Initial, single-file prototype.

babushka.rb

@@ -0,0 +1,325 @@
+require 'rubygems'
+require 'open4'
+
+$log_indent = 0
+RAILS_ROOT = '/Users/ben/projects/corkboard/current'
+RAILS_ENV = 'production'
+
+appname = 'corkboard'
+dbname = 'corkboard'
+
+Dir.chdir RAILS_ROOT
+
+def returning obj, &block
+  yield obj
+  obj
+end
+
+def log message, &block
+  print((' ' * $log_indent * 2) + message)
+  if block_given?
+    print " {\n"
+    $log_indent += 1
+    returning yield do
+      $log_indent -= 1
+      log "}"
+    end
+  else
+    print "\n"
+  end
+end
+
+class Object
+  def in? list
+    list.include? self
+  end
+end
+
+class String
+  # Returns true iff +str+ appears exactly at the start of +self+.
+  def starts_with? str
+    self[0, str.length] == str
+  end
+
+  # Returns true iff +str+ appears exactly at the end of +self+.
+  def ends_with? str
+    self[-str.length, str.length] == str
+  end
+
+  # Return a duplicate of +self+, with +str+ prepended to it if it doesn't already start with +str+.
+  def start_with str
+    starts_with?(str) ? self : str + self
+  end
+
+  # Return a duplicate of +self+, with +str+ appended to it if it doesn't already end with +str+.
+  def end_with str
+    ends_with?(str) ? self : self + str
+  end
+
+  def val_for key
+    split("\n").grep(key).first.sub(/^#{key}\:?/).strip
+  end
+  def / other
+    File.join self, other
+  end
+end
+
+def yaml file_name
+  require 'yaml'
+  YAML::load_file(RAILS_ROOT / file_name)
+end
+
+def shell cmd
+  log "running '#{cmd}'"
+  _stdout, _stderr = nil, nil
+  status = Open4.popen4 cmd do |pid,stdin,stdout,stderr|
+    _stdout, _stderr = stdout.read, stderr.read
+  end
+  returning (status.exitstatus == 0 ? _stdout : false) do |result|
+    log "failed with '#{_stderr.chomp}'" unless result
+  end
+end
+
+def sudo cmd
+  log "(would be sudoing the next command)"
+  shell cmd
+end
+
+def rake cmd
+  shell "rake #{cmd}"
+end
+
+class PkgManager
+  def self.for_system
+    case `uname -s`.chomp
+    when 'Darwin'; MacportsHelper
+    when 'Linux'; AptHelper
+    end.new
+  end
+end
+
+class MacportsHelper < PkgManager
+  def has? pkg_name
+    returning pkg_name.in? existing_packages do |result|
+      log "system #{result ? 'has' : 'doesn\'t have'} #{pkg_name} port"
+    end
+  end
+  def install! *pkgs
+    shell "port install #{pkgs.join(' ')}"
+  end
+  def existing_packages
+    Dir.glob("/opt/local/var/macports/software/*").map {|i| File.basename i }
+  end
+  def cmd_dir cmd_name
+    File.dirname shell("which #{cmd_name}")
+  end
+  def prefix
+    cmd_dir('port').sub(/\/bin\/?$/, '')
+  end
+  def bin_path
+    prefix / 'bin'
+  end
+  def cmd_in_path? cmd_name
+    returning cmd_dir(cmd_name).starts_with?(prefix) do |result|
+      log "#{result ? 'the correct' : 'an incorrect installation of'} #{cmd_name} is in use, at #{cmd_dir(cmd_name)}."
