require 'optparse'
require 'open-uri'
require 'nokogiri'
require 'yaml'
require 'json'

@output = []
@line = nil
@from_station = nil
@to_station = nil
@weight = 'peak_time'
@change_time = 5
@colour = false
debug = false
help = false
ops = nil
VERSION = 'v1.1.2'
INFINITY = 1 << 64
WEIGHTS = ['distance','peak_time','off_peak_time','unimpeded_time']

STDIN.gets.split(' ').each{|arg| ARGV << arg} if ARGV == []
args = ARGV.dup

options = OptionParser.new do |opts|
  opts.banner = "Usage: #{File.basename($0)} -h"
  opts.on( '-s', '--status [LINE]', 'Get the current status of a tube line.' ) {|l| @line = l || 'summary' }
  opts.on( '-f', '--from-station STATION', 'Find route from this station.' ) {|f| @from_station = f }
  opts.on( '-t', '--to-station STATION', 'Find route to this station.' ) {|t| @to_station = t }
  opts.on( '-w', '--weight WEIGHT', 'Shortest route using either distance, peak_time, off_peak_time or unimpeded_time.' ) {|w| @weight = WEIGHTS.include?(w) ? w : 'peak_time' }
  opts.on( '-c', '--change-time TIME', 'Your expected average change time in minutes.' ) {|c| @change_time = c.to_f.round(2) }
  opts.on( '-C', '--colour', 'Enable line colours in the output.' ) { @colour = true }
  opts.on( '-d', '--debug', 'Display debug info.' ) { debug = true }
  opts.on( '-v', '--version', 'blatube version number.' ) { puts VERSION; exit }
  opts.on( '-h', '--help', 'Display this screen.' ) { help = true; ops = opts }
end;options.parse!

@output << "args: #{args.inspect}" if debug
if args == []
  @output << "Usage: #{File.basename($0)} -h"
  puts @output.join ' '
  exit -1
end

class Array
  def pairs
    pairs = []
    self.each_with_index do |element, index|
      pairs << [element,self[index+1]]
    end
    pairs.pop
    pairs
  end
end

#TODO: add via_station
def calculate_shortest_route
  return unless interpret_user_input
  @shortest_route = []
  calculate_routes
  traverse_route @to_station.upcase
  build_route_output
end

def interpret_user_input
  stations = @graph.keys.map {|station| station.split('_')[0]}.uniq.sort
  found_from_station, @from_station = interpret stations, @from_station
  found_to_station, @to_station = interpret stations, @to_station
  return found_from_station && found_to_station
end

def interpret stations, station
  found_station = false
  if stations.include?(station.upcase)
    found_station = true
  elsif (most_likely = stations.map {|stat| stat.match("^#{station.upcase}.*") ? stat : nil}.compact) != []
    if most_likely.size == 1
      station = most_likely.first
      found_station = true
    else
      @output << "Did you mean: #{most_likely.map {|stat| stat.split(' ').map {|word| word.capitalize}.join(' ')}.join(', ')}?"
    end
  elsif (less_likely = stations.map {|stat| stat.match(".*#{station.upcase}.*") ? stat : nil}.compact) != []
    if less_likely.size == 1
      station = less_likely.first
      found_station = true
    else
      @output << "Did you mean: #{less_likely.map {|stat| stat.split(' ').map {|word| word.capitalize}.join(' ')}.join(', ')}?"
    end
  else
    @output << "Could not find a matching station for '#{station}'."
  end
  return found_station, station
end

def calculate_routes
  routes,distances = YAML::load(File.open("cache/#{@from_station}_#{@weight == 'distance' ? @weight : "#{@weight}_#{@change_time}"}.yaml", 'r'))
  @distances = Hash.new(INFINITY).merge distances
  @routes = Hash.new(-1).merge routes
rescue Errno::ENOENT
  add_change_time unless @weight == 'distance'
  run_algorithm @graph, @graph.keys, @from_station.upcase
  File.new("cache/#{@from_station}_#{@weight == 'distance' ? @weight : "#{@weight}_#{@change_time}"}.yaml", 'w') << [@routes,@distances].to_yaml
end

