require "sensu/install/version"
require "optparse"

module Sensu
  module Install
    class << self
      def cli_options(arguments=ARGV)
        options = {
          :verbose => false,
          :plugins => [],
          :extensions => [],
          :clean => false,
          :proxy => nil
        }
        optparse = OptionParser.new do |opts|
          opts.on("-h", "--help", "Display this message") do
            puts opts
            exit
          end
          opts.on("-v", "--verbose", "Enable verbose logging") do
            options[:verbose] = true
          end
          opts.on("-p", "--plugin PLUGIN", "Install a Sensu PLUGIN") do |plugin|
            options[:plugins] << plugin
          end
          opts.on("-P", "--plugins PLUGIN[,PLUGIN]", "PLUGIN or comma-delimited list of Sensu plugins to install") do |plugins|
            options[:plugins].concat(plugins.split(","))
          end
          opts.on("-e", "--extension EXTENSION", "Install a Sensu EXTENSION") do |extension|
            options[:extensions] << extension
          end
          opts.on("-E", "--extensions EXTENSION[,EXT]", "EXTENSION or comma-delimited list of Sensu extensions to install") do |extensions|
            options[:extensions].concat(extensions.split(","))
          end
          opts.on("-s", "--source SOURCE", "Install Sensu plugins and extensions from a custom SOURCE") do |source|
            options[:source] = source
          end
          opts.on("-c", "--clean", "Clean up (remove) other installed versions of the plugin(s) and/or extension(s)") do
            options[:clean] = true
          end
          opts.on("-x", "--proxy PROXY", "Install Sensu plugins and extensions via a PROXY URL") do |proxy|
            options[:proxy] = proxy
          end
        end
        optparse.parse!(arguments)
        options
      end

      def log(message)
        puts "[SENSU-INSTALL] #{message}"
      end

      def gem_installed?(raw_gem, options={})
        log "determining if Sensu gem '#{raw_gem}' is already installed ..."
        gem_name, gem_version = raw_gem.split(":")
        gem_command = "gem list -i #{gem_name}"
        gem_command << " --version '#{gem_version}'" if gem_version
        log gem_command if options[:verbose]
        if system(gem_command)
          log "Sensu gem '#{gem_name}' has already been installed"
          true
        else
          log "Sensu gem '#{gem_name}' has not been installed" if options[:verbose]
          false
        end
      end

      def install_gem(raw_gem, options={})
        log "installing Sensu gem '#{raw_gem}'"
        gem_name, gem_version = raw_gem.split(":")
        gem_command = "gem install #{gem_name}"
        gem_command << " --version '#{gem_version}'" if gem_version
        gem_command << " --no-ri --no-rdoc"
        gem_command << " --verbose" if options[:verbose]
        gem_command << " --source #{options[:source]}" if options[:source]
        gem_command << " --http-proxy #{options[:proxy]}" if options[:proxy]
        log gem_command if options[:verbose]
        unless system(gem_command)
          log "failed to install Sensu gem '#{gem_name}'"
          log "you can run the sensu-install command again with --verbose for more info" unless options[:verbose]
          log "please take note of any failure messages above"
          log "make sure you have build tools installed (e.g. gcc)"
          log "trying to determine the Sensu plugin homepage for #{gem_name} ..."
          system("gem specification #{gem_name} -r | grep homepage")
          exit 2
        end
      end

      def gem_installed_versions(raw_gem, options={})
        gem_name, gem_version = raw_gem.split(":")
        log "determining installed versions of Sensu gem '#{gem_name}' ..."
        gem_command = "gem list #{gem_name}"
        log gem_command if options[:verbose]
        gem_command_output = `#{gem_command}`
        last_line = gem_command_output.split("\n").last
        if last_line == "false"
          []
        else
          /\((.*)\)/.match(last_line)[1].split(", ")
        end
      end

      def clean_gem(raw_gem, options={})
        log "cleaning Sensu gem '#{raw_gem}'"
        gem_name, gem_version = raw_gem.split(":")
        gem_command = "gem clean #{gem_name}"
        if gem_version
          if gem_installed_versions(raw_gem, options) == [gem_version]
            log "Sensu gem '#{gem_name}' version '#{gem_version}' is the only version installed"
          else
            gem_command = "gem uninstall #{gem_name} --version '!= #{gem_version}' -a"
          end
        end
        log gem_command if options[:verbose]
        if system(gem_command)
          log "successfully cleaned Sensu gem '#{gem_name}'"
        else
          log "failed to clean Sensu gem '#{gem_name}'"
        end
      end

      def install_plugins(plugins, options={})
        log "installing Sensu plugins ..."
        log "provided Sensu plugins: #{plugins}" if options[:verbose]
        plugin_gems = plugins.map do |plugin|
          if plugin.start_with?("sensu-plugins-")
            plugin
          else
            "sensu-plugins-#{plugin}"
          end
        end
        log "compiled Sensu plugin gems: #{plugin_gems}" if options[:verbose]
        to_be_installed = plugin_gems.reject do |raw_gem|
          gem_installed?(raw_gem, options)
        end
        log "Sensu plugin gems to be installed: #{to_be_installed}"
        to_be_installed.each do |raw_gem|
          install_gem(raw_gem, options)
        end
        log "successfully installed Sensu plugins: #{to_be_installed}"
        if options[:clean]
          log "cleaning Sensu plugin gems: #{plugin_gems}" if options[:verbose]
          plugin_gems.each do |raw_gem|
            clean_gem(raw_gem, options)
          end
        end
      end

      def install_extensions(extensions, options={})
        if ENV["EMBEDDED_RUBY"] == "false"
          log "EMBEDDED_RUBY must be set to true in order to install extensions"
          log "failed to install extensions: #{extensions}"
          exit 2
        end
        log "installing Sensu extensions ..."
        log "provided Sensu extensions: #{extensions}" if options[:verbose]
        extension_gems = extensions.map do |extension|
          if extension.start_with?("sensu-extensions-")
            extension
          else
            "sensu-extensions-#{extension}"
          end
        end
        log "compiled Sensu extension gems: #{extension_gems}" if options[:verbose]
        to_be_installed = extension_gems.reject do |raw_gem|
          gem_installed?(raw_gem, options)
        end
        log "Sensu extension gems to be installed: #{to_be_installed}"
        to_be_installed.each do |raw_gem|
          install_gem(raw_gem, options)
        end
        log "successfully installed Sensu extensions: #{to_be_installed}"
        if options[:clean]
          log "cleaning Sensu extension gems: #{extension_gems}" if options[:verbose]
          extension_gems.each do |raw_gem|
            clean_gem(raw_gem, options)
          end
        end
      end

      def run
        options = cli_options
        unless options[:plugins].empty?
          install_plugins(options[:plugins], options)
        end
        unless options[:extensions].empty?
          install_extensions(options[:extensions], options)
        end
      end
    end
  end
end