"
+      end
+
+      base_config = base_config.dup
+      (base_config['excludes'] ||= {}).
+        merge!(@options[:excludes] || {}) do |_, a, b|
+        # Concat the arrays together
+        a + b
+      end
+
+      File.open(File.join(target, 'overcommit.yml'), 'w') do |config|
+        YAML.dump(base_config, config)
+      end
+    end
+  end
+end

lib/overcommit/utils.rb

@@ -28,6 +28,10 @@ def script_path(script)
         File.join(File.expand_path('../../hooks/scripts', $0), script)
       end
 
+      def absolute_path(path)
+        File.join(File.expand_path('../../..', __FILE__), path)
+      end
+
       # Shamelessly stolen from:
       # http://stackoverflow.com/questions/1509915/converting-camel-case-to-underscore-case-in-ruby
       def underscorize(str)