# frozen_string_literal: true

require 'spec_helper'
require 'stringio'
require 'ttfunk/subset'

describe 'subsetting' do # rubocop: disable RSpec/DescribeClass
  let(:space_char) { TTFunk::Subset::Unicode::SPACE_CHAR }

  it 'consistently names font for same subsets' do
    font = TTFunk::File.open(test_font('DejaVuSans'))

    subset1 = TTFunk::Subset.for(font, :unicode)
    subset1.use(97)
    name1 = TTFunk::File.new(subset1.encode).name.strings[6]

    subset2 = TTFunk::Subset.for(font, :unicode)
    subset2.use(97)
    name2 = TTFunk::File.new(subset2.encode).name.strings[6]

    expect(name1).to eq name2
  end

  it 'can reconstruct an entire font' do
    font = TTFunk::File.open(test_font('DejaVuSans'))
    subset = TTFunk::Subset.for(font, :unicode)

    font.cmap.unicode.first.code_map.each_key do |code_point|
      subset.use(code_point)
    end

    expect { subset.encode }.to_not raise_error
  end

  it 'always includes the space glyph' do
    font = TTFunk::File.open(test_font('DejaVuSans'))
    subset = TTFunk::Subset.for(font, :unicode)
    new_font = TTFunk::File.new(subset.encode)

    # space should be GID 1 since it's the only glyph in the font
    # (0 is always .notdef)
    expect(new_font.cmap.unicode.first[space_char]).to eq(1)
  end

  it "explodes if the space glyph isn't included" do
    font = TTFunk::File.open(test_font('DejaVuSans'))
    subset = TTFunk::Subset.for(font, :unicode)
    subset.instance_variable_get(:@subset).delete(space_char)
    expect { subset.encode }.to raise_error(/Space glyph .* must be included/)
  end

  it 'changes font names for different subsets' do
    font = TTFunk::File.open(test_font('DejaVuSans'))

    subset1 = TTFunk::Subset.for(font, :unicode)
    subset1.use(97)
    name1 = TTFunk::File.new(subset1.encode).name.strings[6]

    subset2 = TTFunk::Subset.for(font, :unicode)
    subset2.use(97)
    subset2.use(98)
    name2 = TTFunk::File.new(subset2.encode).name.strings[6]

    expect(name1).to_not eq name2
  end

  it 'calculates checksum correctly for empty table data' do
    font = TTFunk::File.open(test_font('Mplus1p'))
    subset1 = TTFunk::Subset.for(font, :unicode)
    expect { subset1.encode }.to_not raise_error
  end

  it 'generates font directory with tables in ascending order' do
    font = TTFunk::File.open(test_font('DejaVuSans'))

    subset = TTFunk::Subset.for(font, :unicode)
    subset.use(97)

    directory = TTFunk::File.new(subset.encode).directory
    table_tags = directory.tables.keys

    expect(table_tags.sort).to eq(table_tags)
    expect(table_tags.first).to be < table_tags.last
  end

  it 'calculates search_range, entry_selector & range_shift values' do
    font = TTFunk::File.open(test_font('DejaVuSans'))

    subset = TTFunk::Subset.for(font, :unicode)
    subset.use(97)
    subset_io = StringIO.new(subset.encode)

    scaler_type, table_count = subset_io.read(6).unpack('Nn')
    search_range, entry_selector, range_shift =
      subset_io.read(6).unpack('nnn')

    # Subset fonts include 14 tables by default.
    expected_table_count = 14
    # Smallest power of two less than number of tables, times 16.
    expected_search_range = 8 * 16
    # Log2 of max power of two smaller than number of tables.
    expected_entry_selector = 3
    # Range shift is defined as 16*table_count - search_range.
    expected_range_shift = (16 * expected_table_count) - expected_search_range

    expect(scaler_type).to eq(font.directory.scaler_type)
    expect(table_count).to eq(expected_table_count)
    expect(search_range).to eq(expected_search_range)
    expect(entry_selector).to eq(expected_entry_selector)
    expect(range_shift).to eq(expected_range_shift)
  end

  it 'knows which characters it includes' do
    font = TTFunk::File.open(test_font('DejaVuSans'))
    unicode = TTFunk::Subset.for(font, :unicode)
    unicode_8bit = TTFunk::Subset.for(font, :unicode_8bit)
    mac_roman = TTFunk::Subset.for(font, :mac_roman)
    windows1252 = TTFunk::Subset.for(font, :windows_1252) # rubocop: disable Naming/VariableNumber

    [unicode, unicode_8bit, mac_roman, windows1252].each do |subset|
      expect(subset).to_not be_includes(97)
      subset.use(97)
      expect(subset).to be_includes(97)
    end
  end

  it 'maps final code 0xFFFF to glyph 0 in generated type 4 cmap' do
    font = TTFunk::File.open(test_font('DejaVuSans'))

    subset = TTFunk::Subset.for(font, :unicode)
    subset.use(97)
    cmap = TTFunk::File.new(subset.encode).cmap

    # Unicode subsets only contain a single format 4 cmap subtable.
    expect(cmap.tables.size).to eq(1)
    format04 = cmap.tables.first
    expect(format04.format).to eq(4)
    expect(format04.code_map[0xFFFF]).to eq(0)
  end

  it 'sorts records in the name table correctly' do
    font = TTFunk::File.open(test_font('DejaVuSans'))

    subset = TTFunk::Subset.for(font, :unicode)
    subset.use(97)
    name = TTFunk::File.new(subset.encode).name

    records = []
    name.entries.each do |entry|
      records << [
        entry[:platform_id],
        entry[:encoding_id],
        entry[:language_id],
        entry[:name_id],
      ]
    end

    expect(records).to eq(records.sort)
  end
end