-- some helper lists for creating the formspecs and evaulating
-- the player's answers

-- general direction of what a prerequirement may be about
local check_what = {
	"- please select -",
	"an internal state (i.e. of a quest)", -- 2
	"a block somewhere", -- 3
	"a trade", -- 4
	"the inventory of the player", -- 5
	"the inventory of the NPC", -- 6
}

-- options for "a trade"
local check_trade = {
	"- please select -",
	"The NPC has the item(s) he wants to sell in his inventory.",
	"The player has the item(s) needed to pay the price.",
	"The NPC ran out of stock.",
	"The player cannot afford the price.",
}

-- options for "the inventory of " (either player or NPC; perhaps blocks later on)
local check_inv = {
	"- please select -",
	"The inventory contains the following item:",
	"The inventory *does not* contain the following item:",
	"There is room for the following item in the inventory:",
	"The inventory is empty.",
}

local check_block = {
	"- please select -",
	"The block is as it is now.",
	"There shall be air instead of this block.",
	"The block is diffrent from how it is now.",
	"I can't punch it. The block is as the block *above* the one I punched.",
}

-- comparison operators for variables
local check_operator = {
	"- please select -", -- 1
	"== (is equal)", -- 2
	"~= (is not equal)", -- 3
	">= (is greater or equal)", -- 4
	">  (is greater)", -- 5
	"<= (is smaller or equal)", -- 6
	"<  (is smaller)", -- 7
	"not (logically invert)", -- 8
	"is_set (has a value)", -- 9
	"is_unset (has no value)" -- 10
}

-- some internal ones...
local check_variable = {
	"- please select -",
	"(internal) hour of ingame day",
	"(internal) player's health points",
}


-- TODO: check inscription of a sign?
-- TODO: invlist as dropdown of inventory lists at detected position
-- TODO: variable as dropdown of allowed variables

-- which diffrent types of preconditions are available?
-- possible variables:
-- 	item		an inventory item or block (check if it exists)
-- 		-> needs to be a minetest.registered_item[ item ]
-- 	text		some text
-- 	pos		a position in the world (not too far from the NPC)
-- 		-> determined by punching
-- 	variable	name of a variable
--
-- TODO: may all boil down to automaticly setting some lua code?
--       -> better write a function for each one that can be called when needed


yl_speak_up.input_fs_edit_preconditions = function(player, formname, fields)
	if(not(player)) then
		return
	end
	local pname = player:get_player_name()
	-- what are we talking about?
	local n_id = yl_speak_up.speak_to[pname].n_id
	local d_id = yl_speak_up.speak_to[pname].d_id
	local o_id = yl_speak_up.speak_to[pname].o_id
	local p_id = yl_speak_up.speak_to[pname].p_id

	-- this only works in edit mode
	if(not(n_id) or yl_speak_up.edit_mode[pname] ~= n_id) then
		return
	end

	-- TODO: make delete work
	-- TODO: make save work
	-- TODO: check parameters

	if(fields.select_block_pos) then
		minetest.chat_send_player(pname,
			"Please punch the block you want to check in your precondition!")
		-- this formspec expects the block punch:
		yl_speak_up.speak_to[pname].expect_block_punch = "edit_preconditions"
		return
	end

	-- select a general direction/type first
	if(fields.select_what) then
		local nr = table.indexof(check_what, fields.select_what)
		yl_speak_up.speak_to[pname].tmp_prereq = { what = nr }

	-- select a subtype for the "a trade" selection
	elseif(fields.select_trade) then
		local nr = table.indexof(check_trade, fields.select_trade)
		yl_speak_up.speak_to[pname].tmp_prereq.trade = nr

	-- select a subtype for the inventory selection (player or NPC)
	elseif(fields.select_inv) then
		local nr = table.indexof(check_inv, fields.select_inv)
		yl_speak_up.speak_to[pname].tmp_prereq.inv = nr

	-- select data regarding a block
	elseif(fields.select_block) then
		local nr = table.indexof(check_block, fields.select_block)
		yl_speak_up.speak_to[pname].tmp_prereq.block = nr

	-- select data regarding a variable
	elseif(fields.select_variable) then
		-- TODO: this needs to include player-specific variables
		local nr = table.indexof(check_variable, fields.select_variable)
		yl_speak_up.speak_to[pname].tmp_prereq.variable = nr

	-- select data regarding an operator
	elseif(fields.select_operator) then
		local nr = table.indexof(check_operator, fields.select_operator)
		yl_speak_up.speak_to[pname].tmp_prereq.operator = nr
	end

