-- 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
}

-- how to store these as p_type in the precondition:
local values_what = {"", "state", "block", "trade", "player_inv", "npc_inv"}

-- options for "a trade"
local check_trade = {
	"- please select -",
	"The NPC has the item(s) he wants to sell in his inventory.", -- 2
	"The player has the item(s) needed to pay the price.", -- 3
	"The NPC ran out of stock.", -- 4
	"The player cannot afford the price.", -- 5
}

-- how to store these as p_value:
local values_trade = {"", "npc_can_sell", "player_can_buy", "npc_is_out_of_stock", "player_has_not_enough"}

-- 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.",
}

-- how to store these as p_value (the actual itemstack gets stored as p_itemstack):
local values_inv = {"", "inv_contains", "inv_does_not_contain", "has_room_for", "inv_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.",
}

-- how to store these as p_value (the actual node data gets stored as p_node, p_param2 and p_pos):
-- Note: "node_is_like" occours twice because it is used to cover blocks that
--       cannot be punched as well as normal blocks.
local values_block = {"", "node_is_like", "node_is_air", "node_is_diffrent_from", "node_is_like"}

-- 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
}

-- how to store these as p_value (the actual variable is stored in p_variable, and the value in p_cmp_value):
local values_operator = {"", "==", "~=", ">=", ">", "<=", "<", "not", "is_set", "is_unset"}

-- 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


-- returns a human-readable text as description of the precondition
-- (as shown in the edit options dialog and in the edit precondition formspec)
yl_speak_up.show_precondition = function(p)
	if(p.p_type == "state") then
		if(p.p_operator == "not") then
			return "not( "..tostring(p.p_variable).." )"
		elseif(p.p_operator == "is_set") then
			return tostring(p.p_variable).." ~= nil (is_set)"
		elseif(p.p_operator == "is_unset") then
			return tostring(p.p_variable).." == nil (is_unset)"
		end
		return tostring(p.p_variable).." "..tostring(p.p_operator).." "..
			tostring(p.p_var_cmp_value)
	elseif(p.p_type == "block") then
		if(not(p.p_pos) or type(p.p_pos) ~= "table"
		  or not(p.p_pos.x) or not(p.p_pos.y) or not(p.p_pos.z)) then
			return "ERROR: p.p_pos is "..minetest.serialize(p.p_pos)
		elseif(p.p_value == "node_is_like") then
			return "The block at "..minetest.pos_to_string(p.p_pos).." is \""..
				tostring(p.p_node).."\" with param2: "..tostring(p.p_param2).."."
		elseif(p.p_value == "node_is_air") then
			return "There is no block at "..minetest.pos_to_string(p.p_pos).."."
		elseif(p.p_value == "node_is_diffrent_from") then
			return "There is another block than \""..tostring(p.p_node).."\" at "..
				minetest.pos_to_string(p.p_pos)..", or it is at least "..
				"rotated diffrently (param2 is not "..tostring(p.p_param2)..")."
		end
	elseif(p.p_type == "trade") then
		local nr = table.indexof(values_trade, p.p_value)
		if(nr and check_trade[ nr ]) then
			return check_trade[ nr ]
		end
	elseif(p.p_type == "player_inv" or p.p_type == "npc_inv") then
		local who = "The player"
		if(p.p_type == "npc_inv") then
			who = "The NPC"
		end
		if(p.p_value == "inv_contains") then
			return who.." has \""..tostring(p.p_itemstack).."\" in his inventory."
		elseif(p.p_value == "inv_does_not_contain") then
			return who.." does not have \""..tostring(p.p_itemstack).."\" in his inventory."
		elseif(p.p_value == "has_room_for") then
			return who.." has room for \""..tostring(p.p_itemstack).."\" in his inventory."
		elseif(p.p_value == "inv_is_empty") then
			return who.." has an empty inventory."
		end
	end
	-- fallback
	return tostring(p.p_value)
end


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

	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

	-- field inputs: those do not trigger a sending of the formspec on their own

	-- are we talking about an inventory?
	local data = yl_speak_up.speak_to[pname].tmp_prereq
	if(fields.inv_stack_name and fields.inv_stack_name ~= ""
	  and data and data.what and data.what >= 5 and data.what <= 6) then
		local parts = fields.inv_stack_name:split(" ")
		local size = 1
		if(parts and #parts > 1) then
			size = tonumber(parts[2])
			if(not(size) or size < 1) then
				size = 1
			end
		end
		-- does the item exist?
		if(minetest.registered_items[ parts[1] ]) then
			data.inv_stack_name = parts[1].." "..tostring(size)
		else
			-- show error message
			yl_speak_up.show_fs(player, "msg", {
				input_to = "yl_speak_up:edit_preconditions",
				formspec = "size[8,2]"..
					"label[0.2,0.5;Error: \""..
					minetest.formspec_escape(fields.inv_stack_name)..
					"\" is not a valid item(stack).]"..
					"button[1.5,1.5;2,0.9;back_from_error_msg;Back]"})
			return
		end

