require 'sinatra/base'
require 'sinatra/json'
require 'yajl'
require 'yajl/json_gem'
require 'csv'

$set = "2017-05-06"
$metafile = "tmp/songtitle"
$setfile = "sets/#{$set}/tracklist.csv"
$cuefile = "sets/#{$set}/#{$set}.cues"

def write_metafile(title)
  File.open($metafile, "a+") do |fp|
    fp.flock(File::LOCK_EX)
    fp.seek(0)
    fp.truncate(0)
    fp.puts(title)
    fp.flush()
    fp.flock(File::LOCK_UN)
  end
end

def write_cuefile(title)
  line = [ Time.now.to_i, title ].to_csv
  File.open($cuefile, "a") do |fp|
    fp.flock(File::LOCK_EX)
    fp.write(line)
    fp.flush()
    fp.flock(File::LOCK_UN)
  end
end

def load_tracklist()
  csv = CSV.read(File.open($setfile), encoding: 'UTF-8')
  names = csv.shift.map(&:to_sym)
  csv = csv.reject {|row| row[0].nil? }
  $tracklist = csv.map do |row|
    Hash[*names.zip(row).flatten]
  end
  $tracklist.unshift({
    index: "0",
    title: " - "
  })
  $tracklist.sort! {|a,b| a[:index].to_i <=> b[:index].to_i }
end

load_tracklist

def tracklist_json
  $tracklist.to_json
end

class App < Sinatra::Base
  configure do
    set :protection, :except => :frame_options
  end

  get '/tracklist.json' do
    json $tracklist
  end

  post '/commit' do
    index = params["index"].to_i
    if ( index < 0 || index > $tracklist.length )
      status 404
      return "No such track index."
    end

    title = ( index < 1 ) ? "-" : $tracklist.detect{|a| a[:index].to_i == index.to_i }[:title]

    write_metafile(title)
    write_cuefile(title)
    "Updated."
  end

  get '/js/handler.js' do
    content_type 'text/javascript'
    erb :handler_js
  end

  get '/css/meta.css' do
    content_type 'text/css'
    erb :meta_css
  end

  get '/' do
    erb :index, :locals => { :mixtitle => $set, :tracklist => tracklist_json }
  end
end