local Adapter = require('milo.miniAdapter')
local class   = require('opus.class')
local Config  = require('opus.config')
local Event   = require('opus.event')
local itemDB  = require('core.itemDB')
local Util    = require('opus.util')

local device   = _G.device
local os       = _G.os
local parallel = _G.parallel

local SCAN_CHUNK_SIZE = 16

local Storage  = class()

local function loadOld(storage)
	storage.nodes = Config.load('milo', { })

	-- TODO: remove - temporary
	if storage.nodes.remoteDefaults then
		storage.nodes.nodes = storage.nodes.remoteDefaults
		storage.nodes.remoteDefaults = nil
	end

	-- TODO: remove - temporary
	if storage.nodes.nodes then
		local categories = {
			input = 'custom',
			trashcan = 'custom',
			machine = 'machine',
			brewingStand = 'machine',
			activity = 'display',
			jobs = 'display',
			ignore = 'ignore',
			hidden = 'ignore',
			manipulator = 'custom',
			storage = 'storage',
		}
		for _, node in pairs(storage.nodes.nodes) do
			if node.lock and type(node.lock) == 'string' then
				node.lock = {
					[ node.lock ] = true,
				}
			end
			if not node.category then
				node.category = categories[node.mtype]
				if not node.category then
					Util.print(node)
					error('invalid node')
				end
			end
		end
		storage.nodes = storage.nodes.nodes
	end
end

function Storage:init()
	local defaults = {
		dirty = true,
		activity = { },
		storageOnline = true,
	}
	Util.merge(self, defaults)
	self.nodes = Config.load('storage', { })

	if Util.empty(self.nodes) then -- TODO: temporary
		loadOld(self)
	end

	Event.on({ 'device_attach', 'device_detach' }, function(e, dev)
_G._syslog('%s: %s', e, tostring(dev))
		self:initStorage() -- this can yield - so we might miss events
	end)
	Event.onInterval(60, function()
		self:showStorage()
	end)
end

function Storage:showStorage()
	local t = { }
	local ignores = {
		ignore = true,
		hidden = true,
	}
	for k,v in pairs(self.nodes) do
		local online = v.adapter and v.adapter.online
		if not online and not ignores[v.mtype] then
			table.insert(t, k)
		end
	end
	if #t > 0 then
		_G._syslog('Adapter:')
		for _, k in pairs(t) do
			_G._syslog(' offline: ' .. k)
		end
		_G._syslog('')
	end
end

function Storage:isOnline()
	return self.storageOnline
end

function Storage:initStorage()
	local online = true

	-- unknown why this is not working below
	for _,v in pairs(device) do
		v.transferLocations = nil
	end

	for k,v in pairs(self.nodes) do
		if v.mtype ~= 'hidden' then
			if v.adapter then
				v.adapter.online = not not device[k]
				if v.adapter.online then
					Util.merge(v.adapter, device[k])
				end
			elseif device[k] and device[k].list and device[k].size and device[k].pullItems then
				if v.adapterType then
					v.adapter = require(v.adapterType)({ side = k })
				else
					v.adapter = Adapter({ side = k })
				end
				v.adapter.online = true
				v.adapter.dirty = true

				if v.adapter.isOn and not v.adapter.isOn() then -- turtle
					v.adapter.turnOn()
				end
			elseif device[k] then
				v.adapter = device[k]
				v.adapter.online = true
			end

			if v.adapter then
				-- force a new getTransferLocations() as the list may have changed
				v.adapter.transferLocations = nil
			end

			if v.mtype == 'storage' then
				online = online and not not (v.adapter and v.adapter.online)
			end
		end
	end

	if online ~= self.storageOnline then
		self.storageOnline = online
		-- TODO: if online, then list items
		os.queueEvent(self.storageOnline and 'storage_online' or 'storage_offline', online)
		_G._syslog('Storage: %s', self.storageOnline and 'online' or 'offline')
	end

	self:listItems()
end

function Storage:saveConfiguration()
	local t = { }
	for k,v  in pairs(self.nodes) do
		t[k] = v.adapter
		v.adapter = nil
	end

