-- route player input to the right functions;
-- return true when the right function has been found
-- called in minetest.register_on_player_receive_fields
yl_speak_up.input_handler = function(player, formname, fields)
	if     formname == "yl_speak_up:optiondialog" then
		yl_speak_up.input_optiondialog(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:setdialog" then
		yl_speak_up.input_setdialog(player, formname, fields)
		return true
	-- handled in fs_save_or_discard_or_back.lua
	elseif formname == "yl_speak_up:save_or_discard_changes" then
		yl_speak_up.input_save_or_discard_changes(player, formname, fields)
		return true
	-- handled in fs_edit_options_dialog.lua
	elseif formname == "yl_speak_up:edit_option_dialog" then
		yl_speak_up.input_edit_option_dialog(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:talk" then
		yl_speak_up.input_talk(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:fashion" then
		yl_speak_up.input_fashion(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:fashion_extended" then
		yl_speak_up.input_fashion_extended(player, formname, fields)
		return true
	-- handled in fs_properties.lua
	elseif formname == "yl_speak_up:properties" then
		yl_speak_up.input_properties(player, formname, fields)
		return true
	-- handled in inventory.lua
	elseif formname == "yl_speak_up:inventory" then
		yl_speak_up.input_inventory(player, formname, fields)
		return true
	-- handled in fs_trade_list.lua
	elseif formname == "yl_speak_up:trade_list" then
		yl_speak_up.input_trade_list(player, formname, fields)
		return true
	-- handled in fs_player_offers_item.lua
	elseif formname == "yl_speak_up:player_offers_item" then
		yl_speak_up.input_player_offers_item(player, formname, fields)
		return true
	-- handled in fs/fs_do_trade_simple.lua
	elseif formname == "yl_speak_up:do_trade_simple" then
		yl_speak_up.input_do_trade_simple(player, formname, fields)
		return true
	-- handled in fs_trade_via_buy_button.lua
	elseif formname == "yl_speak_up:trade_via_buy_button" then
		yl_speak_up.input_trade_via_buy_button(player, formname, fields)
		return true
	-- (as above - also handled in trade_simple.lua)
	elseif formname == "yl_speak_up:add_trade_simple" then
		yl_speak_up.input_add_trade_simple(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:trade_limit" then
		yl_speak_up.input_trade_limit(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:show_log" then
		yl_speak_up.input_show_log(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:show_npc_list" then
		yl_speak_up.input_show_npc_list(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:edit_trade_limit" then
		yl_speak_up.input_edit_trade_limit(player, formname, fields)
		return true
	-- handled in fs_initial_config.lua
	elseif formname == "yl_speak_up:initial_config" then
		yl_speak_up.input_fs_initial_config(player, formname, fields)
		return true
	-- handled in fs_assign_quest_step.lua
	elseif formname == "yl_speak_up:assign_quest_step" then
		yl_speak_up.input_fs_assign_quest_step(player, formname, fields)
		return true
	-- handled in fs_edit_preconditions.lua
	elseif formname == "yl_speak_up:edit_preconditions" then
		yl_speak_up.input_fs_edit_preconditions(player, formname, fields)
		return true
	-- handled in fs_edit_actions.lua
	elseif formname == "yl_speak_up:edit_actions" then
		yl_speak_up.input_fs_edit_actions(player, formname, fields)
		return true
	-- handled in fs_edit_actions.lua
	elseif formname == "yl_speak_up:action_npc_gives" then
		yl_speak_up.input_fs_action_npc_gives(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:action_npc_wants" then
		yl_speak_up.input_fs_action_npc_wants(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:action_text_input" then
		yl_speak_up.input_fs_action_text_input(player, formname, fields)
		return true
	elseif formname == "yl_speak_up:action_evaluate" then
		yl_speak_up.input_fs_action_evaluate(player, formname, fields)
		return true
	-- handled in fs_edit_effects.lua
	elseif formname == "yl_speak_up:edit_effects" then
		yl_speak_up.input_fs_edit_effects(player, formname, fields)
		return true
	-- handled in fs_manage_variables.lua
	elseif formname == "yl_speak_up:manage_variables" then
		yl_speak_up.input_fs_manage_variables(player, formname, fields)
		return true
	-- handled in fs_manage_quests.lua
	elseif formname == "yl_speak_up:manage_quests" then
		yl_speak_up.input_fs_manage_quests(player, formname, fields)
		return true
	-- handled in fs_manage_quest_steps.lua
	elseif formname == "yl_speak_up:manage_quest_steps" then
		yl_speak_up.input_fs_manage_quest_steps(player, formname, fields)
		return true
	-- handled in fs_add_quest_steps.lua
	elseif formname == "yl_speak_up:add_quest_steps" then
		yl_speak_up.input_fs_add_quest_steps(player, formname, fields)
		return true
	-- handled in fs_alternate_text.lua
	elseif formname == "yl_speak_up:show_what_points_to_this_dialog" then
		yl_speak_up.input_fs_show_what_points_to_this_dialog(player, formname, fields)
		return true
	-- create and manage quests
	elseif formname == "yl_speak_up:quest_gui" then
		yl_speak_up.input_quest_gui(player, formname, fields)
		return true
	-- export to .json format for cut&paste
	elseif formname == "yl_speak_up:export" then
		yl_speak_up.input_fs_export(player, formname, fields)
		return true
	-- take notes on what the NPC is for
	elseif formname == "yl_speak_up:notes" then
		yl_speak_up.input_fs_notes(player, formname, fields)
		return true
	end
end


