require 'colorize'
require 'rake/tasklib'
require 'bora/stack'

module Bora
  class Tasks < Rake::TaskLib
    def initialize(stack_name, template_uri = nil)
      @stack_name = stack_name
      @stack = Stack.new(stack_name)
      @colorize = true
      @stack_options = {}
      within_namespace { yield self } if block_given?

      if template_uri
        if @stack_options[:template_body] || @stack_options[:template_url]
          raise "You cannot specify a template in the constructor as well as in the stack_options"
        else
          @stack_options[:template_url] = template_uri
        end
      end

      define_tasks
    end

    attr_writer :stack_options

    def colorize=(value)
      @colorize = value
      String.disable_colorization = !@colorize
    end


    private

    def define_tasks
      define_apply_task
      define_current_template_task
      define_delete_task
      define_diff_task
      define_events_task
      define_generate_task
      define_new_template_task
      define_outputs_task
      define_recreate_task
      define_status_task
      define_validate_task
    end

    def define_apply_task
      within_namespace do
        desc "Creates (or updates) the '#{@stack_name}' stack"
        task :apply => :generate do
          success = invoke_action(@stack.exists? ? "update" : "create", @stack_options)
          if success
            outputs = @stack.outputs
            if outputs && outputs.length > 0
              puts "Stack outputs"
              outputs.each { |output| puts output }
            end
          end
        end
      end
    end

    def define_current_template_task
      within_namespace do
        desc "Shows the current template for '#{@stack_name}' stack"
        task :current_template do
          template = @stack.template
          puts template ? template : "Stack '#{@stack_name}' does not exist"
        end
      end
    end

    def define_delete_task
      within_namespace do
        desc "Deletes the '#{@stack_name}' stack"
        task :delete do
          invoke_action("delete")
        end
      end
    end

    def define_diff_task
      within_namespace do
        desc "Diffs the new template with the '#{@stack_name}' stack's current template"
        task :diff => :generate do
          puts @stack.diff(@stack_options).to_s(@colorize ? :color : :text)
        end
      end
    end

    def define_events_task
      within_namespace do
        desc "Outputs the latest events from the '#{@stack_name}' stack"
        task :events do
          events = @stack.events
          if events
            if events.length > 0
              puts "Events for stack '#{@stack_name}'"
              @stack.events.each { |e| puts e }
            else
              puts "Stack '#{@stack_name}' has no events"
            end
          else
            puts "Stack '#{@stack_name}' does not exist"
          end
        end
      end
    end

    def define_generate_task
      within_namespace do
        task :generate
      end
    end

    def define_new_template_task
      within_namespace do
        desc "Shows the new template for '#{@stack_name}' stack"
        task :new_template => :generate do
          puts @stack.new_template(@stack_options)
        end
      end
    end

    def define_outputs_task
      within_namespace do
        desc "Shows the outputs from the '#{@stack_name}' stack"
        task :outputs do
          outputs = @stack.outputs
          if outputs
            if outputs.length > 0
              puts "Outputs for stack '#{@stack_name}'"
              outputs.each { |output| puts output }
            else
              puts "Stack '#{@stack_name}' has no outputs"
            end
          else
            puts "Stack '#{@stack_name}' does not exist"
          end
        end
      end
    end

    def define_recreate_task
      within_namespace do
        desc "Recreates (deletes then creates) the '#{@stack_name}' stack"
        task :recreate => :generate do
          invoke_action("recreate", @stack_options)
        end
      end
    end

    def define_status_task
      within_namespace do
        desc "Displays the current status of the '#{@stack_name}' stack"
        task :status do
          puts @stack.status
        end
      end
    end

    def define_validate_task
      within_namespace do
        desc "Checks the '#{@stack_name}' stack's template for validity"
        task :validate => :generate do
          puts "Template for stack '#{@stack_name}' is valid" if @stack.validate(@stack_options)
        end
      end
    end

    def invoke_action(action, *args)
      puts "#{action.capitalize} stack '#{@stack_name}'"
      success = @stack.send(action, *args) { |event| puts event }
      if success
        puts "#{action.capitalize} stack '#{@stack_name}' completed successfully"
      else
        if success == nil
          puts "#{action.capitalize} stack '#{@stack_name}' skipped as template has not changed"
        else
          fail("#{action.capitalize} stack '#{@stack_name}' failed")
        end
      end
      success
    end

    def within_namespace
      namespace :stack do
        namespace @stack_name do
          yield
        end
      end
    end

  end
end