	Config.update('storage', self.nodes)

	for k,v  in pairs(t) do
		self.nodes[k].adapter = v
	end
	self:initStorage()
end

function Storage:getSingleNode(mtype)
	local node = Util.find(self.nodes, 'mtype', mtype)
	if node and node.adapter and node.adapter.online then
		return node
	end
end

function Storage:filterNodes(mtype, filter)
	local iter = { }
	for _, v in pairs(self.nodes) do
		if v.mtype == mtype then
			if not filter or filter(v) then
				table.insert(iter, v)
			end
		end
	end

	local i = 0
	return function()
		i = i + 1
		return iter[i]
	end
end

function Storage:filterActive(mtype, filter)
	return self:filterNodes(mtype, function(v)
		if v.adapter and v.adapter.online then
			return not filter and true or filter(v)
		end
	end)
end

function Storage:onlineAdapters()
	local iter = { }
	for _, v in pairs(self.nodes) do
		if v.adapter and v.adapter.online and v.mtype == 'storage' then
			table.insert(iter, v)
		end
	end

	table.sort(iter, function(a, b)
		if not a.priority then
			return false
		elseif not b.priority then
			return true
		end
		return a.priority > b.priority
	end)

	local i = 0
	return function()
		i = i + 1
		local a = iter[i]
		if a then
			return a, a.adapter
		end
	end
end

function Storage:setDirty()
	self.dirty = true
end

function Storage:refresh(throttle)
	self.dirty = true
_G._syslog('STORAGE: Forcing full refresh')
	for _, adapter in self:onlineAdapters() do
		adapter.dirty = true
	end
	return self:listItems(throttle)
end

-- provide a consolidated list of items
function Storage:listItems(throttle)
	if not self.dirty then
		return self.cache
	end

	local timer = Util.timer()
	local cache = { }
	throttle = throttle or Util.throttle()

	local t = { }
	for _, adapter in self:onlineAdapters() do
		if adapter.dirty then
			table.insert(t, function()
				adapter:listItems(throttle)
				if not adapter.__size then
					adapter.__size = adapter.size()
				end
				adapter.dirty = false
			end)
		end
	end

	if #t > 0 then
		local chunk = {}

		-- Split the work into chunks to avoid spamming too many coroutines.
		for i = 1, #t do
			table.insert(chunk, t[i])

			-- When we reach the chunk limit, execute them and start a new chunk
			if #chunk >= SCAN_CHUNK_SIZE then
				parallel.waitForAll(table.unpack(chunk))
				chunk = {}
			end
		end
		
		if #chunk > 0 then
			parallel.waitForAll(table.unpack(chunk))
		end
	end

	for _, adapter in self:onlineAdapters() do
		local rcache = adapter.cache or { }
		for key,v in pairs(rcache) do
			local entry = cache[key]
			if not entry then
				entry = Util.shallowCopy(v)
				entry.count = v.count
				entry.key = key
				cache[key] = entry
			else
				entry.count = entry.count + v.count
			end

			throttle()
		end
	end
	itemDB:flush()
	_G._syslog('STORAGE: refresh '  .. #t .. ' inventories in ' .. Util.round(timer(), 2))

	self.dirty = false
	self.cache = cache

	return self.cache
end

-- provide a raw list of all the items in all storage chests
-- it might be beneficial to move this to the adapter class at some point and cache the raw item list in this class at some point
function Storage:listItemsRaw(throttle)
	local res = {}

	throttle = throttle or Util.throttle()

	for _, v in pairs(self.nodes) do
		if v.category == "storage" then
			local chest = device[v.name]
			local items = chest.list()

			for slot, item in pairs(items) do
				items[slot] = itemDB:get(item, function() return chest.getItemMeta(slot) end)
			end

			res[v.name] = items
			throttle()
		end
	end

	return res
end

-- provide a list of items and which chests provide them
function Storage:listProviders(throttle)
	local res = {}

	local rawItems = self:listItemsRaw(throttle)

	for chest, items in pairs(rawItems) do
		for slot, item in pairs(items) do
			local key = table.concat({item.name, item.damage, item.nbtHash}, ":")
			if not res[key] then
				res[key] = {}
			end
			table.insert(res[key], {item = item, device = device[chest], lockedToThis = (self.nodes[chest].lock or {})[key] or false, slot = slot})
		end
	end
	return res
end

