# See Pagy::Frontend API documentation: https://ddnexus.github.io/pagy/api/frontend
# encoding: utf-8
# frozen_string_literal: true

require 'yaml'

class Pagy

  PAGE_PLACEHOLDER  = '__pagy_page__'  # string used for search and replace, hardcoded also in the pagy.js file

  # I18n static hash loaded at startup, used as default alternative to the i18n gem.
  # see https://ddnexus.github.io/pagy/api/frontend#i18n
  I18n = eval(Pagy.root.join('locales', 'utils', 'i18n.rb').read) #rubocop:disable Security/Eval

  module Helpers
    # This works with all Rack-based frameworks (Sinatra, Padrino, Rails, ...)
    def pagy_url_for(page, pagy, url=false)
      p_vars = pagy.vars; params = request.GET.merge(p_vars[:params]); params[p_vars[:page_param].to_s] = page
      "#{request.base_url if url}#{request.path}?#{Rack::Utils.build_nested_query(pagy_get_params(params))}#{p_vars[:anchor]}"
    end

    # Sub-method called only by #pagy_url_for: here for easy customization of params by overriding
    def pagy_get_params(params) params end
  end

  # All the code here has been optimized for performance: it may not look very pretty
  # (as most code dealing with many long strings), but its performance makes it very sexy! ;)
  module Frontend

    include Helpers

    EMPTY = ''               # EMPTY + 'string' is almost as fast as +'string' but is also 1.9 compatible
    MARK  = PAGE_PLACEHOLDER # backward compatibility in case of helper-overriding in legacy apps

    # Generic pagination: it returns the html with the series of links to the pages
    def pagy_nav(pagy)
      link, p_prev, p_next = pagy_link_proc(pagy), pagy.prev, pagy.next

      html = EMPTY + (p_prev ? %(<span class="page prev">#{link.call p_prev, pagy_t('pagy.nav.prev'), 'aria-label="previous"'}</span> )
                             : %(<span class="page prev disabled">#{pagy_t('pagy.nav.prev')}</span> ))
      pagy.series.each do |item|  # series example: [1, :gap, 7, 8, "9", 10, 11, :gap, 36]
        html << if    item.is_a?(Integer); %(<span class="page">#{link.call item}</span> )               # page link
                elsif item.is_a?(String) ; %(<span class="page active">#{item}</span> )                  # current page
                elsif item == :gap       ; %(<span class="page gap">#{pagy_t('pagy.nav.gap')}</span> )   # page gap
                end
      end
      html << (p_next ? %(<span class="page next">#{link.call p_next, pagy_t('pagy.nav.next'), 'aria-label="next"'}</span>)
                      : %(<span class="page next disabled">#{pagy_t('pagy.nav.next')}</span>))
      %(<nav class="pagy-nav pagination" role="navigation" aria-label="pager">#{html}</nav>)
    end

    # Return examples: "Displaying items 41-60 of 324 in total" of "Displaying Products 41-60 of 324 in total"
    def pagy_info(pagy, item_name=nil)
      path = if (count = pagy.count) == 0 ; 'pagy.info.no_items'
             else pagy.pages == 1 ? 'pagy.info.single_page' : 'pagy.info.multiple_pages'
             end
      pagy_t(path, item_name: item_name || pagy_t(pagy.vars[:i18n_key], count: count), count: count, from: pagy.from, to: pagy.to)
    end

    # Returns a performance optimized proc to generate the HTML links
    # Benchmarked on a 20 link nav: it is ~22x faster and uses ~18x less memory than rails' link_to
    def pagy_link_proc(pagy, link_extra='')
      p_prev, p_next = pagy.prev, pagy.next
      a, b = %(<a href="#{pagy_url_for(PAGE_PLACEHOLDER, pagy)}" #{pagy.vars[:link_extra]} #{link_extra}).split(PAGE_PLACEHOLDER, 2)
      lambda {|n, text=n, extra=''| "#{a}#{n}#{b}#{ if    n == p_prev ; ' rel="prev"'
                                                    elsif n == p_next ; ' rel="next"'
                                                    else                           '' end } #{extra}>#{text}</a>"}
    end

    # Similar to I18n.t: just ~18x faster using ~10x less memory
    # (@pagy_locale explicitly initilized in order to avoid warning)
    def pagy_t(path, vars={}) Pagy::I18n.t(@pagy_locale||=nil, path, vars) end

  end
end