require 'ferrum'
require 'logger'

module Docapurl
  class Browser
    SYSTEM_MAX_PAGE_DOWN_TO_BOTTOM = 50
    attr_accessor :browser, :save_path, :logger, :context, :page

    def initialize(options)
      @save_path = options[:save_path]
      options[:timeout] ||= 30

      options[:slowmo] = 0.5
      @logger = options[:logger] || Logger.new(STDOUT)
      @browser = Ferrum::Browser.new options
      @context = browser.contexts.create
      @page = @context.create_page
      yield(self) if block_given?
    end

    def cap(url, options)
      options[:quality] ||= 90
      options[:full] = true if options[:full].nil?
      options[:path] ||= @save_path
      host = fetch_domain(url)
      options[:path] ||= "screenshot-#{host.to_s == '' ? '' : "#{host}-"}#{Time.now.strftime('%F-%T')}.jpg"
      logger.info "browser begin to visit url #{url}"

      set_callback("before_visit_func", options)
      page.go_to(url)
      set_callback("after_visit_func", options)


      logger.info 'visited'
      max_pagedown = options[:max_pagedown] || 5
      pagedown_to_bottom = options.delete :pagedown_to_bottom
      visit_whole_page(page: page, max_pagedown: max_pagedown, pagedown_to_bottom: pagedown_to_bottom)

      sleep_before_screen = options.delete :sleep_before_screen
      logger.info "sleep #{sleep_before_screen.to_i} second before screenshot"
      sleep(sleep_before_screen.to_i)


      set_callback("before_screenshot_func", options)
      page.screenshot(**options)
      set_callback("after_screenshot_func", options)

      logger.info "screenshot ended, path = #{options[:path]}"
    end

    def close
      return if browser.nil?
      context.dispose unless context.nil?

      logger.info 'close browser'
      browser.quit
    end

    def visit_whole_page( page: nil, max_pagedown: nil, pagedown_to_bottom: false)
      viewport_height = page.viewport_size.last.to_i
      document_height = page.document_size.last.to_i
      return if document_height<= viewport_height

      page_down_count = document_height / viewport_height
      if pagedown_to_bottom
        page_down_count = SYSTEM_MAX_PAGE_DOWN_TO_BOTTOM if page_down_count >SYSTEM_MAX_PAGE_DOWN_TO_BOTTOM
      else
        page_down_count = max_pagedown if page_down_count > max_pagedown

      end

      page_down_count.times do
        logger.info "press PageDown .."
        page.keyboard.type(:PageDown)
      end
      logger.info "press HOME .."
      page.keyboard.type(:Home)
    end

    private

    def set_callback(name, options)
      the_function = options.delete name
      if the_function.nil?
        the_function = options.delete name.to_sym
      end

      the_function.call(self) unless the_function.nil?
    end


    class << self
      def cap(url, path = nil, browser_options = {}, cap_options = {})
        browser = new(browser_options)
        cap_options[:path] = path
        browser.cap(url, cap_options)
      rescue StandardError => e
        browser.logger.error e
      ensure
        browser&.close
      end
    end

    private

    def fetch_domain(url)
      return url unless url.start_with? 'http'

      URI(url).host
    rescue StandardError
      nil
    end
  end
end