-- defrags the storage system
function Storage:defrag(throttle)
	local items = self:listProviders(throttle)
	local slotsSaved = 0

	-- This will make sure the table is sorted in the following order:
	-- Unlocked stacks with less than maxCount items | Locked stacks with less than maxCount items | stacks with more than maxCount items
	-- This way the locked stacks will be filled first
	local function sortFunction(a, b)
		local preferenceA, preferenceB
		preferenceA = (a.item.count == a.item.maxCount and 3)
									or (a.lockedToThis and 2)
									or 1
		preferenceB = (b.item.count == b.item.maxCount and 3)
									or (b.lockedToThis and 2)
									or 1

		if preferenceA < preferenceB then
			return true
		elseif preferenceB > preferenceA then
			return false
		else
			return a.item.count < b.item.count
		end
	end

	for _, providers in pairs(items) do
		table.sort(providers, sortFunction)

		-- We're done when we either compressed the stacks so far, that there's only one left (#providers == 1)
		-- Or when we've compressed so far, that the there's only one stack which has a lower count than the maxCount
		-- Because of the sorting, we know that this will be the stack in providers[1], so we check if providers[2] is at the maxCount
		while #providers > 1 and providers[2].item.count ~= providers[2].item.maxCount do
			local from = providers[1]
			local to

			-- We're pushing to the highest stack which is still below the maxCount, this way as many slots as possible will be filled
			-- This loop is guarenteed to assign a value to "to", as the only cases where it wouldn't (#providers == 1 or no provider with less than maxCount)
			-- are ruled out by the condition of the outer while loop
			for i = 2, #providers do
				-- Give preference to locked chests
				if not (to and to.lockedToThis or false) and providers[i].lockedToThis then
					to = providers[i]
				elseif ((to and to.lockedToThis or false) == providers[i].lockedToThis) and providers[i].item.count < providers[i].item.maxCount then
					to = providers[i]
				elseif providers[i].item.count == providers[i].item.maxCount then
					-- As this slot is already at maxCount, all the remaining ones will also be due to sorting
					-- If any of the remaining providers is locked that doesn't matter. We wouldn't have been able to push there anyways
					break
				end
			end

			local toMove = math.min(to.item.maxCount - to.item.count, from.item.count)
			local s, m = pcall(function()
				from.device.pushItems(to.device.name, from.slot, toMove, to.slot)
			end)

			if not s and m then
				_G._syslog(m)
			end

			if s then
				to.item.count = to.item.count + toMove
				from.item.count = from.item.count - toMove
			else
				-- Do not try to send to the target again after it failed
				for i = 2, #providers do
					if to == providers[i] then
						table.remove(providers, i)
						break
					end
				end
			end

			if from.item.count <= 0 then
				table.remove(providers, 1)
				slotsSaved = slotsSaved + 1
			end

			table.sort(providers, sortFunction)
		end
	end

	return slotsSaved
end

function Storage:updateCache(adapter, item, count)
	if not adapter.cache then
		adapter.dirty = true
		self.dirty = true
		return
	end

	local key = item.key or table.concat({ item.name, item.damage, item.nbtHash }, ':')
	local entry = adapter.cache[key]

	if not entry then
		if count < 0 then
			_G._syslog('STORAGE: update cache - count < 0', 4)
		else
			entry = Util.shallowCopy(item)
			entry.count = count
			entry.key = key
			adapter.cache[key] = entry
		end
	else
		entry.count = entry.count + count
		if entry.count <= 0 then
			adapter.cache[key] = nil
		end
	end

