local PeripheralAPIFake = {}
PeripheralAPIFake.__index = PeripheralAPIFake

local expect = require("cc.expect").expect

local function isPeripheral(peripheral)
	if type(peripheral) ~= "table" then return false end
	local meta = getmetatable(peripheral)

	if type(meta) ~= "table" then return false end
	if meta.__name ~= "peripheral" then return false end
	if type(meta.name) ~= "string" then return false end
	if type(meta.type) ~= "string" then return false end
	if type(meta.types) ~= "table" then return false end
	for _, ty in ipairs(meta.types) do
		if not meta.types[ty] then return false end
	end

	return true
end

-- TODO: Add descriptive error messages to asserts
local function expectPeripheral(index, peripheral)
	if not isPeripheral(peripheral) then
		error(("bad argument #%d (table is not a peripheral)"):format(index), 3)
	end
end

--- Performs a deep clone of a table.
local function cloneTable(t)
	local mt = getmetatable(t)
	setmetatable(t, nil)
	local cloned = {}
	for k, v in pairs(t) do
		if type(v) == "table" then
			cloned[k] = cloneTable(v)
		else
			cloned[k] = v
		end
	end
	setmetatable(t, mt)
	return cloned
end

local function doesTableContain(t, value)
	for _, v in pairs(t) do
		if v == value then
			return true
		end
	end
	return false
end

local function getPeripheralName(peripheral)
	return getmetatable(peripheral).name
end

local function getPeripheralTypes(peripheral)
	return getmetatable(peripheral).types
end

function PeripheralAPIFake.new(peripherals)
	expect(1, peripherals, "table", "nil")

	local self = setmetatable({}, PeripheralAPIFake)
	self.peripherals = {}

	if peripherals then
		for _, peripheral in ipairs(peripherals) do
			self:addPeripehral(peripheral)
		end
	end

	return self
end

function PeripheralAPIFake:newExternalAPI()
	local api = {}

	function api.call(name, method, ...)
		expect(1, name, "string")
		expect(2, method, "string")
		local peripheral = self.peripherals[name]
		if not peripheral then return end
		local func = peripheral[method]
		if type(func) ~= "function" then
			error(("No such method %s"):format(method), 2)
		end
		return func(...)
	end

	function api.find(ty, filter)
		expect(1, ty, "string")
		expect(2, filter, "function", "nil")
		local peripherals = {}
		for name, peripheral in pairs(self.peripherals) do
			local types = getPeripheralTypes(peripheral)
			if doesTableContain(types, ty) then
				local wrapped = api.wrap(name)
				if not filter or filter(name, wrapped) then
					table.insert(peripherals, wrapped)
				end
			end
		end
		return peripherals
	end

	function api.getMethods(name)
		expect(1, name, "string")
		local peripheral = self:getPeripheral(name)
		if not peripheral then return end

		local methods = {}
		for methodName, method in pairs(peripheral) do
			if type(method) == "function" then
				table.insert(methods, methodName)
			end
		end
		return methods
	end

	function api.getName(peripheral)
		expect(1, peripheral, "table", "string")
		expectPeripheral(1, peripheral)
		return getPeripheralName(peripheral)
	end

	function api.getNames()
		return self:listPeripherals()
	end

	function api.getType(peripheral)
		expect(1, peripheral, "table", "string")
		if type(peripheral) == "table" then
			expectPeripheral(1, peripheral)
		end
		local p = self:getPeripheral(peripheral)
		return table.unpack(getPeripheralTypes(p))
	end

	function api.hasType(peripheral, peripheral_type)
		expect(1, peripheral, "table", "string")
		if type(peripheral) == "table" then
			expectPeripheral(1, peripheral)
		end
		expect(2, peripheral_type, "string")
		local p = self:getPeripheral(peripheral)
		if not p then return end

		local types = getPeripheralTypes(peripheral)
		return doesTableContain(types, peripheral_type)
	end

	function api.isPresent(name)
		expect(1, name, "string")
		return self:hasPeripheral(name)
	end

	function api.wrap(name)
		expect(1, name, "string")
		local peripheral = self.peripherals[name]
		if not peripheral then return end
		return cloneTable(peripheral)
	end

	return api
end

function PeripheralAPIFake:addPeripehral(peripheral)
	expect(1, peripheral, "table")
	expectPeripheral(1, peripheral)

	local name = getPeripheralName(peripheral)
	assert(not self.peripherals[name], "Expected peripheral name to be unique, it's not unique")
	assert(not self:hasPeripheral(peripheral), "Peripheral already added to system")

	self.peripherals[name] = peripheral
end

function PeripheralAPIFake:removePeripheral(peripheral)
	expect(1, peripheral, "table", "string")

	if type(peripheral) == "string" then
		self.peripherals[peripheral] = nil
	else
		expectPeripheral(1, peripheral)
		local name = getPeripheralName(peripheral)
		self.peripherals[name] = nil
	end
end

function PeripheralAPIFake:hasPeripheral(peripheral)
	expect(1, peripheral, "table", "string")
	return self:getPeripheral(peripheral) ~= nil
end

function PeripheralAPIFake:getPeripheral(peripheral)
	expect(1, peripheral, "table", "string")

	if type(peripheral) == "string" then
		return self.peripherals[peripheral]
	else
		expectPeripheral(1, peripheral)
		local name = getPeripheralName(peripheral)
		return self.peripherals[name]
	end
end

function PeripheralAPIFake:getPeripheralName(peripheral)
	return getPeripheralName(self:getPeripheral(peripheral))
end

function PeripheralAPIFake:listPeripherals()
	local names = {}
	for _, peripheral in pairs(self.peripherals) do
		table.insert(names, getPeripheralName(peripheral))
	end
	return names
end

return PeripheralAPIFake