--[[
Copyright (c) 2017 Benjamin Chung

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
]]

local arcFns = {}
local arcMt = {__index = arcFns}
function Arc() 
  local ot = {}
  setmetatable(ot, arcMt)
  return ot
end

local arcSetFns = {}
local arcSetMt = {__index=arcSetFns}
function arcSetMt:__add(other)
  local incl = {}
  for _, d in pairs(self) do
    incl[d] = true
  end
  for _, d in pairs(other) do
    incl[d] = true
  end
  local out = {}
  for d, _ in pairs(incl) do
    table.insert(out, d)
  end
  setmetatable(out, arcSetMt)
  return out
end

--[[
local box = "█"
local rels = {
  SB1 = {4,1}, 
  SB2 = {5,1}, 
  SMF1 = {6,2}, 
  SMF2 = {6,3}, 
  SMA1 = {6,4}, 
  SMA2 = {6,5}, 
  SS1 = {5,6}, 
  SS2 = {4,6}, 
  PS1 = {3,6}, 
  PS2 = {2,6}, 
  PMA1 = {1,5}, 
  PMA2 = {1,4}, 
  PMF1 = {1,3}, 
  PMF2 = {1,2}, 
  PB1 = {2,1}, 
  PB2 = {3,1}
}
function arcSetMt:__tostring()
  local out = {{},{},{},{},{},{}}
  for i = 1,6 do
    for j = 1,6 do
      out[i][j] = " "
    end
  end
  for _,d in pairs(self) do
    local x,y = table.unpack(rels[d])
    out[y][x] = box
  end
  for k,v in pairs(out) do
    out[k] = table.concat(out[k],"")
  end
  return table.concat(out, "\n")
end
]]
function arcSetMt:__tostring()
  return "Arc: " .. table.concat(self, " ")
end

local names = {"SB1", "SB2", "SMF1", "SMF2", "SMA1", "SMA2", "SS1", "SS2", "PS1", "PS2", "PMA1", "PMA2", "PMF1", "PMF2", "PB1", "PB2"}
local cardinal = {}
local angles = {}

local da = 2*math.pi/#names
for i=1,#names do
  local angle = da*(i-1) + da/2
  cardinal[angle] = names[i]
  angles[names[i]] = angle
end

function arcFns:new(table)
  assert(type(self) == "table", "new must be called as Arc():new(...)")
  for _,v in pairs(table) do
    assert(angles[v] ~= nil, "invalid arc specification")
  end
  setmetatable(table, arcSetMt)
  return table
end

local sweepFns = { }
local sweepMt = {__index = sweepFns }
arcFns.from = function(self, direction)
  assert(type(self) == "table", "from must be called as Arc():from(...)")
  local ot = { from = math.rad(direction) }
  setmetatable(ot, sweepMt)
  return ot
end

local function normalize_direction(angle)
  if angle > 2*math.pi then return math.fmod(angle, 2*math.pi) end
  if angle < 0 then return 2*math.pi + math.fmod(angle, 2*math.pi) end
  return angle
end

function sweepFns:to(direction)
  assert(type(self.from) == "number", "From direction must be numeric degrees")
  local from = normalize_direction(self.from)
  local to = normalize_direction(math.rad(direction))
  if to < from then to = to + 2*math.pi end
  
  local out = {}
  for i=1,#names do
    local angle = angles[names[i]]
    if from - angle > 0 then angle = angle + 2*math.pi end
    if to > angle then 
      table.insert(out, names[i])
    end
  end
  setmetatable(out, arcSetMt)
  return out
end

local vnames = {"SB1", "SB2", "SMF1", "SMF2", "SMA1", "SMA2", "SS1", "SS2", "PS1", "PS2", "PMA1", "PMA2", "PMF1", "PMF2", "PB1", "PB2"}
setmetatable(vnames, arcSetMt)
arcFns.all = function(self) 
  assert(type(self) == "table", "all must be called as Arc():all()")
  return vnames 
end
local forward = Arc():from(270):to(90)
arcFns.forward = function(self) 
  assert(type(self) == "table", "forward must be called as Arc():forward()")
  return forward 
end
local backward = Arc():from(90):to(270)
arcFns.backward = function(self) 
  assert(type(self) == "table", "backward must be called as Arc():backward()")
  return backward 
end
local port = Arc():from(180):to(0)
arcFns.port = function(self) 
  assert(type(self) == "table", "port must be called as Arc():port()")
  return port 
end
local starboard = Arc():from(0):to(180)
arcFns.starboard = function(self) 
  assert(type(self) == "table", "starboard must be called as Arc():starboard()")
  return starboard 
end