#!/usr/bin/env ruby

HORIZONTAL_STDEV = 24
VERTICAL_STDEV = 24

# board spec from WDF rules
WIRE_WIDTH = 1.56
INNER_DIAMETER_BULL = 12.7
INNER_DIAMETER_25 = 31.8
DOUBLE_OUTER_EDGE = 170.0
TREBLE_OUTER_EDGE = 107.4
DOUBLE_INSIDE_WIDTH = 8.0
TREBLE_INSIDE_WIDTH = 8.0
SECTORS = %w[20 1 18 4 13 6 10 15 2 17 3 19 7 16 8 11 14 9 12 5].map(&:to_i)

SECTOR_ANGLES = SECTORS.each_with_index.inject({}) do |m, (v, i)|
  m[v] = (90 - (i * 360 / SECTORS.length)) % 360
  m
end

# distance from centre to apex of outer wire
# must be ordered outwards from centre
OUTER_DISTS = {
  bull: INNER_DIAMETER_BULL/2 + WIRE_WIDTH/2,
  '25': INNER_DIAMETER_25/2 + WIRE_WIDTH/2,
  small: TREBLE_OUTER_EDGE - WIRE_WIDTH - TREBLE_INSIDE_WIDTH - WIRE_WIDTH/2,
  treble: TREBLE_OUTER_EDGE - WIRE_WIDTH/2,
  big: DOUBLE_OUTER_EDGE - WIRE_WIDTH - DOUBLE_INSIDE_WIDTH - WIRE_WIDTH/2,
  double: DOUBLE_OUTER_EDGE - WIRE_WIDTH/2
}

CENTRE_DISTS = OUTER_DISTS.inject([{}, nil]) { |(h, prev), (k, v)|
  h[k] = prev ? (v - ((v - prev) / 2)) : 0.0
  [h, v]
}[0]