-- show formspec with highest possible version information for the player
-- force_version: optional parameter
yl_speak_up.show_fs_ver = function(pname, formname, formspec, force_version)
	-- if the formspec already calls for a specific formspec version: use that one
	if(string.sub(formspec, 1, 17) == "formspec_version[") then
		minetest.show_formspec(pname, formname, formspec)
		return
	end
	local fs_ver = (yl_speak_up.fs_version[pname] or "2")
	if(force_version) then
		fs_ver = force_version
	end
	minetest.show_formspec(pname, formname,
		"formspec_version["..tostring(fs_ver).."]"..
		formspec)
end


-- call show_formspec with the right input_* function for the right formspec
-- (handles all show_formspec-calls)
yl_speak_up.show_fs = function(player, fs_name, param)
	if(not(player)) then
		return
	end
	local pname = player:get_player_name()
	if(not(yl_speak_up.speak_to[pname])) then
		return
	end

	local last_fs = yl_speak_up.speak_to[pname].last_fs
	-- show the save or discard changes dialog
	if(fs_name and fs_name == "save_or_discard_changes") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:save_or_discard_changes",
			yl_speak_up.get_fs_save_or_discard_changes(player, param))
		return

	-- the player either saved or discarded; we may proceed now
	elseif(fs_name and fs_name == "proceed_after_save") then
		fs_name = yl_speak_up.speak_to[pname].next_fs
		param = yl_speak_up.speak_to[pname].next_fs_param
		yl_speak_up.speak_to[pname].next_fs = nil
		yl_speak_up.speak_to[pname].next_fs_param = nil
		yl_speak_up.speak_to[pname].last_fs = fs_name
		yl_speak_up.speak_to[pname].last_fs_param = param
		if(not(fs_name) or fs_name == "quit") then
			yl_speak_up.reset_vars_for_player(pname, false)
			return
		end

	-- the player clicked on "back" in the above dialog
	elseif(fs_name and fs_name == "show_last_fs") then
		-- call the last formspec again - and with the same parameters
		fs_name = yl_speak_up.speak_to[pname].last_fs
		param = yl_speak_up.speak_to[pname].last_fs_param

