module Rails::Generators

def self.aliases #:nodoc:
  @aliases ||= DEFAULT_ALIASES.dup
end

def self.api_only!
  hide_namespaces "assets", "helper", "css", "js"
  options[:rails].merge!(
    api: true,
    assets: false,
    helper: false,
    template_engine: nil
  )
  if ARGV.first == 'mailer'
    options[:rails].merge!(template_engine: :erb)
  end
end

def self.configure!(config) #:nodoc:
  api_only! if config.api_only
  no_color! unless config.colorize_logging
  aliases.deep_merge! config.aliases
  options.deep_merge! config.options
  fallbacks.merge! config.fallbacks
  templates_path.concat config.templates
  templates_path.uniq!
  hide_namespaces(*config.hidden_namespaces)
end

def self.fallbacks
  @fallbacks ||= {}
end

def self.find_by_namespace(name, base=nil, context=nil) #:nodoc:
  lookups = []
  lookups << "#{base}:#{name}"    if base
  lookups << "#{name}:#{context}" if context
  unless base || context
    unless name.to_s.include?(?:)
      lookups << "#{name}:#{name}"
      lookups << "rails:#{name}"
    end
    lookups << "#{name}"
  end
  lookup(lookups)
  namespaces = Hash[subclasses.map { |klass| [klass.namespace, klass] }]
  lookups.each do |namespace|
    klass = namespaces[namespace]
    return klass if klass
  end
  invoke_fallbacks_for(name, base) || invoke_fallbacks_for(context, name)
end

def self.help(command = 'generate')
  puts "Usage: rails #{command} GENERATOR [args] [options]"
  puts
  puts "General options:"
  puts "  -h, [--help]     # Print generator's options and usage"
  puts "  -p, [--pretend]  # Run but do not make any changes"
  puts "  -f, [--force]    # Overwrite files that already exist"
  puts "  -s, [--skip]     # Skip files that already exist"
  puts "  -q, [--quiet]    # Suppress status output"
  puts
  puts "Please choose a generator below."
  puts
  print_generators
end

def self.hidden_namespaces
  @hidden_namespaces ||= begin
    orm      = options[:rails][:orm]
    test     = options[:rails][:test_framework]
    template = options[:rails][:template_engine]
    css      = options[:rails][:stylesheet_engine]
    [
      "rails",
      "resource_route",
      "#{orm}:migration",
      "#{orm}:model",
      "#{test}:controller",
      "#{test}:helper",
      "#{test}:integration",
      "#{test}:mailer",
      "#{test}:model",
      "#{test}:scaffold",
      "#{test}:view",
      "#{test}:job",
      "#{template}:controller",
      "#{template}:scaffold",
      "#{template}:mailer",
      "#{css}:scaffold",
      "#{css}:assets",
      "css:assets",
      "css:scaffold"
    ]
  end
end

def self.invoke(namespace, args=ARGV, config={})
  names = namespace.to_s.split(':')
  if klass = find_by_namespace(names.pop, names.any? && names.join(':'))
    args << "--help" if args.empty? && klass.arguments.any?(&:required?)
    klass.start(args, config)
  else
    options     = sorted_groups.flat_map(&:last)
    suggestions = options.sort_by {|suggested| levenshtein_distance(namespace.to_s, suggested) }.first(3)
    msg =  "Could not find generator '#{namespace}'. "
    msg << "Maybe you meant #{ suggestions.map {|s| "'#{s}'"}.to_sentence(last_word_connector: " or ", locale: :en) }\n"
    msg << "Run `rails generate --help` for more options."
    puts msg
  end
end

def self.invoke_fallbacks_for(name, base) #:nodoc:
  return nil unless base && fallbacks[base.to_sym]
  invoked_fallbacks = []
  Array(fallbacks[base.to_sym]).each do |fallback|
    next if invoked_fallbacks.include?(fallback)
    invoked_fallbacks << fallback
    klass = find_by_namespace(name, fallback)
    return klass if klass
  end
  nil
end

def self.levenshtein_distance str1, str2
  s = str1
  t = str2
  n = s.length
  m = t.length
  return m if (0 == n)
  return n if (0 == m)
  d = (0..m).to_a
  x = nil
  # avoid duplicating an enumerable object in the loop
  str2_codepoint_enumerable = str2.each_codepoint
  str1.each_codepoint.with_index do |char1, i|
    e = i+1
    str2_codepoint_enumerable.with_index do |char2, j|
      cost = (char1 == char2) ? 0 : 1
      x = [
           d[j+1] + 1, # insertion
           e + 1,      # deletion
           d[j] + cost # substitution
          ].min
      d[j] = e
      e = x
    end
    d[m] = x
  end
  x
end

def self.lookup(namespaces) #:nodoc:
  paths = namespaces_to_paths(namespaces)
  paths.each do |raw_path|
    ["rails/generators", "generators"].each do |base|
      path = "#{base}/#{raw_path}_generator"
      begin
        require path
        return
      rescue LoadError => e
        raise unless e.message =~ /#{Regexp.escape(path)}$/
      rescue Exception => e
        warn "[WARNING] Could not load generator #{path.inspect}. Error: #{e.message}.\n#{e.backtrace.join("\n")}"
      end
    end
  end
end

def self.lookup! #:nodoc:
  $LOAD_PATH.each do |base|
    Dir[File.join(base, "{rails/generators,generators}", "**", "*_generator.rb")].each do |path|
      begin
        path = path.sub("#{base}/", "")
        require path
      rescue Exception
        # No problem
      end
    end
  end
end

def self.namespaces_to_paths(namespaces) #:nodoc:
  paths = []
  namespaces.each do |namespace|
    pieces = namespace.split(":")
    paths << pieces.dup.push(pieces.last).join("/")
    paths << pieces.join("/")
  end
  paths.uniq!
  paths
end

def self.no_color!
  Thor::Base.shell = Thor::Shell::Basic
end

def self.options #:nodoc:
  @options ||= DEFAULT_OPTIONS.dup
end

def self.print_generators
  sorted_groups.each { |b, n| print_list(b, n) }
end

def self.print_list(base, namespaces) #:nodoc:
  namespaces = namespaces.reject do |n|
    hidden_namespaces.include?(n)
  end
  return if namespaces.empty?
  puts "#{base.camelize}:"
  namespaces.each do |namespace|
    puts("  #{namespace}")
  end
  puts
end

def self.public_namespaces
  lookup!
  subclasses.map(&:namespace)
end

def self.sorted_groups
  namespaces = public_namespaces
  namespaces.sort!
  groups = Hash.new { |h,k| h[k] = [] }
  namespaces.each do |namespace|
    base = namespace.split(':').first
    groups[base] << namespace
  end
  rails = groups.delete("rails")
  rails.map! { |n| n.sub(/^rails:/, '') }
  rails.delete("app")
  rails.delete("plugin")
  hidden_namespaces.each { |n| groups.delete(n.to_s) }
  [["rails", rails]] + groups.sort.to_a
end

def self.subclasses
  @subclasses ||= []
end

def self.templates_path #:nodoc:
  @templates_path ||= []
end

def hide_namespaces(*namespaces)
  hidden_namespaces.concat(namespaces)
end