	if not entry then
		_G._syslog('STORAGE: item missing details')
		adapter.dirty = true
		self.dirty = true
	else
		local sentry = self.cache[key]
		if sentry then
			sentry.count = sentry.count + count
			if sentry.count <= 0 then
				self.cache[key] = nil
			end
		elseif count > 0 then
			sentry = Util.shallowCopy(entry)
			sentry.count = count
			self.cache[key] = sentry
		else
			self.dirty = true
		end
	end
end

function Storage:_sn(name)
	local node = self.nodes[name]
	return node and node.displayName or name
end

local function isValidTransfer(adapter, target)
	-- lazily cache transfer locations
	if not adapter.transferLocations then
		adapter.transferLocations = adapter.getTransferLocations()
	end
	for _,v in pairs(adapter.transferLocations) do
		if v == target then
			return true
		end
	end
end

local function rawExport(source, target, item, qty, slot)
	local total = 0
	local transfer

	if isValidTransfer(source, target.name) then
		transfer = function(key, amount)
			return source.pushItems(target.name, key, amount, slot)
		end
	else --if isValidTransfer(target, source.name) then
		transfer = function(key, amount)
			return target.pullItems(source.name, key, amount, slot)
		end
	end
	--[[
		-- TODO: mass storage will require a transfer chest (or something)
	elseif isValidTransfer(source, 'minecraft:chest_0') then
		transfer = function(key, amount)
			local a = source.pushItems('minecraft:chest_0', key, amount, 1)
			return target.pullItems('minecraft:chest_0', 1, amount, slot)
		end
	else
		...
	end
	]]

	local s, m = pcall(function()
		local stacks = source.list()
		for key,stack in Util.rpairs(stacks) do
			if stack.name == item.name and
				 stack.damage == item.damage and
				 stack.nbtHash == item.nbtHash then
				local amount = math.min(qty, stack.count)
				if amount > 0 then
					amount = transfer(key, amount, slot)
					if amount > 0 then
						source.lastUpdate = os.clock()
						target.lastUpdate = os.clock()
					else
						-- break -- this should work ?? is cache out of sync ?
					end
				end
				qty = qty - amount
				total = total + amount
				if qty <= 0 then
					break
				end
			end
		end
	end)

	if not s and m then
		_G._syslog(m)
	end

	return total, m
end

function Storage:export(target, slot, count, item)
	local timer = Util.timer()
	local total = 0
	local key = item.key or table.concat({ item.name, item.damage, item.nbtHash }, ':')

	local function provide(adapter, pcount)
		-- update cache before export to allow for simultaneous calls
		self:updateCache(adapter, item, -pcount)

		local amount = rawExport(adapter, target.adapter, item, pcount, slot)

		if amount ~= pcount then
			-- this *should* only happen if cache is out of sync
			-- or... the target is full
			self:updateCache(adapter, item, pcount - amount)
		end

		if amount > 0 then
			_G._syslog('EXT: %s(%d): %s -> %s%s in %s',
				item.displayName or item.name, amount, self:_sn(adapter.name), self:_sn(target.name),
				slot and string.format('[%d]', slot) or '[*]', Util.round(timer(), 2))
		end
		count = count - amount
		total = total + amount

		return amount
	end

	-- request from adapters with this item
	for _, adapter in self:onlineAdapters() do
		local cache = adapter.cache and adapter.cache[key]
		if cache then
			local request = math.min(count, cache.count)

			local amount = provide(adapter, request)

			-- couldn't provide the amount that was requested
			-- either the target must be full - or the cache is invalid
			if amount ~= request then
				break
			end
			if count <= 0 then
				return total
			end
		end
	end

	if slot then -- ignore warning when exporting to all slots
		_G._syslog('STORAGE warning: %s(%d): %s%s %s failed to export',
			item.displayName or item.name, count, self:_sn(target.name),
			slot and string.format('[%d]', slot) or '[*]', key)
	end

-- TODO: If there are misses when a slot is specified than something is wrong...
-- The caller should confirm the quantity beforehand
-- If no slot and full amount is not exported, then no need to check rest of adapters
-- ... so should not reach here