	-- the player wants to change/edit a precondition
	if(not(fields.back)
	  and (fields.change_prereq or fields.select_what or fields.select_trade
	  or fields.select_inv or fields.select_block
	  or fields.select_variable or fields.select_operator)) then
		yl_speak_up.show_fs(player, "edit_preconditions")
		return
	end

	-- go back to the edit option dialog
	yl_speak_up.show_fs(player, "edit_option_dialog",
		{n_id = n_id, d_id = d_id, o_id = o_id, caller="edit_precondition"})
end


yl_speak_up.get_fs_edit_preconditions = function(player, table_click_result)
	if(not(player)) then
		return ""
	end
	local pname = player:get_player_name()
	-- what are we talking about?
	local n_id = yl_speak_up.speak_to[pname].n_id
	local d_id = yl_speak_up.speak_to[pname].d_id
	local o_id = yl_speak_up.speak_to[pname].o_id
	local p_id = yl_speak_up.speak_to[pname].p_id

	-- this only works in edit mode
	if(not(n_id) or yl_speak_up.edit_mode[pname] ~= n_id) then
		return "size[1,1]label[0,0;You cannot edit this NPC.]"
	end

	local dialog = yl_speak_up.speak_to[pname].dialog
	if(not(dialog) or not(dialog.n_dialogs)
	  or not(dialog.n_dialogs[d_id])
	  or not(dialog.n_dialogs[d_id].d_options)
	  or not(dialog.n_dialogs[d_id].d_options[o_id])) then
		return "size[4,1]label[0,0;Dialog option does not exist.]"
	end

	local prereq = dialog.n_dialogs[d_id].d_options[o_id].o_prerequisites
	if(not(prereq)) then
		prereq = {}
	end

	-- did we arrive here through clicking on a prereq in the dialog edit options menu?
	if(table_click_result) then
		-- which precondition has the player selected?
		local sorted_key_list = yl_speak_up.sort_keys(prereq)
		local selected = minetest.explode_table_event(table_click_result)
		-- use "new" if nothing fits
		p_id = "new"
		if((selected.type == "CHG" or selected.type == "DLC")
		  and selected.row <= #sorted_key_list) then
			p_id = sorted_key_list[ selected.row ]
		end

		-- store which prereq we are talking about
		yl_speak_up.speak_to[pname].p_id = p_id
		-- display the selected prereq
		if(p_id ~= "new") then
			return "formspec_version[3]"..
				"size[20,3]"..
				"bgcolor[#00000000;false]"..
				"label[0.2,0.5;Selected pre(C)ondition:]"..
				"tablecolumns[text;color,span=1;text;text]"..
				"table[0.2,0.8;19.6,0.7;table_of_preconditions;"..
					minetest.formspec_escape(prereq[ p_id ].p_id)..",#FFFF00,"..
					minetest.formspec_escape(prereq[ p_id ].p_type)..","..
					minetest.formspec_escape(prereq[ p_id ].p_value)..";0]"..
				"button[2.0,1.8;1.5,0.9;delete_prereq;Delete]"..
				"button[4.0,1.8;1.5,0.9;change_prereq;Change]"..
				"button[6.0,1.8;1,0.9;back;Back]"
		end
	end

	-- did the player get here through punching a block in the meantime?
	local block_pos = yl_speak_up.speak_to[pname].block_punched
	yl_speak_up.speak_to[pname].block_punched = nil

	local data = yl_speak_up.speak_to[pname].tmp_prereq
	if(not(data) or not(data.what)) then
		data = { what = 1}
	end
	-- fallback
	if(not(p_id)) then
		p_id = "new"
	end
	local save_button = "button[5.0,9.0;1,0.7;save_prereq;Save]"
	local formspec =
		"formspec_version[3]"..
		"size[20,10]"..
		"label[5,0.5;Edit pre(C)ondition \""..minetest.formspec_escape(p_id).."\"]"..
		"label[0.2,1.5;What do you want to check in this precondition?]"..
		"label[0.2,2.0;Something regarding...]"..
		"dropdown[4.0,1.8;14.0,0.6;select_what;"..
			table.concat(check_what, ",")..";"..
			tostring(data.what)..";]"..
		"button[3.0,9.0;1,0.7;back;Abort]"