#TODO: changes on the same line (eg. 'CAMDEN TOWN')
def add_change_time
  @graph.each do |from_station,to_stations|
    next unless current_line = from_station.split('_')[1]
    to_stations.each do |to_station,data|
      data[@weight] += @change_time unless data['line'] == current_line
    end
  end
end

def run_algorithm graph, nodes, start_node
  @distances = Hash.new INFINITY
  @routes = Hash.new -1
  @distances[start_node] = 0
  nodes_size = nodes.size
  while nodes_size > 0
    current_node = nodes.first
    nodes.each {|node| current_node = node if @distances[node] < @distances[current_node]}
    break if @distances[current_node] == INFINITY
    nodes.delete current_node
    nodes_size -= 1
    graph[current_node].keys.each do |next_node|
      new_distance = @distances[current_node] + graph[current_node][next_node][@weight]
      if new_distance < @distances[next_node]
        @distances[next_node] = new_distance
        @routes[next_node] = current_node
      end
    end
  end
  @distances.delete_if {|node, distance| distance == INFINITY}
end

def traverse_route to_station
  if @routes[to_station] != -1
    traverse_route @routes[to_station]
  end
  @shortest_route << to_station
end

#TODO: a nicer way of doing this
def build_route_output
  line_colours = @colour ? YAML::load(File.open('line_colours.yaml')) : Hash.new('')
  verbose_route = ''
  pairs = @shortest_route.pairs
  from,to = pairs.first
  current_line = @graph[from][to]['line']
  verbose_route << "#{line_colours[current_line]}#{from} - #{current_line} (#{@graph[from][to]['direction']})"
  pairs[1..-2].each do |from,to|
    next if (new_line = @graph[from][to]['line']) == current_line || @graph[from][to]['direction'] == nil
    current_line = new_line
    from_s = from.split('_')[0]
    from_1 = from_s[0..(from_s.length/2.0 - 1)]
    from_2 = from_s[(from_s.length/2.0)..-1]
    verbose_route << " - #{from_1}#{line_colours['reset_colour']}#{line_colours[new_line]}#{from_2} - #{new_line} (#{@graph[from][to]['direction']})"
  end
  from,to = pairs.last
  new_line = @graph[from][to]['line']
  from_s = from.split('_')[0]
  from_1 = from_s[0..(from_s.length/2.0 - 1)]
  from_2 = from_s[(from_s.length/2.0)..-1]
  verbose_route << " - #{from_1}#{line_colours['reset_colour']}#{line_colours[new_line]}#{from_2} - #{new_line} (#{@graph[from][to]['direction']})" unless new_line == current_line
  verbose_route << " - #{to}#{line_colours['reset_colour']}"
  @output << verbose_route
  if @weight == 'distance'
    @output << "Distance: #{@distances[@to_station.upcase].round(2)} km"
  else
    minutes = @distances[@to_station.upcase].round(2)
    seconds = (minutes - minutes.to_i) * 60
    @output << "Travel Time: #{minutes.to_i}:#{seconds.round}"
  end
end

def get_line_status
  xml = Nokogiri::HTML(open('http://cloud.tfl.gov.uk/TrackerNet/LineStatus')).remove_namespaces!
  sorted_lines = xml.xpath('//linestatus').sort_by {|xml| xml.xpath('.//line/@name').text}
  if @line && @line != 'summary'
    l_s_xml = nil
    sorted_lines.each {|xml| l_s_xml = xml and break if xml.xpath('.//line/@name').text.upcase.match @line.upcase}
    @output << ("#{l_s_xml.xpath('.//line/@name').text}: #{l_s_xml.xpath('.//status/@description').text}. #{l_s_xml.xpath('./@statusdetails').text}" rescue "Could not find a line matching '#{@line}'")
  else
    line_summary = ''
    sorted_lines.each {|xml| line_summary << "#{xml.xpath('.//line/@name').text}: #{xml.xpath('./@statusdetails').text} " unless xml.xpath('./@statusdetails').text == ''}
    @output << (line_summary == '' ? 'Good Serice on all lines.' : "#{line_summary}Good Service on all other lines.")
  end
end

#TODO: store graph as yaml in a way that works with add_change_time
begin
  if help
    ops.to_s.split(/\n\s*|\s{2,}/).each{|opt| @output << opt}
  elsif @line
    get_line_status
  elsif @from_station && @to_station
    #@graph = YAML::load(File.open('graph.yaml'))
    @graph = JSON.parse(File.open('graph.json').read)
    calculate_shortest_route
  elsif @from_station || @to_station
    @output << 'Please specify the station you are travelling from (-f) and the station you are travelling to (-t).'
  elsif ARGV.size == 2
    #@graph = YAML::load(File.open('graph.yaml'))
    @graph = JSON.parse(File.open('graph.json').read)
    @from_station = ARGV[0]
    @to_station = ARGV[1]
    calculate_shortest_route
  elsif ARGV.size == 1
    @line = ARGV[0]
    get_line_status
  else
    get_line_status
  end
  puts @output.join ' '
rescue StandardError => e
  puts (@output << e.message).join ' '
  puts e.message
  puts e.backtrace
end