local json = require("json") 
local xrf  = {}

xrf.traverseNodesContaining = function(key,obj,cb)
  local metadata = json.decode( obj['model']:getMetadata() )
  -- Blender stores extras in single-object glb's to 'mesh' but multi-object glb's to 'nodes'
  -- hence node_or_mesh
  local keys     = {'nodes','meshes'} 

  for k, tkey in pairs(keys) do 
    local i = 1
    local tree = metadata[tkey]
    xrf.traverse( tree, function(node)
      if node['extras'] ~= nil then 
        if node['extras'][key] ~= nil then
          cb(node,obj['model'], i, metadata)
        end
      end
      i = i + 1
    end)
  end
end

xrf.getNodeFromMesh = function(mesh,metadata, i)
  local node 
  if mesh['mesh'] == nil then 
    local extras = mesh['extras']
    node = metadata['nodes'][i]
    node['extras'] = extras
  end
  return node
end

xrf.calcDimensions = function(bbox)
  local w = math.abs( bbox['maxx'] - bbox['minx'] )
  local h = math.abs( bbox['maxy'] - bbox['miny'] )
  local d = math.abs( bbox['maxz'] - bbox['minz'] )
  return w, h, d
end

xrf.calcCenteredWorldPosition = function(node, model, bbox)
  -- adjust for meshes which don't have origin in their center
  local x, y, z = model:getNodePosition(node['name'], 'root') -- worldcoords
  x = x + ( ( bbox['maxx'] + bbox['minx']) /2  )
  y = y + ( ( bbox['maxy'] + bbox['miny']) /2  )
  z = z + ( ( bbox['maxz'] + bbox['minz']) /2  )
  return x, y, z
end

xrf.calcScale = function(node)
  return {
    node['scale'] and node['scale'][1] or 1,
    node['scale'] and node['scale'][2] or 1,
    node['scale'] and node['scale'][3] or 1,
  }
end

xrf.makeClickable = function( physicsWorld, cb)
  return function(node_or_mesh,model, i, metadata)
    local node      = node_or_mesh
    if node['mesh'] == nil then node = xrf.getNodeFromMesh(node_or_mesh, metadata, i) end
    print("making node " .. node['name'] .. " clickable")
    local meshindex = 1 + node['mesh']
    local mesh      = model:getMesh( meshindex )
    local minx, maxx, miny, maxy, minz, maxz = mesh:getBoundingBox()
    local bbox    = {maxx=maxx, minx=minx, maxy=maxy, miny=miny, maxz=maxz, minz=minz}
    local w, h, d = xrf.calcDimensions( bbox )
    local x, y, z = xrf.calcCenteredWorldPosition( node, model, bbox )
    local scale   = xrf.calcScale(node)
    -- we cannot use newMeshCollider because storage type of modelmesh is not cpu
    local collider = physicsWorld:newBoxCollider( 
      x, y, z,
      scale[1] * (w + 0.01), -- add 0.01 to avoid 0
      scale[2] * (h + 0.01), -- in case of 
      scale[3] * (d + 0.01)  -- planes e.g.
    )
    collider:setUserData( {name = node['name'], node = node, onclick = cb })
  end 
end

-- utility function to traverse recursive table
xrf.traverse = function(arr, cb, key)
  if key == nil then key = 'children' end
  for k, child in pairs(arr) do 
    if type(child) == 'table' then 
      cb(child)
      if type(child[key]) == 'table' then
        if child[key][1] then
          xrf.traverse( child[key], cb, key )
        end
      end
    end
  end
end

return xrf