--[[

	TableUtil.Copy(tbl: table): table
	TableUtil.CopyShallow(tbl: table): table
	TableUtil.Sync(tbl: table, template: table): void
	TableUtil.FastRemove(tbl: table, index: number): void
	TableUtil.FastRemoveFirstValue(tbl: table, value: any): (boolean, number)
	TableUtil.Map(tbl: table, callback: (value: any) -> any): table
	TableUtil.Filter(tbl: table, callback: (value: any) -> boolean): table
	TableUtil.Reduce(tbl: table, callback: (accum: number, value: number) -> number [, initialValue: number]): number
	TableUtil.Assign(target: table, ...sources: table): table
	TableUtil.Extend(tbl: table, extension: table): table
	TableUtil.Reverse(tbl: table): table
	TableUtil.Shuffle(tbl: table [, rng: Random]): table
	TableUtil.Flat(tbl: table [, maxDepth: number = 1]): table
	TableUtil.FlatMap(tbl: callback: (value: any) -> table): table
	TableUtil.Keys(tbl: table): table
	TableUtil.Find(tbl: table, callback: (value: any) -> boolean): (any, number)
	TableUtil.Every(tbl: table, callback: (value: any) -> boolean): boolean
	TableUtil.Some(tbl: table, callback: (value: any) -> boolean): boolean
	TableUtil.IsEmpty(tbl: table): boolean
	TableUtil.EncodeJSON(tbl: table): string
	TableUtil.DecodeJSON(json: string): table

--]]


type Table = {any}
type MapPredicate = (any, any, Table) -> any
type FilterPredicate = (any, any, Table) -> boolean
type ReducePredicate = (number, any, any, Table) -> number
type FindCallback = (any, any, Table) -> boolean

local TableUtil = {}

local HttpService = game:GetService("HttpService")
local rng = Random.new()


local function CopyTable(t: Table): Table
	assert(type(t) == "table", "First argument must be a table")
	local function Copy(tbl)
		local tCopy = table.create(#tbl)
		for k,v in pairs(tbl) do
			if type(v) == "table" then
				tCopy[k] = Copy(v)
			else
				tCopy[k] = v
			end
		end
		return tCopy
	end
	return Copy(t)
end


local function CopyTableShallow(t: Table): Table
	local tCopy = table.create(#t)
	if #t > 0 then
		table.move(t, 1, #t, 1, tCopy)
	else
		for k,v in pairs(t) do tCopy[k] = v end
	end
	return tCopy
end


local function Sync(srcTbl: Table, templateTbl: Table): Table

	assert(type(srcTbl) == "table", "First argument must be a table")
	assert(type(templateTbl) == "table", "Second argument must be a table")

	local tbl = CopyTableShallow(srcTbl)

	-- If 'tbl' has something 'templateTbl' doesn't, then remove it from 'tbl'
	-- If 'tbl' has something of a different type than 'templateTbl', copy from 'templateTbl'
	-- If 'templateTbl' has something 'tbl' doesn't, then add it to 'tbl'
	for k,v in pairs(tbl) do

		local vTemplate = templateTbl[k]

		-- Remove keys not within template:
		if vTemplate == nil then
			tbl[k] = nil

		-- Synchronize data types:
		elseif type(v) ~= type(vTemplate) then
			if type(vTemplate) == "table" then
				tbl[k] = CopyTable(vTemplate)
			else
				tbl[k] = vTemplate
			end

		-- Synchronize sub-tables:
		elseif type(v) == "table" then
			tbl[k] = Sync(v, vTemplate)
		end

	end

	-- Add any missing keys:
	for k,vTemplate in pairs(templateTbl) do

		local v = tbl[k]

		if v == nil then
			if type(vTemplate) == "table" then
				tbl[k] = CopyTable(vTemplate)
			else
				tbl[k] = vTemplate
			end
		end

	end

	return tbl

end


local function FastRemove(t: Table, i: number)
	local n = #t
	t[i] = t[n]
	t[n] = nil
end


local function FastRemoveFirstValue(t: Table, v: any): (boolean, number?)
	local index: number? = table.find(t, v)
	if index then
		FastRemove(t, index)
		return true, index
	end
	return false, nil
end

local function Map(t: Table, f: MapPredicate): Table
	assert(type(t) == "table", "First argument must be a table")
	assert(type(f) == "function", "Second argument must be a function")
	local newT = table.create(#t)
	for k,v in pairs(t) do
		newT[k] = f(v, k, t)
	end
	return newT
end


