require 'os'
require 'open-uri'

module Ruby
  module Terraform
    module_function

    def config
      @config ||= Configuration.new
    end

    class Executable
      class PlatformUnsupported < StandardError; end

      def initialize(config = Ruby::Terraform.config)
        @terraform_version = config.terraform_version
        @download_path = config.download_path
        @download_filename = "#{@terraform_version}-terraform.zip"

        FileUtils.mkdir_p(@download_path)

        raise PlatformUnsupported unless supported?
      end

      def binary
        if OS.windows?
          "#{@download_path}/terraform.exe"
        else
          "#{@download_path}/terraform"
        end
      end

      def download(opts = {})
        return if binary_exist?
        opts[:uri] ||= ENV['TERRAFORM_DOWNLOAD_URL'] || "https://releases.hashicorp.com/#{download_uri}"

        $stderr.puts("Downloading terraform binary from #{uri}") if opts[:verbose]

        open("#{@download_path}/#{@download_filename}", 'wb') do |saved_file|
          open(opts[:uri], 'rb') do |read_file|
            saved_file.write(read_file.read)
          end
        end
      end

      def extract(verbose = false)
        return if binary_exist?

        Decompressor.extract("#{@download_path}/#{@download_filename}", @download_path, verbose)
        make_exe
      end

      private

      def binary_exist?
        File.exist?(binary)
      end

      def supported?
        OS.freebsd? || OS.mac? || OS.windows? || OS.linux?
      end

      def make_exe
        FileUtils.chmod('a+x', binary) if binary_exist? && !OS.windows?
      end

      def download_uri
        return "terraform/#{@terraform_version}/terraform_#{@terraform_version}_freebsd_amd64.zip" if OS.freebsd?
        return "terraform/#{@terraform_version}/terraform_#{@terraform_version}_darwin_amd64.zip" if OS.mac?
        return "terraform/#{@terraform_version}/terraform_#{@terraform_version}_windows_amd64.zip" if OS.windows?
        return "terraform/#{@terraform_version}/terraform_#{@terraform_version}_linux_amd64.zip" if OS.linux?
      end
    end
  end
end