#!/usr/bin/env ruby

require 'fileutils'
require 'open3'

def message(str)
  $stderr.puts('Message: ' + str)
end

def warn(str)
  $stderr.puts('Warning: ' + str)
end

def fail(str)
  $stderr.puts('Error: ' + str)
  exit
end

$stdout.sync = true
repo_clean = `git status --porcelain`.empty?

unless repo_clean
  fail 'git repo needs to be clean to run oss-check. Aborting.'
end

@branch_name = `git symbolic-ref HEAD --short`.strip

if @branch_name == 'master'
  fail "can't run osscheck from 'master' as the script compares "\
       "the performance of this branch against 'master'"
end

@repos = [
  'Alamofire/Alamofire',
  'apple/swift',
  'JohnCoates/Aerial',
  'jpsim/SourceKitten',
  'krzysztofzablocki/Sourcery',
  'kickstarter/ios-oss',
  'Moya/Moya',
  'mozilla-mobile/firefox-ios',
  'Quick/Nimble',
  'Quick/Quick',
  'realm/realm-cocoa',
  'wordpress-mobile/WordPress-iOS'
]

@commits = {}
@branch_durations = {}
@master_durations = {}

def convert_to_link(string)
  string.sub!("#{Dir.pwd}/osscheck/#{@repo_name}", '')
  string.sub!('.swift:', '.swift#L')
  string = string.partition(': warning:').first.partition(': error:').first
  "https://github.com/#{@repo}/blob/#{@commits[@repo]}#{string}"
end

def non_empty_lines(path)
  File.read(path).split(/\n+/).reject(&:empty?)
end

def generate_reports(clone, branch)
  Dir.chdir('osscheck') do
    @repos.each do |repo|
      repo_name = repo.partition('/').last
      if clone
        puts "Cloning #{repo_name}"
        `git clone "https://github.com/#{repo}" --depth 1 2> /dev/null`
        if repo_name == 'swift'
          File.open("swift/.swiftlint.yml", 'w') do |file|
            file << 'included: stdlib'
          end
        end
      end
      Dir.chdir(repo_name) do
        iterations = 5
        print "Linting #{iterations} iterations of #{repo_name} with #{branch}: 1"
        @commits[repo] = `git rev-parse HEAD`.strip
        durations = []
        start = Time.now
        command = '../../.build/release/swiftlint lint --no-cache --enable-all-rules --reporter xcode'
        File.open("../#{branch}_reports/#{repo_name}.txt", 'w') do |file|
          Open3.popen3(command) do |_, stdout, _, _|
            file << stdout.read.chomp
          end
        end
        durations += [Time.now - start]
        for i in 2..iterations
          print "..#{i}"
          start = Time.now
          Open3.popen3(command) { |_, stdout, _, _| stdout.read }
          durations += [Time.now - start]
        end
        puts ''
        average_duration = (durations.reduce(:+) / iterations).round(2)
        if branch == 'branch'
          @branch_durations[repo] = average_duration
        else
          @master_durations[repo] = average_duration
        end
      end
    end
  end
end

# Prep
['osscheck/branch_reports', 'osscheck/master_reports'].each do |dir|
  FileUtils.mkdir_p(dir)
end

# Build branch
puts 'Building branch'
`swift build -c release`

# Generate branch reports
generate_reports(true, 'branch')
# Build master
`git fetch`
`git checkout origin/master`
puts 'Building master'
`swift build -c release`
unless $?.success?
  # Couldn't build, start fresh
  FileUtils.rm_rf %w(Packages .build)
  return_value = nil
  Open3.popen3('swift build -c release') do |_, stdout, _, wait_thr|
    puts stdout.read.chomp
    return_value = wait_thr.value
  end

  unless return_value.success?
    fail 'Could not build master'
    return
  end
end

# Generate master reports
generate_reports(false, 'master')
# Diff and report changes to Danger
@repos.each do |repo|
  @repo_name = repo.partition('/').last

  branch = non_empty_lines("osscheck/branch_reports/#{@repo_name}.txt")
  master = non_empty_lines("osscheck/master_reports/#{@repo_name}.txt")
  @repo = repo

  (master - branch).each do |fixed|
      message "This PR fixed a violation in #{@repo_name}: [#{fixed}](#{convert_to_link(fixed)})"
  end
  (branch - master).each do |violation|
      warn "This PR introduced a violation in #{@repo_name}: [#{violation}](#{convert_to_link(violation)})"
  end
end

@repos.each do |repo|
  branch_duration = @branch_durations[repo]
  master_duration = @master_durations[repo]
  percent_change = 100 * (master_duration - branch_duration) / master_duration
  faster_slower = nil
  if branch_duration < master_duration
      faster_slower = 'faster'
  else
      faster_slower = 'slower'
      percent_change *= -1
  end
  repo_name = repo.partition('/').last
  message "Linting #{repo_name} with this PR took #{branch_duration}s " \
          "vs #{master_duration}s on master (#{percent_change.to_i}\% #{faster_slower})"
end

# Clean up
`git reset --hard HEAD`
FileUtils.rm_rf('osscheck')
`git checkout #{@branch_name}`