CHECKOUTS = { # FIXME better checkout shots
  1 => {
    50=>"BULL", 40=>"D20", 38=>"D19", 36=>"D18", 34=>"D17", 32=>"D16",
    30=>"D15", 28=>"D14", 26=>"D13", 24=>"D12", 22=>"D11", 20=>"D10", 18=>"D9",
    16=>"D8", 14=>"D7", 12=>"D6", 10=>"D5", 8=>"D4", 6=>"D3", 4=>"D2", 2=>"D1"
  },
  2 => {
    110=>"T20", 107=>"T19", 104=>"T18", 101=>"T17", 100=>"T20", 98=>"T20",
    97=>"T19", 96=>"T20", 95=>"T19", 94=>"T18", 93=>"T19", 92=>"T20",
    91=>"T17", 90=>"T18", 89=>"T19", 88=>"T16", 87=>"T17", 86=>"T18",
    85=>"T15", 84=>"T20", 83=>"T17", 82=>"T14", 81=>"T19", 80=>"T20",
    79=>"T19", 78=>"T18", 77=>"T19", 76=>"T20", 75=>"T17", 74=>"T16",
    73=>"T19", 72=>"T16", 71=>"T19", 70=>"T20", 69=>"T19", 68=>"T18",
    67=>"T17", 66=>"T16", 65=>"T15", 64=>"T14", 63=>"T13", 62=>"T12",
    61=>"T11", 60=>"20", 59=>"19", 58=>"18", 57=>"17", 56=>"16", 55=>"15",
    54=>"14", 53=>"13", 52=>"20", 51=>"19", 50=>"18", 49=>"17", 48=>"16",
    47=>"15", 46=>"14", 45=>"13", 44=>"12", 43=>"3", 42=>"10", 41=>"17",
    40=>"D20", 39=>"7", 38=>"D19", 37=>"17", 36=>"D18", 35=>"3", 34=>"D17",
    33=>"17", 32=>"D16", 31=>"7", 30=>"D15", 29=>"17", 28=>"D14", 27=>"3",
    26=>"D13", 25=>"17", 24=>"D12", 23=>"7", 22=>"D11", 21=>"17", 20=>"D10",
    19=>"3", 18=>"D9", 17=>"1", 16=>"D8", 15=>"7", 14=>"D7", 13=>"5", 12=>"D6",
    11=>"3", 10=>"D5", 9=>"1", 8=>"D4", 7=>"3", 6=>"D3", 5=>"1", 4=>"D2",
    3=>"1", 2=>"D1"
  },
  3 => {
    170=>"T20", 167=>"T19", 164=>"T19", 161=>"T20", 160=>"T20", 158=>"T20",
    157=>"T20", 156=>"T20", 155=>"T20", 154=>"T19", 153=>"T20", 152=>"T20",
    151=>"T20", 150=>"T20", 149=>"T20", 148=>"T20", 147=>"T19", 146=>"T19",
    145=>"T20", 144=>"T20", 143=>"T20", 142=>"T20", 141=>"T19", 140=>"T15",
    139=>"T19", 138=>"T20", 137=>"T14", 136=>"T20", 135=>"BULL", 134=>"T14",
    133=>"T14", 132=>"BULL", 131=>"T19", 130=>"T20", 129=>"T19", 128=>"T20",
    127=>"T20", 126=>"T19", 125=>"BULL", 124=>"T20", 123=>"T19", 122=>"T18",
    121=>"T20", 120=>"T20", 119=>"T19", 118=>"T20", 117=>"T20", 116=>"T19",
    115=>"T19", 114=>"T20", 113=>"T19", 112=>"T20", 111=>"T19", 110=>"T19",
    109=>"T20", 108=>"T20", 107=>"T19", 106=>"T20", 105=>"T20", 104=>"T19",
    103=>"T19", 102=>"T20", 101=>"T19", 100=>"T20", 99=>"T19", 98=>"T20",
    97=>"T19", 96=>"T20", 95=>"T19", 94=>"T18", 93=>"T19", 92=>"T20",
    91=>"T17", 90=>"T20", 89=>"T19", 88=>"T20", 87=>"T17", 86=>"T18",
    85=>"T15", 84=>"T20", 83=>"T17", 82=>"BULL", 81=>"T19", 80=>"T20",
    79=>"T19", 78=>"T18", 77=>"T19", 76=>"T16", 75=>"T17", 74=>"T14",
    73=>"T19", 72=>"T16", 71=>"T13", 70=>"T18", 69=>"T15", 68=>"T12",
    67=>"T17", 66=>"T14", 65=>"BULL", 64=>"T16", 63=>"T13", 62=>"T10",
    61=>"BULL", 60=>"20", 59=>"19", 58=>"18", 57=>"17", 56=>"16", 55=>"15",
    54=>"14", 53=>"13", 52=>"20", 51=>"19", 50=>"18", 49=>"17", 48=>"16",
    47=>"15", 46=>"14", 45=>"13", 44=>"12", 43=>"11", 42=>"10", 41=>"9",
    40=>"D20", 39=>"7", 38=>"D19", 37=>"5", 36=>"D18", 35=>"3", 34=>"D17",
    33=>"1", 32=>"D16", 31=>"15", 30=>"D15", 29=>"13", 28=>"D14", 27=>"11",
    26=>"D13", 25=>"9", 24=>"D12", 23=>"7", 22=>"D11", 21=>"5", 20=>"D10",
    19=>"3", 18=>"D9", 17=>"1", 16=>"D8", 15=>"7", 14=>"D7", 13=>"5", 12=>"D6",
    11=>"3", 10=>"D5", 9=>"1", 8=>"D4", 7=>"3", 6=>"D3", 5=>"1", 4=>"D2",
    3=>"1", 2=>"D1"
  }
}

def get_coordinates(angle, radius)
  t = angle * Math::PI / 180
  x = radius * Math.cos(t)
  y = radius * Math.sin(t)

  [x, y]
end

def gauss
  theta = 2 * Math::PI * rand
  r = Math.sqrt(-2 * Math.log(1 - rand))
  [r * Math.cos(theta), r * Math.sin(theta)]
end

def throw_dart(angle, radius)
  x, y = get_coordinates(angle, radius)
  x_offset, y_offset = gauss
  x += HORIZONTAL_STDEV * x_offset
  y += VERTICAL_STDEV * y_offset

  d_angle = Math.atan2(y, x) * 180 / Math::PI
  d_radius = Math.sqrt(x**2 + y**2)