+    end
+  end
+end
+class AptHelper < PkgManager
+  def self.has? pkg_name
+    returning shell "dpkg -s #{pkg_name}" do |result|
+      log "system #{result ? 'has' : 'doesn\'t have'} #{pkg_name} package"
+    end
+  end
+  def self.install! *pkgs
+    shell "apt-get install #{pkgs.join(' ')}"
+  end
+end
+class GemHelper < PkgManager
+  def self.has? pkg_name
+    returning shell "gem list -i #{pkg_name}" do |result|
+      log "system #{result ? 'has' : 'doesn\'t have'} #{pkg_name} gem"
+    end
+  end
+  def self.install! *pkgs
+    sudo "gem install #{pkgs.join(' ')}"
+  end
+end
+
+
+def pkg_manager
+  PkgManager.for_system
+end
+
+class DepDefiner
+  def initialize &block
+    @defines = {:requires => []}
+    instance_eval &block
+  end
+  def requires *deps
+    @defines[:requires] = deps
+  end
+  def met? &block
+    @defines[:met?] = block
+  end
+  def meet &block
+    @defines[:meet] = block
+  end
+
+  # def self.block_writer name
+  #   define_method name do |&block|
+  #     instance_variable_set name, block
+  #   end
+  # end
+  def self.attr_setter *names
+    names.each {|name|
+      define_method name do |obj|
+        instance_variable_set "@#{name}", obj
+      end
+    }
+  end
+
+  def payload
+    {
+      :requires => @defines[:requires],
+      :met? => @defines[:met?],
+      :meet => @defines[:meet]
+    }
+  end
+end
+
+class PkgDepDefiner < DepDefiner
+
+  attr_setter :pkg, :provides
+
+  def payload
+    super.merge({
+      :met? => lambda {
+        @pkg[:macports].all? {|pkg_name| pkg_manager.has?(pkg_name) } &&
+        @provides.all? {|cmd_name|
+          pkg_manager.cmd_in_path? cmd_name
+        }
+      },
+      :meet => lambda {
+        'lol'
+      }
+    })
+  end
+
+end
+
+class GemDepDefiner < DepDefiner
+
+  attr_setter :pkg
+
+  def payload
+    super.merge({
+      :met? => lambda {
+        @pkg.all? {|pkg_name| GemHelper.has?(pkg_name) }
+      },
+      :meet => lambda {
+        'lol'
+      }
+    })
+  end
+
+end
+
+class Dep
+  attr_reader :name
+
+  def initialize name, block, definer_class = DepDefiner
+    @name = name
+    @defines = definer_class.new(&block).payload
+    [:requires, :met?, :meet].each {|item|
+      raise "You need to specify '#{item}' in the dep \"#{name}\" definition." if @defines[item].nil?
+    }
+    # log "Dep #{name} depends on #{@defines[:requires].inspect}"
+    Dep.register self
+  end
+
+  def self.register dep
+    @@deps ||= {}
+    raise "There is already a registered dep called '#{dep.name}'." unless @@deps[dep.name].nil?
+    @@deps[dep.name] = dep
+  end
+  def self.for name
+    @@deps[name]
+  end
+
+  def dep_task method_name
+    @defines[:requires].all? {|requirement|
+      if (dep = Dep.for(requirement)).nil?
+        raise "dep '#{name}' requires '#{requirement}', which doesn't exist."
+      else
+        dep.send method_name
+      end
+    }
+  end
+
+  def met?
+    @cached_met ||= dep_task(:met?) && @defines[:met?].call
+  end
+
+  def meet
+    log "#{name}..." do
+      # begin
+        dep_task(:meet) && (met? || @defines[:meet].call)
+      # rescue Exception => e
+      #   log "Tried to install #{@name}, and #{e.to_s} out of fucking nowhere."
+      #   log e.backtrace.inspect
+      #   false
+      # end
+    end
+  end
+end
+
+def dep name, &block
+  Dep.new name, block
+end
+
+def pkg_dep name, &block
+  Dep.new name, block, PkgDepDefiner
+end
+def gem_dep name, &block
+  Dep.new name, block, GemDepDefiner
+end
+dep 'migrated db' do
+  requires 'db access', 'existing db'
+  met? { shell "rake db:version".val_for('Current version') == Dir.glob('db/migrate').sort.last.split('_', 2).first }
+  meet { rake "db:migrate --trace" }
+end
+
+dep 'existing db' do
+  requires 'db gem', 'db access'
+  met? { shell("rake db:create")['already exists'] }
+  meet { rake "db:create" }
+end
+
+gem_dep 'db gem' do
+  requires 'db software'
+  pkg 'pg'
+  # gem_dep({
+  #   'mysql' => 'mysql',
+  #   'postgresql' => 'pg',
+  #   'sqlite3' => 'sqlite3'
+  # }[yaml('config/database.yml')[RAILS_ENV]['adapter']])
+end
+
+dep 'db access' do
+  requires 'db software'
+  met? { shell "echo '\\d' | psql #{dbname}" }
+  meet { sudo "createuser #{appname}" }
+end
+
+pkg_dep 'db software' do
+  pkg :macports => 'postgresql83-server', :apt => 'postgresql-8.2'
+  provides 'psql'
+  # provides({
+  #   'mysql' => AptPkg.new('mysql-server', 'mysql5'),
+  #   'postgresql' => AptPkg.new('postgresql-8.2', 'psql'),
+  #   'sqlite3' => 'sqlite3'
+  # }[yaml('config/database.yml')[RAILS_ENV]['adapter']])
+end
+
+Dep.for('migrated db').meet