# frozen_string_literal: true

require "negarmoji/character"
require "json"

module Emoji # :nodoc:
  extend self

  def data_file
    File.expand_path("../../db/negarmoji.json", __dir__)
  end

  def all
    return @all if defined? @all

    @all = []
    parse_data_file
    @all
  end

  # Public: Initialize an Emoji::Character instance and yield it to the block.
  # The character is added to the `Emoji.all` set.
  def create(name)
    emoji = Emoji::Character.new(name)
    all << edit_emoji(emoji) { yield emoji if block_given? }
    emoji
  end

  # Public: Yield an negarmoji to the block and update the indices in case its
  # aliases or unicode_aliases lists changed.
  def edit_emoji(emoji)
    @names_index ||= {}
    @unicodes_index ||= {}

    yield emoji

    emoji.aliases.each do |name|
      @names_index[name] = emoji
    end
    emoji.unicode_aliases.each do |unicode|
      @unicodes_index[unicode] = emoji
    end

    emoji
  end

  # Public: Find an negarmoji by its aliased name. Return nil if missing.
  def find_by_alias(name)
    names_index[name]
  end

  # Public: Find an negarmoji by its unicode character. Return nil if missing.
  def find_by_unicode(unicode)
    unicodes_index[unicode]
  end

  private

  VARIATION_SELECTOR_16 = "\u{fe0f}"

  # Characters which must have VARIATION_SELECTOR_16 to render as color negarmoji:
  TEXT_GLYPHS = [
    "\u{1f237}", # Japanese "monthly amount" button
    "\u{1f202}", # Japanese "service charge" button
    "\u{1f170}", # A button (blood type)
    "\u{1f171}", # B button (blood type)
    "\u{1f17e}", # O button (blood type)
    "\u{00a9}", # copyright
    "\u{00ae}", # registered
    "\u{2122}", # trade mark
    "\u{3030}" # wavy dash
  ].freeze

  private_constant :VARIATION_SELECTOR_16, :TEXT_GLYPHS

  def parse_data_file
    data = File.open(data_file, "r:UTF-8") do |file|
      JSON.parse(file.read, :symbolize_names => true)
    end

    dedup = if "".respond_to?(:-@)
              # Ruby >= 2.3 this is equivalent to .freeze
              # Ruby >= 2.5 this will freeze and dedup
              ->(str) { -str }
            else
              ->(str) { str.freeze }
            end

    append_unicode = lambda do |emoji, raw|
      unless TEXT_GLYPHS.include?(raw) || emoji.unicode_aliases.include?(raw)
        emoji.add_unicode_alias(dedup.call(raw))
      end
    end

    data.each do |raw_emoji|
      create(nil) do |emoji|
        raw_emoji.fetch(:aliases).each { |name| emoji.add_alias(dedup.call(name)) }
        if (raw = raw_emoji[:emoji])
          append_unicode.call(emoji, raw)
          start_pos = 0
          while (found_index = raw.index(VARIATION_SELECTOR_16, start_pos))
            # register every variant where one VARIATION_SELECTOR_16 is removed
            raw_alternate = raw.dup
            raw_alternate[found_index] = ""
            append_unicode.call(emoji, raw_alternate)
            start_pos = found_index + 1
          end
          if start_pos.positive?
            # register a variant with all VARIATION_SELECTOR_16 removed
            append_unicode.call(emoji, raw.gsub(VARIATION_SELECTOR_16, ""))
          else
            # register a variant where VARIATION_SELECTOR_16 is added
            append_unicode.call(emoji, "#{raw}#{VARIATION_SELECTOR_16}")
          end
        end
        raw_emoji.fetch(:tags).each { |tag| emoji.add_tag(dedup.call(tag)) }

        emoji.category = dedup.call(raw_emoji[:category])
        emoji.description = dedup.call(raw_emoji[:description])
        emoji.unicode_version = dedup.call(raw_emoji[:unicode_version])
        emoji.ios_version = dedup.call(raw_emoji[:ios_version])
      end
    end
  end

  def names_index
    all unless defined? @all
    @names_index
  end

  def unicodes_index
    all unless defined? @all
    @unicodes_index
  end
end

# Preload negarmoji into memory.
Emoji.all