local function Filter(t: Table, f: FilterPredicate): Table
	assert(type(t) == "table", "First argument must be a table")
	assert(type(f) == "function", "Second argument must be a function")
	local newT = table.create(#t)
	if #t > 0 then
		local n = 0
		for i,v in ipairs(t) do
			if f(v, i, t) then
				n += 1
				newT[n] = v
			end
		end
	else
		for k,v in pairs(t) do
			if f(v, k, t) then
				newT[k] = v
			end
		end
	end
	return newT
end


local function Reduce(t: Table, f: ReducePredicate, init: number?): number
	assert(type(t) == "table", "First argument must be a table")
	assert(type(f) == "function", "Second argument must be a function")
	assert(init == nil or type(init) == "number", "Third argument must be a number or nil")
	local result = init or 0
	for k,v in pairs(t) do
		result = f(result, v, k, t)
	end
	return result
end


local function Assign(target: Table, ...: Table): Table
	local tbl = CopyTableShallow(target)
	for _,src in ipairs({...}) do
		for k,v in pairs(src) do
			tbl[k] = v
		end
	end
	return tbl
end


local function Extend(target: Table, extension: Table): Table
	local tbl = CopyTableShallow(target)
	for _,v in ipairs(extension) do
		table.insert(tbl, v)
	end
	return tbl
end


local function Reverse(tbl: Table): Table
	local n = #tbl
	local tblRev = table.create(n)
	for i = 1,n do
		tblRev[i] = tbl[n - i + 1]
	end
	return tblRev
end


local function Shuffle(tbl: Table, rngOverride: Random?): Table
	assert(type(tbl) == "table", "First argument must be a table")
	local shuffled = CopyTableShallow(tbl)
	local random = rngOverride or rng
	for i = #tbl, 2, -1 do
		local j = random:NextInteger(1, i)
		shuffled[i], shuffled[j] = shuffled[j], shuffled[i]
	end
	return shuffled
end


local function Flat(tbl: Table, depth: number?): Table
	local maxDepth: number = depth or 1
	local flatTbl = table.create(#tbl)
	local function Scan(t: Table, d: number)
		for _,v in ipairs(t) do
			if type(v) == "table" and d < maxDepth then
				Scan(v, d + 1)
			else
				table.insert(flatTbl, v)
			end
		end
	end
	Scan(tbl, 0)
	return flatTbl
end


local function FlatMap(tbl: Table, callback: MapPredicate): Table
	return Flat(Map(tbl, callback))
end


local function Keys(tbl: Table): Table
	local keys = table.create(#tbl)
	for k in pairs(tbl) do
		table.insert(keys, k)
	end
	return keys
end


local function Find(tbl: Table, callback: FindCallback): (any?, any?)
	for k,v in pairs(tbl) do
		if callback(v, k, tbl) then
			return v, k
		end
	end
	return nil, nil
end


local function Every(tbl: Table, callback: FindCallback): boolean
	for k,v in pairs(tbl) do
		if not callback(v, k, tbl) then
			return false
		end
	end
	return true
end


local function Some(tbl: Table, callback: FindCallback): boolean
	for k,v in pairs(tbl) do
		if callback(v, k, tbl) then
			return true
		end
	end
	return false
end


local function IsEmpty(tbl)
	return next(tbl) == nil
end


local function EncodeJSON(tbl: any): string
	return HttpService:JSONEncode(tbl)
end


local function DecodeJSON(str: string): any
	return HttpService:JSONDecode(str)
end


TableUtil.Copy = CopyTable
TableUtil.CopyShallow = CopyTableShallow
TableUtil.Sync = Sync
TableUtil.FastRemove = FastRemove
TableUtil.FastRemoveFirstValue = FastRemoveFirstValue
TableUtil.Map = Map
TableUtil.Filter = Filter
TableUtil.Reduce = Reduce
TableUtil.Assign = Assign
TableUtil.Extend = Extend
TableUtil.Reverse = Reverse
TableUtil.Shuffle = Shuffle
TableUtil.Flat = Flat
TableUtil.FlatMap = FlatMap
TableUtil.Keys = Keys
TableUtil.Find = Find
TableUtil.Every = Every
TableUtil.Some = Some
TableUtil.IsEmpty = IsEmpty
TableUtil.EncodeJSON = EncodeJSON
TableUtil.DecodeJSON = DecodeJSON


return TableUtil