local path = (...):gsub('%.[^%.]+$', '')
local types = require(path .. '.types')

local schema = {}
schema.__index = schema

function schema.create(config)
  assert(type(config.query) == 'table', 'must provide query object')

  local self = {}
  for k, v in pairs(config) do
    self[k] = v
  end

  self.typeMap = {
    Int = types.int,
    Float = types.float,
    String = types.string,
    Boolean = types.boolean,
    ID = types.id
  }

  self.interfaceMap = {}
  self.directiveMap = {}

  local function generateTypeMap(node)
    if self.typeMap[node.name] and self.typeMap[node.name] == node then return end

    if node.__type == 'NonNull' or node.__type == 'List' then
      return generateTypeMap(node.ofType)
    end

    if self.typeMap[node.name] and self.typeMap[node.name] ~= node then
      error('Encountered multiple types named "' .. node.name .. '"')
    end

    self.typeMap[node.name] = node

    if node.__type == 'Object' and node.interfaces then
      for _, interface in ipairs(node.interfaces) do
        generateTypeMap(interface)
        self.interfaceMap[interface.name] = self.interfaceMap[interface.name] or {}
        self.interfaceMap[interface.name][node] = node
      end
    end

    if node.__type == 'Object' or node.__type == 'Interface' or node.__type == 'InputObject' then
      if type(node.fields) == 'function' then node.fields = node.fields() end
      for fieldName, field in pairs(node.fields) do
        if field.arguments then
          for _, argument in pairs(field.arguments) do
            generateTypeMap(argument)
          end
        end

        generateTypeMap(field.kind)
      end
    end
  end

  generateTypeMap(self.query)

  self.directives = self.directives or {
    types.include,
    types.skip
  }

  if self.directives then
    for _, directive in ipairs(self.directives) do
      self.directiveMap[directive.name] = directive
    end
  end

  return setmetatable(self, schema)
end

function schema:getType(name)
  if not name then return end
  return self.typeMap[name]
end

function schema:getImplementors(interface)
  local kind = self:getType(interface)
  local isInterface = kind and kind.__type == 'Interface'
  return self.interfaceMap[interface] or (isInterface and {} or nil)
end

function schema:getDirective(name)
  if not name then return false end
  return self.directiveMap[name]
end

return schema