env_checker.rb

# 需要检查的 gem 以及对应的版本
requireGems = {
    'psych' => '>= 2.1',
}

# cocoapods & psych
requireGems.each do |gem_name, gem_ver_reqs|
    gdep = Gem::Dependency.new(gem_name, *gem_ver_reqs)
    found_gspec = gdep.matching_specs.max_by(&:version)
    if found_gspec

    else
        puts "ERROR:  Requirement '#{gdep}' not satisfied; use `gem install` to install required version"
        exit 1
    end
end

# node
node_run_code = system "node -v"
puts node_run_code
if node_run_code != true
  puts "ERROR: please install node; use `brew install node` to install"
  puts "温馨提示：安装完后建议设置镜像以加速后面的过程"
  puts "> npm config set registry https://registry.npm.taobao.org --global"
  puts "> npm config set disturl https://npm.taobao.org/dist --global"
  exit 1
end

class VersionChecker

  # 依赖的名字
  def self.tool_name
  end

  # 希望安装的版本
  def self.wanted_version
  end

  # 是否安装了这个依赖
  def self.check_has_install?
  end

  # 已安装的版本是否满足当前的需求
  def self.is_version_satisfied?(version)
  end

  # 安装指定的版本
  def self.install(version)
  end

  # 更新到指定的版本
  def self.update(version)
  end

  # 子类无需重写
  def self.check
    if check_has_install?
      if is_version_satisfied?(wanted_version)
        puts "✅ #{tool_name} 版本检测通过"
      else
        puts "⌛️ 正在更新 #{tool_name}"
        update(wanted_version)
      end
    else
      puts "⌛️ 正在安装 #{tool_name}"
      install(wanted_version)
    end
  end

end

class KSChecker < VersionChecker
  def self.tool_name
    'ks'
  end

  def self.wanted_version
    '1.3.1'
  end

  def self.check_has_install?
    `which ks`.start_with?("/")
  end

  def self.is_version_satisfied?(version)
    version_prefix = 'ks version'
    output = `ks -v`
    false unless output.start_with?(version_prefix)
      
    current_version = output[version_prefix.length..-1].strip
    Gem::Version.new(current_version) >= Gem::Version.new(version)    
  end

  def self.install(version)
    system "brew install xxx"
  end

  def self.update(version)
    system 'ks update'
  end
end

class CocoaPodsChecker < VersionChecker
  def self.tool_name
    'CocoaPods'
  end

  def self.wanted_version
    '1.3.1'
  end

  def self.check_has_install?
    `which pod`.start_with?("/")
  end

  def self.is_version_satisfied?(version)
    output = `pod --version`
    current_version = output.strip
    Gem::Version.new(current_version) == Gem::Version.new(version)    
  end

  def self.install(version)
    system "gem install cocoapods -v #{version}"
  end

  def self.update(version)
    # 卸载之前的所有版本
    system "gem uninstall cocoapods --version \'!=#{version}\'"
    install(version)
  end
end

checkers = [KSChecker, CocoaPodsChecker]
checkers.each{ |c|
  c.check
}