-- ================
-- Private helpers
-- ================
local setmetatable = setmetatable
local Node = require("Graph/Node")


-- Internal class constructor
local class = function(...)
local klass = {}
klass.__index = klass
klass.__call = function(_,...) return klass:new(...) end
function klass:new(...)
  local instance = setmetatable({}, klass)
  klass.__init(instance, ...)
  return instance
end
return setmetatable(klass,{__call = klass.__call})
end

local Graph = class()
Graph.__tostring = function(g) return ("Graph") end

function Graph:__init(vertices, edges)
  self.vertices = vertices
  self.edges = edges
  self.nodes = {}

  for _,e in pairs(edges) do 
    if self.nodes[e.p1.id] == nil then
      self.nodes[e.p1.id] = Node(e.p1.id)
    end
    if self.nodes[e.p2.id] == nil then
      self.nodes[e.p2.id] = Node(e.p2.id)
    end
    self.nodes[e.p1.id]:link(self.nodes[e.p2.id])
    self.nodes[e.p2.id]:link(self.nodes[e.p1.id])
  end
  for _,v in pairs(vertices) do
    if self.nodes[v.id] == nil then
      self.nodes[v.id] = Node(v.id)
    end
  end
end

function Graph:contains_vertex(v)
  if self.vertices[v.id] then return true end
  return false
end

function Graph:append_vertex(v)
  assert(v.id ~= nil, "vertex not configured")
  assert(self.vertices[v.id] == nil, "vertex already existing")
  self.vertices[v.id] = v
  self.nodes[v.id] = Node(v.id)
end

function Graph:contains_edge(e)
  for _,edge in pairs(self.edges) do
    if e == edge then return true end
  end
  return false
end


function Graph:append_edge(e)
for _,edge in pairs(self.edges) do
  assert(e ~= edge, "Edge already existing")
end
table.insert(self.edges, e)
self.nodes[e.p1.id]:link(self.nodes[e.p2.id])
self.nodes[e.p2.id]:link(self.nodes[e.p1.id])
end

return Graph