-- Luanti
-- Copyright (C) 2013 sapier
-- SPDX-License-Identifier: LGPL-2.1-or-later

--------------------------------------------------------------------------------
-- TODO improve doc                                                           --
-- TODO code cleanup                                                          --
-- Generic implementation of a filter/sortable list                           --
-- Usage:                                                                     --
-- Filterlist needs to be initialized on creation. To achieve this you need   --
-- to pass following functions:                                               --
-- raw_fct() (mandatory):                                                     --
--     function returning a table containing the elements to be filtered      --
-- compare_fct(element1,element2) (mandatory):                                --
--     function returning true/false if element1 is same element as element2  --
-- uid_match_fct(element1,uid) (optional)                                     --
--     function telling if uid is attached to element1                        --
-- filter_fct(element,filtercriteria) (optional)                              --
--     function returning true/false if filtercriteria met to element         --
-- fetch_param (optional)                                                     --
--     parameter passed to raw_fct to acquire correct raw data                --
--                                                                            --
--------------------------------------------------------------------------------
filterlist = {}

--------------------------------------------------------------------------------
function filterlist.refresh(self)
	self.m_raw_list = self.m_raw_list_fct(self.m_fetch_param)
	filterlist.process(self)
end

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function filterlist.create(raw_fct,compare_fct,uid_match_fct,filter_fct,fetch_param)

	assert((raw_fct ~= nil) and (type(raw_fct) == "function"))
	assert((compare_fct ~= nil) and (type(compare_fct) == "function"))

	local self = {}

	self.m_raw_list_fct  = raw_fct
	self.m_compare_fct   = compare_fct
	self.m_filter_fct    = filter_fct
	self.m_uid_match_fct = uid_match_fct

	self.m_filtercriteria = nil
	self.m_fetch_param = fetch_param

	self.m_sortmode = "none"
	self.m_sort_list = {}

	self.m_processed_list = nil
	self.m_raw_list = self.m_raw_list_fct(self.m_fetch_param)

	self.add_sort_mechanism = filterlist.add_sort_mechanism
	self.set_filtercriteria = filterlist.set_filtercriteria
	self.get_filtercriteria = filterlist.get_filtercriteria
	self.set_sortmode       = filterlist.set_sortmode
	self.get_list           = filterlist.get_list
	self.get_raw_list       = filterlist.get_raw_list
	self.get_raw_element    = filterlist.get_raw_element
	self.get_raw_index      = filterlist.get_raw_index
	self.get_current_index  = filterlist.get_current_index
	self.size               = filterlist.size
	self.uid_exists_raw     = filterlist.uid_exists_raw
	self.raw_index_by_uid   = filterlist.raw_index_by_uid
	self.refresh            = filterlist.refresh

	filterlist.process(self)

	return self
end

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function filterlist.add_sort_mechanism(self,name,fct)
	self.m_sort_list[name] = fct
end

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function filterlist.set_filtercriteria(self,criteria)
	if criteria == self.m_filtercriteria and
		type(criteria) ~= "table" then
		return
	end
	self.m_filtercriteria = criteria
	filterlist.process(self)
end

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function filterlist.get_filtercriteria(self)
	return self.m_filtercriteria
end

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--supported sort mode "alphabetic|none"
function filterlist.set_sortmode(self,mode)
	if (mode == self.m_sortmode) then
		return
	end
	self.m_sortmode = mode
	filterlist.process(self)
end

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function filterlist.get_list(self)
	return self.m_processed_list
end

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function filterlist.get_raw_list(self)
	return self.m_raw_list
end

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function filterlist.get_raw_element(self,idx)
	if type(idx) ~= "number" then
		idx = tonumber(idx)
	end

	if idx ~= nil and idx > 0 and idx <= #self.m_raw_list then
		return self.m_raw_list[idx]
	end

	return nil
end

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function filterlist.get_raw_index(self,listindex)
	assert(self.m_processed_list ~= nil)

	if listindex ~= nil and listindex > 0 and
		listindex <= #self.m_processed_list then
		local entry = self.m_processed_list[listindex]

		for i,v in ipairs(self.m_raw_list) do

			if self.m_compare_fct(v,entry) then
				return i
			end
		end
	end

	return 0
end

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function filterlist.get_current_index(self,listindex)
	assert(self.m_processed_list ~= nil)

	if listindex ~= nil and listindex > 0 and
		listindex <= #self.m_raw_list then
		local entry = self.m_raw_list[listindex]

		for i,v in ipairs(self.m_processed_list) do

			if self.m_compare_fct(v,entry) then
				return i
			end
		end
	end

	return 0
end

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function filterlist.process(self)
	assert(self.m_raw_list ~= nil)

	if self.m_sortmode == "none" and
		self.m_filtercriteria == nil then
		self.m_processed_list = self.m_raw_list
		return
	end

	self.m_processed_list = {}

	for k,v in pairs(self.m_raw_list) do
		if self.m_filtercriteria == nil or
			self.m_filter_fct(v,self.m_filtercriteria) then
			self.m_processed_list[#self.m_processed_list + 1] = v
		end
	end

	if self.m_sortmode == "none" then
		return
	end

	if self.m_sort_list[self.m_sortmode] ~= nil and
		type(self.m_sort_list[self.m_sortmode]) == "function" then

		self.m_sort_list[self.m_sortmode](self)
	end
end

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function filterlist.size(self)
	if self.m_processed_list == nil then
		return 0
	end

	return #self.m_processed_list
end

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function filterlist.uid_exists_raw(self,uid)
	for i,v in ipairs(self.m_raw_list) do
		if self.m_uid_match_fct(v,uid) then
			return true
		end
	end
	return false
end

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function filterlist.raw_index_by_uid(self, uid)
	local elementcount = 0
	local elementidx = 0
	for i,v in ipairs(self.m_raw_list) do
		if self.m_uid_match_fct(v,uid) then
			elementcount = elementcount +1
			elementidx = i
		end
	end


	-- If there are more elements than one with same name uid can't decide which
	-- one is meant. self shouldn't be possible but just for sure.
	if elementcount > 1 then
		elementidx=0
	end

	return elementidx
end

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-- COMMON helper functions                                                    --
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
function compare_worlds(world1,world2)
	if world1.path ~= world2.path then
		return false
	end

	if world1.name ~= world2.name then
		return false
	end

	if world1.gameid ~= world2.gameid then
		return false
	end

	return true
end

--------------------------------------------------------------------------------
function sort_worlds_alphabetic(self)

	table.sort(self.m_processed_list, function(a, b)
		--fixes issue #857 (crash due to sorting nil in worldlist)
		if a == nil or b == nil then
			if a == nil and b ~= nil then return false end
			if b == nil and a ~= nil then return true end
			return false
		end
		if a.name:lower() == b.name:lower() then
			return a.name < b.name
		end
		return a.name:lower() < b.name:lower()
	end)
end