-- but... there is the case where exporting to all slots of the target
-- this is valid

	return total
end

local function rawInsert(source, target, slot, qty)
	local count = 0

	local s, m = pcall(function()
		if isValidTransfer(source, target.name) then
--_syslog('pull %s %s %d %d', source.name, target.name, slot, qty)
			count = source.pullItems(target.name, slot, qty)
		else
--_syslog('push %s %s', target.name, source.name)
			count = target.pushItems(source.name, slot, qty)
		end
	end)
	if not s and m then
		_G._syslog(m)
	end

	if count > 0 then
		source.lastUpdate = os.clock()
		target.lastUpdate = os.clock()
	end

	return count
end

function Storage:import(source, slot, count, item)
	if not source then error('Storage:import: source is required') end
	if not slot   then error('Storage:import: slot is required')   end

	local timer = Util.timer()
	local total = 0
	local key = item.key or table.concat({ item.name, item.damage, item.nbtHash }, ':')

	if not self.cache then
		self:listItems()
	end

	local entry = itemDB:get(key)
	if not entry then
		if item.displayName then
			 -- this item already has metadata
			entry = itemDB:add(item)
		else
			 -- get the metadata from the device and add to db
			entry = itemDB:add(source.adapter.getItemMeta(slot))
		end
		itemDB:flush()
	end
	item = entry

	local function insert(adapter)
		local amount = rawInsert(adapter, source.adapter, slot, count)

		if amount > 0 then
			self:updateCache(adapter, item, amount)

			_G._syslog('INS: %s(%d): %s[%d] -> %s in %s',
				item.displayName or item.name, amount,
				self:_sn(source.name), slot, self:_sn(adapter.name), Util.round(timer(), 2))

			-- record that we have imported this item into storage during this cycle
			self.activity[key] = (self.activity[key] or 0) + amount
		end
		count = count - amount
		total = total + amount
	end

	-- find a chest locked with this item
	local doVoid

	for node in self:onlineAdapters() do
		if node.lock and node.lock[key] then
			insert(node.adapter, item)
			if count > 0 and node.void then
				doVoid = true
			end
		end
		if count <= 0 then
			return total
		end
	end

	if doVoid then
		return total + self:trash(source, slot, count, item)
	end

	-- is this item in some chest
	if self.cache[key] then
		for node, adapter in self:onlineAdapters() do
			if count <= 0 then
				return total
			end
			if not node.lock and adapter.cache and adapter.cache[key] then
				insert(adapter)
			end
		end
	end

	-- high to low priority
	for node in self:onlineAdapters() do
		if count <= 0 then
			break
		end
		if not node.lock then
			insert(node.adapter)
		end
	end

	if count ~= 0 then
		_G._syslog('STORAGE warning: %s(%d): %s -> INSERT failed',
			item.displayName or item.name, count,
			self:_sn(source.name))
	end

	return total
end

-- When importing items into a locked chest, trash any remaining items if full
-- TODO: use all available trashcans
function Storage:trash(source, slot, count, item)
	local timer = Util.timer()
	local target = Util.find(self.nodes, 'mtype', 'trashcan')
	local amount = 0
	if target and target.adapter and target.adapter.online then
		local s, m = pcall(function()
			if isValidTransfer(source.adapter, target.name) then
				amount = source.adapter.pushItems(target.name, slot, count)
			else
				amount = target.adapter.pullItems(source.name, slot, count)
			end

			_G._syslog('TRA: %s(%d): %s%s -> %s in %s',
				item.displayName or item.name, amount, self:_sn(source.name),
				slot and string.format('[%d]', slot) or '[*]', self:_sn(target.name), Util.round(timer(), 2))
		end)
		if not s and m then
			_G._syslog(m)
		end
	end

	if amount ~= count then
		_G._syslog('STORAGE warning: %s(%d): %s -> TRASH failed',
			item.displayName or item.name, count - amount,
			self:_sn(source.name))
	end

	return amount
end

return Storage