  [d_angle, d_radius]
end

def get_sector(angle)
  sector = SECTOR_ANGLES.detect do |v, c|
    dist = (c - angle).abs % 360
    dist = 360 - dist if dist > 180
    dist < 360 / SECTORS.length / 2 #TODO hit wire
  end

  sector && sector.first
end

def get_ring(radius)
  ring = OUTER_DISTS.detect do |sym, dist|
    radius**2 < dist**2
  end

  ring ? ring[0] : :out
end

def get_segment(angle, radius)
  sec = get_sector(angle)
  ring = get_ring(radius)

  case ring
  when :bull
    'BULL'
  when :'25'
    '25'
  when :small, :big
    "#{sec}"
  when :double
    "D#{sec}"
  when :treble
    "T#{sec}"
  when :out
    'OUT'
  end
end

def get_points(segment)
  case segment
  when 'BULL'
    50
  when /^T(\d+)$/
    3 * $1.to_i
  when /^D(\d+)$/
    2 * $1.to_i
  when /^(\d+)$/
    $1.to_i
  else
    0
  end
end

def get_segment_coordinates(segment)
  sector, ring =
    case segment
    when 'BULL'
      [20, :bull]
    when '25'
      [20, :'25']
    when /^T(\d+)$/
      [$1.to_i, :treble]
    when /^D(\d+)$/
      [$1.to_i, :double]
    when /^(\d+)$/
      [$1.to_i, :big]
    end

  [SECTOR_ANGLES[sector], CENTRE_DISTS[ring]]
end

def next_dart(rem, in_hand)
  segment = CHECKOUTS[in_hand][rem] || (in_hand == 1 ? '20' : 'T20')

  get_segment_coordinates(segment)
end

def play_visit(rem)
  v_rem = rem

  darts = []
  bust = false

  3.times do
    t_angle, t_radius = next_dart(v_rem, 3 - darts.length)
    d_angle, d_radius = throw_dart(t_angle, t_radius)

    segment = get_segment(d_angle, d_radius)
    darts << segment
    d_points = get_points(segment)
    v_rem -= d_points

    if (v_rem < 0 || v_rem == 1 ||
      (v_rem == 0 && segment != 'BULL' && segment !~ /^D/))

      v_rem = rem
      bust = true
      break
    end

    break if v_rem.zero?
  end

  [v_rem, rem - v_rem, darts, bust]
end

def colour_points(points)
  str = "%3s" % points

  if points == 180
    "\e[1;38;5;82m#{str}\e[0m"
  elsif points > 139
    "\e[38;5;82m#{str}\e[0m"
  elsif points > 99
    "\e[38;5;154m#{str}\e[0m"
  elsif points > 59
    "\e[38;5;226m#{str}\e[0m"
  elsif points > 39
    "\e[38;5;214m#{str}\e[0m"
  elsif points > 19
    "\e[38;5;202m#{str}\e[0m"
  else
    "\e[38;5;196m#{str}\e[0m"
  end
end

def visit_darts(darts)
  str = darts.map { |x| '%3s' % x }.join(' ')
  str += '    ' * (3 - darts.length)
  str
end

def output_visit(n, rem, points = nil, darts = nil, bust = false)
  str = '(%2s)  %3s' % [n, rem]
  str << '  %s' % colour_points(points) if points
  str << "    \e[38;5;235m%s\e[0m" % visit_darts(darts) if darts
  str << " \e[38;5;88mBUST\e[0m" if bust
  str << " \e[38;5;76mWIN\e[0m" if rem.zero?

  puts str
end

def play_match(start_points = 501, output = true)
  rem = start_points
  m_darts = []

  output_visit(m_darts.length, rem) if output

  while rem != 0
    rem, points, darts, bust = play_visit(rem)
    m_darts << darts

    output_visit(m_darts.length, rem, points, darts, bust) if output

    if rem.zero? && output
      puts
      req = (((m_darts.length - 1) * 3) + m_darts[-1].length)
      puts "darts: %s" % req
      puts "average: %.2f" % (start_points.to_f / req * 3)
    end
  end

  m_darts
end

def test_average
  avgs = (0..10000).map do |x|
    m_darts = play_match(501, false)
    req = (((m_darts.length - 1) * 3) + m_darts[-1].length)
    (501.to_f / req * 3)
  end

  avg = avgs.sum / avgs.length
  stdev = Math.sqrt(avgs.sum { |x| (x - avg) ** 2 } / (avgs.length - 1))

  puts
  puts avg
  puts stdev
end

play_match
#test_average