require 'spec_helper'
require 'wgif/installer'

describe WGif::Installer do
  let(:installer) { described_class.new }

  before do
    @mock_stdout = StringIO.new
    @real_stdout, $stdout = $stdout, @mock_stdout
  end

  after do
    $stdout = @real_stdout
  end

  context 'checking for Homebrew' do

    it 'finds Homebrew when it exists' do
      expect(Kernel).to receive(:system).with('brew info > /dev/null')
        .and_return(true)
      expect(installer.homebrew_installed?).to eq(true)
    end

    it 'returns false when Homebrew does not exist' do
      expect(Kernel).to receive(:system).with('brew info > /dev/null')
        .and_return(false)
      expect(installer.homebrew_installed?).to eq(false)
    end

  end

  context 'checking for dependencies' do

    it 'returns true if dependencies are installed' do
      expect(Kernel).to receive(:system).with('which ffmpeg > /dev/null')
        .and_return(true)
      expect(Kernel).to receive(:system).with('which convert > /dev/null')
        .and_return(true)
      expect(installer.dependencies_installed?).to eq(true)
    end

    it 'returns false if dependencies are not installed' do
      expect(Kernel).to receive(:system).with('which ffmpeg > /dev/null')
        .and_return(true)
      expect(Kernel).to receive(:system).with('which convert > /dev/null')
        .and_return(false)
      expect(installer.dependencies_installed?).to eq(false)
    end

  end

  context 'installing dependencies' do

    it 'does not install dependencies if they are found' do
      expect(Kernel).to receive(:system).with('which ffmpeg > /dev/null')
        .and_return(true)
      expect(Kernel).not_to receive(:system).with('brew install ffmpeg')
      installer.install('ffmpeg', 'ffmpeg')
    end

    it 'installs dependencies' do
      expect(Kernel).to receive(:system).with('which ffmpeg > /dev/null')
        .and_return(false)
      expect(Kernel).to receive(:system).with('brew install ffmpeg')
      installer.install('ffmpeg', 'ffmpeg')
    end

    it 'has a list of its dependencies' do
      expect(installer.class::DEPENDENCIES)
        .to eq([['ffmpeg', 'ffmpeg'],
                ['imagemagick', 'convert']])
    end

    it 'checks if a dependency exists' do
      expect(Kernel).to receive(:system).with('which convert > /dev/null')
      installer.installed?('convert')
    end

  end

  context 'running' do

    it 'installs all dependencies' do
      expect(Kernel).to receive(:system).with('brew info > /dev/null')
        .and_return(true)
      expect(Kernel).to receive(:system).with('which ffmpeg > /dev/null').twice
        .and_return(true)
      expect(Kernel).to receive(:system).with('which convert > /dev/null').twice
        .and_return(false)
      expect(Kernel).to receive(:system).with('brew install imagemagick')
      expect { installer.run }.to raise_error(SystemExit)
    end

    it 'prints a helpful error if homebrew is not found' do
      expect(Kernel).to receive(:system).with('which ffmpeg > /dev/null')
        .and_return(true)
      expect(Kernel).to receive(:system).with('which convert > /dev/null')
        .and_return(false)
      expect(Kernel).to receive(:system).with('brew info > /dev/null')
        .and_return(false)
      expect { installer.run }.to raise_error(SystemExit)
      expect(@mock_stdout.string)
        .to eq("WGif can't find Homebrew. Visit http://brew.sh/ to get it.\n")
    end

    it 'prints a helpful message if all dependencies are installed' do
      expect(Kernel).to receive(:system).with('which ffmpeg > /dev/null')
        .and_return(true)
      expect(Kernel).to receive(:system).with('which convert > /dev/null')
        .and_return(true)
      expect { installer.run }.to raise_error(SystemExit)
      expect(@mock_stdout.string)
        .to eq("All dependencies are installed. Go make a gif.\n")
    end
  end
end