	-- "an internal state (i.e. of a quest)", -- 2
	if(data.what and data.what == 2) then
		if(not(data.variable) or data.variable == 1) then
			data.variable = 1
			-- not enough selected yet for saving
			save_button = ""
		elseif(not(data.operator) or data.operator == 1) then
			data.operator = 1
			save_button = ""
		end
		local field_for_value = "field[11.2,4.8;7.0,0.6;var_cmp_value;;]"
		-- do not show value input field for unary operators
		if(not(data.operator) or data.operator == 1 or data.operator >= 8) then
			field_for_value = "label[11.2,5.1;- not used for this operator -]"
		end
		-- TODO: the list of available variables needs to be extended
		--       with the ones the player has read access to
		formspec = formspec..
			"label[0.2,3.3;The following expression shall be true:]"..
			"label[0.2,4.3;Name of variable:]"..
			"dropdown[0.2,4.8;6.5,0.6;select_variable;"..
				table.concat(check_variable, ",")..";"..
				tostring(data.variable)..";]"..
			"label[7.0,4.3;Operator:]"..
			"dropdown[7.0,4.8;4.0,0.6;select_operator;"..
				table.concat(check_operator, ",")..";"..
				tostring(data.operator)..";]"..
			"label[11.2,4.3;Value to compare with:]"..
			field_for_value

	-- "a trade", -- 4
	elseif(data.what and data.what == 4) then
		if(not(data.trade) or data.trade == 1) then
			data.trade = 1
			-- not enough selected yet for saving
			save_button = ""
		end
		formspec = formspec..
			"label[0.2,3.3;If the action is a trade, the following shall be true:]"..
			"dropdown[4.0,3.5;16.0,0.6;select_trade;"..
				table.concat(check_trade, ",")..";"..
				tostring(data.trade)..";]"

	-- "the inventory of the player", -- 5
	-- "the inventory of the NPC", -- 6
	elseif(data.what and data.what >= 5 and data.what <= 6) then
		if(not(data.inv) or data.inv == 1) then
			data.inv = 1
			-- not enough selected yet for saving
			save_button = ""
		end
		formspec = formspec..
			"label[0.2,3.3;The following shall be true about the inventory:]"..
			"dropdown[4.0,3.5;16.0,0.6;select_inv;"..
				table.concat(check_inv, ",")..";"..
				tostring(data.inv)..";]"..
			"label[0.2,4.5;Name of the item(stack):]"..
			"field[4.0,4.3;16.0,0.6;inv_stack_name;;]"..
			"tooltip[inv_stack_name;Enter name of the block and amount.\n"..
				"Example: \"default:apple 3\" for three apples,\n"..
				"         \"farming:bread\" for a bread.]"

	-- "a block somewhere", -- 3
	elseif(data.what and data.what == 3) then
		local block_pos_str = "- none set -"
		local node = {name = "- unknown -", param2 = "- unkown -"}
		if(not(block_pos) and data and data.block_pos) then
			block_pos = data.block_pos
		end
		if(block_pos) then
			-- store for later usage
			data.block_pos = block_pos
			tmp_pos = {x=block_pos.x, y=block_pos.y, z=block_pos.z}
			-- "I can't punch it. The block is as the block *above* the one I punched.",
			if(data.block and data.block == 5) then
				tmp_pos.y = block_pos.y + 1
			end
			block_pos_str = minetest.pos_to_string(tmp_pos)
			node = minetest.get_node_or_nil(tmp_pos)
			if(not(node)) then
				node = {name = "- unknown -", param2 = "- unkown -"}
			end
			-- "There shall be air instead of this block.",
			if(data.block and data.block == 3) then
				node = {name = "air", param2 = 0}
			end
			-- cache that (in case a sapling grows or someone else changes it)
			data.node_data = node
		end
		if(node.name == "- unknown -") then
			save_button = ""
		end
		if(not(data.block) or data.block == 1) then
			data.block = 1
			-- not enough selected yet for saving
			save_button = ""
		end
		formspec = formspec..
			"label[0.2,3.3;The following shall be true about the block:]"..
			"dropdown[4.0,3.5;16.0,0.6;select_block;"..
				table.concat(check_block, ",")..";"..
				tostring(data.block)..";]"..
			"label[0.2,4.8;Position of the block:]"..
			"label[4.0,4.8;"..minetest.formspec_escape(block_pos_str).."]"..
			"label[0.2,5.8;Name of block:]"..
			"label[4.0,5.8;"..minetest.formspec_escape(node.name).."]"..
			"label[0.2,6.8;Orientation (param2):]"..
			"label[4.0,6.8;"..minetest.formspec_escape(node.param2).."]"..
			"button_exit[10.0,5.5;4.0,0.7;select_block_pos;Set position of block]"..
			"tooltip[select_block_pos;Click on this button to select a block.\n"..
				"This menu will close and you will be asked to punch\n"..
				"the block at the position you want to check.\n"..
				"After punching it, you will be returned to this menu.]"
	end

	return formspec..save_button
end