Module:data tables

local export = {}

local base_location = "Module:data tables"
local metadata = mw.loadData(base_location .. "/metadata")
--"Module:data tables/data"
local shard_location_base = metadata
local shards = metadata
local tables = metadata
--[[
		{"grc_RLBG_lemma_to_index",
		"grc_RWoodhouse_lemma_to_headwords",
		"grc_RWoodhouse_lemma_to_infinitives",
		"la_RMA_index_to_phrases",
		"grc_RCunliffe_lemma_to_index",
		"la_RMA_lemmas_no_collision_to_ix_phrase" }
]]

--[[
local function load_tables_unsharded()
	local function maybe_mw_load(x)
		local success, val = pcall(mw.loadData, x)
		return success and val or nil end
	local unsharded, i = {}, 0
	while #unsharded == i do
		---shard_location_base
		local val = maybe_mw_load(shard_location_base.."Unsharded"..tostring(i))
		if val ~= nil then
			unsharded = val end
		i = i + 1
	end
	return unsharded
end

local unsharded = load_tables_unsharded()
--]]

local function map(f, xs)
	local ys = {}
	for i, x in pairs(xs) do ys = f(x) end
	return ys
end

local function map_string(f, s)
	local ys = {}
	for i = 1, #s do ys = f(s:sub(i, i)) end
	return ys
end

local function fold(f, l, xs)
	for _, x in pairs(xs) do l = f(l, x) end
	return l
end

local function hash(s)
	return fold(function(x, y) return x + y end,
		0,
		map_string(string.byte, s)) % shards
end

function export.list_tables()
	return map(function(x) return x end, tables)
end

function export.load_table(n)
	local t = {}
	for i = 1, shards do
		local curr = mw.loadData(shard_location_base .. (i - 1))
		if curr ~= nil then
			for k, v in pairs(curr) do
				t = v
			end
		end
	end
	--[[
	for i,curr in pairs(unsharded) do 
		if curr ~= nil then
			for k,v in pairs(curr) do
				t=v end end end
	--]]
	return t
end

--[[
eventually: 
	1 :	loop through all unsharded if multiple
	2 :	index k in unsharded and shard separately,
		returning from unsharded preferentially		]]
function export.index_table(t, k)
	local shard = mw.loadData(shard_location_base .. hash(k))
	--[[
	if unsharded ~= nil
		and unsharded ~= nil
		and unsharded ~= nil
			then
		
		return unsharded
	else
	--]]
	if shard ~= nil then
		return shard
	else
		return nil
	end
	-- end
end

function export.index_table_all(t, ks)
	local baskets, result = {}, {}
	for _, k in pairs(ks) do
		local h = hash(k)
		if baskets == nil then
			baskets = { k }
		else
			baskets) + 1] = k
		end
	end
	for h, b in pairs(baskets) do
		local shard = mw.loadData(shard_location_base .. h)
		for _, k in pairs(b) do
			-- here, loop over all unsharded if multiple
			if unsharded ~= nil
					and unsharded ~= nil
					and unsharded ~= nil then
				result = unsharded
			else
				if shard ~= nil then
					result = shard
				end
			end
		end
	end
	return result
end

function export.select(t, p)
	return nil --Not implemented.
end

return export