	-- do we need to check if there is something that needs saving?
	elseif(fs_name
	  -- msg is just a loop for displaying (mostly error) messages
	  and fs_name ~= "msg"
	  and fs_name ~= "player_offers_item"
	  -- is the player editing the NPC? that is: might there be any changes?
	  and (yl_speak_up.edit_mode[pname] == yl_speak_up.speak_to[pname].n_id)) then
		local last_fs = yl_speak_up.speak_to[pname].last_fs
		local d_id = yl_speak_up.speak_to[pname].d_id
		local o_id = yl_speak_up.speak_to[pname].o_id
		-- only these two formspecs need to ask specificly if the data ought to be saved
		if(last_fs == "talk" or last_fs == "edit_option_dialog" or fs_name == "quit") then
			local last_param = yl_speak_up.speak_to[pname].last_fs_param
			local show_save_fs = false
			if(not(param)) then
				param = {}
			end
			-- set the target dialog
			yl_speak_up.speak_to[pname].target_dialog = param.d_id
			-- if we are switching from one dialog to another: is it the same?
			if(last_fs == "talk" and fs_name == last_fs
			  and param and param.d_id and param.d_id ~= d_id) then
				-- diffrent parameters: save (if needed)
				show_save_fs = true
			elseif(fs_name == "talk" and param and param.do_save) then
				-- player clicked on save button
				show_save_fs = true
			-- leaving a dialog: save!
			elseif(last_fs == "talk" and fs_name ~= last_fs) then
				show_save_fs = true
			-- clicking on "save" in an edit option dialog: save!
			elseif(last_fs == "edit_option_dialog" and fs_name == last_fs
			  and param and param.caller and param.caller == "save_option") then
				show_save_fs = true
			-- leaving editing an option: save!
			elseif(last_fs == "edit_option_dialog" and fs_name ~= last_fs) then
				show_save_fs = true
			-- quitting: save!
			elseif(fs_name == "quit") then
				yl_speak_up.speak_to[pname].target_dialog = nil
				show_save_fs = true
			end
			-- show the save or discard dialog
			if(show_save_fs) then
				yl_speak_up.speak_to[pname].next_fs = fs_name
				yl_speak_up.speak_to[pname].next_fs_param = param
				-- check first if it's necessary to ask for save or discard
				yl_speak_up.input_save_or_discard_changes(player, "", {})
				return
			end
		end
		-- store the new formspec
		yl_speak_up.speak_to[pname].last_fs = fs_name
		-- and its parameter
		yl_speak_up.speak_to[pname].last_fs_param = param
	end

	-- this is here mostly to fascilitate debugging - so that really all calls to
	-- minetest.show_formspec are routed through here
	if(fs_name == "msg") then
		if(not(param)) then
			param = {}
		end
		yl_speak_up.show_fs_ver(pname, param.input_to, param.formspec, 1)


	elseif(fs_name == "quit") then
		return

	-- staff-based editing
	elseif(fs_name == "optiondialog") then
		if(not(param)) then
			param = {}
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:optiondialog",
			yl_speak_up.get_fs_optiondialog(player, param.n_id, param.d_id, param.o_id, param.p_id, param.r_id))

	elseif(fs_name == "setdialog") then
		if(not(param)) then
			param = {}
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:setdialog",
			yl_speak_up.get_fs_setdialog(player, param.n_id, param.d_id))

	elseif(fs_name == "edit_option_dialog") then
		-- the optional "caller" parameter can be used for debugging
		if(not(param)) then
			param = {}
		end
		yl_speak_up.speak_to[pname].o_id = param.o_id
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:edit_option_dialog",
			yl_speak_up.get_fs_edit_option_dialog(player, param.n_id, param.d_id, param.o_id,
				param.caller))

	elseif(fs_name == "talk") then
		if(not(param)) then
			param = {}
		end
		if(param.d_id and param.d_id == "d_end") then
			yl_speak_up.stop_talking(pname)
			return
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:talk",
			-- recursion depth from autoanswer: 0 (the player selected manually)
			yl_speak_up.get_fs_talkdialog(player, param.n_id, param.d_id, param.alternate_text,0))

	elseif(fs_name == "fashion") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:fashion",
			yl_speak_up.get_fs_fashion(pname))

	elseif(fs_name == "fashion_extended") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:fashion_extended",
			yl_speak_up.get_fs_fashion_extended(pname))

	elseif(fs_name == "properties") then
		if(not(param)) then
			param = {}
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:properties",
			yl_speak_up.get_fs_properties(pname, param.selected),
			1)

	elseif(fs_name == "inventory") then
		-- this is a very classical formspec; it works far better with OLD fs;
		-- force formspec version 1
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:inventory",
			yl_speak_up.get_fs_inventory(player),
			1)

	elseif(fs_name == "trade_list") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:trade_list",
			yl_speak_up.get_fs_trade_list(player, param))

	elseif(fs_name == "player_offers_item") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:player_offers_item",
			yl_speak_up.get_fs_player_offers_item(player, param), 1)

