require "csv"

class Sheet
  include Enumerable

  def initialize(path, **opts)
    @path = path
    @csv = CSV.read(path, headers: true, **opts)
    @data = csv.map(&:to_h)
    @headers = csv.first.headers
  end

  attr_accessor :data
  attr_reader :csv, :headers, :dest

  def each(&block)
    data.each(&block)
  end

  def generate
    each.reduce([headers.join(';')]) do |csv, row|
      csv.push(headers.map { |h| row[h] }.join(';'))
    end.join("\n")
  end

  def save(dest)
    File.open(dest, 'w') do |f|
      f << generate
    end
  end
end

if $0 == __FILE__
  require "rubygems"
  require "rspec"
  require "fileutils"

  RSpec.describe Sheet do
    let(:sheet) do
      <<-CSV
a,b,c
one,two,three
x,y,z
CSV
    end

    let(:path) { "test.csv" }

    before do
      File.open(path, "w") { |w| w << sheet }
    end

    subject do
      Sheet.new(path)
    end

    it "loads sheet data" do
      expect(subject.each.to_a).to(
        eq(
          [
            {
              "a" => "one",
              "b" => "two",
              "c" => "three"
            },
            {
              "a" => "x",
              "b" => "y",
              "c" => "z"
            }
          ]
        )
      )
    end

    it 'loads sheet headers' do
      expect(subject.headers).to eq(%w[a b c])
    end

    it 'can regenerate' do
      subject.data[0]['c'] = 'hello!'
      expect(subject.generate).to eq(
        <<-CSV
a,b,c
one,two,hello!
x,y,z
CSV
        .chomp
      )
    end

    it 'can add a header' do
      subject.headers.push('more')

      expect(subject.generate).to eq(
        <<-CSV
a,b,c,more
one,two,three,
x,y,z,
CSV
        .chomp
      )
    end

    it "can't save a copy with a path" do
      expect do
        subject.save
      end.to raise_error(ArgumentError)
    end

    it "can save a copy with a path" do
      out_path = 'test-output.csv'

      FileUtils.rm_rf(out_path)

      subject.save(out_path)

      expect(File.read(out_path)).to eq(
        <<-CSV
a,b,c
one,two,three
x,y,z
CSV
        .chomp
      )
    end
  end

  RSpec::Core::Runner.run([__FILE__])
end