	-- comparison value for a variable
	elseif(fields.var_cmp_value
	  and data and data.what and data.what >= 5 and data.what <= 6) then
		data.var_cmp_value = fields.var_cmp_value
	end

	-- the save button was pressed
	if(fields.save_prereq and data and data.what and values_what[ data.what ]) then
		-- for creating the new prerequirement; normal elements: p_type, p_value, p_id
		local pq = {}
		-- determine p_type
		pq.p_type = values_what[ data.what ]

		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
			-- this really should not happen during the normal course of operation
			-- (only if the player sends forged formspec data or a bug occoured)
			minetest.chat_send_player(pname, "Dialog or option does not exist.")
			return
		end
		local prereq = dialog.n_dialogs[d_id].d_options[o_id].o_prerequisites
		-- set p_id appropriately
		if(not(p_id) or p_id == "new") then
			p_id = "p_"..yl_speak_up.find_next_id(prereq)
			if(not(prereq)) then
				dialog.n_dialogs[d_id].d_options[o_id].o_prerequisites = {}
				prereq = dialog.n_dialogs[d_id].d_options[o_id].o_prerequisites
			end
		end
		pq.p_id = p_id

		-- "an internal state (i.e. of a quest)", -- 2
		if(data.what == 2) then
			pq.p_value = values_operator[ data.operator ]
			pq.p_var_cmp_value = (data.var_cmp_value or "")
			-- TODO: p_variable

		-- "a block somewhere", -- 3
		elseif(data.what == 3) then
			pq.p_value = values_block[ data.block ]
			if(not(data.block_pos) or not(data.node_data) or not(data.node_data.name)) then
				yl_speak_up.show_fs(player, "msg", {
					input_to = "yl_speak_up:edit_preconditions",
					formspec = "size[8,2]"..
						"label[0.2,0.5;Error: Please select a block first!]"..
						"button[1.5,1.5;2,0.9;back_from_error_msg;Back]"})
				return
			end
			-- for "node_is_air", there is no need to store node name and parameter
			if(pq.p_value
			  and (pq.p_value == "node_is_like"
			    or pq.p_value == "node_is_diffrent_from")) then
				pq.p_node   = data.node_data.name
				pq.p_param2 = data.node_data.param2
			end
			-- we also need to store the position of the node
			pq.p_pos = {x = data.block_pos.x, y = data.block_pos.y, z = data.block_pos.z }
			-- "I can't punch it. The block is as the block *above* the one I punched.",
			if(data.block == 5) then
				pq.p_pos.y = pq.p_pos.y + 1
			end

		-- "a trade", -- 4
		elseif(data.what == 4) then
			-- this depends on the trade associated with that option; therefore,
			-- it does not need any more parameters (they come dynamicly from the
			-- trade)
			pq.p_value = values_trade[ data.trade ]

		-- "the inventory of the player", -- 5
		-- "the inventory of the NPC", -- 6
		elseif(data.what == 5 or data.what == 6) then
			pq.p_value = values_inv[ data.inv ]
			if(pq.p_value and pq.p_value ~= "inv_is_empty") then
				-- we have checked this value earlier on
				pq[ "p_itemstack" ] = data.inv_stack_name
			end
		end

		-- only save if something was actually selected
		if(pq.p_value) then
			-- store the change in the dialog
			dialog.n_dialogs[d_id].d_options[o_id].o_prerequisites[ p_id ] = pq
			-- clear up data
			yl_speak_up.speak_to[pname].p_id = nil
			yl_speak_up.speak_to[pname].tmp_prereq = nil
			-- record this as a change, but do not save do disk yet
			table.insert(yl_speak_up.npc_was_changed[ n_id ],
				"Dialog "..tostring(d_id)..": ".."Pre(C)ondition "..tostring(p_id)..
				" added/changed for option "..tostring(o_id)..".")
			-- TODO: when trying to save: save to disk as well?
			-- show the new/changed precondition
			yl_speak_up.show_fs(player, "edit_preconditions", p_id)
			return
		end
	end


	-- selections in a dropdown menu (they trigger sending the formspec)

	-- 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
	  or fields.back_from_error_msg)) 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 or prereq[ table_click_result ]) then
		if(not(prereq[ 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

			if( p_id == "new" and #sorted_key_list >= yl_speak_up.max_prerequirements) then
				return "size[9,1.5]"..
					"label[0.2,0.0;There are only up to "..
						minetest.formspec_escape(yl_speak_up.max_prerequirements)..
						" pre(C)onditions allowed per dialog option.]"..
						"button[2.0,0.8;1.0,0.9;back;Back]"
			end
		else
			-- allow to directly specify a p_id to show
			p_id = table_click_result
		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(
						yl_speak_up.show_precondition(prereq[ p_id ]))..";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;;"..
			minetest.formspec_escape(data.var_cmp_value or "- enter 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;;"..(data.inv_stack_name or "").."]"..
			"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