	elseif(fs_name == "trade_simple") then
		-- the optional parameter param is the trade_id
		if(not(param) and yl_speak_up.speak_to[pname]) then
			param = yl_speak_up.speak_to[pname].trade_id
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:do_trade_simple",
			yl_speak_up.get_fs_do_trade_simple(player, param), 1)

	elseif(fs_name == "trade_via_buy_button") then
		-- the optional parameter param is the trade_id
		if(not(param) and yl_speak_up.speak_to[pname]) then
			param = yl_speak_up.speak_to[pname].trade_id
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:trade_via_buy_button",
			yl_speak_up.get_fs_trade_via_buy_button(player, param), 1)

	elseif(fs_name == "add_trade_simple") then
		-- the optional parameter param is the trade_id
		if(not(param) and yl_speak_up.speak_to[pname]) then
			param = yl_speak_up.speak_to[pname].trade_id
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:add_trade_simple",
			yl_speak_up.get_fs_add_trade_simple(player, param), 1)

	elseif(fs_name == "trade_limit") then
		if(not(param)) then
			param = {}
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:trade_limit",
			yl_speak_up.get_fs_trade_limit(player, param.selected))

	elseif(fs_name == "show_log") then
		if(not(param)) then
			param = {}
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:show_log",
			yl_speak_up.get_fs_show_log(player, param.log_type))

	elseif(fs_name == "show_npc_list") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:show_npc_list",
			yl_speak_up.get_fs_show_npc_list(player, nil))


	elseif(fs_name == "edit_trade_limit") then
		if(not(param)) then
			param = {}
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:edit_trade_limit",
			yl_speak_up.get_fs_edit_trade_limit(player, param.selected_row), 1)

	elseif(fs_name == "initial_config") then
		if(not(param)) then
			param = {}
		end
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:initial_config",
			yl_speak_up.get_fs_initial_config(player, param.n_id, param.d_id,
				param.is_initial_config))

	elseif(fs_name == "assign_quest_step") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:assign_quest_step",
			yl_speak_up.get_fs_assign_quest_step(player, param))

	elseif(fs_name == "edit_preconditions") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:edit_preconditions",
			yl_speak_up.get_fs_edit_preconditions(player, param))

	elseif(fs_name == "edit_actions") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:edit_actions",
			yl_speak_up.get_fs_edit_actions(player, param))

	elseif(fs_name == "edit_effects") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:edit_effects",
			yl_speak_up.get_fs_edit_effects(player, param))

	-- action related
	elseif(fs_name == "action_npc_gives") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:action_npc_gives",
			yl_speak_up.get_fs_action_npc_gives(player, param), 1)

	elseif(fs_name == "action_npc_wants") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:action_npc_wants",
			yl_speak_up.get_fs_action_npc_wants(player, param), 1)

	elseif(fs_name == "action_text_input") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:action_text_input",
			yl_speak_up.get_fs_action_text_input(player, param))

	elseif(fs_name == "action_evaluate") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:action_evaluate",
			yl_speak_up.get_fs_action_evaluate(player, param))

	elseif(fs_name == "manage_variables") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:manage_variables",
			yl_speak_up.get_fs_manage_variables(player, param))

	elseif(fs_name == "manage_quests") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:manage_quests",
			yl_speak_up.get_fs_manage_quests(player, param))

	elseif(fs_name == "manage_quest_steps") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:manage_quest_steps",
			yl_speak_up.get_fs_manage_quest_steps(player, param))

	elseif(fs_name == "add_quest_steps") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:add_quest_steps",
			yl_speak_up.get_fs_add_quest_steps(player, param))

	elseif(fs_name == "show_what_points_to_this_dialog") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:show_what_points_to_this_dialog",
			yl_speak_up.show_what_points_to_this_dialog(player, param))

	elseif(fs_name == "quest_gui") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:quest_gui",
			yl_speak_up.get_fs_quest_gui(player, param))

	elseif(fs_name == "export") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:export",
			yl_speak_up.get_fs_export(player, param))

	elseif(fs_name == "notes") then
		yl_speak_up.show_fs_ver(pname, "yl_speak_up:notes",
			yl_speak_up.get_fs_notes(player, param))

	-- fallback in case of wrong call
	else
		minetest.chat_send_player(pname, "Error: Trying to show wrong "..
			"formspec: \""..tostring(fs_name).."\". Please notify "..
			"an admin.")
	end
end