class Concourse

def self.validate_fly_target task, task_args
  unless task_args[:fly_target]
    raise "ERROR: must specify a fly target, like `rake #{task.name}[targetname]`"
  end
  return task_args[:fly_target]
end

def create_tasks!
  unless Dir.exist? DIRECTORY
    mkdir_p DIRECTORY
  end
  unless File.exist? pipeline_erb_filename
    raise "ERROR: concourse pipeline template #{pipeline_erb_filename.inspect} does not exist"
  end
  CLOBBER.include pipeline_filename
  namespace :concourse do
    #
    #  pipeline commands
    #
    desc "generate and validate the pipeline file for #{project_name}"
    task "generate" => pipeline_filename do |t|
      File.open pipeline_filename, "w" do |f|
        f.write ERB.new(File.read(pipeline_erb_filename)).result(binding)
      end
      sh "fly validate-pipeline -c #{pipeline_filename}"
    end
    desc "upload the pipeline file for #{project_name}"
    task "set", [:fly_target] => ["generate"] do |t, args|
      fly_target = Concourse.validate_fly_target t, args
      sh "fly -t #{fly_target} set-pipeline -p #{project_name} -c #{pipeline_filename}"
    end
    %w[expose hide pause unpause].each do |command|
      desc "#{command} the #{project_name} pipeline"
      task "#{command}", [:fly_target] do |t, args|
        fly_target = Concourse.validate_fly_target t, args
        sh "fly -t #{fly_target} #{command}-pipeline -p #{project_name}"
      end
    end
    desc "remove generate pipeline file"
    task "clean" do |t|
      rm_f pipeline_filename
    end
    #
    #  task commands
    #
    desc "list all the available tasks from the #{project_name} pipeline"
    task "tasks" => "generate" do
      tasks = []
      each_task do |job, task|
        tasks << "#{job["name"]}/#{task["task"]}"
      end
      puts "Available Concourse tasks for #{project_name} are:"
      tasks.each { |task| puts " * #{task}" }
    end
    desc "fly execute the specified task"
    task "task", [:fly_target, :task_name, :fly_execute_args] => "generate" do |t, args|
      fly_target = Concourse.validate_fly_target t, args
      task_name        = args[:task_name]
      fly_execute_args = args[:fly_execute_args] || "--input=git-master=."
      unless task_name
        raise "ERROR: must specify a task name, like `rake #{t.name}[taskname]`"
      end
      concourse_task = find_task task_name
      raise "ERROR: could not find task `#{task_name}`" unless concourse_task
      puts concourse_task.to_yaml
      Tempfile.create do |f|
        f.write concourse_task["config"].to_yaml
        f.close
        sh "fly -t #{fly_target} execute #{fly_execute_args} -c #{f.path} -x"
      end
    end
  end
end

def each_task
  pipeline = YAML.load_file(pipeline_filename)
  pipeline["jobs"].each do |job|
    job["plan"].each do |task|
      yield job, task if task["task"]
    end
  end
end

def find_task task_name
  job_name, task_name = *task_name.split("/")
  each_task do |job, task|
    return task if task["task"] == task_name && job["name"] == job_name
  end
  nil
end

def initialize project_name
  @project_name = project_name
  @pipeline_filename = File.join(DIRECTORY, "#{project_name}.yml")
  @pipeline_erb_filename = "#{pipeline_filename}.erb"
end